Merge branch 'develop'

Python headers are not installed in Cygwin and Cygwin64, so the compiler
picks up Win32 headers in C:\Python27\Include and fails.

.travis.yml

@@ -0,0 +1,380 @@
+# Copyright 2016 Edward Diener
+# Copyright 2017 Cromwell D. Enage
+# Copyright 2021 Andrey Semashev
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at
+# http://boost.org/LICENSE_1_0.txt)
+
+language: cpp
+
+python: "2.7"
+
+branches:
+  only:
+    - master
+    - develop
+    - /feature\/.*/
+
+env:
+  matrix:
+    - BOGUS_JOB=true
+
+matrix:
+
+  exclude:
+    - env: BOGUS_JOB=true
+
+  include:
+# gcc, Linux
+    - os: linux
+      dist: trusty
+      compiler: gcc-4.4
+      env: TOOLSET=gcc COMPILER=g++-4.4 CXXSTD=98,0x
+      addons:
+        apt:
+          packages:
+            - g++-4.4
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: trusty
+      compiler: gcc-4.6
+      env: TOOLSET=gcc COMPILER=g++-4.6 CXXSTD=03,0x
+      addons:
+        apt:
+          packages:
+            - g++-4.6
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: trusty
+      compiler: gcc-4.7
+      env: TOOLSET=gcc COMPILER=g++-4.7 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - g++-4.7
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-4.8
+      env: TOOLSET=gcc COMPILER=g++-4.8 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - g++-4.8
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-4.9
+      env: TOOLSET=gcc COMPILER=g++-4.9 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - g++-4.9
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-5
+      env: TOOLSET=gcc COMPILER=g++-5 CXXSTD=03,11,14
+      addons:
+        apt:
+          packages:
+            - g++-5
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-6
+      env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - g++-6
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-6
+      env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=03,11,14,1z CXXSTD_DIALECT=cxxstd-dialect=gnu
+      addons:
+        apt:
+          packages:
+            - g++-6
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-7
+      env: TOOLSET=gcc COMPILER=g++-7 CXXSTD=03,11,14,17
+      addons:
+        apt:
+          packages:
+            - g++-7
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-7
+      env: TOOLSET=gcc COMPILER=g++-7 CXXSTD=03,11,14,17 CXXSTD_DIALECT=cxxstd-dialect=gnu
+      addons:
+        apt:
+          packages:
+            - g++-7
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: xenial
+      compiler: gcc-8
+      env: TOOLSET=gcc COMPILER=g++-8 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - g++-8
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: bionic
+      compiler: gcc-9
+      env: TOOLSET=gcc COMPILER=g++-9 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - g++-9
+          sources:
+            - sourceline: "ppa:ubuntu-toolchain-r/test"
+
+    - os: linux
+      dist: focal
+      compiler: gcc-10
+      env: TOOLSET=gcc COMPILER=g++-10 CXXSTD=03,11,14,17,20
+      addons:
+        apt:
+          packages:
+            - g++-10
+          sources:
+            - sourceline: "ppa:ubuntu-toolchain-r/test"
+
+# clang, Linux
+    - os: linux
+      dist: trusty
+      compiler: clang-3.5
+      env: TOOLSET=clang COMPILER=clang++-3.5 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - clang-3.5
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-3.5 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: trusty
+      compiler: clang-3.6
+      env: TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - clang-3.6
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-3.6 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: trusty
+      compiler: clang-3.7
+      env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - clang-3.7
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-3.7 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: xenial
+      compiler: clang-3.8
+      env: TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.8
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.8 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: xenial
+      compiler: clang-3.9
+      env: TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.9
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.9 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: xenial
+      compiler: clang-4
+      env: TOOLSET=clang COMPILER=clang++-4.0 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-4.0
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-4.0 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: xenial
+      compiler: clang-5
+      env: TOOLSET=clang COMPILER=clang++-5.0 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-5.0
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-5.0 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: xenial
+      compiler: clang-6
+      env: TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=03,11,14,1z,2a
+      addons:
+        apt:
+          packages:
+            - clang-6.0
+            - libc6-dbg
+            - libc++-dev
+            - libstdc++-8-dev
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-6.0 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: xenial
+      compiler: clang-7
+      env: TOOLSET=clang COMPILER=clang++-7 CXXSTD=14,1z,2a
+      addons:
+        apt:
+          packages:
+            - clang-7
+            - libc6-dbg
+            - libc++-dev
+            - libstdc++-8-dev
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-7 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: xenial
+      compiler: clang-8
+      env: TOOLSET=clang COMPILER=clang++-8 CXXSTD=14,1z,2a
+      addons:
+        apt:
+          packages:
+            - clang-8
+            - libc6-dbg
+            - libc++-dev
+            - libstdc++-8-dev
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: bionic
+      compiler: clang-9
+      env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=14,17,2a
+      addons:
+        apt:
+          packages:
+            - clang-9
+            - libstdc++-9-dev
+          sources:
+            - sourceline: "ppa:ubuntu-toolchain-r/test"
+            - sourceline: "deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: linux
+      dist: focal
+      compiler: clang-10
+      env: TOOLSET=clang COMPILER=clang++-10 CXXSTD=14,17,20
+      addons:
+        apt:
+          packages:
+            - clang-10
+            - libstdc++-9-dev
+          sources:
+            - sourceline: "ppa:ubuntu-toolchain-r/test"
+            - sourceline: "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-10 main"
+              key_url: "https://apt.llvm.org/llvm-snapshot.gpg.key"
+
+    - os: osx
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+      osx_image: xcode7.3
+
+    - os: osx
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+      osx_image: xcode8.3
+
+    - os: osx
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+      osx_image: xcode9.4.1
+
+install:
+  - GIT_FETCH_JOBS=8
+  - BOOST_BRANCH=develop
+  - if [ "$TRAVIS_BRANCH" = "master" ]; then BOOST_BRANCH=master; fi
+  - cd ..
+  - git clone -b $TRAVIS_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+  - cd boost-root
+  - git submodule init tools/build
+  - git submodule init tools/boostdep
+  - git submodule init tools/boost_install
+  - git submodule init libs/headers
+  - git submodule init libs/config
+  - git submodule init libs/parameter_python
+  - git submodule update --jobs $GIT_FETCH_JOBS
+  - cp -r $TRAVIS_BUILD_DIR/* libs/parameter
+  - python tools/boostdep/depinst/depinst.py --git_args "--jobs $GIT_FETCH_JOBS" parameter
+  - ./bootstrap.sh
+  - ./b2 headers
+
+script:
+  - |-
+    echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
+  - ./b2 --verbose-test libs/config/test//config_info toolset=$TOOLSET cxxstd=$CXXSTD || true
+  - BUILD_JOBS=`(nproc || sysctl -n hw.ncpu) 2> /dev/null`
+  - ./b2 -j $BUILD_JOBS libs/parameter/test toolset=$TOOLSET cxxstd=$CXXSTD $CXXSTD_DIALECT
+
+notifications:
+  email:
+    on_success: always

CMakeLists.txt

@@ -0,0 +1,36 @@
+# Copyright 2019 Mike Dev
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
+#
+# NOTE: CMake support for Boost.Parameter is currently experimental at best
+#       and the interface is likely to change in the future
+
+cmake_minimum_required( VERSION 3.5 )
+project( BoostParameter LANGUAGES CXX)
+
+option(BOOST_PARAMETER_INCLUDE_TESTS OFF "Include Boost.Parameter tests")
+
+add_library( boost_parameter INTERFACE )
+add_library( Boost::parameter ALIAS boost_parameter )
+
+target_include_directories( boost_parameter INTERFACE include )
+
+target_link_libraries( boost_parameter
+    INTERFACE
+        Boost::config
+        Boost::core
+        Boost::function
+        Boost::fusion
+        # TODO: we only need mp11 or mpl
+        Boost::mp11
+        Boost::mpl
+        Boost::optional
+        Boost::preprocessor
+        Boost::type_traits
+        Boost::utility
+)
+
+if(BOOST_PARAMETER_INCLUDE_TESTS)
+    enable_testing()
+    add_subdirectory(test)
+endif()

README.md

@@ -0,0 +1,26 @@
+# Boost.Parameter
+
+Boost.Parameter, part of collection of the [Boost C++ Libraries](https://github.com/boostorg), is a header-only library that implements named parameters for functions and templates in C++.
+
+### Directories
+
+* **doc** - Documentation sources
+* **include** - Interface headers of Boost.Parameter
+* **test** - Boost.Parameter unit tests
+
+### More information
+
+* [Documentation](https://www.boost.org/libs/parameter)
+* [Report bugs](https://github.com/boostorg/parameter/issues/new). Be sure to mention Boost version, platform and compiler you're using. A small compilable code sample to reproduce the problem is always good as well.
+* Submit your patches as [pull requests](https://github.com/boostorg/parameter/compare) against **develop** branch. Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).
+
+### Build status
+
+Branch          | Travis CI | AppVeyor | Test Matrix | Dependencies |
+:-------------: | --------- | -------- | ----------- | ------------ |
+[`master`](https://github.com/boostorg/parameter/tree/master) | [![Travis CI](https://travis-ci.org/boostorg/parameter.svg?branch=master)](https://travis-ci.org/boostorg/parameter) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/e9iptg55otiv040a/branch/master?svg=true)](https://ci.appveyor.com/project/Lastique/parameter/branch/master) | [![Tests](https://img.shields.io/badge/matrix-master-brightgreen.svg)](http://www.boost.org/development/tests/master/developer/parameter.html) | [![Dependencies](https://img.shields.io/badge/deps-master-brightgreen.svg)](https://pdimov.github.io/boostdep-report/master/parameter.html)
+[`develop`](https://github.com/boostorg/parameter/tree/develop) | [![Travis CI](https://travis-ci.org/boostorg/parameter.svg?branch=develop)](https://travis-ci.org/boostorg/parameter) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/e9iptg55otiv040a/branch/develop?svg=true)](https://ci.appveyor.com/project/Lastique/parameter/branch/develop) | [![Tests](https://img.shields.io/badge/matrix-develop-brightgreen.svg)](http://www.boost.org/development/tests/develop/developer/parameter.html) | [![Dependencies](https://img.shields.io/badge/deps-develop-brightgreen.svg)](https://pdimov.github.io/boostdep-report/develop/parameter.html)
+
+### License
+
+Distributed under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).

appveyor.yml

@@ -0,0 +1,73 @@
+# Copyright 2017 Edward Diener
+# Copyright 2017 Cromwell D. Enage
+# Copyright 2021 Andrey Semashev
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at
+# http://boost.org/LICENSE_1_0.txt)
+
+version: 1.0.{build}-{branch}
+
+shallow_clone: true
+
+branches:
+  only:
+    - master
+    - develop
+    - /feature\/.*/
+
+environment:
+  matrix:
+    - ARGS: toolset=msvc-9.0,msvc-10.0,msvc-11.0,msvc-12.0 address-model=32
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - ARGS: toolset=msvc-14.0 address-model=32,64 cxxstd=14,latest
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - ARGS: toolset=msvc-14.1 address-model=32,64 cxxstd=14,17,latest
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    - ARGS: toolset=msvc-14.2 address-model=32,64 cxxstd=14,17,latest
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+    - ARGS: toolset=gcc address-model=32 cxxstd=03,11,14,1z
+      PATH: C:\cygwin\bin;%PATH%
+      # Cygwin does not have python headers installed, the compiler picks up Win32 headers in C:\Python27\Include and fails
+      BOOST_PARAMETER_TEST_WITHOUT_PYTHON_TESTS: 1
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - ARGS: toolset=gcc address-model=64 cxxstd=03,11,14,1z
+      PATH: C:\cygwin64\bin;%PATH%
+      # Cygwin64 does not have python headers installed, the compiler picks up Win32 headers in C:\Python27\Include and fails
+      BOOST_PARAMETER_TEST_WITHOUT_PYTHON_TESTS: 1
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - ARGS: toolset=gcc address-model=32 cxxstd=03,11 linkflags=-Wl,-allow-multiple-definition
+      PATH: C:\MinGW\bin;%PATH%
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - ARGS: toolset=gcc address-model=32 cxxstd=03,11,14
+      PATH: C:\mingw-w64\i686-5.3.0-posix-dwarf-rt_v4-rev0\mingw32\bin;%PATH%
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - ARGS: toolset=gcc address-model=64 cxxstd=03,11,14,1z
+      PATH: C:\mingw-w64\x86_64-6.3.0-posix-seh-rt_v5-rev1\mingw64\bin;%PATH%
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - ARGS: toolset=gcc address-model=64 cxxstd=03,11,14,1z
+      PATH: C:\mingw-w64\x86_64-7.3.0-posix-seh-rt_v5-rev0\mingw64\bin;%PATH%
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+
+install:
+  - set GIT_FETCH_JOBS=8
+  - set BOOST_BRANCH=develop
+  - if "%APPVEYOR_REPO_BRANCH%" == "master" set BOOST_BRANCH=master
+  - cd ..
+  - git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+  - cd boost-root
+  - git submodule init tools/build
+  - git submodule init tools/boostdep
+  - git submodule init tools/boost_install
+  - git submodule init libs/headers
+  - git submodule init libs/config
+  - git submodule init libs/parameter_python
+  - git submodule update --jobs %GIT_FETCH_JOBS%
+  - xcopy /s /e /q %APPVEYOR_BUILD_FOLDER% libs\parameter
+  - python tools/boostdep/depinst/depinst.py --git_args "--jobs %GIT_FETCH_JOBS%" parameter
+  - cmd /c bootstrap
+  - b2 headers
+
+build: off
+
+test_script:
+  - b2 -j %NUMBER_OF_PROCESSORS% libs/parameter/test %ARGS%

doc/Jamfile.v2

@@ -1,9 +1,12 @@
+# Copyright David Abrahams 2006. Distributed under the Boost
+# Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
 import docutils ;
 
-import path ;
-sources = [ path.glob . : *.rst ] ;
+sources = [ glob *.rst ] ;
 bases = $(sources:S=) ;
-  
+
 # This is a path relative to the html/ subdirectory where the
 # generated output will eventually be moved.
 stylesheet = "--stylesheet=rst.css" ;
@@ -13,9 +16,15 @@ for local b in $(bases)
     html $(b) : $(b).rst : 
       
       # 
-      <docutils-html>"-gdt --traceback --trim-footnote-reference-space --footnote-references=superscript "$(stylesheet)
+      <docutils-html>"-gdt --link-stylesheet --traceback --trim-footnote-reference-space --footnote-references=superscript "$(stylesheet)
   ;
 }
 
 alias htmls : $(bases) ;
 stage html : $(bases) ;
+
+###############################################################################
+alias boostdoc ;
+explicit boostdoc ;
+alias boostrelease : html ;
+explicit boostrelease ;

doc/html/rst.css

@@ -1,3 +1,8 @@
+/* Copyright David Abrahams 2006. Distributed under the Boost
+   Software License, Version 1.0. (See accompanying
+   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 
+*/
+
 @import "../../../../rst.css";
 
 div.section div.section div.section dl {
@@ -14,8 +19,12 @@ img {
 }
 
 span.vellipsis {
-  line-height: 30% ;
-  font-size: 200% ;
+  display: block;
+  width: 5px;
+  height: 22px;
+  background: url("vellipsis.gif");
+  margin-left: 3em;
+  text-indent: -1000px;
 }
 
 

include/boost/parameter.hpp

@@ -1,16 +1,30 @@
-// Copyright David Abrahams, Daniel Wallin 2005. Use, modification and 
-// distribution is subject to the Boost Software License, Version 1.0. 
-// (See accompanying file LICENSE_1_0.txt or copy at 
+// Copyright David Abrahams, Daniel Wallin 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
+//  See www.boost.org/libs/parameter for documentation.
+
 #ifndef BOOST_PARAMETER_050401_HPP
 #define BOOST_PARAMETER_050401_HPP
 
 #include <boost/parameter/parameters.hpp>
+#include <boost/parameter/are_tagged_arguments.hpp>
+#include <boost/parameter/is_argument_pack.hpp>
+#include <boost/parameter/required.hpp>
+#include <boost/parameter/optional.hpp>
+#include <boost/parameter/deduced.hpp>
+#include <boost/parameter/template_keyword.hpp>
 #include <boost/parameter/keyword.hpp>
+#include <boost/parameter/nested_keyword.hpp>
 #include <boost/parameter/binding.hpp>
+#include <boost/parameter/value_type.hpp>
 #include <boost/parameter/macros.hpp>
 #include <boost/parameter/match.hpp>
+#include <boost/parameter/name.hpp>
+#include <boost/parameter/compose.hpp>
+#include <boost/parameter/preprocessor.hpp>
+#include <boost/parameter/preprocessor_no_spec.hpp>
 
-#endif // BOOST_PARAMETER_050401_HPP
+#endif  // include guard
 

include/boost/parameter/are_tagged_arguments.hpp

@@ -0,0 +1,125 @@
+// Copyright Cromwell D. Enage 2018.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_HPP
+#define BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+namespace boost { namespace parameter {
+
+    template <typename TaggedArg0, typename ...TaggedArgs>
+    struct are_tagged_arguments;
+}} // namespace boost::parameter
+
+#include <boost/parameter/aux_/is_tagged_argument.hpp>
+
+namespace boost { namespace parameter {
+
+    template <typename TaggedArg0>
+    struct are_tagged_arguments<TaggedArg0>
+      : ::boost::parameter::aux::is_tagged_argument<TaggedArg0>
+    {
+    };
+}} // namespace boost::parameter
+
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+
+namespace boost { namespace parameter {
+
+    template <typename TaggedArg0, typename ...TaggedArgs>
+    struct are_tagged_arguments
+      : ::boost::mpl::if_<
+            ::boost::parameter::aux::is_tagged_argument<TaggedArg0>
+          , ::boost::parameter::are_tagged_arguments<TaggedArgs...>
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+}} // namespace boost::parameter
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#define BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_END_Z(z, n, false_t) , false_t>
+/**/
+
+#include <boost/parameter/aux_/is_tagged_argument.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_BEGIN_Z(z, n, prefix)           \
+    ::boost::mpl::eval_if<                                                   \
+        ::boost::parameter::aux::is_tagged_argument<BOOST_PP_CAT(prefix, n)>,
+/**/
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/preprocessor/arithmetic/sub.hpp>
+#include <boost/preprocessor/facilities/intercept.hpp>
+#include <boost/preprocessor/repetition/repeat.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
+
+#define BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_OVERLOADS_Z(z, n, prefix)       \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename prefix)>                 \
+    struct are_tagged_arguments<                                             \
+        BOOST_PP_ENUM_PARAMS_Z(z, n, prefix)                                 \
+        BOOST_PP_ENUM_TRAILING_PARAMS_Z(                                     \
+            z                                                                \
+          , BOOST_PP_SUB(BOOST_PARAMETER_COMPOSE_MAX_ARITY, n)               \
+          , ::boost::parameter::void_ BOOST_PP_INTERCEPT                     \
+        )                                                                    \
+    > : BOOST_PP_CAT(BOOST_PP_REPEAT_, z)(                                   \
+            n                                                                \
+          , BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_BEGIN_Z                     \
+          , prefix                                                           \
+        )                                                                    \
+        ::boost::mpl::true_                                                  \
+        BOOST_PP_CAT(BOOST_PP_REPEAT_, z)(                                   \
+            n                                                                \
+          , BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_END_Z                       \
+          , ::boost::mpl::false_                                             \
+        )::type                                                              \
+    {                                                                        \
+    };
+/**/
+
+#include <boost/preprocessor/arithmetic/inc.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+
+namespace boost { namespace parameter {
+
+    template <
+        BOOST_PP_ENUM_BINARY_PARAMS(
+            BOOST_PP_INC(BOOST_PARAMETER_COMPOSE_MAX_ARITY)
+          , typename TaggedArg
+          , = ::boost::parameter::void_ BOOST_PP_INTERCEPT
+        )
+    >
+    struct are_tagged_arguments;
+}} // namespace boost::parameter
+
+#include <boost/preprocessor/repetition/repeat_from_to.hpp>
+
+namespace boost { namespace parameter {
+
+    BOOST_PP_REPEAT_FROM_TO(
+        1
+      , BOOST_PP_INC(BOOST_PARAMETER_COMPOSE_MAX_ARITY)
+      , BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_OVERLOADS_Z
+      , TaggedArg
+    )
+}} // namespace boost::parameter
+
+#undef BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_OVERLOADS_Z
+#undef BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_BEGIN_Z
+#undef BOOST_PARAMETER_ARE_TAGGED_ARGUMENTS_END_Z
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
+

include/boost/parameter/aux_/always_true_predicate.hpp

@@ -0,0 +1,42 @@
+// Copyright Cromwell D. Enage 2019.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_ALWAYS_TRUE_PREDICATE_HPP
+#define BOOST_PARAMETER_AUX_ALWAYS_TRUE_PREDICATE_HPP
+
+#include <boost/parameter/config.hpp>
+#include <boost/mpl/bool.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#endif
+#else
+#include <boost/mpl/always.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+    struct always_true_predicate
+    {
+        template <typename ...>
+        struct apply
+        {
+            typedef ::boost::mpl::true_ type;
+        };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        template <typename ...>
+        using fn = ::boost::mp11::mp_true;
+#endif
+    };
+#else
+    typedef ::boost::mpl::always< ::boost::mpl::true_> always_true_predicate;
+#endif  // BOOST_NO_CXX11_VARIADIC_TEMPLATES
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/as_lvalue.hpp

@@ -0,0 +1,25 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_AS_LVALUE_HPP
+#define BOOST_PARAMETER_AUX_AS_LVALUE_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    T const& as_lvalue(T const& value)
+    {
+        return value;
+    }
+
+    template <typename T>
+    T& as_lvalue(T& value)
+    {
+        return value;
+    }
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/augment_predicate.hpp

@@ -0,0 +1,198 @@
+// Copyright Cromwell D. Enage 2018.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUGMENT_PREDICATE_HPP
+#define BOOST_PARAMETER_AUGMENT_PREDICATE_HPP
+
+#include <boost/parameter/keyword_fwd.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/type_traits/is_lvalue_reference.hpp>
+#include <boost/type_traits/is_scalar.hpp>
+#include <boost/type_traits/is_same.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename V, typename R, typename Tag>
+    struct augment_predicate_check_consume_ref
+      : ::boost::mpl::eval_if<
+            ::boost::is_scalar<V>
+          , ::boost::mpl::true_
+          , ::boost::mpl::eval_if<
+                ::boost::is_same<
+                    typename Tag::qualifier
+                  , ::boost::parameter::consume_reference
+                >
+              , ::boost::mpl::if_<
+                    ::boost::is_lvalue_reference<R>
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+              , boost::mpl::true_
+            >
+        >::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/type_traits/is_const.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename V, typename R, typename Tag>
+    struct augment_predicate_check_out_ref
+      : ::boost::mpl::eval_if<
+            ::boost::is_same<
+                typename Tag::qualifier
+              , ::boost::parameter::out_reference
+            >
+          , ::boost::mpl::eval_if<
+                ::boost::is_lvalue_reference<R>
+              , ::boost::mpl::if_<
+                    ::boost::is_const<V>
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+              , ::boost::mpl::false_
+            >
+          , ::boost::mpl::true_
+        >::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/lambda_tag.hpp>
+#include <boost/mpl/apply_wrap.hpp>
+#include <boost/mpl/lambda.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <
+        typename Predicate
+      , typename R
+      , typename Tag
+      , typename T
+      , typename Args
+    >
+    class augment_predicate
+    {
+        typedef typename ::boost::mpl::lambda<
+            Predicate
+          , ::boost::parameter::aux::lambda_tag
+        >::type _actual_predicate;
+
+     public:
+        typedef typename ::boost::mpl::eval_if<
+            typename ::boost::mpl::if_<
+                ::boost::parameter::aux
+                ::augment_predicate_check_consume_ref<T,R,Tag>
+              , ::boost::parameter::aux
+                ::augment_predicate_check_out_ref<T,R,Tag>
+              , ::boost::mpl::false_
+            >::type
+          , ::boost::mpl::apply_wrap2<_actual_predicate,T,Args>
+          , ::boost::mpl::false_
+        >::type type;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename V, typename R, typename Tag>
+    using augment_predicate_check_consume_ref_mp11 = ::boost::mp11::mp_if<
+        ::std::is_scalar<V>
+      , ::boost::mp11::mp_true
+      , ::boost::mp11::mp_if<
+            ::std::is_same<
+                typename Tag::qualifier
+              , ::boost::parameter::consume_reference
+            >
+          , ::boost::mp11::mp_if<
+                ::std::is_lvalue_reference<R>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_true
+            >
+          , boost::mp11::mp_true
+        >
+    >;
+
+    template <typename V, typename R, typename Tag>
+    using augment_predicate_check_out_ref_mp11 = ::boost::mp11::mp_if<
+        ::std::is_same<
+            typename Tag::qualifier
+          , ::boost::parameter::out_reference
+        >
+      , ::boost::mp11::mp_if<
+            ::std::is_lvalue_reference<R>
+          , ::boost::mp11::mp_if<
+                ::std::is_const<V>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_true
+            >
+          , ::boost::mp11::mp_false
+        >
+      , ::boost::mp11::mp_true
+    >;
+}}} // namespace boost::parameter::aux
+
+#include <boost/mp11/list.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <
+        typename Predicate
+      , typename R
+      , typename Tag
+      , typename T
+      , typename Args
+    >
+    struct augment_predicate_mp11_impl
+    {
+        using type = ::boost::mp11::mp_if<
+            ::boost::mp11::mp_if<
+                ::boost::parameter::aux
+                ::augment_predicate_check_consume_ref_mp11<T,R,Tag>
+              , ::boost::parameter::aux
+                ::augment_predicate_check_out_ref_mp11<T,R,Tag>
+              , ::boost::mp11::mp_false
+            >
+          , ::boost::mp11
+            ::mp_apply_q<Predicate,::boost::mp11::mp_list<T,Args> >
+          , ::boost::mp11::mp_false
+        >;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/has_nested_template_fn.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <
+        typename Predicate
+      , typename R
+      , typename Tag
+      , typename T
+      , typename Args
+    >
+    using augment_predicate_mp11 = ::boost::mp11::mp_if<
+        ::boost::parameter::aux::has_nested_template_fn<Predicate>
+      , ::boost::parameter::aux
+        ::augment_predicate_mp11_impl<Predicate,R,Tag,T,Args>
+      , ::boost::parameter::aux
+        ::augment_predicate<Predicate,R,Tag,T,Args>
+    >;
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
+

include/boost/parameter/aux_/cast.hpp

@@ -0,0 +1,12 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_CAST_060902_HPP
+#define BOOST_PARAMETER_CAST_060902_HPP
+
+#include <boost/parameter/aux_/preprocessor/impl/function_cast.hpp>
+
+#endif  // include guard
+

include/boost/parameter/aux_/default.hpp

@@ -1,67 +1,111 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef DEFAULT_050329_HPP
-#define DEFAULT_050329_HPP
+#ifndef BOOST_PARAMETER_AUX_DEFAULT_HPP
+#define BOOST_PARAMETER_AUX_DEFAULT_HPP
 
 namespace boost { namespace parameter { namespace aux {
 
-// A wrapper for the default value passed by the user when resolving
-// the value of the parameter with the given Keyword
-template <class Keyword, class Value>
-struct default_
-{
-    default_(Value& x)
-      : value(x)
-    {}
-
-    Value& value;
-};
-
-//
-// lazy_default -- 
-//
-//    A wrapper for the default value computation function passed by
-//    the user when resolving the value of the parameter with the
-//    given keyword
-//
-#if BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
-// These compilers need a little extra help with overload
-// resolution; we have empty_arg_list's operator[] accept a base
-// class to make that overload less preferable.
-template <class KW, class DefaultComputer>
-struct lazy_default_base
-{
-    lazy_default_base(DefaultComputer const& x)
-      : compute_default(x)
-    {}
-    DefaultComputer const& compute_default;
-};
-
-template <class KW, class DefaultComputer>
-struct lazy_default
-  : lazy_default_base<KW,DefaultComputer>
-  {
-      lazy_default(DefaultComputer const & x)
-        : lazy_default_base<KW,DefaultComputer>(x)
-      {}
-  };
-# define BOOST_PARAMETER_lazy_default_fallback lazy_default_base
-#else 
-template <class KW, class DefaultComputer>
-struct lazy_default
-{
-    lazy_default(const DefaultComputer& x)
-      : compute_default(x)
-    {}
-    DefaultComputer const& compute_default;
-};
-# define BOOST_PARAMETER_lazy_default_fallback lazy_default
-#endif 
+    // A wrapper for the default value passed by the user when resolving
+    // the value of the parameter with the given Keyword
+    template <typename Keyword, typename Value>
+    struct default_
+    {
+        inline BOOST_CONSTEXPR default_(Value& x) : value(x)
+        {
+        }
 
+        Value& value;
+    };
 }}} // namespace boost::parameter::aux
 
-#endif // DEFAULT_050329_HPP
+#include <boost/parameter/config.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // lazy_default -- A wrapper for the default value computation function
+    // passed by the user when resolving the value of the parameter with the
+    // given keyword.
+#if BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
+    // These compilers need a little extra help with overload resolution;
+    // we have empty_arg_list's operator[] accept a base class
+    // to make that overload less preferable.
+    template <typename KW, typename DefaultComputer>
+    struct lazy_default_base
+    {
+        inline BOOST_CONSTEXPR lazy_default_base(DefaultComputer& x)
+          : compute_default(x)
+        {
+        }
+
+        DefaultComputer& compute_default;
+    };
+
+    template <typename KW, typename DefaultComputer>
+    struct lazy_default
+      : ::boost::parameter::aux::lazy_default_base<KW,DefaultComputer>
+    {
+        inline BOOST_CONSTEXPR lazy_default(DefaultComputer& x)
+          : ::boost::parameter::aux::lazy_default_base<KW,DefaultComputer>(x)
+        {
+        }
+    };
+#else   // !BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
+    template <typename KW, typename DefaultComputer>
+    struct lazy_default
+    {
+        inline BOOST_CONSTEXPR lazy_default(DefaultComputer& x)
+          : compute_default(x)
+        {
+        }
+
+        DefaultComputer& compute_default;
+    };
+#endif  // EDG workarounds needed.
+}}} // namespace boost::parameter::aux
+
+#if BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
+#define BOOST_PARAMETER_lazy_default_fallback \
+    ::boost::parameter::aux::lazy_default_base
+/**/
+#else
+#define BOOST_PARAMETER_lazy_default_fallback \
+    ::boost::parameter::aux::lazy_default
+/**/
+#endif
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#include <utility>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Keyword, typename Value>
+    struct default_r_
+    {
+        inline BOOST_CONSTEXPR default_r_(Value&& x)
+          : value(::std::forward<Value>(x))
+        {
+        }
+
+#if BOOST_WORKAROUND(BOOST_MSVC, < 1910)
+        // MSVC 2015 miscompiles moves for classes containing rvalue ref members
+        // using the default generated move constructor
+        // when moving into a function
+        // https://github.com/boostorg/parameter/pull/109
+        inline BOOST_CONSTEXPR default_r_(default_r_&& x)
+          : value(::std::forward<Value>(x.value))
+        {
+        }
+#endif
+
+        Value&& value;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
 

include/boost/parameter/aux_/has_nested_template_fn.hpp

@@ -0,0 +1,111 @@
+// Copyright Cromwell D. Enage 2019.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_HAS_NESTED_TEMPLATE_FN_HPP
+#define BOOST_PARAMETER_AUX_HAS_NESTED_TEMPLATE_FN_HPP
+
+#include <boost/parameter/aux_/yesno.hpp>
+#include <boost/parameter/aux_/preprocessor/nullptr.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/identity.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    template <template <typename ...> class F>
+    struct has_nested_template_fn_variadic
+    {
+    };
+#else
+    template <template <typename P0, typename P1> class F>
+    struct has_nested_template_fn_arity_2
+    {
+    };
+#endif
+
+    template <typename T>
+    class has_nested_template_fn_impl
+    {
+        template <typename U>
+        static ::boost::parameter::aux::no_tag _check(...);
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        template <typename U>
+        static ::boost::parameter::aux::yes_tag
+            _check(
+                ::boost::mp11::mp_identity<U> const volatile*
+              , ::boost::parameter::aux::has_nested_template_fn_variadic<
+                    U::template fn
+                >* = BOOST_PARAMETER_AUX_PP_NULLPTR
+            );
+#else
+        template <typename U>
+        static BOOST_CONSTEXPR ::boost::parameter::aux::yes_tag
+            _check(
+                ::boost::mpl::identity<U> const volatile*
+              , ::boost::parameter::aux::has_nested_template_fn_arity_2<
+                    U::template fn
+                >* = BOOST_PARAMETER_AUX_PP_NULLPTR
+            );
+#endif
+
+     public:
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_bool<
+#else
+        typedef ::boost::mpl::bool_<
+#endif
+            sizeof(
+                ::boost::parameter::aux::has_nested_template_fn_impl<T>
+                ::template _check<T>(
+                    static_cast<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+                        ::boost::mp11::mp_identity<T> const volatile*
+#else
+                        ::boost::mpl::identity<T> const volatile*
+#endif
+                    >(BOOST_PARAMETER_AUX_PP_NULLPTR)
+                )
+            ) == sizeof(::boost::parameter::aux::yes_tag)
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        >;
+#else
+        > type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+#else
+#include <boost/type_traits/remove_const.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using has_nested_template_fn = typename ::boost::parameter::aux
+    ::has_nested_template_fn_impl<typename ::std::remove_const<T>::type>
+    ::type;
+#else
+    struct has_nested_template_fn
+      : ::boost::parameter::aux::has_nested_template_fn_impl<
+            typename ::boost::remove_const<T>::type
+        >::type
+    {
+    };
+#endif
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/is_maybe.hpp

@@ -0,0 +1,52 @@
+// Copyright Daniel Wallin, David Abrahams 2010.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_IS_MAYBE_050329_HPP
+#define BOOST_PARAMETER_IS_MAYBE_050329_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct maybe_base
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    using is_maybe = ::std::is_base_of<
+        ::boost::parameter::aux::maybe_base
+      , typename ::std::remove_const<T>::type
+    >;
+}}} // namespace boost::parameter::aux
+
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/is_base_of.hpp>
+#include <boost/type_traits/remove_const.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct is_maybe
+      : ::boost::mpl::if_<
+            ::boost::is_base_of<
+                ::boost::parameter::aux::maybe_base
+              , typename ::boost::remove_const<T>::type
+            >
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
+

include/boost/parameter/aux_/is_placeholder.hpp

@@ -0,0 +1,64 @@
+// Copyright Cromwell D. Enage 2019.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_IS_PLACEHOLDER_HPP
+#define BOOST_PARAMETER_AUX_IS_PLACEHOLDER_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#else
+#include <boost/mpl/bool.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct is_mpl_placeholder
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_false
+#else
+      : ::boost::mpl::false_
+#endif
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/arg_fwd.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <int I>
+    struct is_mpl_placeholder< ::boost::mpl::arg<I> >
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_true
+#else
+      : ::boost::mpl::true_
+#endif
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/bind.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct is_mp11_placeholder : ::boost::mp11::mp_false
+    {
+    };
+
+    template < ::std::size_t I>
+    struct is_mp11_placeholder< ::boost::mp11::mp_arg<I> >
+      : ::boost::mp11::mp_true
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
+

include/boost/parameter/aux_/is_tagged_argument.hpp

@@ -0,0 +1,95 @@
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_IS_TAGGED_ARGUMENT_HPP
+#define BOOST_PARAMETER_IS_TAGGED_ARGUMENT_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct tagged_argument_base
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/config.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING) || \
+    (0 < BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY)
+#include <boost/type_traits/is_base_of.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // This metafunction identifies tagged_argument specializations
+    // and their derived classes.
+    template <typename T>
+    struct is_tagged_argument
+      : ::boost::mpl::if_<
+            // Cannot use is_convertible<> to check if T is derived from
+            // tagged_argument_base. -- Cromwell D. Enage
+            ::boost::is_base_of<
+                ::boost::parameter::aux::tagged_argument_base
+              , typename ::boost::remove_const<
+                    typename ::boost::remove_reference<T>::type
+                >::type
+            >
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#else   // no perfect forwarding support and no exponential overloads
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/is_lvalue_reference.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct is_tagged_argument_aux
+      : ::boost::is_convertible<
+            T*
+          , ::boost::parameter::aux::tagged_argument_base const*
+        >
+    {
+    };
+
+    // This metafunction identifies tagged_argument specializations
+    // and their derived classes.
+    template <typename T>
+    struct is_tagged_argument
+      : ::boost::mpl::if_<
+            ::boost::is_lvalue_reference<T>
+          , ::boost::mpl::false_
+          , ::boost::parameter::aux::is_tagged_argument_aux<T>
+        >::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // perfect forwarding support, or exponential overloads
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    using is_tagged_argument_mp11 = ::std::is_base_of<
+        ::boost::parameter::aux::tagged_argument_base
+      , typename ::std::remove_const<
+            typename ::std::remove_reference<T>::type
+        >::type
+    >;
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
+

include/boost/parameter/aux_/lambda_tag.hpp

@@ -0,0 +1,16 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_LAMBDA_TAG_HPP
+#define BOOST_PARAMETER_AUX_LAMBDA_TAG_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Tag type passed to MPL lambda.
+    struct lambda_tag;
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/maybe.hpp

@@ -0,0 +1,151 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+//
+// 2009.10.21 TDS remove depenency on boost::python::detail::referent_storage
+//
+#ifndef BOOST_PARAMETER_MAYBE_091021_HPP
+#define BOOST_PARAMETER_MAYBE_091021_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct referent_size;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/config.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct referent_size<T&>
+    {
+        BOOST_STATIC_CONSTANT(::std::size_t, value = sizeof(T));
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/type_traits/aligned_storage.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // A metafunction returning a POD type which can store U, where T == U&.
+    // If T is not a reference type, returns a POD which can store T.
+    template <typename T>
+    struct referent_storage
+      : ::boost::aligned_storage<
+            ::boost::parameter::aux::referent_size<T>::value
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/is_maybe.hpp>
+#include <boost/optional/optional.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/type_traits/add_lvalue_reference.hpp>
+#include <boost/type_traits/remove_cv.hpp>
+#if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+#include <boost/type_traits/add_const.hpp>
+#endif
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct maybe : ::boost::parameter::aux::maybe_base
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::std::add_lvalue_reference<
+            typename ::std::add_const<T>::type
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::boost::add_lvalue_reference<
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+            T const
+#else
+            typename ::boost::add_const<T>::type
+#endif
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+        >::type reference;
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::std::remove_cv<
+            typename ::std::remove_reference<reference>::type
+#else
+        typedef typename ::boost::remove_cv<
+            BOOST_DEDUCED_TYPENAME ::boost::remove_reference<reference>::type
+#endif
+        >::type non_cv_value;
+
+        inline explicit maybe(T value_) : value(value_), constructed(false)
+        {
+        }
+
+        inline maybe() : value(), constructed(false)
+        {
+        }
+
+        ~maybe()
+        {
+            if (this->constructed)
+            {
+                this->destroy();
+            }
+        }
+
+        inline reference construct(reference value_) const
+        {
+            return value_;
+        }
+
+        template <typename U>
+        reference construct2(U const& value_) const
+        {
+            new (this->m_storage.address()) non_cv_value(value_);
+            this->constructed = true;
+            return *reinterpret_cast<non_cv_value*>(
+                this->m_storage.address()
+            );
+        }
+
+        template <typename U>
+        inline reference construct(U const& value_) const
+        {
+            return this->construct2(value_);
+        }
+
+        void destroy()
+        {
+            reinterpret_cast<non_cv_value*>(
+                this->m_storage.address()
+            )->~non_cv_value();
+        }
+
+        typedef reference(
+            ::boost::parameter::aux::maybe<T>::*safe_bool
+        )() const;
+
+        inline operator safe_bool() const
+        {
+            return this->value ? &::boost::parameter::aux::maybe<T>::get : 0;
+        }
+
+        inline reference get() const
+        {
+            return this->value.get();
+        }
+
+     private:
+        ::boost::optional<T> value;
+        mutable bool constructed;
+        mutable typename ::boost::parameter::aux
+        ::referent_storage<reference>::type m_storage;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/name.hpp

@@ -0,0 +1,93 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_NAME_HPP
+#define BOOST_PARAMETER_AUX_NAME_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct name_tag_base
+    {
+    };
+
+    template <typename Tag>
+    struct name_tag
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/bool.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct is_name_tag : ::boost::mpl::false_
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/value_type.hpp>
+#include <boost/mpl/placeholders.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+#if !defined(BOOST_NO_SFINAE) && \
+    !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x592))
+#include <boost/parameter/aux_/lambda_tag.hpp>
+#include <boost/mpl/lambda.hpp>
+#include <boost/mpl/bind.hpp>
+#include <boost/mpl/quote.hpp>
+#include <boost/core/enable_if.hpp>
+
+namespace boost { namespace mpl {
+
+    template <typename T>
+    struct lambda<
+        T
+      , typename ::boost::enable_if<
+            ::boost::parameter::aux::is_name_tag<T>
+          , ::boost::parameter::aux::lambda_tag
+        >::type
+    >
+    {
+        typedef ::boost::mpl::true_ is_le;
+        typedef ::boost::mpl::bind3<
+            ::boost::mpl::quote3< ::boost::parameter::value_type>
+          , ::boost::mpl::arg<2>
+          , T
+          , void
+        > result_;
+        typedef result_ type;
+    };
+}} // namespace boost::mpl
+
+#endif  // SFINAE enabled, not Borland.
+
+#include <boost/parameter/aux_/void.hpp>
+
+#define BOOST_PARAMETER_TAG_PLACEHOLDER_TYPE(tag)                            \
+    ::boost::parameter::value_type<                                          \
+        ::boost::mpl::_2,tag,::boost::parameter::void_                       \
+    >
+/**/
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_TAG_MP11_PLACEHOLDER_VALUE(name, tag)                \
+    template <typename ArgumentPack>                                         \
+    using name = typename ::boost::parameter                                 \
+    ::value_type<ArgumentPack,tag,::boost::parameter::void_>::type
+/**/
+
+#include <boost/parameter/binding.hpp>
+
+#define BOOST_PARAMETER_TAG_MP11_PLACEHOLDER_BINDING(name, tag)              \
+    template <typename ArgumentPack>                                         \
+    using name = typename ::boost::parameter                                 \
+    ::binding<ArgumentPack,tag,::boost::parameter::void_>::type
+/**/
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
+

include/boost/parameter/aux_/overloads.hpp

@@ -1,77 +0,0 @@
-// Copyright David Abrahams, Daniel Wallin 2003. Use, modification and 
-// distribution is subject to the Boost Software License, Version 1.0. 
-// (See accompanying file LICENSE_1_0.txt or copy at 
-// http://www.boost.org/LICENSE_1_0.txt)
-
-// This file generates overloads in this format:
-//
-//     template<class A0, class A1>
-//     typename mpl::apply_wrap1<
-//         aux::make_arg_list<
-//             PS0,A0
-//           , aux::make_arg_list<
-//                 PS1,A1
-//               , mpl::identity<aux::empty_arg_list>
-//             >
-//         >
-//      , unnamed_list
-//     >::type
-//     operator()(A0 const& a0, A1 const& a1) const
-//     {
-//         typedef typename mpl::apply_wrap1<
-//             aux::make_arg_list<
-//                 PS0,A0
-//               , aux::make_arg_list<
-//                     PS1,A1
-//                   , mpl::identity<aux::empty_arg_list>
-//                 >
-//             >
-//         >::type arg_tuple;
-//
-//         return arg_tuple(
-//             a0
-//           , a1
-//           , aux::void_()
-//             ...
-//         );
-//     }
-//
-
-#if !defined(BOOST_PP_IS_ITERATING)
-# error Boost.Parameters - do not include this file!
-#endif
-
-#define N BOOST_PP_ITERATION()
-
-#define BOOST_PARAMETER_open_list(z, n, text) \
-    aux::make_arg_list< \
-        BOOST_PP_CAT(PS, n), BOOST_PP_CAT(A, n)
-
-#define BOOST_PARAMETER_close_list(z, n, text) > 
-
-#define BOOST_PARAMETER_arg_list(n) \
-    mpl::apply_wrap1< \
-    BOOST_PP_ENUM(N, BOOST_PARAMETER_open_list, _) \
-  , mpl::always<aux::empty_arg_list> \
-    BOOST_PP_REPEAT(N, BOOST_PARAMETER_close_list, _) \
-  , unnamed_list>
-
-template<BOOST_PP_ENUM_PARAMS(N, class A)>
-typename BOOST_PARAMETER_arg_list(N)::type
-operator()(BOOST_PP_ENUM_BINARY_PARAMS(N, A, const& a)) const
-{
-    typedef typename BOOST_PARAMETER_arg_list(N)::type arg_tuple;
-
-    return arg_tuple(
-        BOOST_PP_ENUM_PARAMS(N, a)
-        BOOST_PP_ENUM_TRAILING_PARAMS(
-            BOOST_PP_SUB(BOOST_PARAMETER_MAX_ARITY, N)
-          , aux::void_() BOOST_PP_INTERCEPT
-        ));
-}
-
-#undef BOOST_PARAMETER_arg_list
-#undef BOOST_PARAMETER_open_list
-#undef BOOST_PARAMETER_close_list
-#undef N
-

include/boost/parameter/aux_/pack/as_parameter_requirements.hpp

@@ -0,0 +1,32 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_AS_PARAMETER_REQUIREMENTS_HPP
+#define BOOST_PARAMETER_AUX_PACK_AS_PARAMETER_REQUIREMENTS_HPP
+
+#include <boost/parameter/aux_/pack/parameter_requirements.hpp>
+#include <boost/parameter/aux_/pack/tag_type.hpp>
+#include <boost/parameter/aux_/pack/predicate.hpp>
+#include <boost/parameter/deduced.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Converts a ParameterSpec into a specialization of
+    // parameter_requirements.  We need to do this in order to get the
+    // tag_type into the type in a way that can be conveniently matched
+    // by a satisfies(...) member function in arg_list.
+    template <typename ParameterSpec>
+    struct as_parameter_requirements
+    {
+        typedef ::boost::parameter::aux::parameter_requirements<
+            typename ::boost::parameter::aux::tag_type<ParameterSpec>::type
+          , typename ::boost::parameter::aux::predicate<ParameterSpec>::type
+          , ::boost::parameter::aux::has_default<ParameterSpec>
+        > type;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/deduce_tag.hpp

@@ -0,0 +1,217 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_DEDUCE_TAG_HPP
+#define BOOST_PARAMETER_AUX_PACK_DEDUCE_TAG_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <
+        typename Argument
+      , typename ArgumentPack
+      , typename DeducedArgs
+      , typename UsedArgs
+      , typename TagFn
+      , typename EmitsErrors
+    >
+    struct deduce_tag;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/lambda_tag.hpp>
+#include <boost/parameter/config.hpp>
+#include <boost/mpl/apply_wrap.hpp>
+#include <boost/mpl/lambda.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Predicate, typename Argument, typename ArgumentPack>
+    struct deduce_tag_condition_mpl
+      : ::boost::mpl::apply_wrap2<
+            typename ::boost::mpl::lambda<
+                Predicate
+              , ::boost::parameter::aux::lambda_tag
+            >::type
+          , Argument
+          , ArgumentPack
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/has_nested_template_fn.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/utility.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Predicate, typename Argument, typename ArgumentPack>
+    struct deduce_tag_condition_mp11
+    {
+        using type = ::boost::mp11::mp_apply_q<
+            Predicate
+          , ::boost::mp11::mp_list<Argument,ArgumentPack>
+        >;
+    };
+
+    template <typename Predicate, typename Argument, typename ArgumentPack>
+    using deduce_tag_condition = ::boost::mp11::mp_if<
+        ::boost::parameter::aux::has_nested_template_fn<Predicate>
+      , ::boost::parameter::aux
+        ::deduce_tag_condition_mp11<Predicate,Argument,ArgumentPack>
+      , ::boost::parameter::aux
+        ::deduce_tag_condition_mpl<Predicate,Argument,ArgumentPack>
+    >;
+}}} // namespace boost::parameter::aux
+
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/assert.hpp>
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+#include <boost/parameter/aux_/set.hpp>
+#include <boost/parameter/aux_/pack/tag_type.hpp>
+#include <boost/parameter/aux_/pack/tag_deduced.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Helper for deduce_tag<...>, below.
+    template <
+        typename Argument
+      , typename ArgumentPack
+      , typename DeducedArgs
+      , typename UsedArgs
+      , typename TagFn
+      , typename EmitsErrors
+    >
+    class deduce_tag0
+    {
+        typedef typename DeducedArgs::spec _spec;
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::boost::parameter::aux::deduce_tag_condition<
+            typename _spec::predicate
+#else
+        typedef typename ::boost::mpl::apply_wrap2<
+            typename ::boost::mpl::lambda<
+                typename _spec::predicate
+              , ::boost::parameter::aux::lambda_tag
+            >::type
+#endif
+          , Argument
+          , ArgumentPack
+        >::type _condition;
+
+#if !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        // Deduced parameter matches several arguments.
+        BOOST_MPL_ASSERT((
+            typename ::boost::mpl::eval_if<
+                typename ::boost::parameter::aux::has_key_<
+                    UsedArgs
+                  , typename ::boost::parameter::aux::tag_type<_spec>::type
+                >::type
+              , ::boost::mpl::eval_if<
+                    _condition
+                  , ::boost::mpl::if_<
+                        EmitsErrors
+                      , ::boost::mpl::false_
+                      , ::boost::mpl::true_
+                    >
+                  , ::boost::mpl::true_
+                >
+              , ::boost::mpl::true_
+            >::type
+        ));
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+     public:
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = typename ::boost::mp11::mp_if<
+#else
+        typedef typename ::boost::mpl::eval_if<
+#endif
+            _condition
+          , ::boost::parameter::aux
+            ::tag_deduced<UsedArgs,_spec,Argument,TagFn>
+          , ::boost::parameter::aux::deduce_tag<
+                Argument
+              , ArgumentPack
+              , typename DeducedArgs::tail
+              , UsedArgs
+              , TagFn
+              , EmitsErrors
+            >
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        >::type;
+#else
+        >::type type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/void.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+#else
+#include <boost/mpl/pair.hpp>
+#include <boost/type_traits/is_same.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Tries to deduced a keyword tag for a given Argument.
+    // Returns an mpl::pair<> consisting of the tagged_argument<>,
+    // and an mpl::set<> where the new tag has been inserted.
+    //
+    //  Argument:     The argument type to be tagged.
+    //
+    //  ArgumentPack: The ArgumentPack built so far.
+    //
+    //  DeducedArgs:  A specialization of deduced_item<> (see below).
+    //                A list containing only the deduced ParameterSpecs.
+    //
+    //  UsedArgs:     An mpl::set<> containing the keyword tags used so far.
+    //
+    //  TagFn:        A metafunction class used to tag positional or deduced
+    //                arguments with a keyword tag.
+    template <
+        typename Argument
+      , typename ArgumentPack
+      , typename DeducedArgs
+      , typename UsedArgs
+      , typename TagFn
+      , typename EmitsErrors
+    >
+    struct deduce_tag
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_if<
+            ::std::is_same<DeducedArgs,::boost::parameter::void_>
+          , ::boost::mp11::mp_identity<
+                ::boost::mp11::mp_list< ::boost::parameter::void_,UsedArgs>
+            >
+#else
+      : ::boost::mpl::eval_if<
+            ::boost::is_same<DeducedArgs,::boost::parameter::void_>
+          , ::boost::mpl::pair< ::boost::parameter::void_,UsedArgs>
+#endif
+          , ::boost::parameter::aux::deduce_tag0<
+                Argument
+              , ArgumentPack
+              , DeducedArgs
+              , UsedArgs
+              , TagFn
+              , EmitsErrors
+            >
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/deduced_item.hpp

@@ -0,0 +1,34 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_DEDUCED_ITEM_HPP
+#define BOOST_PARAMETER_AUX_PACK_DEDUCED_ITEM_HPP
+
+#include <boost/parameter/aux_/void.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // A typelist that stored deduced parameter specs.
+    template <
+        typename ParameterSpec
+      , typename Tail = ::boost::parameter::void_
+    >
+    struct deduced_item
+    {
+        typedef ParameterSpec spec;
+        typedef Tail tail;
+    };
+
+    // Evaluate Tail and construct deduced_item list.
+    template <typename Spec, typename Tail>
+    struct make_deduced_item
+    {
+        typedef ::boost::parameter::aux
+        ::deduced_item<Spec,typename Tail::type> type;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/insert_tagged.hpp

@@ -0,0 +1,23 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_INSERT_TAGGED_HPP
+#define BOOST_PARAMETER_AUX_PACK_INSERT_TAGGED_HPP
+
+#include <boost/parameter/aux_/set.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Inserts Tagged::key_type into the UserArgs set.
+    // Extra indirection to lazily evaluate Tagged::key_type.
+    template <typename UsedArgs, typename Tagged>
+    struct insert_tagged
+      : ::boost::parameter::aux::insert_<UsedArgs,typename Tagged::key_type>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/is_named_argument.hpp

@@ -0,0 +1,43 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_IS_NAMED_ARGUMENT_HPP
+#define BOOST_PARAMETER_AUX_PACK_IS_NAMED_ARGUMENT_HPP
+
+#include <boost/parameter/aux_/template_keyword.hpp>
+#include <boost/parameter/aux_/is_tagged_argument.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using is_named_argument = ::boost::mp11::mp_if<
+        ::boost::parameter::aux::is_template_keyword<T>
+      , ::boost::mp11::mp_true
+      , ::boost::parameter::aux::is_tagged_argument_mp11<T>
+    >;
+#else
+    struct is_named_argument
+      : ::boost::mpl::if_<
+            ::boost::parameter::aux::is_template_keyword<T>
+          , ::boost::mpl::true_
+          , ::boost::parameter::aux::is_tagged_argument<T>
+        >::type
+    {
+    };
+#endif
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/item.hpp

@@ -0,0 +1,47 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_ITEM_HPP
+#define BOOST_PARAMETER_AUX_PACK_ITEM_HPP
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+#include <boost/type_traits/is_const.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    // A parameter spec item typelist.
+    template <
+        typename Spec
+      , typename Arg
+      , typename Tail = ::boost::parameter::void_
+    >
+    struct item
+    {
+        typedef Spec spec;
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+        typedef ::boost::is_const<
+            typename ::boost::remove_reference<Arg>::type
+        > is_arg_const;
+#endif
+        typedef Arg arg;
+        typedef Tail tail;
+    };
+
+    template <typename Spec, typename Arg, typename Tail>
+    struct make_item
+    {
+        typedef boost::parameter::aux
+        ::item<Spec,Arg,typename Tail::type> type;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/make_arg_list.hpp

@@ -0,0 +1,438 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Copyright Cromwell D. Enage 2018.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_MAKE_ARG_LIST_HPP
+#define BOOST_PARAMETER_AUX_PACK_MAKE_ARG_LIST_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <
+        typename List
+      , typename DeducedArgs
+      , typename TagFn
+      , typename IsPositional
+      , typename UsedArgs
+      , typename ArgumentPack
+      , typename Error
+      , typename EmitsErrors
+    >
+    struct make_arg_list_aux;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/arg_list.hpp>
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/parameter/aux_/pack/unmatched_argument.hpp>
+#include <boost/parameter/aux_/pack/tag_type.hpp>
+#include <boost/parameter/aux_/pack/is_named_argument.hpp>
+#include <boost/parameter/aux_/pack/insert_tagged.hpp>
+#include <boost/parameter/aux_/pack/deduce_tag.hpp>
+#include <boost/parameter/deduced.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/pair.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/apply_wrap.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    template <typename ArgumentPack, typename TaggedArg, typename EmitsErrors>
+    struct append_to_make_arg_list
+    {
+        using type = ::boost::mp11::mp_push_front<
+            ArgumentPack
+          , ::boost::parameter::aux::flat_like_arg_tuple<
+                typename TaggedArg::key_type
+              , TaggedArg
+              , EmitsErrors
+            >
+        >;
+    };
+#endif
+
+    // Borland needs the insane extra-indirection workaround below so that
+    // it doesn't magically drop the const qualifier from the argument type.
+    template <
+        typename List
+      , typename DeducedArgs
+      , typename TagFn
+      , typename IsPositional
+      , typename UsedArgs
+      , typename ArgumentPack
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+      , typename _argument
+#endif
+      , typename Error
+      , typename EmitsErrors
+    >
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+    class make_arg_list00
+#else
+    class make_arg_list0
+#endif
+    {
+#if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+        typedef typename List::arg _argument;
+#endif
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using _arg_type = typename ::std::remove_const<
+            typename ::std::remove_reference<_argument>::type
+        >::type;
+        using _is_tagged = ::boost::parameter::aux
+        ::is_named_argument<_argument>;
+#else
+        typedef typename ::boost::remove_const<
+            typename ::boost::remove_reference<_argument>::type
+        >::type _arg_type;
+        typedef ::boost::parameter::aux
+        ::is_named_argument<_argument> _is_tagged;
+#endif
+        typedef typename List::spec _parameter_spec;
+        typedef typename ::boost::parameter::aux
+        ::tag_type<_parameter_spec>::type _tag;
+
+        // If this argument is either explicitly tagged or a deduced
+        // parameter, then turn off positional matching.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using _is_positional = ::boost::mp11::mp_if<
+            IsPositional
+          , ::boost::mp11::mp_if<
+                ::boost::parameter::aux::is_deduced<_parameter_spec>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_if<
+                    _is_tagged
+                  , ::boost::mp11::mp_false
+                  , ::boost::mp11::mp_true
+                >
+            >
+          , ::boost::mp11::mp_false
+        >;
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::boost::mpl::eval_if<
+            IsPositional
+          , ::boost::mpl::eval_if<
+                ::boost::parameter::aux::is_deduced<_parameter_spec>
+              , ::boost::mpl::false_
+              , ::boost::mpl::if_<
+                    _is_tagged
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+            >
+          , ::boost::mpl::false_
+        >::type _is_positional;
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+        // If this parameter is explicitly tagged, then add it to the
+        // used-parmeters set.  We only really need to add parameters
+        // that are deduced, but we would need a way to check if
+        // a given tag corresponds to a deduced parameter spec.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using _used_args = typename ::boost::mp11::mp_if<
+            _is_tagged
+          , ::boost::parameter::aux::insert_tagged<UsedArgs,_arg_type>
+          , ::boost::mp11::mp_identity<UsedArgs>
+        >::type;
+#else
+        typedef typename ::boost::mpl::eval_if<
+            _is_tagged
+          , ::boost::parameter::aux::insert_tagged<UsedArgs,_arg_type>
+          , ::boost::mpl::identity<UsedArgs>
+        >::type _used_args;
+#endif
+
+        // If this parameter is neither explicitly tagged nor positionally
+        // matched, then deduce the tag from the deduced parameter specs.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using _deduced_data = typename ::boost::mp11::mp_if<
+            ::boost::mp11::mp_if<
+                _is_tagged
+              , ::boost::mp11::mp_true
+              , _is_positional
+            >
+          , ::boost::mp11::mp_identity<
+                ::boost::mp11::mp_list< ::boost::parameter::void_,_used_args>
+            >
+#else
+        typedef typename ::boost::mpl::eval_if<
+            typename ::boost::mpl::if_<
+                _is_tagged
+              , ::boost::mpl::true_
+              , _is_positional
+            >::type
+          , ::boost::mpl::pair< ::boost::parameter::void_,_used_args>
+#endif
+          , ::boost::parameter::aux::deduce_tag<
+                _argument
+              , ArgumentPack
+              , DeducedArgs
+              , _used_args
+              , TagFn
+              , EmitsErrors
+            >
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        >::type;
+#else
+        >::type _deduced_data;
+#endif
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        // If this parameter is explicitly tagged ...
+        using _tagged = ::boost::mp11::mp_if<
+            _is_tagged
+            // ... just use it
+          , _arg_type
+            // ... else ...
+          , ::boost::mp11::mp_if<
+                // if positional matching is turned on ...
+                _is_positional
+                // ... tag it positionally
+              , ::boost::mp11::mp_apply_q<
+                    TagFn
+                  , ::boost::mp11::mp_list<_tag,_argument>
+                >
+                // ... else, use the deduced tag
+              , ::boost::mp11::mp_at_c<_deduced_data,0>
+            >
+        >;
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        // If this parameter is explicitly tagged ...
+        typedef typename ::boost::mpl::eval_if<
+            _is_tagged
+            // ... just use it
+          , ::boost::mpl::identity<_arg_type>
+            // ... else ...
+          , ::boost::mpl::eval_if<
+                // if positional matching is turned on ...
+                _is_positional
+                // ... tag it positionally
+              , ::boost::mpl::apply_wrap2<TagFn,_tag,_argument>
+                // ... else, use the deduced tag
+              , ::boost::mpl::first<_deduced_data>
+            >
+        >::type _tagged;
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+        // Build the arg_list incrementally, prepending new nodes.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using _error = ::boost::mp11::mp_if<
+            ::boost::mp11::mp_if<
+                ::std::is_same<Error,::boost::parameter::void_>
+              , ::std::is_same<_tagged,::boost::parameter::void_>
+              , ::boost::mp11::mp_false
+            >
+#else
+        typedef typename ::boost::mpl::if_<
+            typename ::boost::mpl::if_<
+                ::boost::is_same<Error,::boost::parameter::void_>
+              , ::boost::is_same<_tagged,::boost::parameter::void_>
+              , ::boost::mpl::false_
+            >::type
+#endif
+          , ::boost::parameter::aux::unmatched_argument<_argument>
+          , ::boost::parameter::void_
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        >;
+#else
+        >::type _error;
+#endif
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using _argument_pack = typename ::boost::mp11::mp_if<
+            ::std::is_same<_tagged,::boost::parameter::void_>
+          , ::boost::mp11::mp_identity<ArgumentPack>
+          , ::boost::parameter::aux
+            ::append_to_make_arg_list<ArgumentPack,_tagged,EmitsErrors>
+        >::type;
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::boost::mpl::if_<
+            ::boost::is_same<_tagged,::boost::parameter::void_>
+          , ArgumentPack
+#if defined(BOOST_NO_SFINAE) || BOOST_WORKAROUND(BOOST_MSVC, < 1800)
+          , ::boost::parameter::aux::arg_list<_tagged,ArgumentPack>
+#else
+          , ::boost::parameter::aux
+            ::arg_list<_tagged,ArgumentPack,EmitsErrors>
+#endif
+        >::type _argument_pack;
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+     public:
+        typedef typename ::boost::parameter::aux::make_arg_list_aux<
+            typename List::tail
+          , DeducedArgs
+          , TagFn
+          , _is_positional
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+          , ::boost::mp11::mp_at_c<_deduced_data,1>
+#else
+          , typename _deduced_data::second
+#endif
+          , _argument_pack
+          , _error
+          , EmitsErrors
+        >::type type;
+    };
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+    template <
+        typename List
+      , typename DeducedArgs
+      , typename TagFn
+      , typename IsPositional
+      , typename UsedArgs
+      , typename ArgumentPack
+      , typename Error
+      , typename EmitsErrors
+    >
+    struct make_arg_list0
+    {
+        typedef typename ::boost::mpl::eval_if<
+            typename List::is_arg_const
+          , ::boost::parameter::aux::make_arg_list00<
+                List
+              , DeducedArgs
+              , TagFn
+              , IsPositional
+              , UsedArgs
+              , ArgumentPack
+              , typename List::arg const
+              , Error
+              , EmitsErrors
+            >
+          , ::boost::parameter::aux::make_arg_list00<
+                List
+              , DeducedArgs
+              , TagFn
+              , IsPositional
+              , UsedArgs
+              , ArgumentPack
+              , typename List::arg
+              , Error
+              , EmitsErrors
+            >
+        >::type type;
+    };
+#endif  // Borland workarounds needed.
+
+    // Returns an ArgumentPack where the list of arguments has been tagged
+    // with keyword tags.
+    //
+    //   List:         A specialization of item<> (see below). Contains both
+    //                 the ordered ParameterSpecs, and the given arguments.
+    //
+    //   DeducedArgs:  A specialization of deduced_item<> (see below).
+    //                 A list containing only the deduced ParameterSpecs.
+    //
+    //   TagFn:        A metafunction class used to tag positional or deduced
+    //                 arguments with a keyword tag.
+    //
+    //   IsPositional: An mpl::bool_<> specialization indicating if positional
+    //                 matching is to be performed.
+    //
+    //   DeducedSet:   An mpl::set<> containing the keyword tags used so far.
+    //
+    //   ArgumentPack: The ArgumentPack built so far. This is initially an
+    //                 empty_arg_list and is built incrementally.
+    template <
+        typename List
+      , typename DeducedArgs
+      , typename TagFn
+      , typename IsPositional
+      , typename DeducedSet
+      , typename ArgumentPack
+      , typename Error
+      , typename EmitsErrors
+    >
+    struct make_arg_list_aux
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_if<
+            ::std::is_same<List,::boost::parameter::void_>
+          , ::boost::mp11::mp_identity<
+                ::boost::mp11::mp_list<ArgumentPack,Error>
+            >
+#else
+      : ::boost::mpl::eval_if<
+            ::boost::is_same<List,::boost::parameter::void_>
+          , ::boost::mpl::identity< ::boost::mpl::pair<ArgumentPack,Error> >
+#endif
+          , ::boost::parameter::aux::make_arg_list0<
+                List
+              , DeducedArgs
+              , TagFn
+              , IsPositional
+              , DeducedSet
+              , ArgumentPack
+              , Error
+              , EmitsErrors
+            >
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/set.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // VC6.5 was choking on the default parameters for make_arg_list_aux,
+    // so this just forwards to that adding in the defaults.
+    template <
+        typename List
+      , typename DeducedArgs
+      , typename TagFn
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      , typename EmitsErrors = ::boost::mp11::mp_true
+#else
+      , typename EmitsErrors = ::boost::mpl::true_
+#endif
+    >
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using make_arg_list = ::boost::parameter::aux::make_arg_list_aux<
+#else
+    struct make_arg_list
+      : ::boost::parameter::aux::make_arg_list_aux<
+#endif
+            List
+          , DeducedArgs
+          , TagFn
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+          , ::boost::mp11::mp_true
+#else
+          , ::boost::mpl::true_
+#endif
+          , ::boost::parameter::aux::set0
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+          , ::boost::parameter::aux::flat_like_arg_list<>
+#else
+          , ::boost::parameter::aux::empty_arg_list
+#endif
+          , ::boost::parameter::void_
+          , EmitsErrors
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    >;
+#else
+        >
+    {
+    };
+#endif
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/make_deduced_items.hpp

@@ -0,0 +1,53 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_MAKE_DEDUCED_ITEMS_HPP
+#define BOOST_PARAMETER_AUX_PACK_MAKE_DEDUCED_ITEMS_HPP
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/parameter/aux_/pack/deduced_item.hpp>
+#include <boost/parameter/deduced.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+#else
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/type_traits/is_same.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Spec, typename Tail>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using make_deduced_items = ::boost::mp11::mp_if<
+        ::std::is_same<Spec,::boost::parameter::void_>
+      , ::boost::mp11::mp_identity< ::boost::parameter::void_>
+      , ::boost::mp11::mp_if<
+            ::boost::parameter::aux::is_deduced<Spec>
+          , ::boost::parameter::aux::make_deduced_item<Spec,Tail>
+          , Tail
+        >
+    >;
+#else
+    struct make_deduced_items
+      : ::boost::mpl::eval_if<
+            ::boost::is_same<Spec,::boost::parameter::void_>
+          , ::boost::mpl::identity< ::boost::parameter::void_>
+          , ::boost::mpl::eval_if<
+                ::boost::parameter::aux::is_deduced<Spec>
+              , ::boost::parameter::aux::make_deduced_item<Spec,Tail>
+              , Tail
+            >
+        >
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/make_items.hpp

@@ -0,0 +1,45 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_MAKE_ITEMS_HPP
+#define BOOST_PARAMETER_AUX_PACK_MAKE_ITEMS_HPP
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/parameter/aux_/pack/item.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+#else
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/type_traits/is_same.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Creates a item typelist.
+    template <typename Spec, typename Arg, typename Tail>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using make_items = ::boost::mp11::mp_if<
+        ::std::is_same<Arg,::boost::parameter::void_>
+      , ::boost::mp11::mp_identity< ::boost::parameter::void_>
+      , ::boost::parameter::aux::make_item<Spec,Arg,Tail>
+    >;
+#else
+    struct make_items
+      : ::boost::mpl::eval_if<
+            ::boost::is_same<Arg,::boost::parameter::void_>
+          , ::boost::mpl::identity< ::boost::parameter::void_>
+          , ::boost::parameter::aux::make_item<Spec,Arg,Tail>
+        >
+    {
+    };
+#endif
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/make_parameter_spec_items.hpp

@@ -0,0 +1,244 @@
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_MAKE_PARAMETER_SPEC_ITEMS_HPP
+#define BOOST_PARAMETER_AUX_PACK_MAKE_PARAMETER_SPEC_ITEMS_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // This recursive metafunction forwards successive elements of
+    // parameters::parameter_spec to make_deduced_items<>.
+    // -- Cromwell D. Enage
+    template <typename SpecSeq>
+    struct make_deduced_list;
+
+    // Helper for match_parameters_base_cond<...>, below.
+    template <typename ArgumentPackAndError, typename SpecSeq>
+    struct match_parameters_base_cond_helper;
+
+    // Helper metafunction for make_parameter_spec_items<...>, below.
+    template <typename SpecSeq, typename ...Args>
+    struct make_parameter_spec_items_helper;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/void.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename SpecSeq>
+    struct make_parameter_spec_items_helper<SpecSeq>
+    {
+        typedef ::boost::parameter::void_ type;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/pack/make_deduced_items.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/list.hpp>
+#else
+#include <boost/mpl/front.hpp>
+#include <boost/mpl/pop_front.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename SpecSeq>
+    struct make_deduced_list_not_empty
+      : ::boost::parameter::aux::make_deduced_items<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_front<SpecSeq>
+#else
+            typename ::boost::mpl::front<SpecSeq>::type
+#endif
+          , ::boost::parameter::aux::make_deduced_list<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+                ::boost::mp11::mp_pop_front<SpecSeq>
+#else
+                typename ::boost::mpl::pop_front<SpecSeq>::type
+#endif
+            >
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/empty.hpp>
+#include <boost/mpl/identity.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename SpecSeq>
+    struct make_deduced_list
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_if<
+            ::boost::mp11::mp_empty<SpecSeq>
+          , ::boost::mp11::mp_identity< ::boost::parameter::void_>
+#else
+      : ::boost::mpl::eval_if<
+            ::boost::mpl::empty<SpecSeq>
+          , ::boost::mpl::identity< ::boost::parameter::void_>
+#endif
+          , ::boost::parameter::aux::make_deduced_list_not_empty<SpecSeq>
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/pair.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/is_same.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename ArgumentPackAndError>
+    struct is_arg_pack_error_void
+      : ::boost::mpl::if_<
+            ::boost::is_same<
+                typename ::boost::mpl::second<ArgumentPackAndError>::type
+              , ::boost::parameter::void_
+            >
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Checks if the arguments match the criteria of overload resolution.
+    // If NamedList satisfies the PS0, PS1, ..., this is a metafunction
+    // returning parameters.  Otherwise it has no nested ::type.
+    template <typename ArgumentPackAndError, typename SpecSeq>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using match_parameters_base_cond = ::boost::mp11::mp_if<
+        ::boost::mp11::mp_empty<SpecSeq>
+      , ::std::is_same<
+            ::boost::mp11::mp_at_c<ArgumentPackAndError,1>
+          , ::boost::parameter::void_
+        >
+      , ::boost::parameter::aux::match_parameters_base_cond_helper<
+            ArgumentPackAndError
+          , SpecSeq
+        >
+    >;
+#else
+    struct match_parameters_base_cond
+      : ::boost::mpl::eval_if<
+            ::boost::mpl::empty<SpecSeq>
+          , ::boost::parameter::aux
+            ::is_arg_pack_error_void<ArgumentPackAndError>
+          , ::boost::parameter::aux::match_parameters_base_cond_helper<
+                ArgumentPackAndError
+              , SpecSeq
+            >
+        >
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/pack/satisfies.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename ArgumentPackAndError, typename SpecSeq>
+    struct match_parameters_base_cond_helper
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_if<
+#else
+      : ::boost::mpl::eval_if<
+#endif
+            ::boost::parameter::aux::satisfies_requirements_of<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+                ::boost::mp11::mp_at_c<ArgumentPackAndError,0>
+              , ::boost::mp11::mp_front<SpecSeq>
+#else
+                typename ::boost::mpl::first<ArgumentPackAndError>::type
+              , typename ::boost::mpl::front<SpecSeq>::type
+#endif
+            >
+          , ::boost::parameter::aux::match_parameters_base_cond<
+                ArgumentPackAndError
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+              , ::boost::mp11::mp_pop_front<SpecSeq>
+#else
+              , typename ::boost::mpl::pop_front<SpecSeq>::type
+#endif
+            >
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+          , ::boost::mp11::mp_false
+#else
+          , ::boost::mpl::false_
+#endif
+        >
+    {
+    };
+
+    // This parameters item chaining metafunction class does not require
+    // the lengths of the SpecSeq and of Args parameter pack to match.
+    // Used by argument_pack to build the items in the resulting arg_list.
+    // -- Cromwell D. Enage
+    template <typename SpecSeq, typename ...Args>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using make_parameter_spec_items = ::boost::mp11::mp_if<
+        ::boost::mp11::mp_empty<SpecSeq>
+      , ::boost::mp11::mp_identity< ::boost::parameter::void_>
+      , ::boost::parameter::aux
+        ::make_parameter_spec_items_helper<SpecSeq,Args...>
+    >;
+#else
+    struct make_parameter_spec_items
+      : ::boost::mpl::eval_if<
+            ::boost::mpl::empty<SpecSeq>
+          , ::boost::mpl::identity< ::boost::parameter::void_>
+          , ::boost::parameter::aux
+            ::make_parameter_spec_items_helper<SpecSeq,Args...>
+        >
+    {
+    };
+#endif
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/pack/make_items.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename SpecSeq, typename A0, typename ...Args>
+    struct make_parameter_spec_items_helper<SpecSeq,A0,Args...>
+      : ::boost::parameter::aux::make_items<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_front<SpecSeq>
+#else
+            typename ::boost::mpl::front<SpecSeq>::type
+#endif
+          , A0
+          , ::boost::parameter::aux::make_parameter_spec_items<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+                ::boost::mp11::mp_pop_front<SpecSeq>
+#else
+                typename ::boost::mpl::pop_front<SpecSeq>::type
+#endif
+              , Args...
+            >
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/parameter_requirements.hpp

@@ -0,0 +1,25 @@
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_PARAMETER_REQUIREMENTS_HPP
+#define BOOST_PARAMETER_AUX_PACK_PARAMETER_REQUIREMENTS_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Used to pass static information about parameter requirements through
+    // the satisfies() overload set (below).  The matched function is never
+    // invoked, but its type indicates whether a parameter matches at
+    // compile-time.
+    template <typename Keyword, typename Predicate, typename HasDefault>
+    struct parameter_requirements
+    {
+        typedef Keyword keyword;
+        typedef Predicate predicate;
+        typedef HasDefault has_default;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/predicate.hpp

@@ -0,0 +1,87 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_PREDICATE_HPP
+#define BOOST_PARAMETER_AUX_PACK_PREDICATE_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // helper for get_predicate<...>, below
+    template <typename T>
+    struct get_predicate_or_default
+    {
+        typedef T type;
+    };
+
+    // helper for predicate<...>, below
+    template <typename T>
+    struct get_predicate
+      : ::boost::parameter::aux
+        ::get_predicate_or_default<typename T::predicate>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/use_default.hpp>
+#include <boost/parameter/aux_/always_true_predicate.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <>
+    struct get_predicate_or_default< ::boost::parameter::aux::use_default>
+    {
+        typedef ::boost::parameter::aux::always_true_predicate type;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/required.hpp>
+#include <boost/parameter/optional.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/identity.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using predicate = ::boost::mp11::mp_if<
+        ::boost::mp11::mp_if<
+            ::boost::parameter::aux::is_optional<T>
+          , ::boost::mp11::mp_true
+          , ::boost::parameter::aux::is_required<T>
+        >
+      , ::boost::parameter::aux::get_predicate<T>
+      , ::boost::mp11::mp_identity<
+            ::boost::parameter::aux::always_true_predicate
+        >
+    >;
+#else
+    struct predicate
+      : ::boost::mpl::eval_if<
+            typename ::boost::mpl::if_<
+                ::boost::parameter::aux::is_optional<T>
+              , ::boost::mpl::true_
+              , ::boost::parameter::aux::is_required<T>
+            >::type
+          , ::boost::parameter::aux::get_predicate<T>
+          , ::boost::mpl::identity<
+                ::boost::parameter::aux::always_true_predicate
+            >
+        >
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/satisfies.hpp

@@ -0,0 +1,142 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_SATISFIES_HPP
+#define BOOST_PARAMETER_AUX_PACK_SATISFIES_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if BOOST_WORKAROUND(BOOST_MSVC, == 1310)
+#include <boost/parameter/aux_/arg_list.hpp>
+#include <boost/parameter/aux_/augment_predicate.hpp>
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/apply_wrap.hpp>
+#include <boost/type_traits/is_same.hpp>
+#else   // !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#else
+#include <boost/mpl/bool.hpp>
+#endif
+#include <boost/parameter/aux_/yesno.hpp>
+#include <boost/parameter/aux_/preprocessor/nullptr.hpp>
+#endif  // MSVC-7.1 workarounds needed
+
+namespace boost { namespace parameter { namespace aux {
+
+#if BOOST_WORKAROUND(BOOST_MSVC, == 1310)
+    template <typename ArgList, typename ParameterRequirements, typename Bound>
+    struct satisfies_impl
+      : ::boost::parameter::aux::augment_predicate<
+            typename ParameterRequirements::predicate
+          , typename ArgList::reference
+          , typename ArgList::key_type
+          , Bound
+          , ArgList
+        >
+    {
+    };
+#endif
+
+    // Returns mpl::true_ iff the given ParameterRequirements are satisfied by
+    // ArgList.
+    template <typename ArgList, typename ParameterRequirements>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using satisfies = ::boost::mp11::mp_bool<
+        sizeof(
+            ::boost::parameter::aux::to_yesno(
+                ArgList::satisfies(
+                    static_cast<ParameterRequirements*>(
+                        BOOST_PARAMETER_AUX_PP_NULLPTR
+                    )
+                  , static_cast<ArgList*>(BOOST_PARAMETER_AUX_PP_NULLPTR)
+                )
+            )
+        ) == sizeof(::boost::parameter::aux::yes_tag)
+    >;
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+    class satisfies
+    {
+#if BOOST_WORKAROUND(BOOST_MSVC, == 1310)
+        // VC7.1 can't handle the sizeof() implementation below,
+        // so we use this instead.
+        typedef typename ::boost::mpl::apply_wrap3<
+            typename ArgList::binding
+          , typename ParameterRequirements::keyword
+          , ::boost::parameter::void_
+          , ::boost::mpl::false_
+        >::type _bound;
+
+     public:
+        typedef typename ::boost::mpl::eval_if<
+            ::boost::is_same<_bound,::boost::parameter::void_>
+          , typename ParameterRequirements::has_default
+          , ::boost::mpl::eval_if<
+                ::boost::is_same<
+                    ArgList
+                  , ::boost::parameter::aux::empty_arg_list
+                >
+              , ::boost::mpl::false_
+              , ::boost::parameter::aux::satisfies_impl<
+                    ArgList
+                  , ParameterRequirements
+                  , _bound
+                >
+            >
+        >::type type;
+#else   // !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
+        BOOST_STATIC_CONSTANT(
+            bool, _value = (
+                sizeof(
+                    ::boost::parameter::aux::to_yesno(
+                        ArgList::satisfies(
+                            static_cast<ParameterRequirements*>(
+                                BOOST_PARAMETER_AUX_PP_NULLPTR
+                            )
+                          , static_cast<ArgList*>(BOOST_PARAMETER_AUX_PP_NULLPTR)
+                        )
+                    )
+                ) == sizeof(::boost::parameter::aux::yes_tag)
+            )
+        );
+
+     public:
+        typedef ::boost::mpl::bool_<
+            ::boost::parameter::aux
+            ::satisfies<ArgList,ParameterRequirements>::_value
+        > type;
+#endif  // MSVC-7.1 workarounds needed
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/pack/as_parameter_requirements.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Returns mpl::true_ if the requirements of the given ParameterSpec
+    // are satisfied by ArgList.
+    template <typename ArgList, typename ParameterSpec>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using satisfies_requirements_of = ::boost::parameter::aux::satisfies<
+        ArgList
+      , typename ::boost::parameter::aux
+        ::as_parameter_requirements<ParameterSpec>::type
+    >;
+#else
+    struct satisfies_requirements_of
+      : ::boost::parameter::aux::satisfies<
+            ArgList
+          , typename ::boost::parameter::aux
+            ::as_parameter_requirements<ParameterSpec>::type
+        >::type
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/tag_deduced.hpp

@@ -0,0 +1,59 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_TAG_DEDUCED_HPP
+#define BOOST_PARAMETER_AUX_PACK_TAG_DEDUCED_HPP
+
+#include <boost/parameter/aux_/set.hpp>
+#include <boost/parameter/aux_/pack/tag_type.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/pair.hpp>
+#include <boost/mpl/apply_wrap.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Tags a deduced argument Arg with the keyword tag of Spec using TagFn.
+    // Returns the tagged argument and the mpl::set<> UsedArgs with the
+    // tag of Spec inserted.
+    template <typename UsedArgs, typename Spec, typename Arg, typename TagFn>
+    struct tag_deduced
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_list<
+            ::boost::mp11::mp_apply_q<
+                TagFn
+              , ::boost::mp11::mp_list<
+                    typename ::boost::parameter::aux::tag_type<Spec>::type
+                  , Arg
+                >
+            >
+#else
+        typedef ::boost::mpl::pair<
+            typename ::boost::mpl::apply_wrap2<
+                TagFn
+              , typename ::boost::parameter::aux::tag_type<Spec>::type
+              , Arg
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , typename ::boost::parameter::aux::insert_<
+                UsedArgs
+              , typename ::boost::parameter::aux::tag_type<Spec>::type
+            >::type
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        >;
+#else
+        > type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/tag_keyword_arg.hpp

@@ -0,0 +1,30 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_TAG_KEYWORD_ARG_HPP
+#define BOOST_PARAMETER_AUX_PACK_TAG_KEYWORD_ARG_HPP
+
+#include <boost/parameter/aux_/tag.hpp>
+#include <boost/parameter/config.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct tag_keyword_arg
+    {
+        template <typename K, typename T>
+        struct apply
+        {
+            typedef typename ::boost::parameter::aux::tag<K,T>::type type;
+        };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        template <typename K, typename T>
+        using fn = typename ::boost::parameter::aux::tag<K,T>::type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/tag_keyword_arg_ref.hpp

@@ -0,0 +1,67 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_TAG_KEYWORD_ARG_REF_HPP
+#define BOOST_PARAMETER_AUX_PACK_TAG_KEYWORD_ARG_REF_HPP
+
+#include <boost/parameter/aux_/unwrap_cv_reference.hpp>
+#include <boost/parameter/aux_/tagged_argument.hpp>
+#include <boost/parameter/config.hpp>
+
+namespace boost { namespace parameter { namespace aux { 
+
+    template <
+        typename Keyword
+      , typename ActualArg
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+      , typename = typename ::boost::parameter::aux
+        ::is_cv_reference_wrapper<ActualArg>::type
+#endif
+    >
+    struct tag_ref
+    {
+        typedef ::boost::parameter::aux::tagged_argument<
+            Keyword
+          , typename ::boost::parameter::aux
+            ::unwrap_cv_reference<ActualArg>::type
+        > type;
+    };
+}}} // namespace boost::parameter::aux_
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+
+#include <boost/mpl/bool.hpp>
+
+namespace boost { namespace parameter { namespace aux { 
+
+    template <typename Keyword, typename ActualArg>
+    struct tag_ref<Keyword,ActualArg,::boost::mpl::false_>
+    {
+        typedef ::boost::parameter::aux
+        ::tagged_argument<Keyword,ActualArg> type;
+    };
+}}} // namespace boost::parameter::aux_
+
+#endif  // Borland workarounds needed.
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct tag_keyword_arg_ref
+    {
+        template <typename K, typename T>
+        struct apply
+        {
+            typedef typename ::boost::parameter::aux::tag_ref<K,T>::type type;
+        };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        template <typename K, typename T>
+        using fn = typename ::boost::parameter::aux::tag_ref<K,T>::type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/tag_template_keyword_arg.hpp

@@ -0,0 +1,30 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_TAG_TEMPLATE_KEYWORD_ARG_HPP
+#define BOOST_PARAMETER_AUX_PACK_TAG_TEMPLATE_KEYWORD_ARG_HPP
+
+#include <boost/parameter/template_keyword.hpp>
+#include <boost/parameter/config.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct tag_template_keyword_arg
+    {
+        template <typename K, typename T>
+        struct apply
+        {
+            typedef ::boost::parameter::template_keyword<K,T> type;
+        };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        template <typename K, typename T>
+        using fn = ::boost::parameter::template_keyword<K,T>;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/pack/tag_type.hpp

@@ -0,0 +1,89 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_TAG_TYPE_HPP
+#define BOOST_PARAMETER_AUX_PACK_TAG_TYPE_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // helper for tag_type<...>, below.
+    template <typename T>
+    struct get_tag_type0
+    {
+        typedef typename T::key_type type;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/deduced.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/eval_if.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct get_tag_type
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_if<
+#else
+      : ::boost::mpl::eval_if<
+#endif
+            ::boost::parameter::aux::is_deduced0<T>
+          , ::boost::parameter::aux::get_tag_type0<typename T::key_type>
+          , ::boost::parameter::aux::get_tag_type0<T>
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/required.hpp>
+#include <boost/parameter/optional.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    using tag_type = ::boost::mp11::mp_if<
+        ::boost::mp11::mp_if<
+            ::boost::parameter::aux::is_optional<T>
+          , ::boost::mp11::mp_true
+          , ::boost::parameter::aux::is_required<T>
+        >
+      , ::boost::parameter::aux::get_tag_type<T>
+      , ::boost::mp11::mp_identity<T>
+    >;
+}}} // namespace boost::parameter::aux
+
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/identity.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct tag_type
+      : ::boost::mpl::eval_if<
+            typename ::boost::mpl::if_<
+                ::boost::parameter::aux::is_optional<T>
+              , ::boost::mpl::true_
+              , ::boost::parameter::aux::is_required<T>
+            >::type
+          , ::boost::parameter::aux::get_tag_type<T>
+          , ::boost::mpl::identity<T>
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
+

include/boost/parameter/aux_/pack/unmatched_argument.hpp

@@ -0,0 +1,41 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PACK_UNMATCHED_ARGUMENT_HPP
+#define BOOST_PARAMETER_AUX_PACK_UNMATCHED_ARGUMENT_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/assert.hpp>
+#include <boost/type_traits/is_same.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct unmatched_argument
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        static_assert(::std::is_same<T,void>::value, "T == void");
+#else
+        BOOST_MPL_ASSERT((
+            typename ::boost::mpl::if_<
+                ::boost::is_same<T,void>
+              , ::boost::mpl::true_
+              , ::boost::mpl::false_
+            >::type
+        ));
+#endif
+        typedef int type;
+    }; 
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/parameter_requirements.hpp

@@ -1,25 +1,12 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef PARAMETER_REQUIREMENTS_050331_HPP
-#define PARAMETER_REQUIREMENTS_050331_HPP
+#ifndef BOOST_PARAMETER_AUX_PARAMETER_REQUIREMENTS_HPP
+#define BOOST_PARAMETER_AUX_PARAMETER_REQUIREMENTS_HPP
 
-namespace boost { namespace parameter { namespace aux {
+#include <boost/parameter/aux_/pack/parameter_requirements.hpp>
 
-// Used to pass static information about parameter requirements
-// through the satisfies() overload set (below).  The
-// matched function is never invoked, but its type indicates whether
-// a parameter matches at compile-time
-template <class Keyword, class Predicate, class HasDefault>
-struct parameter_requirements
-{
-    typedef Keyword keyword;
-    typedef Predicate predicate;
-    typedef HasDefault has_default;
-};
+#endif  // include guard
 
-}}} // namespace boost::parameter::aux
-
-#endif // PARAMETER_REQUIREMENTS_050331_HPP

include/boost/parameter/aux_/parenthesized_type.hpp

@@ -0,0 +1,12 @@
+// Copyright David Abrahams 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PARENTHESIZED_TYPE_DWA2006414_HPP
+#define BOOST_PARAMETER_AUX_PARENTHESIZED_TYPE_DWA2006414_HPP
+
+#include <boost/parameter/aux_/preprocessor/impl/parenthesized_type.hpp>
+
+#endif  // include guard
+

include/boost/parameter/aux_/pp_impl/argument_pack.hpp

@@ -0,0 +1,91 @@
+// Copyright Daniel Wallin 2006.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PP_IMPL_ARGUMENT_PACK_HPP
+#define BOOST_PARAMETER_AUX_PP_IMPL_ARGUMENT_PACK_HPP
+
+#include <boost/parameter/aux_/pack/tag_keyword_arg.hpp>
+#include <boost/parameter/aux_/pack/make_arg_list.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#include <boost/parameter/aux_/pack/make_parameter_spec_items.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/list.hpp>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/pair.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Parameters, typename ...Args>
+    struct argument_pack
+    {
+        typedef typename ::boost::parameter::aux::make_arg_list<
+            typename ::boost::parameter::aux::make_parameter_spec_items<
+                typename Parameters::parameter_spec
+              , Args...
+            >::type
+          , typename Parameters::deduced_list
+          , ::boost::parameter::aux::tag_keyword_arg
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+          , ::boost::mp11::mp_false
+#else
+          , ::boost::mpl::false_
+#endif
+        >::type result;
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_at_c<result,0>;
+#else
+        typedef typename ::boost::mpl::first<result>::type type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/parameter/aux_/pack/make_items.hpp>
+#include <boost/parameter/aux_/preprocessor/no_perfect_forwarding_begin.hpp>
+#include <boost/preprocessor/facilities/intercept.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_binary_params.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/pair.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <
+        typename Parameters
+        BOOST_PP_ENUM_TRAILING_BINARY_PARAMS(
+            BOOST_PARAMETER_MAX_ARITY
+          , typename A
+          , = ::boost::parameter::void_ BOOST_PP_INTERCEPT
+        )
+    >
+    struct argument_pack
+    {
+        typedef typename ::boost::parameter::aux::make_arg_list<
+            typename BOOST_PARAMETER_build_arg_list(
+                BOOST_PARAMETER_MAX_ARITY
+              , ::boost::parameter::aux::make_items
+              , typename Parameters::parameter_spec
+              , A
+            )::type
+          , typename Parameters::deduced_list
+          , ::boost::parameter::aux::tag_keyword_arg
+          , ::boost::mpl::false_
+        >::type result;
+        typedef typename ::boost::mpl::first<result>::type type;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/preprocessor/no_perfect_forwarding_end.hpp>
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
+

include/boost/parameter/aux_/pp_impl/match.hpp

@@ -0,0 +1,55 @@
+// Copyright Daniel Wallin 2006.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PP_IMPL_MATCH_HPP
+#define BOOST_PARAMETER_AUX_PP_IMPL_MATCH_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Recast the ParameterSpec's nested match metafunction
+    // as a free metafunction.
+    //
+    // No more limits set by BOOST_PARAMETER_MAX_ARITY. -- Cromwell D. Enage
+    template <typename Parameters, typename ...Args>
+    struct match : Parameters::BOOST_NESTED_TEMPLATE match<Args...>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#else
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/preprocessor/facilities/intercept.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_binary_params.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Recast the ParameterSpec's nested match metafunction
+    // as a free metafunction.
+    template <
+        typename Parameters
+        BOOST_PP_ENUM_TRAILING_BINARY_PARAMS(
+            BOOST_PARAMETER_MAX_ARITY
+          , typename A
+          , = ::boost::parameter::void_ BOOST_PP_INTERCEPT
+        )
+    >
+    struct match
+      : Parameters::BOOST_NESTED_TEMPLATE match<
+            BOOST_PP_ENUM_PARAMS(BOOST_PARAMETER_MAX_ARITY, A)
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
+

include/boost/parameter/aux_/pp_impl/unwrap_predicate.hpp

@@ -0,0 +1,97 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PP_IMPL_UNWRAP_PREDICATE_HPP
+#define BOOST_PARAMETER_AUX_PP_IMPL_UNWRAP_PREDICATE_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Given Match, which is "void x" where x is an argument matching
+    // criterion, extract a corresponding MPL predicate.
+    template <typename Match>
+    struct unwrap_predicate;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/always_true_predicate.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Match anything
+    template <>
+    struct unwrap_predicate<void*>
+    {
+        typedef ::boost::parameter::aux::always_true_predicate type;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/config.hpp>
+
+#if BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x580))
+#include <boost/parameter/aux_/void.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    // A matching predicate is explicitly specified.
+#if BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x580))
+    template <typename Predicate>
+    struct unwrap_predicate< ::boost::parameter::aux::voidstar(Predicate)>
+    {
+        typedef Predicate type;
+    };
+#else
+    template <typename Predicate>
+    struct unwrap_predicate<void *(Predicate)>
+    {
+        typedef Predicate type;
+    };
+#endif   // SunProCC workarounds needed.
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+#else
+#include <boost/mpl/placeholders.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    // A type to which the argument is supposed to be convertible is
+    // specified.
+    template <typename Target>
+    struct unwrap_predicate<void (Target)>
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        struct type
+        {
+            template <typename Argument, typename ArgumentPack>
+            struct apply
+              : ::boost::mpl::if_<
+                    ::std::is_convertible<Argument,Target>
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::false_
+                >
+            {
+            };
+
+            template <typename Argument, typename ArgumentPack>
+            using fn = ::std::is_convertible<Argument,Target>;
+        };
+#else
+        typedef ::boost::mpl::if_<
+            ::boost::is_convertible< ::boost::mpl::_,Target>
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+        > type;
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/binary_seq_to_args.hpp

@@ -0,0 +1,65 @@
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_BINARY_SEQ_TO_ARGS_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_BINARY_SEQ_TO_ARGS_HPP
+
+#include <boost/preprocessor/seq/elem.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_0_1(n, prefix_seq)          \
+    BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(0, prefix_seq), n) const&
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_1_1(n, prefix_seq)          \
+    BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(0, prefix_seq), n)&
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_0_2(n, prefix_seq)          \
+    BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_0_1(n, prefix_seq)              \
+    BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(1, prefix_seq), n)
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_1_2(n, prefix_seq)          \
+    BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_1_1(n, prefix_seq)              \
+    BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(1, prefix_seq), n)
+/**/
+
+#include <boost/preprocessor/seq/size.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_0(prefix_seq)               \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_0_                          \
+      , BOOST_PP_SEQ_SIZE(prefix_seq)                                        \
+    )
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_1(prefix_seq)               \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_1_                          \
+      , BOOST_PP_SEQ_SIZE(prefix_seq)                                        \
+    )
+/**/
+
+#include <boost/parameter/aux_/preprocessor/convert_binary_seq.hpp>
+
+// This macro converts the specified Boost.Preprocessor sequence of 1s and 0s
+// into a formal function parameter list.
+//
+// Example:
+// BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARGS((1)(0)(1)(0), (P)(p))
+// expands to
+// P0 & p0, P1 const& p1, P2 & p2, P3 const& p3
+#define BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARGS(binary_seq, prefix_seq)    \
+    BOOST_PARAMETER_AUX_PP_CONVERT_BINARY_SEQ(                               \
+        binary_seq                                                           \
+      , BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_0(prefix_seq)               \
+      , BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARG_1(prefix_seq)               \
+      , prefix_seq                                                           \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/convert_binary_seq.hpp

@@ -0,0 +1,57 @@
+// Copyright Cromwell D. Enage 2013.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_CONVERT_BINARY_SEQ_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_CONVERT_BINARY_SEQ_HPP
+
+#include <boost/preprocessor/seq/size.hpp>
+#include <boost/preprocessor/seq/push_back.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_AUGMENT_BINARY_SEQ_INDEX_FOLD_OP(s, seq, idx) \
+    BOOST_PP_SEQ_PUSH_BACK(seq, (idx, BOOST_PP_SEQ_SIZE(seq)))
+/**/
+
+#include <boost/preprocessor/control/iif.hpp>
+#include <boost/preprocessor/seq/elem.hpp>
+#include <boost/preprocessor/tuple/elem.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_CONVERT_BINARY_SEQ_FOLD_OP(s, seq, elem) \
+    ( \
+        BOOST_PP_SEQ_PUSH_BACK( \
+            BOOST_PP_SEQ_ELEM(0, seq) \
+          , BOOST_PP_IIF( \
+                BOOST_PP_TUPLE_ELEM(2, 0, elem) \
+              , BOOST_PP_SEQ_ELEM(2, seq) \
+              , BOOST_PP_SEQ_ELEM(1, seq) \
+            )(BOOST_PP_TUPLE_ELEM(2, 1, elem), BOOST_PP_SEQ_ELEM(3, seq)) \
+        ) \
+    )(BOOST_PP_SEQ_ELEM(1, seq))(BOOST_PP_SEQ_ELEM(2, seq)) \
+    (BOOST_PP_SEQ_ELEM(3, seq))
+/**/
+
+#include <boost/parameter/aux_/preprocessor/seq_enum.hpp>
+#include <boost/preprocessor/facilities/empty.hpp>
+#include <boost/preprocessor/seq/seq.hpp>
+#include <boost/preprocessor/seq/fold_left.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_CONVERT_BINARY_SEQ(seq, macro0, macro1, data) \
+    BOOST_PARAMETER_SEQ_ENUM( \
+        BOOST_PP_SEQ_ELEM( \
+            0 \
+          , BOOST_PP_SEQ_FOLD_LEFT( \
+                BOOST_PARAMETER_AUX_PP_CONVERT_BINARY_SEQ_FOLD_OP \
+              , (BOOST_PP_SEQ_NIL)(macro0)(macro1)(data) \
+              , BOOST_PP_SEQ_FOLD_LEFT( \
+                    BOOST_PARAMETER_AUX_PP_AUGMENT_BINARY_SEQ_INDEX_FOLD_OP \
+                  , BOOST_PP_EMPTY() \
+                  , seq \
+                ) \
+            ) \
+        ) \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/flatten.hpp

@@ -0,0 +1,12 @@
+// Copyright Daniel Wallin 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_FLATTEN_051217_HPP
+#define BOOST_PARAMETER_FLATTEN_051217_HPP
+
+#include <boost/parameter/aux_/preprocessor/impl/flatten.hpp>
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/for_each.hpp

@@ -0,0 +1,12 @@
+// Copyright Daniel Wallin 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_FOR_EACH_051217_HPP
+#define BOOST_PARAMETER_FOR_EACH_051217_HPP
+
+#include <boost/parameter/aux_/preprocessor/impl/for_each.hpp>
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/argument_specs.hpp

@@ -0,0 +1,24 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_ARGUMENT_SPECS_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_ARGUMENT_SPECS_HPP
+
+#include <boost/preprocessor/tuple/elem.hpp>
+
+// Accessor macros for the argument specs tuple.
+#define BOOST_PARAMETER_FN_ARG_QUALIFIER(x) BOOST_PP_TUPLE_ELEM(4, 0, x)
+#define BOOST_PARAMETER_FN_ARG_KEYWORD(x) BOOST_PP_TUPLE_ELEM(4, 1, x)
+#define BOOST_PARAMETER_FN_ARG_PRED(x) BOOST_PP_TUPLE_ELEM(4, 2, x)
+#define BOOST_PARAMETER_FN_ARG_DEFAULT(x) BOOST_PP_TUPLE_ELEM(4, 3, x)
+
+#include <boost/parameter/aux_/preprocessor/qualifier.hpp>
+
+#define BOOST_PARAMETER_FN_ARG_NAME(x)                                       \
+    BOOST_PARAMETER_UNQUALIFIED(BOOST_PARAMETER_FN_ARG_KEYWORD(x))
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/arity_range.hpp

@@ -0,0 +1,42 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_ARITY_RANGE_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_ARITY_RANGE_HPP
+
+// Helper macros for BOOST_PARAMETER_ARITY_RANGE.
+#define BOOST_PARAMETER_ARITY_RANGE_M_optional(state) state
+#define BOOST_PARAMETER_ARITY_RANGE_M_deduced_optional(state) state
+
+#include <boost/preprocessor/arithmetic/inc.hpp>
+
+#define BOOST_PARAMETER_ARITY_RANGE_M_required(state) BOOST_PP_INC(state)
+#define BOOST_PARAMETER_ARITY_RANGE_M_deduced_required(state)                \
+    BOOST_PP_INC(state)
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/argument_specs.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_ARITY_RANGE_M(s, state, x)                           \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PARAMETER_ARITY_RANGE_M_                                       \
+      , BOOST_PARAMETER_FN_ARG_QUALIFIER(x)                                  \
+    )(state)
+/**/
+
+#include <boost/preprocessor/seq/fold_left.hpp>
+#include <boost/preprocessor/seq/size.hpp>
+
+// Calculates [begin, end) arity range.
+#define BOOST_PARAMETER_ARITY_RANGE(args)                                    \
+    (                                                                        \
+        BOOST_PP_SEQ_FOLD_LEFT(BOOST_PARAMETER_ARITY_RANGE_M, 0, args)       \
+      , BOOST_PP_INC(BOOST_PP_SEQ_SIZE(args))                                \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/flatten.hpp

@@ -0,0 +1,143 @@
+// Copyright Daniel Wallin 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FLATTEN_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FLATTEN_HPP
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPLIT_required required,
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPLIT_optional optional,
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPLIT_deduced deduced,
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_IDENTITY(x) x
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC0_DUMMY_ELEM(z, n, data) ~
+
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPLIT(sub)                            \
+    BOOST_PP_CAT(BOOST_PARAMETER_AUX_PP_FLATTEN_SPLIT_, sub)
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_AS_DEDUCED(x)                    \
+    BOOST_PP_CAT(deduced_, x)
+/**/
+
+#include <boost/preprocessor/detail/split.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_QUALIFIER(sub)                        \
+    BOOST_PP_SPLIT(0, BOOST_PARAMETER_AUX_PP_FLATTEN_SPLIT(sub))
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_ARGS(sub)                             \
+    BOOST_PP_SPLIT(1, BOOST_PARAMETER_AUX_PP_FLATTEN_SPLIT(sub))
+/**/
+
+#include <boost/preprocessor/tuple/elem.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_ARITY_optional(arities)               \
+    BOOST_PP_TUPLE_ELEM(3, 0, arities)
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_ARITY_required(arities)               \
+    BOOST_PP_TUPLE_ELEM(3, 1, arities)
+/**/
+
+#include <boost/preprocessor/arithmetic/sub.hpp>
+#include <boost/preprocessor/repetition/enum_trailing.hpp>
+#include <boost/preprocessor/tuple/rem.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC0(r, n, elem, data)               \
+    ((                                                                       \
+        BOOST_PP_TUPLE_ELEM(3, 2, data)                                      \
+      , BOOST_PP_TUPLE_REM(BOOST_PP_TUPLE_ELEM(3, 0, data)) elem             \
+        BOOST_PP_ENUM_TRAILING(                                              \
+            BOOST_PP_SUB(                                                    \
+                BOOST_PP_TUPLE_ELEM(3, 1, data)                              \
+              , BOOST_PP_TUPLE_ELEM(3, 0, data)                              \
+            )                                                                \
+          , BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC0_DUMMY_ELEM                  \
+          , ~                                                                \
+        )                                                                    \
+    ))
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/for_each.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_AUX(                             \
+    r, arity, max_arity, spec, xform                                         \
+)                                                                            \
+    BOOST_PARAMETER_AUX_PP_FOR_EACH_R(                                       \
+        r                                                                    \
+      , arity                                                                \
+      , BOOST_PARAMETER_AUX_PP_FLATTEN_ARGS(spec)                            \
+      , (                                                                    \
+            arity                                                            \
+          , max_arity                                                        \
+          , xform(BOOST_PARAMETER_AUX_PP_FLATTEN_QUALIFIER(spec))            \
+        )                                                                    \
+      , BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC0                                 \
+    )
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_optional(r, arities, spec)       \
+    BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_AUX(                                 \
+        r                                                                    \
+      , BOOST_PP_CAT(                                                        \
+            BOOST_PARAMETER_AUX_PP_FLATTEN_ARITY_                            \
+          , BOOST_PARAMETER_AUX_PP_FLATTEN_QUALIFIER(spec)                   \
+        )(arities)                                                           \
+      , BOOST_PP_TUPLE_ELEM(3, 2, arities)                                   \
+      , spec                                                                 \
+      , BOOST_PARAMETER_AUX_PP_FLATTEN_IDENTITY                              \
+    )
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_required(r, arities, spec)       \
+    BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_optional(r, arities, spec)
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_deduced_M(r, arities, n, spec)   \
+    BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_AUX(                                 \
+        r                                                                    \
+      , BOOST_PP_CAT(                                                        \
+            BOOST_PARAMETER_AUX_PP_FLATTEN_ARITY_                            \
+          , BOOST_PARAMETER_AUX_PP_FLATTEN_QUALIFIER(spec)                   \
+        )(arities)                                                           \
+      , BOOST_PP_TUPLE_ELEM(3, 2, arities)                                   \
+      , spec                                                                 \
+      , BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_AS_DEDUCED                       \
+    )
+/**/
+
+#include <boost/preprocessor/seq/for_each_i.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_deduced(r, arities, spec)        \
+    BOOST_PP_SEQ_FOR_EACH_I_R(                                               \
+        r                                                                    \
+      , BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_deduced_M                        \
+      , arities                                                              \
+      , BOOST_PARAMETER_AUX_PP_FLATTEN_ARGS(spec)                            \
+    )
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC(r, arities, spec)                \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC_                                 \
+      , BOOST_PARAMETER_AUX_PP_FLATTEN_QUALIFIER(spec)                       \
+    )(r, arities, spec)
+/**/
+
+#include <boost/preprocessor/seq/for_each.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FLATTEN(                                      \
+    opt_arity, req_arity, wanted_arity, specs                                \
+)                                                                            \
+    BOOST_PP_SEQ_FOR_EACH(                                                   \
+        BOOST_PARAMETER_AUX_PP_FLATTEN_SPEC                                  \
+      , (opt_arity, req_arity, wanted_arity)                                 \
+      , specs                                                                \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/for_each.hpp

@@ -0,0 +1,152 @@
+// Copyright Daniel Wallin 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FOR_EACH_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FOR_EACH_HPP
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_head_aux2(x, y) (x, y), ~
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_head_aux3(x, y, z) (x, y, z), ~
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_head_aux4(x, y, z, u) (x, y, z, u), ~
+
+#define                                                                      \
+BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux_BOOST_PARAMETER_AUX_PP_FOR_EACH_END_S
+/**/
+
+#include <boost/preprocessor/detail/split.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_SPLIT_FIRST(x)                  \
+    BOOST_PP_SPLIT(0, x)
+/**/
+
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_head(n, x)                           \
+    BOOST_PP_SPLIT(                                                          \
+        0                                                                    \
+      , BOOST_PP_CAT(BOOST_PARAMETER_AUX_PP_FOR_EACH_head_aux, n) x          \
+    )
+/**/
+
+#include <boost/preprocessor/facilities/is_empty.hpp>
+#include <boost/preprocessor/logical/not.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux_check(x)                    \
+    BOOST_PP_NOT(BOOST_PP_IS_EMPTY(                                          \
+        BOOST_PP_CAT(BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux_, x)           \
+    )), ~
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux2(x, y)                      \
+    BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux_check(x)
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux3(x, y, z)                   \
+    BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux_check(x)
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux4(x, y, z, u)                \
+    BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux_check(x)
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux0(n, x)                      \
+    BOOST_PP_CAT(BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux, n) x
+/**/
+
+#include <boost/preprocessor/tuple/elem.hpp>
+
+#if BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred(r, state)                       \
+    BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_SPLIT_FIRST(                        \
+        BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux0(                           \
+            BOOST_PP_TUPLE_ELEM(5, 3, state)                                 \
+          , BOOST_PP_TUPLE_ELEM(5, 0, state)                                 \
+        )                                                                    \
+    )
+/**/
+
+#else   // !(BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC())
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_pred(r, state)                       \
+    BOOST_PP_SPLIT(                                                          \
+        0                                                                    \
+      , BOOST_PARAMETER_AUX_PP_FOR_EACH_pred_aux0(                           \
+            BOOST_PP_TUPLE_ELEM(5, 3, state)                                 \
+          , BOOST_PP_TUPLE_ELEM(5, 0, state)                                 \
+        )                                                                    \
+    )
+/**/
+
+#endif  // BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()
+
+#include <boost/preprocessor/arithmetic/inc.hpp>
+#include <boost/preprocessor/tuple/eat.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_op(r, state)                         \
+    (                                                                        \
+        BOOST_PP_TUPLE_EAT(BOOST_PP_TUPLE_ELEM(5, 3, state))                 \
+            BOOST_PP_TUPLE_ELEM(5, 0, state)                                 \
+      , BOOST_PP_TUPLE_ELEM(5, 1, state)                                     \
+      , BOOST_PP_TUPLE_ELEM(5, 2, state)                                     \
+      , BOOST_PP_TUPLE_ELEM(5, 3, state)                                     \
+      , BOOST_PP_INC(BOOST_PP_TUPLE_ELEM(5, 4, state))                       \
+    )
+/**/
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_macro(r, state)                      \
+    BOOST_PP_TUPLE_ELEM(5, 2, state)(                                        \
+        r                                                                    \
+      , BOOST_PP_TUPLE_ELEM(5, 4, state)                                     \
+      , BOOST_PARAMETER_AUX_PP_FOR_EACH_head(                                \
+            BOOST_PP_TUPLE_ELEM(5, 3, state)                                 \
+          , BOOST_PP_TUPLE_ELEM(5, 0, state)                                 \
+        )                                                                    \
+      , BOOST_PP_TUPLE_ELEM(5, 1, state)                                     \
+    )
+/**/
+
+#include <boost/preprocessor/punctuation/comma_if.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_build_end_sentinel(z, n, text)       \
+    BOOST_PP_COMMA_IF(n) BOOST_PARAMETER_AUX_PP_FOR_EACH_END_S
+/**/
+
+#include <boost/preprocessor/repetition/repeat.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_build_end_sentinel_tuple(arity)      \
+    (                                                                        \
+        BOOST_PP_REPEAT(                                                     \
+            arity, BOOST_PARAMETER_AUX_PP_FOR_EACH_build_end_sentinel, _     \
+        )                                                                    \
+    )
+/**/
+
+#include <boost/preprocessor/repetition/for.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH_R(r, arity, list, data, macro)       \
+    BOOST_PP_CAT(BOOST_PP_FOR_, r)(                                          \
+        (list                                                                \
+            BOOST_PARAMETER_AUX_PP_FOR_EACH_build_end_sentinel_tuple(arity)  \
+          , data                                                             \
+          , macro                                                            \
+          , arity                                                            \
+          , 0                                                                \
+        )                                                                    \
+      , BOOST_PARAMETER_AUX_PP_FOR_EACH_pred                                 \
+      , BOOST_PARAMETER_AUX_PP_FOR_EACH_op                                   \
+      , BOOST_PARAMETER_AUX_PP_FOR_EACH_macro                                \
+    )
+/**/
+
+#include <boost/preprocessor/repetition/deduce_r.hpp>
+
+#define BOOST_PARAMETER_AUX_PP_FOR_EACH(arity, list, data, macro)            \
+    BOOST_PARAMETER_AUX_PP_FOR_EACH_R(                                       \
+        BOOST_PP_DEDUCE_R(), arity, list, data, macro                        \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/forwarding_overloads.hpp

@@ -0,0 +1,509 @@
+// Copyright Daniel Wallin 2006.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FORWARDING_OVERLOADS_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FORWARDING_OVERLOADS_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#include <boost/preprocessor/cat.hpp>
+
+// Expands to a forwarding parameter for a constructor or forwarding function.
+#define BOOST_PARAMETER_FUNCTION_ARG_TYPE_Z(z, n, type_prefix)               \
+    BOOST_PP_CAT(type_prefix, n)&&
+/**/
+
+#include <utility>
+
+// Expands to an argument passed from a forwarding function to the front-end
+// implementation function, or from a constructor to its delegate.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_PARAM_Z(z, n, type_prefix)          \
+    ::std::forward<BOOST_PP_CAT(type_prefix, n)>(BOOST_PP_CAT(a, n))
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/parenthesized_type.hpp>
+#include <boost/preprocessor/tuple/elem.hpp>
+
+// Expands to the default constructor, whose job is to pass an empty back to
+// the delegate constructor of the base class.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_0_Z(z, n, data)                 \
+    inline BOOST_PP_TUPLE_ELEM(2, 0, data)()                                 \
+      : BOOST_PARAMETER_PARENTHESIZED_TYPE(BOOST_PP_TUPLE_ELEM(2, 1, data))( \
+            BOOST_PP_CAT(constructor_parameters, __LINE__)()()               \
+        )                                                                    \
+    {                                                                        \
+    }
+/**/
+
+#include <boost/parameter/aux_/pp_impl/argument_pack.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/function_name.hpp>
+#include <boost/preprocessor/control/expr_if.hpp>
+
+// Expands to a 0-arity forwarding function, whose job is to pass an empty
+// pack to the front-end implementation function.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_0_Z(z, n, data)            \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(BOOST_PP_TUPLE_ELEM(4, 1, data))  \
+    inline BOOST_PARAMETER_FUNCTION_RESULT_NAME(                             \
+        BOOST_PP_TUPLE_ELEM(4, 1, data)                                      \
+      , BOOST_PP_TUPLE_ELEM(4, 3, data)                                      \
+    )<                                                                       \
+        ::boost::parameter::aux::argument_pack<                              \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, data)                              \
+              , BOOST_PP_TUPLE_ELEM(4, 3, data)                              \
+            )                                                                \
+        >::type                                                              \
+    >::type                                                                  \
+    BOOST_PARAMETER_MEMBER_FUNCTION_NAME(BOOST_PP_TUPLE_ELEM(3, 0, data))()  \
+    BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 3, data), const)                 \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 2, data), this->)     \
+        BOOST_PARAMETER_FUNCTION_IMPL_NAME(                                  \
+            BOOST_PP_TUPLE_ELEM(4, 1, data)                                  \
+          , BOOST_PP_TUPLE_ELEM(4, 3, data)                                  \
+        )(                                                                   \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, data)                              \
+              , BOOST_PP_TUPLE_ELEM(4, 3, data)                              \
+            )()()                                                            \
+        );                                                                   \
+    }
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/function_forward_match.hpp>
+#include <boost/preprocessor/repetition/enum.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+
+// Expands to a forwarding function, whose job is to consolidate its arguments
+// into a pack for the front-end implementation function to take in.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_1_Z(z, n, data)            \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename ParameterArgumentType)>  \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(BOOST_PP_TUPLE_ELEM(4, 1, data))  \
+    inline typename BOOST_PARAMETER_FUNCTION_RESULT_NAME(                    \
+        BOOST_PP_TUPLE_ELEM(4, 1, data)                                      \
+      , BOOST_PP_TUPLE_ELEM(4, 3, data)                                      \
+    )<                                                                       \
+        typename ::boost::parameter::aux::argument_pack<                     \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, data)                              \
+              , BOOST_PP_TUPLE_ELEM(4, 3, data)                              \
+            )                                                                \
+          , BOOST_PP_CAT(BOOST_PP_ENUM_, z)(                                 \
+                n                                                            \
+              , BOOST_PARAMETER_FUNCTION_ARG_TYPE_Z                          \
+              , ParameterArgumentType                                        \
+            )                                                                \
+        >::type                                                              \
+    >::type                                                                  \
+    BOOST_PARAMETER_MEMBER_FUNCTION_NAME(BOOST_PP_TUPLE_ELEM(4, 0, data))(   \
+        BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, ParameterArgumentType, && a)     \
+        BOOST_PARAMETER_FUNCTION_FORWARD_MATCH_Z(                            \
+            z                                                                \
+          , BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, data)                              \
+              , BOOST_PP_TUPLE_ELEM(4, 3, data)                              \
+            )                                                                \
+          , n                                                                \
+          , ParameterArgumentType                                            \
+        )                                                                    \
+    ) BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 3, data), const)               \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 2, data), this->)     \
+        BOOST_PARAMETER_FUNCTION_IMPL_NAME(                                  \
+            BOOST_PP_TUPLE_ELEM(4, 1, data)                                  \
+          , BOOST_PP_TUPLE_ELEM(4, 3, data)                                  \
+        )(                                                                   \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, data)                              \
+              , BOOST_PP_TUPLE_ELEM(4, 3, data)                              \
+            )()(                                                             \
+                BOOST_PP_CAT(BOOST_PP_ENUM_, z)(                             \
+                    n                                                        \
+                  , BOOST_PARAMETER_FUNCTION_FORWARD_PARAM_Z                 \
+                  , ParameterArgumentType                                    \
+                )                                                            \
+            )                                                                \
+        );                                                                   \
+    }
+/**/
+
+#include <boost/preprocessor/comparison/equal.hpp>
+
+// Expands to a constructor whose job is to consolidate its arguments into a
+// pack for the delegate constructor of the base class to take in.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_1_Z(z, n, data)                 \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename ParameterArgumentType)>  \
+    BOOST_PP_EXPR_IF(BOOST_PP_EQUAL(n, 1), explicit)                         \
+    inline BOOST_PP_TUPLE_ELEM(2, 0, data)(                                  \
+        BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, ParameterArgumentType, && a)     \
+        BOOST_PARAMETER_FUNCTION_FORWARD_MATCH_Z(                            \
+            z                                                                \
+          , BOOST_PP_CAT(constructor_parameters, __LINE__)                   \
+          , n                                                                \
+          , ParameterArgumentType                                            \
+        )                                                                    \
+    ) : BOOST_PARAMETER_PARENTHESIZED_TYPE(BOOST_PP_TUPLE_ELEM(2, 1, data))( \
+            BOOST_PP_CAT(constructor_parameters, __LINE__)()(                \
+                BOOST_PP_CAT(BOOST_PP_ENUM_, z)(                             \
+                    n                                                        \
+                  , BOOST_PARAMETER_FUNCTION_FORWARD_PARAM_Z                 \
+                  , ParameterArgumentType                                    \
+                )                                                            \
+            )                                                                \
+        )                                                                    \
+    {                                                                        \
+    }
+/**/
+
+#include <boost/preprocessor/control/if.hpp>
+
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_Z(z, n, data)              \
+    BOOST_PP_IF(                                                             \
+        n                                                                    \
+      , BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_1_Z                        \
+      , BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_0_Z                        \
+    )(z, n, data)
+/**/
+
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_Z(z, n, data)                   \
+    BOOST_PP_IF(                                                             \
+        n                                                                    \
+      , BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_1_Z                             \
+      , BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_0_Z                             \
+    )(z, n, data)
+/**/
+
+#include <boost/preprocessor/repetition/repeat_from_to.hpp>
+
+// Helper macro for BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS_AUX(nm, impl, r, is_m, c) \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        BOOST_PP_TUPLE_ELEM(2, 0, r)                                         \
+      , BOOST_PP_TUPLE_ELEM(2, 1, r)                                         \
+      , BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_Z                          \
+      , (                                                                    \
+            nm                                                               \
+          , impl                                                             \
+          , BOOST_PP_IF(                                                     \
+                BOOST_PARAMETER_MEMBER_FUNCTION_IS_STATIC(nm)                \
+              , 0                                                            \
+              , is_m                                                         \
+            )                                                                \
+          , c                                                                \
+        )                                                                    \
+    )
+/**/
+
+// Helper macro for BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS_AUX(class_, base, range)       \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        BOOST_PP_TUPLE_ELEM(2, 0, range)                                     \
+      , BOOST_PP_TUPLE_ELEM(2, 1, range)                                     \
+      , BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_Z                               \
+      , (class_, base)                                                       \
+    )
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/arity_range.hpp>
+
+// Expands to the layer of forwarding functions for the function with the
+// specified name, whose arguments determine the range of arities.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS(name, impl, a, is_m, c)   \
+    BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS_AUX(                          \
+        name, impl, BOOST_PARAMETER_ARITY_RANGE(a), is_m, c                  \
+    )
+/**/
+
+// Expands to the layer of forwarding functions for the constructor in the
+// specified class, whose arguments determine the range of arities.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS(class_, base, args)            \
+    BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS_AUX(                               \
+        class_, base, BOOST_PARAMETER_ARITY_RANGE(args)                      \
+    )
+/**/
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#include <boost/parameter/aux_/preprocessor/impl/parenthesized_type.hpp>
+#include <boost/preprocessor/seq/seq.hpp>
+#include <boost/preprocessor/tuple/elem.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+// Expands to the default constructor, whose job is to pass an empty argument
+// pack back to the delegate constructor of the base class.
+#define BOOST_PARAMETER_DEFAULT_CONSTRUCTOR(z, n, seq)                       \
+    inline                                                                   \
+    BOOST_PP_TUPLE_ELEM(2, 0, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq)))()   \
+      : BOOST_PARAMETER_PARENTHESIZED_TYPE(                                  \
+            BOOST_PP_TUPLE_ELEM(                                             \
+                2, 1, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))              \
+            )                                                                \
+        )(BOOST_PP_CAT(constructor_parameters, __LINE__)()())                \
+    {                                                                        \
+    }
+/**/
+
+#include <boost/parameter/aux_/pp_impl/argument_pack.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/function_name.hpp>
+#include <boost/preprocessor/control/expr_if.hpp>
+
+// Expands to a 0-arity forwarding function, whose job is to pass an empty
+// argument pack to the front-end implementation function.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_0_ARITY(z, n, seq)         \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(                                  \
+        BOOST_PP_TUPLE_ELEM(                                                 \
+            4, 1, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))                  \
+        )                                                                    \
+    )                                                                        \
+    inline BOOST_PARAMETER_FUNCTION_RESULT_NAME(                             \
+        BOOST_PP_TUPLE_ELEM(                                                 \
+            4, 1, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))                  \
+        )                                                                    \
+      , BOOST_PP_TUPLE_ELEM(                                                 \
+            4, 3, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))                  \
+        )                                                                    \
+    )<                                                                       \
+        ::boost::parameter::aux::argument_pack<                              \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(                                         \
+                    4, 1, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))          \
+                )                                                            \
+              , BOOST_PP_TUPLE_ELEM(                                         \
+                    4, 3, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))          \
+                )                                                            \
+            )                                                                \
+        >::type                                                              \
+    >::type                                                                  \
+    BOOST_PARAMETER_MEMBER_FUNCTION_NAME(                                    \
+        BOOST_PP_TUPLE_ELEM(                                                 \
+            4, 0, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))                  \
+        )                                                                    \
+    )() BOOST_PP_EXPR_IF(                                                    \
+        BOOST_PP_TUPLE_ELEM(                                                 \
+            4, 3, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))                  \
+        )                                                                    \
+      , const                                                                \
+    )                                                                        \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(                                             \
+            BOOST_PP_TUPLE_ELEM(                                             \
+                4, 2, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))              \
+            )                                                                \
+          , this->                                                           \
+        ) BOOST_PARAMETER_FUNCTION_IMPL_NAME(                                \
+            BOOST_PP_TUPLE_ELEM(                                             \
+                4, 1, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))              \
+            )                                                                \
+          , BOOST_PP_TUPLE_ELEM(                                             \
+                4, 3, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))              \
+            )                                                                \
+        )(                                                                   \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(                                         \
+                    4, 1, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))          \
+                )                                                            \
+              , BOOST_PP_TUPLE_ELEM(                                         \
+                    4, 3, BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(seq))          \
+                )                                                            \
+            )()()                                                            \
+        );                                                                   \
+    }
+/**/
+
+#include <boost/parameter/aux_/preprocessor/binary_seq_to_args.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/function_forward_match.hpp>
+#include <boost/preprocessor/comparison/equal.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/seq/size.hpp>
+
+// Expands to a constructor whose job is to consolidate its arguments into a
+// pack for the delegate constructor of the base class to take in.  Each
+// element in BOOST_PP_SEQ_TAIL(seq) determines the const-ness of the
+// corresponding argument.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_R(r, seq)                       \
+    template <                                                               \
+        BOOST_PP_ENUM_PARAMS(                                                \
+            BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_TAIL(seq))                        \
+          , typename ParameterArgumentType                                   \
+        )                                                                    \
+    >                                                                        \
+    BOOST_PP_EXPR_IF(                                                        \
+        BOOST_PP_EQUAL(BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_TAIL(seq)), 1)         \
+      , explicit                                                             \
+    )                                                                        \
+    inline BOOST_PP_TUPLE_ELEM(2, 0, BOOST_PP_SEQ_HEAD(seq))(                \
+        BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARGS(                           \
+            BOOST_PP_SEQ_TAIL(seq), (ParameterArgumentType)(a)               \
+        )                                                                    \
+        BOOST_PARAMETER_FUNCTION_FORWARD_MATCH(                              \
+            BOOST_PP_CAT(constructor_parameters, __LINE__)                   \
+          , BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_TAIL(seq))                        \
+          , ParameterArgumentType                                            \
+        )                                                                    \
+    ) : BOOST_PARAMETER_PARENTHESIZED_TYPE(                                  \
+            BOOST_PP_TUPLE_ELEM(2, 1, BOOST_PP_SEQ_HEAD(seq))                \
+        )(                                                                   \
+            BOOST_PP_CAT(constructor_parameters, __LINE__)()(                \
+                BOOST_PP_ENUM_PARAMS(                                        \
+                    BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_TAIL(seq)), a             \
+                )                                                            \
+            )                                                                \
+        )                                                                    \
+    {                                                                        \
+    }
+/**/
+
+// Expands to a forwarding function, whose job is to consolidate its arguments
+// into a pack for the front-end implementation function to take in.  Each
+// element in BOOST_PP_SEQ_TAIL(seq) determines the const-ness of the
+// corresponding argument.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_R(r, seq)                  \
+    template <                                                               \
+        BOOST_PP_ENUM_PARAMS(                                                \
+            BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_TAIL(seq))                        \
+          , typename ParameterArgumentType                                   \
+        )                                                                    \
+    >                                                                        \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(                                  \
+        BOOST_PP_TUPLE_ELEM(4, 1, BOOST_PP_SEQ_HEAD(seq))                    \
+    )                                                                        \
+    inline typename BOOST_PARAMETER_FUNCTION_RESULT_NAME(                    \
+        BOOST_PP_TUPLE_ELEM(4, 1, BOOST_PP_SEQ_HEAD(seq))                    \
+      , BOOST_PP_TUPLE_ELEM(4, 3, BOOST_PP_SEQ_HEAD(seq))                    \
+    )<                                                                       \
+        typename ::boost::parameter::aux::argument_pack<                     \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, BOOST_PP_SEQ_HEAD(seq))            \
+              , BOOST_PP_TUPLE_ELEM(4, 3, BOOST_PP_SEQ_HEAD(seq))            \
+            )                                                                \
+          , BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARGS(                       \
+                BOOST_PP_SEQ_TAIL(seq), (ParameterArgumentType)              \
+            )                                                                \
+        >::type                                                              \
+    >::type                                                                  \
+    BOOST_PARAMETER_MEMBER_FUNCTION_NAME(                                    \
+        BOOST_PP_TUPLE_ELEM(4, 0, BOOST_PP_SEQ_HEAD(seq))                    \
+    )(                                                                       \
+        BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARGS(                           \
+            BOOST_PP_SEQ_TAIL(seq), (ParameterArgumentType)(a)               \
+        )                                                                    \
+        BOOST_PARAMETER_FUNCTION_FORWARD_MATCH(                              \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, BOOST_PP_SEQ_HEAD(seq))            \
+              , BOOST_PP_TUPLE_ELEM(4, 3, BOOST_PP_SEQ_HEAD(seq))            \
+            )                                                                \
+          , BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_TAIL(seq))                        \
+          , ParameterArgumentType                                            \
+        )                                                                    \
+    ) BOOST_PP_EXPR_IF(                                                      \
+        BOOST_PP_TUPLE_ELEM(4, 3, BOOST_PP_SEQ_HEAD(seq)), const             \
+    )                                                                        \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(                                             \
+            BOOST_PP_TUPLE_ELEM(4, 2, BOOST_PP_SEQ_HEAD(seq))                \
+          , this->                                                           \
+        ) BOOST_PARAMETER_FUNCTION_IMPL_NAME(                                \
+            BOOST_PP_TUPLE_ELEM(4, 1, BOOST_PP_SEQ_HEAD(seq))                \
+          , BOOST_PP_TUPLE_ELEM(4, 3, BOOST_PP_SEQ_HEAD(seq))                \
+        )(                                                                   \
+            BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(                     \
+                BOOST_PP_TUPLE_ELEM(4, 1, BOOST_PP_SEQ_HEAD(seq))            \
+              , BOOST_PP_TUPLE_ELEM(4, 3, BOOST_PP_SEQ_HEAD(seq))            \
+            )()(                                                             \
+                BOOST_PP_ENUM_PARAMS(                                        \
+                    BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_TAIL(seq)), a             \
+                )                                                            \
+            )                                                                \
+        );                                                                   \
+    }
+/**/
+
+#include <boost/parameter/aux_/preprocessor/binary_seq_for_each.hpp>
+#include <boost/preprocessor/control/if.hpp>
+
+// Expands to all constructors that take in n arguments.  Enables
+// BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS_AUX to use
+// BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_Z within BOOST_PP_REPEAT_FROM_TO.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_Z(z, n, data)                   \
+    BOOST_PP_IF(                                                             \
+        n                                                                    \
+      , BOOST_PARAMETER_AUX_PP_BINARY_SEQ_FOR_EACH_Z                         \
+      , BOOST_PARAMETER_DEFAULT_CONSTRUCTOR                                  \
+    )(z, n, (BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_R)(data))
+/**/
+
+// Expands to all forwarding functions that take in n arguments.  Enables
+// BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS_AUX to use
+// BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_Z within BOOST_PP_REPEAT_FROM_TO.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_Z(z, n, data)              \
+    BOOST_PP_IF(                                                             \
+        n                                                                    \
+      , BOOST_PARAMETER_AUX_PP_BINARY_SEQ_FOR_EACH_Z                         \
+      , BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_0_ARITY                    \
+    )(z, n, (BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_R)(data))
+/**/
+
+#include <boost/preprocessor/repetition/repeat_from_to.hpp>
+
+// Helper macro for BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS_AUX(class_, base, range)       \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        BOOST_PP_TUPLE_ELEM(2, 0, range)                                     \
+      , BOOST_PP_TUPLE_ELEM(2, 1, range)                                     \
+      , BOOST_PARAMETER_CONSTRUCTOR_OVERLOAD_Z                               \
+      , (class_, base)                                                       \
+    )
+/**/
+
+// Helper macro for BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS_AUX(nm, impl, r, is_m, c) \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        BOOST_PP_TUPLE_ELEM(2, 0, r)                                         \
+      , BOOST_PP_TUPLE_ELEM(2, 1, r)                                         \
+      , BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOAD_Z                          \
+      , (                                                                    \
+            nm                                                               \
+          , impl                                                             \
+          , BOOST_PP_IF(                                                     \
+                BOOST_PARAMETER_MEMBER_FUNCTION_IS_STATIC(impl)              \
+              , 0                                                            \
+              , is_m                                                         \
+            )                                                                \
+          , c                                                                \
+        )                                                                    \
+    )
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/arity_range.hpp>
+
+// Expands to the layer of forwarding functions for the constructor in the
+// specified class, whose arguments determine the range of arities.
+#define BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS(class_, base, args)            \
+    BOOST_PARAMETER_CONSTRUCTOR_OVERLOADS_AUX(                               \
+        class_                                                               \
+      , base                                                                 \
+      , BOOST_PARAMETER_ARITY_RANGE(args)                                    \
+    )
+/**/
+
+// Expands to the layer of forwarding functions for the function with the
+// specified name, whose arguments determine the range of arities.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS(name, impl, a, is_m, c)   \
+    BOOST_PARAMETER_FUNCTION_FORWARD_OVERLOADS_AUX(                          \
+        name                                                                 \
+      , impl                                                                 \
+      , BOOST_PARAMETER_ARITY_RANGE(a)                                       \
+      , is_m                                                                 \
+      , c                                                                    \
+    )
+/**/
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/function_cast.hpp

@@ -0,0 +1,730 @@
+// Copyright Daniel Wallin 2006.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_CAST_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_CAST_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Handles possible implicit casts.  Used by preprocessor.hpp
+    // to normalize user input.
+    //
+    // cast<void*>::execute() is identity
+    // cast<void*(X)>::execute() is identity
+    // cast<void(X)>::execute() casts to X
+    //
+    // preprocessor.hpp uses this like this:
+    //
+    //     #define X(value, predicate)
+    //         cast<void predicate>::execute(value)
+    //
+    //     X(something, *)
+    //     X(something, *(predicate))
+    //     X(something, (int))
+    template <typename VoidExpr, typename Args>
+    struct cast;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/use_default_tag.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T, typename B>
+    inline ::boost::parameter::aux::use_default_tag
+        forward(::boost::parameter::aux::use_default_tag)
+    {
+        return ::boost::parameter::aux::use_default_tag();
+    }
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Args>
+    struct cast<void*,Args>
+    {
+        template <typename T, typename B>
+        struct apply
+        {
+            typedef typename ::boost::mpl
+            ::if_<B,T,::boost::mpl::true_>::type type;
+        };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        template <typename T, typename B>
+        using fn = ::boost::mp11::mp_if<B,T,::boost::mp11::mp_true>;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/void.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Predicate, typename Args>
+    struct cast<void*(Predicate),Args>
+      : ::boost::parameter::aux::cast<void*,Args>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/placeholders.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // This is a hack used in cast<> to turn the user supplied type,
+    // which may or may not be a placeholder expression, into one,
+    // so that it will be properly evaluated by mpl::apply.
+    template <typename T, typename Dummy = ::boost::mpl::_1>
+    struct as_placeholder_expr
+    {
+        typedef T type;
+    };
+}}} // namespace boost::parameter::aux
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/list.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Target, typename Source, typename Args>
+    struct apply_target_fn
+    {
+        using type = ::boost::mp11
+        ::mp_apply_q<Target,::boost::mp11::mp_list<Source,Args> >;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif
+
+#include <boost/mpl/apply.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/parameter/aux_/has_nested_template_fn.hpp>
+#include <type_traits>
+#else
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Target, typename Source, typename Args>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using is_target_same_as_source = ::std::is_same<
+        typename ::std::remove_const<
+            typename ::std::remove_reference<
+                typename ::boost::mp11::mp_if<
+                    ::boost::parameter::aux::has_nested_template_fn<Target>
+                  , ::boost::parameter::aux
+                    ::apply_target_fn<Target,Source,Args>
+                  , ::boost::mpl::apply2<
+                        ::boost::parameter::aux::as_placeholder_expr<Target>
+                      , Source
+                      , Args
+                    >
+                >::type
+            >::type
+        >::type
+      , typename ::std::remove_const<Source>::type
+    >;
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+    struct is_target_same_as_source
+      : ::boost::mpl::if_<
+            ::boost::is_same<
+                typename ::boost::remove_const<
+                    typename ::boost::remove_reference<
+                        typename ::boost::mpl::apply2<
+                            ::boost::parameter::aux
+                            ::as_placeholder_expr<Target>
+                          , Source
+                          , Args
+                        >::type
+                    >::type
+                >::type
+              , typename ::boost::remove_const<Source>::type
+            >
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#if !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/type_traits/add_const.hpp>
+#include <boost/type_traits/is_const.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Covers the case where is_convertible<Source,Target> but not
+    // is_same<Source,Target>.  Use cases are covered
+    // by test/normalize_argument_types.cpp
+    template <typename Source, typename Target>
+    class cast_convert
+    {
+        typedef ::boost::parameter::aux::cast_convert<Source,Target> _self;
+
+     public:
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = typename ::boost::mp11::mp_if<
+            ::std::is_const<Source>
+          , ::std::add_const<Target>
+          , ::std::remove_const<Target>
+        >::type;
+#else
+        typedef typename boost::mpl::eval_if<
+            ::boost::is_const<Source>
+          , ::boost::add_const<Target>
+          , ::boost::remove_const<Target>
+        >::type type;
+#endif
+
+     private:
+        inline static typename _self::type
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            _copy(typename ::std::remove_const<Target>::type value)
+#else
+            _copy(typename ::boost::remove_const<Target>::type value)
+#endif
+        {
+            return value;
+        }
+
+     public:
+        inline static typename _self::type evaluate(Source&& source)
+        {
+            return _self::_copy(source);
+        }
+    };
+
+    template <typename Target, typename Source, typename Args>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using cast_impl = ::std::remove_reference<
+        typename ::boost::mp11::mp_if<
+            ::boost::parameter::aux::has_nested_template_fn<Target>
+          , ::boost::parameter::aux
+            ::is_target_same_as_source<Target,Source,Args>
+          , ::boost::mpl::apply2<
+                ::boost::parameter::aux::as_placeholder_expr<Target>
+              , Source
+              , Args
+            >
+        >::type
+    >;
+#else
+    struct cast_impl
+      : ::boost::remove_reference<
+            typename ::boost::mpl::apply2<
+                ::boost::parameter::aux::as_placeholder_expr<Target>
+              , Source
+              , Args
+            >::type
+        >
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/identity.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Target, typename Args>
+    struct cast<void(Target),Args>
+    {
+        template <typename T, typename B>
+        struct apply
+        {
+            typedef typename ::boost::mpl::eval_if<
+                B
+              , ::boost::mpl::eval_if<
+                    ::boost::parameter::aux
+                    ::is_target_same_as_source<Target,T,Args>
+                  , ::boost::mpl::identity<T>
+                  , ::boost::parameter::aux::cast_impl<Target,T,Args>
+                >
+              , ::boost::parameter::aux
+                ::is_target_same_as_source<Target,T,Args>
+            >::type type;
+        };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        template <typename T, typename B>
+        using fn = typename ::boost::mp11::mp_if<
+            B
+          , ::boost::mp11::mp_if<
+                ::boost::parameter::aux
+                ::is_target_same_as_source<Target,T,Args>
+              , ::boost::mp11::mp_identity<T>
+              , ::boost::parameter::aux::cast_impl<Target,T,Args>
+            >
+          , ::boost::parameter::aux
+            ::is_target_same_as_source<Target,T,Args>
+        >::type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/value_type.hpp>
+
+#if !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mpl/apply_wrap.hpp>
+#endif
+
+// Expands to the target type of the argument as indicated by the predicate.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_FUNCTION_CAST_T(tag, predicate, args)                \
+    ::boost::mp11::mp_apply_q<                                               \
+        ::boost::parameter::aux::cast<void predicate, args>                  \
+      , ::boost::mp11::mp_list<                                              \
+            typename ::boost::parameter::value_type<                         \
+                args                                                         \
+              , tag                                                          \
+              , ::boost::parameter::aux::use_default_tag                     \
+            >::type                                                          \
+          , ::boost::mp11::mp_true                                           \
+        >                                                                    \
+    >
+/**/
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_FUNCTION_CAST_T(tag, predicate, args)                \
+    typename ::boost::mpl::apply_wrap2<                                      \
+        ::boost::parameter::aux::cast<void predicate, args>                  \
+      , typename ::boost::parameter::value_type<                             \
+            args                                                             \
+          , tag                                                              \
+          , ::boost::parameter::aux::use_default_tag                         \
+        >::type                                                              \
+      , ::boost::mpl::true_                                                  \
+    >::type
+/**/
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+// Expands to boost::mpl::true_ if and only if the argument's source and
+// target types are the same.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_FUNCTION_CAST_B(tag, predicate, args)                \
+    ::boost::mp11::mp_apply_q<                                               \
+        ::boost::parameter::aux::cast<void predicate, args>                  \
+      , ::boost::mp11::mp_list<                                              \
+            typename ::boost::parameter::value_type<                         \
+                args                                                         \
+              , tag                                                          \
+              , ::boost::parameter::aux::use_default_tag                     \
+            >::type                                                          \
+          , ::boost::mp11::mp_false                                          \
+        >                                                                    \
+    >
+/**/
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_FUNCTION_CAST_B(tag, predicate, args)                \
+    typename ::boost::mpl::apply_wrap2<                                      \
+        ::boost::parameter::aux::cast<void predicate, args>                  \
+      , typename ::boost::parameter::value_type<                             \
+            args                                                             \
+          , tag                                                              \
+          , ::boost::parameter::aux::use_default_tag                         \
+        >::type                                                              \
+      , ::boost::mpl::false_                                                 \
+    >::type
+/**/
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+#include <boost/core/enable_if.hpp>
+#include <utility>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // If the source and target types are not the same,
+    // then perform an implicit conversion.
+    template <typename Target, typename B, typename Source>
+    inline typename ::boost::lazy_disable_if<
+        B
+      , ::boost::parameter::aux::cast_convert<Source,Target>
+    >::type
+        forward(Source&& source)
+    {
+        return ::boost::parameter::aux::cast_convert<Source,Target>
+        ::evaluate(::std::forward<Source>(source));
+    }
+
+    // If the source and target types are the same,
+    // then simply forward the argument.
+    // However, treat rvalue references to scalars as const lvalue references.
+    template <typename T, typename B>
+    inline typename ::boost::enable_if<B,T const&>::type forward(T const& t)
+    {
+        return t;
+    }
+
+    template <typename T, typename B>
+    inline typename ::boost::enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        ::boost::mp11::mp_if<
+            B
+          , ::boost::mp11::mp_if<
+                ::std::is_const<T>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_true
+            >
+          , ::boost::mp11::mp_false
+        >
+#else
+        typename ::boost::mpl::eval_if<
+            B
+          , ::boost::mpl::if_<
+                ::boost::is_const<T>
+              , ::boost::mpl::false_
+              , ::boost::mpl::true_
+            >
+          , ::boost::mpl::false_
+        >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+      , T&
+    >::type
+        forward(T& t)
+    {
+        return t;
+    }
+}}} // namespace boost::parameter::aux
+
+#include <boost/type_traits/is_scalar.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T, typename B>
+    inline typename ::boost::enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        ::boost::mp11::mp_if<
+            B
+          , ::boost::mp11::mp_if<
+                ::std::is_scalar<T>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_true
+            >
+          , ::boost::mp11::mp_false
+        >
+#else
+        typename ::boost::mpl::eval_if<
+            B
+          , ::boost::mpl::if_<
+                ::boost::is_scalar<T>
+              , ::boost::mpl::false_
+              , ::boost::mpl::true_
+            >
+          , ::boost::mpl::false_
+        >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+      , T const&&
+    >::type
+        forward(T const&& t)
+    {
+        return static_cast<T const&&>(t);
+    }
+
+    template <typename T, typename B>
+    inline typename ::boost::enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        ::boost::mp11::mp_if<
+            B
+          , ::boost::mp11::mp_if<
+                ::std::is_scalar<T>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_true
+            >
+          , ::boost::mp11::mp_false
+        >
+#else
+        typename ::boost::mpl::eval_if<
+            B
+          , ::boost::mpl::if_<
+                ::boost::is_scalar<T>
+              , ::boost::mpl::false_
+              , ::boost::mpl::true_
+            >
+          , ::boost::mpl::false_
+        >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+      , T&&
+    >::type
+        forward(T&& t)
+    {
+        return ::std::forward<T>(t);
+    }
+}}} // namespace boost::parameter::aux
+
+#elif BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+#define BOOST_PARAMETER_FUNCTION_CAST_T(value_t, predicate, args) value_t
+#define BOOST_PARAMETER_FUNCTION_CAST_B(value, predicate, args) value
+#else   // no perfect forwarding support and no Borland workarounds needed
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Handles possible implicit casts.  Used by preprocessor.hpp
+    // to normalize user input.
+    //
+    // cast<void*>::execute() is identity
+    // cast<void*(X)>::execute() is identity
+    // cast<void(X)>::execute() casts to X
+    //
+    // preprocessor.hpp uses this like this:
+    //
+    //     #define X(value, predicate)
+    //         cast<void predicate>::execute(value)
+    //
+    //     X(something, *)
+    //     X(something, *(predicate))
+    //     X(something, (int))
+    template <typename VoidExpr, typename Args>
+    struct cast;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/use_default_tag.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Args>
+    struct cast<void*,Args>
+    {
+        template <typename T>
+        struct apply
+        {
+            typedef T& type;
+        };
+
+        inline static ::boost::parameter::aux::use_default_tag
+            execute(::boost::parameter::aux::use_default_tag)
+        {
+            return ::boost::parameter::aux::use_default_tag();
+        }
+
+        template <typename U>
+        inline static U& execute(U& value)
+        {
+            return value;
+        }
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/void.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Predicate, typename Args>
+#if BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x580))
+    struct cast< ::boost::parameter::aux::voidstar(Predicate),Args>
+#else
+    struct cast<void*(Predicate),Args>
+#endif
+      : ::boost::parameter::aux::cast<void*,Args>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/placeholders.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // This is a hack used in cast<> to turn the user supplied type,
+    // which may or may not be a placeholder expression, into one,
+    // so that it will be properly evaluated by mpl::apply.
+    template <typename T, typename Dummy = ::boost::mpl::_1>
+    struct as_placeholder_expr
+    {
+        typedef T type;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/apply.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Target, typename Source, typename Args>
+    struct is_target_same_as_source
+      : ::boost::mpl::if_<
+            ::boost::is_same<
+                typename ::boost::remove_const<
+                    typename ::boost::remove_reference<
+                        typename ::boost::mpl::apply2<
+                            ::boost::parameter::aux
+                            ::as_placeholder_expr<Target>
+                          , Source
+                          , Args
+                        >::type
+                    >::type
+                >::type
+              , typename ::boost::remove_const<Source>::type
+            >
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+
+    template <
+        typename Target
+      , typename Source
+      , typename Args
+      , typename Enable = ::boost::parameter::aux
+        ::is_target_same_as_source<Target,Source,Args>
+    >
+    struct cast_impl
+    {
+        typedef Source& type;
+
+        inline static Source& evaluate(Source& value)
+        {
+            return value;
+        }
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/type_traits/add_const.hpp>
+#include <boost/type_traits/add_lvalue_reference.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Covers the case where is_convertible<Source,Target> but not
+    // is_same<Source,Target>.  Use cases are covered
+    // by test/normalize_argument_types.cpp
+    template <typename Source, typename Target>
+    class cast_convert
+    {
+        typedef ::boost::parameter::aux::cast_convert<Source,Target> _self;
+
+     public:
+        typedef typename ::boost::add_lvalue_reference<
+            typename ::boost::add_const<Target>::type
+        >::type type;
+
+     private:
+        template <typename U>
+        inline static typename _self::type _mod_const(U const& u)
+        {
+            return u;
+        }
+
+        inline static Target _copy(Target value)
+        {
+            return value;
+        }
+
+     public:
+        inline static typename _self::type evaluate(Source& source)
+        {
+            return _self::_mod_const(_self::_copy(source));
+        }
+    };
+
+    template <typename Target, typename Source, typename Args>
+    struct cast_impl<Target,Source,Args,::boost::mpl::false_>
+      : ::boost::parameter::aux::cast_convert<
+            Source,
+            typename ::boost::mpl::apply2<
+                ::boost::parameter::aux::as_placeholder_expr<Target>
+              , Source
+              , Args
+            >::type
+        >
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/eval_if.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Target, typename Args>
+    struct cast<void(Target),Args>
+    {
+        template <typename T>
+        struct apply
+        {
+            typedef typename ::boost::mpl::eval_if<
+                    ::boost::parameter::aux
+                    ::is_target_same_as_source<Target,T,Args>
+                  , ::boost::add_lvalue_reference<T>
+                  , ::boost::parameter::aux::cast_impl<
+                        Target
+                      , T
+                      , Args
+                      , ::boost::mpl::false_
+                    >
+            >::type type;
+        };
+
+        inline static ::boost::parameter::aux::use_default_tag
+            execute(::boost::parameter::aux::use_default_tag)
+        {
+            return ::boost::parameter::aux::use_default_tag();
+        }
+
+        template <typename U>
+        inline static typename ::boost::parameter::aux
+        ::cast_impl<Target,U const,Args>::type
+            execute(U const& value)
+        {
+            return ::boost::parameter::aux
+            ::cast_impl<Target,U const,Args>::evaluate(value);
+        }
+
+        template <typename U>
+        inline static typename ::boost::parameter::aux
+        ::cast_impl<Target,U,Args>::type
+            execute(U& value)
+        {
+            return ::boost::parameter::aux
+            ::cast_impl<Target,U,Args>::evaluate(value);
+        }
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/apply_wrap.hpp>
+#include <boost/parameter/value_type.hpp>
+
+// Expands to the reference-qualified target type of the argument
+// as indicated by the predicate.
+#define BOOST_PARAMETER_FUNCTION_CAST_T(tag, predicate, args)                \
+    typename ::boost::mpl::apply_wrap1<                                      \
+        ::boost::parameter::aux::cast<void predicate, args>                  \
+      , typename ::boost::parameter::value_type<                             \
+            args                                                             \
+          , tag                                                              \
+          , ::boost::parameter::aux::use_default_tag                         \
+        >::type                                                              \
+    >::type
+/**/
+
+// Expands to the converted or passed-through value
+// as indicated by the predicate.
+#define BOOST_PARAMETER_FUNCTION_CAST_B(value, predicate, args)              \
+    ::boost::parameter::aux::cast<void predicate, args>::execute(value)
+/**/
+
+#endif  // perfect forwarding support, or Borland workarounds needed
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/function_dispatch_layer.hpp

@@ -0,0 +1,474 @@
+// Copyright Daniel Wallin 2006.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_DISPATCH_LAYER_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_DISPATCH_LAYER_HPP
+
+#include <boost/preprocessor/cat.hpp>
+
+// Expands to keyword_tag_type for some keyword_tag.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_TYPE(keyword_tag)              \
+    BOOST_PP_CAT(keyword_tag, _type)
+/**/
+
+// Expands to a template parameter for each dispatch function.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_TEMPLATE_ARG(r, macro, arg)        \
+  , typename BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_TYPE(macro(arg))
+/**/
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+// Expands to a forwarding parameter for a dispatch function.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_DEFN(r, macro, arg)            \
+  , BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_TYPE(macro(arg))&& macro(arg)
+/**/
+
+#include <utility>
+
+// Expands to an argument passed from one dispatch function to the next.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_FWD(r, macro, arg)             \
+  , ::std::forward<                                                          \
+        BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_TYPE(macro(arg))               \
+    >(macro(arg))
+/**/
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+// Expands to a forwarding parameter for a dispatch function.  The parameter
+// type stores its const-ness.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_DEFN(r, macro, arg)            \
+  , BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_TYPE(macro(arg))& macro(arg)
+/**/
+
+#include <boost/parameter/aux_/as_lvalue.hpp>
+
+// Expands to an argument passed from one dispatch function to the next.
+// Explicit forwarding takes the form of forcing the argument to be an lvalue.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_FWD(r, macro, arg)             \
+  , ::boost::parameter::aux::as_lvalue(macro(arg))
+/**/
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+
+#include <boost/parameter/aux_/preprocessor/impl/argument_specs.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/split_args.hpp>
+#include <boost/preprocessor/seq/for_each.hpp>
+#include <boost/preprocessor/seq/first_n.hpp>
+
+// Iterates through all required arguments and the first n optional arguments,
+// passing each argument to the specified macro.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_REPEAT(macro, n, split_args)   \
+    BOOST_PP_SEQ_FOR_EACH(                                                   \
+        macro                                                                \
+      , BOOST_PARAMETER_FN_ARG_NAME                                          \
+      , BOOST_PARAMETER_SPLIT_ARG_REQ_SEQ(split_args)                        \
+    )                                                                        \
+    BOOST_PP_SEQ_FOR_EACH(                                                   \
+        macro                                                                \
+      , BOOST_PARAMETER_FN_ARG_NAME                                          \
+      , BOOST_PP_SEQ_FIRST_N(                                                \
+            n, BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(split_args)                 \
+        )                                                                    \
+    )
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/function_dispatch_tuple.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/function_name.hpp>
+#include <boost/preprocessor/control/if.hpp>
+
+// Produces a name for the dispatch functions.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_NAME(x, n)                         \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(                                                     \
+                BOOST_PARAMETER_FUNCTION_DISPATCH_IS_CONST(x)                \
+              , boost_param_dispatch_const_                                  \
+              , boost_param_dispatch_                                        \
+            )                                                                \
+          , BOOST_PP_CAT(BOOST_PP_CAT(n, boost_), __LINE__)                  \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(                                \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_BASE_NAME(x)                   \
+        )                                                                    \
+    )
+/**/
+
+// Expands to the template parameter list of the dispatch function with all
+// required and first n optional parameters; also extracts the static keyword
+// if present.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_TPL(n, x)                     \
+    template <                                                               \
+        typename ResultType, typename Args                                   \
+        BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_REPEAT(                        \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_TEMPLATE_ARG                   \
+          , n                                                                \
+          , BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)                  \
+        )                                                                    \
+    > BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(                                \
+        BOOST_PARAMETER_FUNCTION_DISPATCH_BASE_NAME(x)                       \
+    )
+/**/
+
+#include <boost/parameter/aux_/use_default_tag.hpp>
+#include <boost/preprocessor/control/expr_if.hpp>
+#include <boost/preprocessor/punctuation/comma_if.hpp>
+
+// Expands to the result type, name, parenthesized list of all required and
+// n optional parameters, and const-ness of the dispatch function; the bit
+// value b determines whether or not this dispatch function takes in
+// boost::parameter::aux::use_default_tag as its last parameter.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_PRN(n, x, b1, b2)             \
+    ResultType BOOST_PARAMETER_FUNCTION_DISPATCH_NAME(x, b1)(                \
+        ResultType(*)(), Args const& args, long                              \
+        BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_REPEAT(                        \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_DEFN                       \
+          , n                                                                \
+          , BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)                  \
+        )                                                                    \
+        BOOST_PP_COMMA_IF(b2)                                                \
+        BOOST_PP_EXPR_IF(b2, ::boost::parameter::aux::use_default_tag)       \
+    ) BOOST_PP_EXPR_IF(BOOST_PARAMETER_FUNCTION_DISPATCH_IS_CONST(x), const)
+/**/
+
+// Expands to a forward declaration of the dispatch function that takes in
+// all required and the first n optional parameters, but not
+// boost::parameter::aux::use_default_tag.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_FWD_DECL_0_Z(z, n, x)              \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_TPL(n, x)                         \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_PRN(n, x, 0, 0);
+/**/
+
+// Expands to a forward declaration of the dispatch function that takes in
+// all required parameters, the first n optional parameters, and
+// boost::parameter::aux::use_default_tag.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_FWD_DECL_1_Z(z, n, x)              \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_TPL(n, x)                         \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_PRN(n, x, 0, 1);
+/**/
+
+#include <boost/preprocessor/seq/elem.hpp>
+
+// Expands to the default value of the (n + 1)th optional parameter.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_DEFAULT_AUX(n, s_args)             \
+    BOOST_PARAMETER_FN_ARG_DEFAULT(                                          \
+        BOOST_PP_SEQ_ELEM(n, BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(s_args))      \
+    )
+/**/
+
+#include <boost/parameter/keyword.hpp>
+
+// Expands to the assignment portion which binds the default value to the
+// (n + 1)th optional parameter before composing it with the argument-pack
+// parameter passed in to the n-th dispatch function.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_DEFAULT(n, s_args, tag_ns)         \
+    ::boost::parameter::keyword<                                             \
+        tag_ns::BOOST_PARAMETER_FN_ARG_NAME(                                 \
+            BOOST_PP_SEQ_ELEM(n, BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(s_args))  \
+        )                                                                    \
+    >::instance = BOOST_PARAMETER_FUNCTION_DISPATCH_DEFAULT_AUX(n, s_args)
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/function_cast.hpp>
+
+// Takes in the arg tuple (name, pred) and the tag namespace.
+// Extracts the corresponding required argument from the pack.
+// This form enables BOOST_PARAMETER_FUNCTION_DISPATCH_LAYER to use it
+// from within BOOST_PP_SEQ_FOR_EACH.
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+// The boost::parameter::aux::forward wrapper is necessary to transmit the
+// target type to the next dispatch function.  Otherwise, the argument will
+// retain its original type. -- Cromwell D. Enage
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_CAST_R(r, tag_ns, arg)         \
+  , ::boost::parameter::aux::forward<                                        \
+        BOOST_PARAMETER_FUNCTION_CAST_T(                                     \
+            tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                         \
+          , BOOST_PARAMETER_FN_ARG_PRED(arg)                                 \
+          , Args                                                             \
+        )                                                                    \
+      , BOOST_PARAMETER_FUNCTION_CAST_B(                                     \
+            tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                         \
+          , BOOST_PARAMETER_FN_ARG_PRED(arg)                                 \
+          , Args                                                             \
+        )                                                                    \
+    >(                                                                       \
+        args[                                                                \
+            ::boost::parameter::keyword<                                     \
+                tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                     \
+            >::instance                                                      \
+        ]                                                                    \
+    )
+/**/
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+// The explicit type cast is necessary to transmit the target type to the next
+// dispatch function.  Otherwise, the argument will retain its original type.
+// -- Cromwell D. Enage
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_CAST_R(r, tag_ns, arg)         \
+  , BOOST_PARAMETER_FUNCTION_CAST_T(                                         \
+        tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                             \
+      , BOOST_PARAMETER_FN_ARG_PRED(arg)                                     \
+      , Args                                                                 \
+    )(                                                                       \
+        args[                                                                \
+            ::boost::parameter::keyword<                                     \
+                tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                     \
+            >::instance                                                      \
+        ]                                                                    \
+    )
+/**/
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+
+// Takes in the arg tuple (name, pred, default) and the tag namespace.
+// Extracts the corresponding optional argument from the pack if specified,
+// otherwise temporarily passes use_default_tag() to the dispatch functions.
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+// The boost::parameter::aux::forward wrapper is necessary to transmit the
+// target type to the next dispatch function.  Otherwise, the argument will
+// retain its original type. -- Cromwell D. Enage
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_OPT_ARG_CAST(arg, tag_ns)          \
+    ::boost::parameter::aux::forward<                                        \
+        BOOST_PARAMETER_FUNCTION_CAST_T(                                     \
+            tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                         \
+          , BOOST_PARAMETER_FN_ARG_PRED(arg)                                 \
+          , Args                                                             \
+        )                                                                    \
+      , BOOST_PARAMETER_FUNCTION_CAST_B(                                     \
+            tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                         \
+          , BOOST_PARAMETER_FN_ARG_PRED(arg)                                 \
+          , Args                                                             \
+        )                                                                    \
+    >(                                                                       \
+        args[                                                                \
+            ::boost::parameter::keyword<                                     \
+                tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                     \
+            >::instance || ::boost::parameter::aux::use_default_tag()        \
+        ]                                                                    \
+    )
+/**/
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_OPT_ARG_CAST(arg, tag_ns)          \
+    BOOST_PARAMETER_FUNCTION_CAST_B(                                         \
+        args[                                                                \
+            ::boost::parameter::keyword<                                     \
+                tag_ns::BOOST_PARAMETER_FN_ARG_NAME(arg)                     \
+            >::instance || ::boost::parameter::aux::use_default_tag()        \
+        ]                                                                    \
+      , BOOST_PARAMETER_FN_ARG_PRED(arg)                                     \
+      , Args                                                                 \
+    )
+/**/
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+
+#include <boost/parameter/aux_/preprocessor/nullptr.hpp>
+
+// Expands to three dispatch functions that take in all required parameters
+// and the first n optional parameters.  The third dispatch function bears
+// the same name as the first but takes in use_default_tag as the last
+// parameter.  The second dispatch function bears a different name from the
+// other two.
+//
+// x is a tuple:
+//
+//   (name, split_args, is_const, tag_namespace)
+//
+// Where name is the base name of the functions, and split_args is a tuple:
+//
+//   (required_count, required_args, optional_count, required_args)
+//
+// The first dispatch function queries args if it has bound the (n + 1)th
+// optional parameter to a user-defined argument.  If so, then it forwards
+// its own arguments followed by the user-defined argument to the dispatch
+// function that takes in all required parameters and the first (n + 1)
+// optional parameters, but not use_default_tag.   Otherwise, it forwards
+// its own arguments to the third dispatch function.
+//
+// The third dispatch function appends the default value of the (n + 1)th
+// optional parameter to its copy of args.  Then it forwards this copy, all
+// required parameters, and the first n (not n + 1) optional parameters to
+// the second dispatch function.
+//
+// The second dispatch function forwards its arguments, then the (n + 1)th
+// optional parameter that it extracts from args, to the other-named dispatch
+// function that takes in all required parameters and the first (n + 1)
+// optional parameters, but not use_default_tag.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_OVERLOAD_Z(z, n, x)                \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_TPL(n, x)                         \
+    inline BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_PRN(n, x, 0, 0)            \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(                                             \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_IS_MEMBER(x)                   \
+          , this->                                                           \
+        ) BOOST_PARAMETER_FUNCTION_DISPATCH_NAME(x, 0)(                      \
+            static_cast<ResultType(*)()>(BOOST_PARAMETER_AUX_PP_NULLPTR)     \
+          , args                                                             \
+          , 0L                                                               \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_REPEAT(                    \
+                BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_FWD                    \
+              , n                                                            \
+              , BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)              \
+            )                                                                \
+          , BOOST_PARAMETER_FUNCTION_DISPATCH_OPT_ARG_CAST(                  \
+                BOOST_PP_SEQ_ELEM(                                           \
+                    n                                                        \
+                  , BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(                       \
+                        BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)      \
+                    )                                                        \
+                )                                                            \
+              , BOOST_PARAMETER_FUNCTION_DISPATCH_TAG_NAMESPACE(x)           \
+            )                                                                \
+        );                                                                   \
+    }                                                                        \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_TPL(n, x)                         \
+    inline BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_PRN(n, x, 1, 0)            \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(                                             \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_IS_MEMBER(x)                   \
+          , this->                                                           \
+        ) BOOST_PARAMETER_FUNCTION_DISPATCH_NAME(x, 0)(                      \
+            static_cast<ResultType(*)()>(BOOST_PARAMETER_AUX_PP_NULLPTR)     \
+          , args                                                             \
+          , 0L                                                               \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_REPEAT(                    \
+                BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_FWD                    \
+              , n                                                            \
+              , BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)              \
+            )                                                                \
+          , args[                                                            \
+                ::boost::parameter::keyword<                                 \
+                    BOOST_PARAMETER_FUNCTION_DISPATCH_TAG_NAMESPACE(x)::     \
+                    BOOST_PARAMETER_FN_ARG_NAME(                             \
+                        BOOST_PP_SEQ_ELEM(                                   \
+                            n                                                \
+                          , BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(               \
+                            BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)  \
+                            )                                                \
+                        )                                                    \
+                    )                                                        \
+                >::instance                                                  \
+            ]                                                                \
+        );                                                                   \
+    }                                                                        \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_TPL(n, x)                         \
+    inline BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_PRN(n, x, 0, 1)            \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(                                             \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_IS_MEMBER(x)                   \
+          , this->                                                           \
+        ) BOOST_PARAMETER_FUNCTION_DISPATCH_NAME(x, 1)(                      \
+            static_cast<ResultType(*)()>(BOOST_PARAMETER_AUX_PP_NULLPTR)     \
+          , (args                                                            \
+              , BOOST_PARAMETER_FUNCTION_DISPATCH_DEFAULT(                   \
+                    n                                                        \
+                  , BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)          \
+                  , BOOST_PARAMETER_FUNCTION_DISPATCH_TAG_NAMESPACE(x)       \
+                )                                                            \
+            )                                                                \
+          , 0L                                                               \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_REPEAT(                    \
+                BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_FWD                    \
+              , n                                                            \
+              , BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)              \
+            )                                                                \
+        );                                                                   \
+    }
+/**/
+
+#include <boost/preprocessor/arithmetic/inc.hpp>
+#include <boost/preprocessor/control/if.hpp>
+#include <boost/preprocessor/repetition/repeat_from_to.hpp>
+#include <boost/preprocessor/tuple/eat.hpp>
+
+// x is a tuple:
+//
+//   (base_name, split_args, is_member, is_const, tag_namespace)
+//
+// Generates all dispatch functions for the function named base_name.  Each
+// dispatch function that takes in n optional parameters passes the default
+// value of the (n + 1)th optional parameter to the next dispatch function.
+// The last dispatch function is the back-end implementation, so only the
+// header is generated: the user is expected to supply the body.
+//
+// Also generates the front-end implementation function, which uses
+// BOOST_PARAMETER_FUNCTION_CAST to extract each argument from the argument
+// pack.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_LAYER(fwd_decl, x)                 \
+    BOOST_PP_IF(fwd_decl, BOOST_PP_REPEAT_FROM_TO, BOOST_PP_TUPLE_EAT(4))(   \
+        0                                                                    \
+      , BOOST_PP_INC(                                                        \
+            BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(                             \
+                BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)              \
+            )                                                                \
+        )                                                                    \
+      , BOOST_PARAMETER_FUNCTION_DISPATCH_FWD_DECL_0_Z                       \
+      , x                                                                    \
+    )                                                                        \
+    BOOST_PP_IF(fwd_decl, BOOST_PP_REPEAT_FROM_TO, BOOST_PP_TUPLE_EAT(4))(   \
+        0                                                                    \
+      , BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(                                 \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)                  \
+        )                                                                    \
+      , BOOST_PARAMETER_FUNCTION_DISPATCH_FWD_DECL_1_Z                       \
+      , x                                                                    \
+    )                                                                        \
+    template <typename Args> BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(         \
+        BOOST_PARAMETER_FUNCTION_DISPATCH_BASE_NAME(x)                       \
+    ) inline typename BOOST_PARAMETER_FUNCTION_RESULT_NAME(                  \
+        BOOST_PARAMETER_FUNCTION_DISPATCH_BASE_NAME(x)                       \
+      , BOOST_PARAMETER_FUNCTION_DISPATCH_IS_CONST(x)                        \
+    )<Args>::type BOOST_PARAMETER_FUNCTION_IMPL_NAME(                        \
+        BOOST_PARAMETER_FUNCTION_DISPATCH_BASE_NAME(x)                       \
+      , BOOST_PARAMETER_FUNCTION_DISPATCH_IS_CONST(x)                        \
+    )(Args const& args)                                                      \
+    BOOST_PP_EXPR_IF(BOOST_PARAMETER_FUNCTION_DISPATCH_IS_CONST(x), const)   \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(                                             \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_IS_MEMBER(x)                   \
+          , this->                                                           \
+        ) BOOST_PARAMETER_FUNCTION_DISPATCH_NAME(x, 0)(                      \
+            static_cast<                                                     \
+                typename BOOST_PARAMETER_FUNCTION_RESULT_NAME(               \
+                    BOOST_PARAMETER_FUNCTION_DISPATCH_BASE_NAME(x)           \
+                  , BOOST_PARAMETER_FUNCTION_DISPATCH_IS_CONST(x)            \
+                )<Args>::type(*)()                                           \
+            >(BOOST_PARAMETER_AUX_PP_NULLPTR)                                \
+          , args                                                             \
+          , 0L                                                               \
+            BOOST_PP_SEQ_FOR_EACH(                                           \
+                BOOST_PARAMETER_FUNCTION_DISPATCH_ARG_CAST_R                 \
+              , BOOST_PARAMETER_FUNCTION_DISPATCH_TAG_NAMESPACE(x)           \
+              , BOOST_PARAMETER_SPLIT_ARG_REQ_SEQ(                           \
+                    BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)          \
+                )                                                            \
+            )                                                                \
+        );                                                                   \
+    }                                                                        \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        0                                                                    \
+      , BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(                                 \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)                  \
+        )                                                                    \
+      , BOOST_PARAMETER_FUNCTION_DISPATCH_OVERLOAD_Z                         \
+      , x                                                                    \
+    )                                                                        \
+    BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_TPL(                              \
+        BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(                                 \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)                  \
+        )                                                                    \
+      , x                                                                    \
+    )                                                                        \
+    inline BOOST_PARAMETER_FUNCTION_DISPATCH_HEAD_PRN(                       \
+        BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(                                 \
+            BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)                  \
+        )                                                                    \
+      , x                                                                    \
+      , 0                                                                    \
+      , 0                                                                    \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/function_dispatch_tuple.hpp

@@ -0,0 +1,33 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_DISPATCH_TUPLE_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_DISPATCH_TUPLE_HPP
+
+#include <boost/preprocessor/tuple/elem.hpp>
+
+// Accessor macros for the input tuple to the dispatch macros.
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_BASE_NAME(x)                       \
+    BOOST_PP_TUPLE_ELEM(5, 0, x)
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_SPLIT_ARGS(x)                      \
+    BOOST_PP_TUPLE_ELEM(5, 1, x)
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_IS_MEMBER(x)                       \
+    BOOST_PP_TUPLE_ELEM(5, 2, x)
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_IS_CONST(x)                        \
+    BOOST_PP_TUPLE_ELEM(5, 3, x)
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_DISPATCH_TAG_NAMESPACE(x)                   \
+    BOOST_PP_TUPLE_ELEM(5, 4, x)
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/function_forward_match.hpp

@@ -0,0 +1,43 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_FORWARD_MATCH_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_FORWARD_MATCH_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if !defined(BOOST_NO_SFINAE) && \
+    !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x592))
+
+#include <boost/parameter/aux_/pp_impl/match.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
+
+// Expands to an extra argument that is well-formed
+// iff all Args... satisfy the requirements set by params.
+#define BOOST_PARAMETER_FUNCTION_FORWARD_MATCH(params, n, prefix)            \
+  , typename ::boost::parameter::aux::match<                                 \
+        params BOOST_PP_ENUM_TRAILING_PARAMS(n, prefix)                      \
+    >::type = params()
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_FORWARD_MATCH_Z(z, params, n, prefix)       \
+  , typename ::boost::parameter::aux::match<                                 \
+        params BOOST_PP_ENUM_TRAILING_PARAMS_Z(z, n, prefix)                 \
+    >::type = params()
+/**/
+
+#else   // SFINAE/Borland workarounds needed.
+
+#define BOOST_PARAMETER_FUNCTION_FORWARD_MATCH(params, n, prefix)            \
+  , params = params()
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_FORWARD_MATCH_Z(z, params, n, prefix)       \
+  , params = params()
+/**/
+
+#endif
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/function_name.hpp

@@ -0,0 +1,152 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_NAME_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_FUNCTION_NAME_HPP
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_CHECK_STATIC_static ()
+/**/
+
+#include <boost/parameter/aux_/preprocessor/is_nullary.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_IS_STATIC(name)                      \
+    BOOST_PARAMETER_IS_NULLARY(                                              \
+        BOOST_PP_CAT(BOOST_PARAMETER_MEMBER_FUNCTION_CHECK_STATIC_, name)    \
+    )
+/**/
+
+#include <boost/preprocessor/seq/seq.hpp>
+#include <boost/config.hpp>
+
+#if defined(BOOST_MSVC)
+
+// Workaround for MSVC preprocessor.
+//
+// When stripping static from "static f", msvc will produce " f".  The leading
+// whitespace doesn't go away when pasting the token with something else, so
+// this thing is a hack to strip the whitespace.
+#define BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC_static (
+/**/
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC_AUX(name)               \
+    BOOST_PP_CAT(BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC_, name))
+/**/
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC(name)                   \
+    BOOST_PP_SEQ_HEAD(                                                       \
+        BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC_AUX(name)               \
+    )
+/**/
+
+#else
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC_static
+/**/
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC(name)                   \
+    BOOST_PP_CAT(BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC_, name)
+/**/
+
+#endif  // MSVC workarounds needed
+
+#include <boost/preprocessor/control/expr_if.hpp>
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(name)                         \
+    BOOST_PP_EXPR_IF(                                                        \
+        BOOST_PARAMETER_MEMBER_FUNCTION_IS_STATIC(name), static              \
+    )
+/**/
+
+#include <boost/preprocessor/control/if.hpp>
+#include <boost/preprocessor/tuple/eat.hpp>
+
+#define BOOST_PARAMETER_MEMBER_FUNCTION_NAME(name)                           \
+    BOOST_PP_IF(                                                             \
+        BOOST_PARAMETER_MEMBER_FUNCTION_IS_STATIC(name)                      \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_STRIP_STATIC                         \
+      , name BOOST_PP_TUPLE_EAT(1)                                           \
+    )(name)
+/**/
+
+// Produces a name for a parameter specification for the function named base.
+#define BOOST_PARAMETER_FUNCTION_SPECIFICATION_NAME(base, is_const)          \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(                                                     \
+                is_const                                                     \
+              , boost_param_parameters_const_                                \
+              , boost_param_parameters_                                      \
+            )                                                                \
+          , __LINE__                                                         \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(base)                           \
+    )
+/**/
+
+// Produces a name for a result type metafunction for the no-spec function
+// named base.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(base, is_const)         \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(                                                     \
+                is_const                                                     \
+              , boost_param_no_spec_result_const_                            \
+              , boost_param_no_spec_result_                                  \
+            )                                                                \
+          , __LINE__                                                         \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(base)                           \
+    )
+/**/
+
+// Produces a name for a result type metafunction for the function named base.
+#define BOOST_PARAMETER_FUNCTION_RESULT_NAME(base, is_const)                 \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(                                                     \
+                is_const                                                     \
+              , boost_param_result_const_                                    \
+              , boost_param_result_                                          \
+            )                                                                \
+          , __LINE__                                                         \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(base)                           \
+    )
+/**/
+
+// Produces a name for the implementation function to which the no-spec
+// function named base forwards its result type and argument pack.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_IMPL_NAME(base, is_const)           \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(                                                     \
+                is_const                                                     \
+              , boost_param_no_spec_impl_const                               \
+              , boost_param_no_spec_impl                                     \
+            )                                                                \
+          , __LINE__                                                         \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(base)                           \
+    )
+/**/
+
+// Can't do boost_param_impl_ ## basee
+// because base might start with an underscore.
+// daniel: what? how is that relevant? the reason for using CAT()
+// is to make sure base is expanded. i'm not sure we need to here,
+// but it's more stable to do it.
+#define BOOST_PARAMETER_FUNCTION_IMPL_NAME(base, is_const)                   \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(is_const, boost_param_impl_const, boost_param_impl)  \
+          , __LINE__                                                         \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(base)                           \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/no_spec_overloads.hpp

@@ -0,0 +1,331 @@
+// Copyright Cromwell D. Enage 2018.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_NO_SPEC_OVERLOADS_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_NO_SPEC_OVERLOADS_HPP
+
+#include <boost/parameter/aux_/preprocessor/impl/function_name.hpp>
+
+// Defines the no-spec implementation function header.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_IMPL_HEAD(name, is_const)           \
+    template <typename ResultType, typename Args>                            \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(name) ResultType                  \
+        BOOST_PARAMETER_NO_SPEC_FUNCTION_IMPL_NAME(                          \
+            name, is_const                                                   \
+        )(ResultType(*)(), Args const& args)
+/**/
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#include <boost/parameter/aux_/preprocessor/impl/parenthesized_return_type.hpp>
+
+// Expands to the result metafunction for the specified no-spec function.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_HEAD(result, name, is_const)        \
+    template <typename TaggedArg0, typename ...TaggedArgs>                   \
+    using BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(name, is_const)       \
+    = typename BOOST_PARAMETER_PARENTHESIZED_RETURN_TYPE(result);
+/**/
+#else
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_HEAD(result, name, is_const)        \
+    template <typename TaggedArg0, typename ...TaggedArgs>                   \
+    struct BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(name, is_const)      \
+      : BOOST_PARAMETER_PARENTHESIZED_RETURN_TYPE(result)                    \
+    {                                                                        \
+    };
+/**/
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+#include <boost/parameter/compose.hpp>
+#include <boost/parameter/are_tagged_arguments.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/parenthesized_type.hpp>
+#include <boost/core/enable_if.hpp>
+
+// Exapnds to a variadic constructor that is enabled if and only if all its
+// arguments are tagged arguments.  The enclosing class must inherit from the
+// specified base class, which in turn must implement a constructor that takes
+// in the argument pack that this one passes on.
+#define BOOST_PARAMETER_NO_SPEC_CONSTRUCTOR(class_, base)                    \
+    template <                                                               \
+        typename TaggedArg0                                                  \
+      , typename ...TaggedArgs                                               \
+      , typename = typename ::boost::enable_if<                              \
+            ::boost::parameter                                               \
+            ::are_tagged_arguments<TaggedArg0,TaggedArgs...>                 \
+        >::type                                                              \
+    > inline explicit                                                        \
+    class_(TaggedArg0 const& arg0, TaggedArgs const&... args)                \
+      : BOOST_PARAMETER_PARENTHESIZED_TYPE(base)(                            \
+            ::boost::parameter::compose(arg0, args...)                       \
+        )                                                                    \
+    {                                                                        \
+    }
+/**/
+
+// Exapnds to a variadic constructor that is enabled if and only if all its
+// arguments are tagged arguments.  The specified function must be able to
+// take in the argument pack that this constructor passes on.
+#define BOOST_PARAMETER_NO_SPEC_NO_BASE_CONSTRUCTOR(class_, func)            \
+    template <                                                               \
+        typename TaggedArg0                                                  \
+      , typename ...TaggedArgs                                               \
+      , typename = typename ::boost::enable_if<                              \
+            ::boost::parameter                                               \
+            ::are_tagged_arguments<TaggedArg0,TaggedArgs...>                 \
+        >::type                                                              \
+    > inline explicit                                                        \
+    class_(TaggedArg0 const& arg0, TaggedArgs const&... args)                \
+    {                                                                        \
+        func(::boost::parameter::compose(arg0, args...));                    \
+    }
+/**/
+
+#include <boost/parameter/aux_/preprocessor/nullptr.hpp>
+#include <boost/preprocessor/control/expr_if.hpp>
+
+// Exapnds to a variadic function that is enabled if and only if
+// all its arguments are tagged arguments.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_OVERLOAD(name, impl, is_m, c)       \
+    template <typename TaggedArg0, typename ...TaggedArgs>                   \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(impl)                             \
+    inline typename ::boost::lazy_enable_if<                                 \
+        ::boost::parameter                                                   \
+        ::are_tagged_arguments<TaggedArg0,TaggedArgs...>                     \
+      , BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(                        \
+            impl, c                                                          \
+        )<TaggedArg0,TaggedArgs...>                                          \
+    >::type BOOST_PARAMETER_MEMBER_FUNCTION_NAME(name)                       \
+    (TaggedArg0 const& arg0, TaggedArgs const&... args)                      \
+    BOOST_PP_EXPR_IF(c, const)                                               \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(is_m, this->)                                \
+        BOOST_PARAMETER_NO_SPEC_FUNCTION_IMPL_NAME(impl, c)(                 \
+            static_cast<                                                     \
+                typename BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(       \
+                    impl, c                                                  \
+                )<TaggedArg0,TaggedArgs...>::type(*)()                       \
+            >(BOOST_PARAMETER_AUX_PP_NULLPTR)                                \
+          , ::boost::parameter::compose(arg0, args...)                       \
+        );                                                                   \
+    }
+/**/
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/parenthesized_return_type.hpp>
+#include <boost/preprocessor/facilities/intercept.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+
+// Expands to the result metafunction for the specified no-spec function.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_HEAD(result, name, is_const)        \
+    template <                                                               \
+        BOOST_PP_ENUM_BINARY_PARAMS(                                         \
+            BOOST_PARAMETER_COMPOSE_MAX_ARITY                                \
+          , typename TaggedArg                                               \
+          , = ::boost::parameter::void_ BOOST_PP_INTERCEPT                   \
+        )                                                                    \
+    >                                                                        \
+    struct BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(name, is_const)      \
+      : BOOST_PARAMETER_PARENTHESIZED_RETURN_TYPE(result)                    \
+    {                                                                        \
+    };
+/**/
+
+#include <boost/parameter/compose.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/parenthesized_type.hpp>
+#include <boost/preprocessor/comparison/equal.hpp>
+#include <boost/preprocessor/control/expr_if.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/tuple/elem.hpp>
+
+#if defined(BOOST_NO_SFINAE)
+
+// Exapnds to a tagged-argument constructor overload that passes the argument
+// pack to the base class delegate constructor.
+#define BOOST_PARAMETER_NO_SPEC_CONSTRUCTOR_OVERLOAD_Z(z, n, data)           \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename TaggedArg)>              \
+    BOOST_PP_EXPR_IF(BOOST_PP_EQUAL(n, 1), explicit) inline                  \
+    BOOST_PP_TUPLE_ELEM(2, 0, data)(                                         \
+        BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, TaggedArg, const& arg)           \
+    ) : BOOST_PARAMETER_PARENTHESIZED_TYPE(BOOST_PP_TUPLE_ELEM(2, 1, data))( \
+            ::boost::parameter::compose(BOOST_PP_ENUM_PARAMS_Z(z, n, arg))   \
+        )                                                                    \
+    {                                                                        \
+    }
+/**/
+
+// Exapnds to a tagged-argument constructor overload that passes the argument
+// pack to the delegate function.
+#define BOOST_PARAMETER_NO_SPEC_NO_BASE_CONSTRUCTOR_OVERLOAD_Z(z, n, data)   \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename TaggedArg)>              \
+    BOOST_PP_EXPR_IF(BOOST_PP_EQUAL(n, 1), explicit) inline                  \
+    BOOST_PP_TUPLE_ELEM(2, 0, data)(                                         \
+        BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, TaggedArg, const& a)             \
+    )                                                                        \
+    {                                                                        \
+        BOOST_PP_TUPLE_ELEM(2, 1, data)(                                     \
+            ::boost::parameter::compose(BOOST_PP_ENUM_PARAMS_Z(z, n, a))     \
+        );                                                                   \
+    }
+/**/
+
+#include <boost/parameter/aux_/preprocessor/nullptr.hpp>
+
+// Exapnds to a tagged-argument function overload.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_OVERLOAD_Z(z, n, data)              \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename TaggedArg)>              \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(BOOST_PP_TUPLE_ELEM(4, 1, data))  \
+    inline typename BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(            \
+        BOOST_PP_TUPLE_ELEM(4, 1, data)                                      \
+      , BOOST_PP_TUPLE_ELEM(4, 3, data)                                      \
+    )<BOOST_PP_ENUM_PARAMS_Z(z, n, TaggedArg)>::type                         \
+        BOOST_PARAMETER_MEMBER_FUNCTION_NAME(                                \
+            BOOST_PP_TUPLE_ELEM(4, 0, data)                                  \
+        )(BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, TaggedArg, const& arg))        \
+        BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 3, data), const)             \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 2, data), this->)     \
+        BOOST_PARAMETER_NO_SPEC_FUNCTION_IMPL_NAME(                          \
+            BOOST_PP_TUPLE_ELEM(4, 1, data)                                  \
+          , BOOST_PP_TUPLE_ELEM(4, 3, data)                                  \
+        )(                                                                   \
+            static_cast<                                                     \
+                typename BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(       \
+                    BOOST_PP_TUPLE_ELEM(4, 1, data)                          \
+                  , BOOST_PP_TUPLE_ELEM(4, 3, data)                          \
+                )<BOOST_PP_ENUM_PARAMS_Z(z, n, TaggedArg)>::type(*)()        \
+            >(BOOST_PARAMETER_AUX_PP_NULLPTR)                                \
+          , ::boost::parameter::compose(BOOST_PP_ENUM_PARAMS_Z(z, n, arg))   \
+        );                                                                   \
+    }
+/**/
+
+#else   // !defined(BOOST_NO_SFINAE)
+
+#include <boost/parameter/are_tagged_arguments.hpp>
+#include <boost/parameter/aux_/preprocessor/nullptr.hpp>
+#include <boost/core/enable_if.hpp>
+
+// Exapnds to a tagged-argument constructor overload that passes the argument
+// pack to the base class delegate constructor.  This constructor is enabled
+// if and only if all its arguments are tagged arguments.
+#define BOOST_PARAMETER_NO_SPEC_CONSTRUCTOR_OVERLOAD_Z(z, n, data)           \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename TaggedArg)>              \
+    BOOST_PP_EXPR_IF(BOOST_PP_EQUAL(n, 1), explicit) inline                  \
+    BOOST_PP_TUPLE_ELEM(2, 0, data)(                                         \
+        BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, TaggedArg, const& arg)           \
+      , typename ::boost::enable_if<                                         \
+            ::boost::parameter::are_tagged_arguments<                        \
+                BOOST_PP_ENUM_PARAMS_Z(z, n, TaggedArg)                      \
+            >                                                                \
+        >::type* = BOOST_PARAMETER_AUX_PP_NULLPTR                            \
+    ) : BOOST_PARAMETER_PARENTHESIZED_TYPE(BOOST_PP_TUPLE_ELEM(2, 1, data))( \
+            ::boost::parameter::compose(BOOST_PP_ENUM_PARAMS_Z(z, n, arg))   \
+        )                                                                    \
+    {                                                                        \
+    }
+/**/
+
+// Exapnds to a tagged-argument constructor overload that passes the argument
+// pack to the delegate function.  This constructor is enabled if and only if
+// all its arguments are tagged arguments.
+#define BOOST_PARAMETER_NO_SPEC_NO_BASE_CONSTRUCTOR_OVERLOAD_Z(z, n, data)   \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename TaggedArg)>              \
+    BOOST_PP_EXPR_IF(BOOST_PP_EQUAL(n, 1), explicit) inline                  \
+    BOOST_PP_TUPLE_ELEM(2, 0, data)(                                         \
+        BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, TaggedArg, const& a)             \
+      , typename ::boost::enable_if<                                         \
+            ::boost::parameter::are_tagged_arguments<                        \
+                BOOST_PP_ENUM_PARAMS_Z(z, n, TaggedArg)                      \
+            >                                                                \
+        >::type* = BOOST_PARAMETER_AUX_PP_NULLPTR                            \
+    )                                                                        \
+    {                                                                        \
+        BOOST_PP_TUPLE_ELEM(2, 1, data)(                                     \
+            ::boost::parameter::compose(BOOST_PP_ENUM_PARAMS_Z(z, n, a))     \
+        );                                                                   \
+    }
+/**/
+
+// Exapnds to a function overload that is enabled if and only if
+// all its arguments are tagged arguments.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_OVERLOAD_Z(z, n, data)              \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename TaggedArg)>              \
+    BOOST_PARAMETER_MEMBER_FUNCTION_STATIC(BOOST_PP_TUPLE_ELEM(4, 1, data))  \
+    inline typename ::boost::lazy_enable_if<                                 \
+        ::boost::parameter                                                   \
+        ::are_tagged_arguments<BOOST_PP_ENUM_PARAMS_Z(z, n, TaggedArg)>      \
+      , BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(                        \
+            BOOST_PP_TUPLE_ELEM(4, 1, data)                                  \
+          , BOOST_PP_TUPLE_ELEM(4, 3, data)                                  \
+        )<BOOST_PP_ENUM_PARAMS_Z(z, n, TaggedArg)>                           \
+    >::type BOOST_PARAMETER_MEMBER_FUNCTION_NAME(                            \
+        BOOST_PP_TUPLE_ELEM(4, 0, data)                                      \
+    )(BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, TaggedArg, const& arg))            \
+    BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 3, data), const)                 \
+    {                                                                        \
+        return BOOST_PP_EXPR_IF(BOOST_PP_TUPLE_ELEM(4, 2, data), this->)     \
+        BOOST_PARAMETER_NO_SPEC_FUNCTION_IMPL_NAME(                          \
+            BOOST_PP_TUPLE_ELEM(4, 1, data)                                  \
+          , BOOST_PP_TUPLE_ELEM(4, 3, data)                                  \
+        )(                                                                   \
+            static_cast<                                                     \
+                typename BOOST_PARAMETER_NO_SPEC_FUNCTION_RESULT_NAME(       \
+                    BOOST_PP_TUPLE_ELEM(4, 1, data)                          \
+                  , BOOST_PP_TUPLE_ELEM(4, 3, data)                          \
+                )<BOOST_PP_ENUM_PARAMS_Z(z, n, TaggedArg)>::type(*)()        \
+            >(BOOST_PARAMETER_AUX_PP_NULLPTR)                                \
+          , ::boost::parameter::compose(BOOST_PP_ENUM_PARAMS_Z(z, n, arg))   \
+        );                                                                   \
+    }
+/**/
+
+#endif  // BOOST_NO_SFINAE
+
+#include <boost/preprocessor/arithmetic/inc.hpp>
+#include <boost/preprocessor/repetition/repeat_from_to.hpp>
+
+// Emulates a variadic constructor that is enabled if and only if all its
+// arguments are tagged arguments.  The enclosing class must inherit from the
+// specified base class, which in turn must implement a constructor that takes
+// in the argument pack that this one passes on.
+#define BOOST_PARAMETER_NO_SPEC_CONSTRUCTOR(class_, base)                    \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        1                                                                    \
+      , BOOST_PP_INC(BOOST_PARAMETER_COMPOSE_MAX_ARITY)                      \
+      , BOOST_PARAMETER_NO_SPEC_CONSTRUCTOR_OVERLOAD_Z                       \
+      , (class_, base)                                                       \
+    )
+/**/
+
+// Emulates a variadic constructor that is enabled if and only if all its
+// arguments are tagged arguments.  The specified function must be able to
+// take in the argument pack that this constructor passes on.
+#define BOOST_PARAMETER_NO_SPEC_NO_BASE_CONSTRUCTOR(class_, func)            \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        1                                                                    \
+      , BOOST_PP_INC(BOOST_PARAMETER_COMPOSE_MAX_ARITY)                      \
+      , BOOST_PARAMETER_NO_SPEC_NO_BASE_CONSTRUCTOR_OVERLOAD_Z               \
+      , (class_, func)                                                       \
+    )
+/**/
+
+// Emulates a variadic function that is enabled if and only if
+// all its arguments are tagged arguments.
+#define BOOST_PARAMETER_NO_SPEC_FUNCTION_OVERLOAD(name, impl, is_m, c)       \
+    BOOST_PP_REPEAT_FROM_TO(                                                 \
+        1                                                                    \
+      , BOOST_PP_INC(BOOST_PARAMETER_COMPOSE_MAX_ARITY)                      \
+      , BOOST_PARAMETER_NO_SPEC_FUNCTION_OVERLOAD_Z                          \
+      , (name, impl, is_m, c)                                                \
+    )
+/**/
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/parenthesized_return_type.hpp

@@ -0,0 +1,122 @@
+// Copyright Cromwell D. Enage 2019.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_PARENTHESIZED_RETURN_TYPE_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_PARENTHESIZED_RETURN_TYPE_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // A metafunction that transforms void(*)(T) -> identity<T>
+    template <typename UnaryFunctionPointer>
+    struct unaryfunptr_return_type;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/identity.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Arg>
+    struct unaryfunptr_return_type<void(*)(Arg)>
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_identity<Arg>;
+#else
+        typedef ::boost::mpl::identity<Arg> type;
+#endif
+    };
+
+    template <>
+    struct unaryfunptr_return_type<void(*)(void)>
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_identity<void>;
+#else
+        typedef ::boost::mpl::identity<void> type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#if !defined(BOOST_NO_SFINAE)
+#include <boost/core/enable_if.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Pred, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::enable_if<Pred,Ret>)>
+    {
+        typedef ::boost::enable_if<Pred,Ret> type;
+    };
+
+    template <bool b, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::enable_if_c<b,Ret>)>
+    {
+        typedef ::boost::enable_if_c<b,Ret> type;
+    };
+
+    template <typename Pred, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::lazy_enable_if<Pred,Ret>)>
+    {
+        typedef ::boost::lazy_enable_if<Pred,Ret> type;
+    };
+
+    template <bool b, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::lazy_enable_if_c<b,Ret>)>
+    {
+        typedef ::boost::lazy_enable_if_c<b,Ret> type;
+    };
+
+    template <typename Pred, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::disable_if<Pred,Ret>)>
+    {
+        typedef ::boost::disable_if<Pred,Ret> type;
+    };
+
+    template <bool b, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::disable_if_c<b,Ret>)>
+    {
+        typedef ::boost::disable_if_c<b,Ret> type;
+    };
+
+    template <typename B, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::lazy_disable_if<B,Ret>)>
+    {
+        typedef ::boost::lazy_disable_if<B,Ret> type;
+    };
+
+    template <bool b, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::boost::lazy_disable_if_c<b,Ret>)>
+    {
+        typedef ::boost::lazy_disable_if_c<b,Ret> type;
+    };
+}}} // namespace boost::parameter::aux
+
+#if !defined(BOOST_NO_CXX11_HDR_TYPE_TRAITS)
+#include <type_traits>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <bool b, typename Ret>
+    struct unaryfunptr_return_type<void(*)(::std::enable_if<b,Ret>)>
+    {
+        typedef ::std::enable_if<b,Ret> type;
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_NO_CXX11_HDR_TYPE_TRAITS
+#endif  // BOOST_NO_SFINAE
+
+// A macro that takes a parenthesized C++ type name (T) and transforms it
+// into an un-parenthesized type expression equivalent to identity<T>.
+#define BOOST_PARAMETER_PARENTHESIZED_RETURN_TYPE(x)                         \
+    ::boost::parameter::aux::unaryfunptr_return_type< void(*)x >::type
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/parenthesized_type.hpp

@@ -0,0 +1,34 @@
+// Copyright David Abrahams 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_PARENTHESIZED_TYPE_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_PARENTHESIZED_TYPE_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // A metafunction that transforms void(*)(T) -> T
+    template <typename UnaryFunctionPointer>
+    struct unaryfunptr_arg_type;
+
+    template <typename Arg>
+    struct unaryfunptr_arg_type<void(*)(Arg)>
+    {
+        typedef Arg type;
+    };
+
+    template <>
+    struct unaryfunptr_arg_type<void(*)(void)>
+    {
+        typedef void type;
+    };
+}}} // namespace boost::parameter::aux
+
+// A macro that takes a parenthesized C++ type name (T) and transforms it
+// into an un-parenthesized type expression equivalent to T.
+#define BOOST_PARAMETER_PARENTHESIZED_TYPE(x)                                \
+    ::boost::parameter::aux::unaryfunptr_arg_type< void(*)x >::type
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/specification.hpp

@@ -0,0 +1,109 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_SPECIFICATION_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_SPECIFICATION_HPP
+
+#include <boost/parameter/optional.hpp>
+
+// Helper macros for BOOST_PARAMETER_SPECIFICATION_ELEM_R.
+#define BOOST_PARAMETER_QUALIFIED_TAG_optional(tag)                          \
+    optional<tag
+/**/
+
+#include <boost/parameter/required.hpp>
+
+#define BOOST_PARAMETER_QUALIFIED_TAG_required(tag)                          \
+    required<tag
+/**/
+
+#include <boost/parameter/deduced.hpp>
+
+#define BOOST_PARAMETER_QUALIFIED_TAG_deduced_optional(tag)                  \
+    optional< ::boost::parameter::deduced<tag>
+/**/
+
+#define BOOST_PARAMETER_QUALIFIED_TAG_deduced_required(tag)                  \
+    required< ::boost::parameter::deduced<tag>
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/argument_specs.hpp>
+#include <boost/parameter/config.hpp>
+#include <boost/preprocessor/punctuation/comma_if.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+
+#include <boost/parameter/aux_/use_default.hpp>
+
+#define BOOST_PARAMETER_SPECIFICATION_ELEM_R(r, tag_namespace, i, elem)      \
+    BOOST_PP_COMMA_IF(i) ::boost::parameter::BOOST_PP_CAT(                   \
+        BOOST_PARAMETER_QUALIFIED_TAG_                                       \
+      , BOOST_PARAMETER_FN_ARG_QUALIFIER(elem)                               \
+    )(tag_namespace::BOOST_PARAMETER_FN_ARG_NAME(elem))                      \
+      , ::boost::parameter::aux::use_default                                 \
+    >
+/**/
+
+#else   // !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+
+#include <boost/parameter/aux_/pp_impl/unwrap_predicate.hpp>
+
+// Expands to each boost::parameter::parameters<> element type.
+#define BOOST_PARAMETER_SPECIFICATION_ELEM_R(r, tag_namespace, i, elem)      \
+    BOOST_PP_COMMA_IF(i) ::boost::parameter::BOOST_PP_CAT(                   \
+        BOOST_PARAMETER_QUALIFIED_TAG_                                       \
+      , BOOST_PARAMETER_FN_ARG_QUALIFIER(elem)                               \
+    )(tag_namespace::BOOST_PARAMETER_FN_ARG_NAME(elem))                      \
+      , typename ::boost::parameter::aux::unwrap_predicate<                  \
+            void BOOST_PARAMETER_FN_ARG_PRED(elem)                           \
+        >::type                                                              \
+    >
+/**/
+
+#endif  // Borland workarounds needed.
+
+#include <boost/parameter/parameters.hpp>
+#include <boost/parameter/aux_/preprocessor/impl/function_name.hpp>
+#include <boost/preprocessor/control/if.hpp>
+#include <boost/preprocessor/seq/for_each_i.hpp>
+
+// Expands to a boost::parameter::parameters<> specialization for the
+// function named base.  Used by BOOST_PARAMETER_CONSTRUCTOR_AUX and
+// BOOST_PARAMETER_FUNCTION_HEAD for their respective ParameterSpec models.
+#define BOOST_PARAMETER_SPECIFICATION(tag_ns, base, split_args, is_const)    \
+    template <typename BoostParameterDummy>                                  \
+    struct BOOST_PP_CAT(                                                     \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(                                                     \
+                is_const                                                     \
+              , boost_param_params_const_                                    \
+              , boost_param_params_                                          \
+            )                                                                \
+          , __LINE__                                                         \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(base)                           \
+    ) : ::boost::parameter::parameters<                                      \
+            BOOST_PP_SEQ_FOR_EACH_I(                                         \
+                BOOST_PARAMETER_SPECIFICATION_ELEM_R, tag_ns, split_args     \
+            )                                                                \
+        >                                                                    \
+    {                                                                        \
+    };                                                                       \
+    typedef BOOST_PP_CAT(                                                    \
+        BOOST_PP_CAT(                                                        \
+            BOOST_PP_IF(                                                     \
+                is_const                                                     \
+              , boost_param_params_const_                                    \
+              , boost_param_params_                                          \
+            )                                                                \
+          , __LINE__                                                         \
+        )                                                                    \
+      , BOOST_PARAMETER_MEMBER_FUNCTION_NAME(base)                           \
+    )<int>
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/impl/split_args.hpp

@@ -0,0 +1,71 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_SPLIT_ARGS_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IMPL_SPLIT_ARGS_HPP
+
+#include <boost/preprocessor/tuple/elem.hpp>
+
+// Accessor macros for the split_args tuple.
+#define BOOST_PARAMETER_SPLIT_ARG_REQ_COUNT(x) BOOST_PP_TUPLE_ELEM(4, 0, x)
+#define BOOST_PARAMETER_SPLIT_ARG_REQ_SEQ(x) BOOST_PP_TUPLE_ELEM(4, 1, x)
+#define BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(x) BOOST_PP_TUPLE_ELEM(4, 2, x)
+#define BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(x) BOOST_PP_TUPLE_ELEM(4, 3, x)
+
+#include <boost/preprocessor/arithmetic/inc.hpp>
+#include <boost/preprocessor/seq/push_back.hpp>
+
+// Helper macros for BOOST_PARAMETER_FUNCTION_SPLIT_ARGS.
+#define BOOST_PARAMETER_FUNCTION_SPLIT_ARG_required(s_a, arg)                \
+    (                                                                        \
+        BOOST_PP_INC(BOOST_PARAMETER_SPLIT_ARG_REQ_COUNT(s_a))               \
+      , BOOST_PP_SEQ_PUSH_BACK(BOOST_PARAMETER_SPLIT_ARG_REQ_SEQ(s_a), arg)  \
+      , BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(s_a)                             \
+      , BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(s_a)                               \
+    )
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_SPLIT_ARG_deduced_required(split_args, arg) \
+    BOOST_PARAMETER_FUNCTION_SPLIT_ARG_required(split_args, arg)
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_SPLIT_ARG_optional(s_a, arg)                \
+    (                                                                        \
+        BOOST_PARAMETER_SPLIT_ARG_REQ_COUNT(s_a)                             \
+      , BOOST_PARAMETER_SPLIT_ARG_REQ_SEQ(s_a)                               \
+      , BOOST_PP_INC(BOOST_PARAMETER_SPLIT_ARG_OPT_COUNT(s_a))               \
+      , BOOST_PP_SEQ_PUSH_BACK(BOOST_PARAMETER_SPLIT_ARG_OPT_SEQ(s_a), arg)  \
+    )
+/**/
+
+#define BOOST_PARAMETER_FUNCTION_SPLIT_ARG_deduced_optional(split_args, arg) \
+    BOOST_PARAMETER_FUNCTION_SPLIT_ARG_optional(split_args, arg)
+/**/
+
+#include <boost/parameter/aux_/preprocessor/impl/argument_specs.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_FUNCTION_SPLIT_ARG(s, split_args, arg)               \
+    BOOST_PP_CAT(                                                            \
+        BOOST_PARAMETER_FUNCTION_SPLIT_ARG_                                  \
+      , BOOST_PARAMETER_FN_ARG_QUALIFIER(arg)                                \
+    )(split_args, arg)
+/**/
+
+#include <boost/preprocessor/seq/fold_left.hpp>
+#include <boost/preprocessor/seq/seq.hpp>
+
+// Expands from the flattened BOOST_PARAMETER_FUNCTION et. al. arg sequence to
+// the tuple (required_count, required_args, optional_count, optional_args).
+#define BOOST_PARAMETER_FUNCTION_SPLIT_ARGS(args)                            \
+    BOOST_PP_SEQ_FOLD_LEFT(                                                  \
+        BOOST_PARAMETER_FUNCTION_SPLIT_ARG                                   \
+      , (0, BOOST_PP_SEQ_NIL, 0, BOOST_PP_SEQ_NIL)                           \
+      , args                                                                 \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/inc_binary_seq.hpp

@@ -0,0 +1,78 @@
+// Copyright Cromwell D. Enage 2013.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_INC_BINARY_SEQ_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_INC_BINARY_SEQ_HPP
+
+#include <boost/preprocessor/seq/push_back.hpp>
+
+// This macro keeps the rest of the sequence if carry == 0.
+#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_0(seq, element) \
+    (BOOST_PP_SEQ_PUSH_BACK(seq, element), 0)
+/**/
+
+#include <boost/preprocessor/control/iif.hpp>
+
+// This macro updates the rest of the sequence if carry == 1.
+#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_1(seq, element) \
+    (BOOST_PP_SEQ_PUSH_BACK(seq, BOOST_PP_IIF(element, 0, 1)), element)
+/**/
+
+#include <boost/preprocessor/tuple/elem.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+// This macro maintains a tuple (seq, carry), where seq is the intermediate
+// result and carry is a flag that will unset upon finding an element == 0.
+#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_OP(s, result_tuple, element) \
+    BOOST_PP_CAT( \
+        BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_ \
+      , BOOST_PP_TUPLE_ELEM(2, 1, result_tuple) \
+    )(BOOST_PP_TUPLE_ELEM(2, 0, result_tuple), element)
+/**/
+
+// This macro keeps the sequence at its original length if carry == 0.
+#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_0(seq) seq
+/**/
+
+// This macro appends a zero to seq if carry == 1.
+#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_1(seq) \
+    BOOST_PP_SEQ_PUSH_BACK(seq, 0)
+/**/
+
+// This macro takes in the tuple (seq, carry), with carry indicating whether
+// or not seq originally contained all 1s.  If so, then seq now contains all
+// 0s, and this macro pushes an extra 0 before expanding to the new sequence.
+// Otherwise, this macro expands to seq as is.
+#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL(seq_and_carry) \
+    BOOST_PP_CAT( \
+        BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_ \
+      , BOOST_PP_TUPLE_ELEM(2, 1, seq_and_carry) \
+    )(BOOST_PP_TUPLE_ELEM(2, 0, seq_and_carry))
+/**/
+
+#include <boost/preprocessor/seq/seq.hpp>
+#include <boost/preprocessor/seq/fold_left.hpp>
+
+// This macro treats the specified sequence of 1s and 0s like a binary number
+// in reverse and expands to a sequence representing the next value up.
+// However, if the input sequence contains all 1s, then the output sequence
+// will contain one more element but all 0s.
+//
+// Examples:
+// seq = (1)(0)(1)(0) --> return (0)(1)(1)(0)
+// seq = (1)(1)(1)(0) --> return (0)(0)(0)(1)
+// seq = (1)(1)(1)(1) --> return (0)(0)(0)(0)(0)
+#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ(seq) \
+    BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL( \
+        BOOST_PP_SEQ_FOLD_LEFT( \
+            BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_OP \
+          , (BOOST_PP_SEQ_NIL, 1) \
+          , seq \
+        ) \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/is_binary.hpp

@@ -0,0 +1,31 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IS_BINARY_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IS_BINARY_HPP
+
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+// From Paul Mensonides
+#include <boost/preprocessor/punctuation/comma.hpp>
+#include <boost/preprocessor/detail/split.hpp>
+#define BOOST_PARAMETER_IS_BINARY(x) \
+    BOOST_PP_SPLIT(1, BOOST_PARAMETER_IS_BINARY_C x BOOST_PP_COMMA() 0)
+/**/
+#include <boost/preprocessor/punctuation/paren.hpp>
+#include <boost/preprocessor/tuple/eat.hpp>
+#define BOOST_PARAMETER_IS_BINARY_C(x,y) \
+    ~, 1 BOOST_PP_RPAREN() \
+    BOOST_PP_TUPLE_EAT(2) BOOST_PP_LPAREN() ~
+/**/
+#else
+#include <boost/preprocessor/detail/is_binary.hpp>
+#define BOOST_PARAMETER_IS_BINARY(x) BOOST_PP_IS_BINARY(x)
+#endif
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/is_nullary.hpp

@@ -0,0 +1,32 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_IS_NULLARY_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_IS_NULLARY_HPP
+
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+// From Paul Mensonides
+#include <boost/preprocessor/punctuation/comma.hpp>
+#include <boost/preprocessor/detail/split.hpp>
+#define BOOST_PARAMETER_IS_NULLARY(x) \
+    BOOST_PP_SPLIT(1, BOOST_PARAMETER_IS_NULLARY_C x BOOST_PP_COMMA() 0)
+/**/
+#include <boost/preprocessor/punctuation/paren.hpp>
+#include <boost/preprocessor/tuple/eat.hpp>
+#define BOOST_PARAMETER_IS_NULLARY_C() \
+    ~, 1 BOOST_PP_RPAREN() \
+    BOOST_PP_TUPLE_EAT(2) BOOST_PP_LPAREN() ~
+/**/
+#else
+#include <boost/preprocessor/detail/is_nullary.hpp>
+#define BOOST_PARAMETER_IS_NULLARY(x) BOOST_PP_IS_NULLARY(x)
+/**/
+#endif
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/no_perfect_forwarding_begin.hpp

@@ -0,0 +1,165 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// No include guard.  This file is intended for multiple inclusion.
+
+#define BOOST_PARAMETER_right_angle(z, n, _) >
+/**/
+
+#define BOOST_PARAMETER_satisfies_end(z, n, false_t) ,false_t>
+/**/
+
+#include <boost/preprocessor/seq/elem.hpp>
+#include <boost/preprocessor/cat.hpp>
+
+// Generates:
+//
+//   make<
+//       parameter_spec##0, argument_type##0
+//     , make<
+//           parameter_spec##1, argument_type##1
+//         , ... boost::mpl::identity<boost::parameter::aux::empty_arg_list>
+//    ...>
+//   >
+#define BOOST_PARAMETER_make_arg_list(z, n, names)                           \
+    BOOST_PP_SEQ_ELEM(0, names)<                                             \
+        BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(1, names), n),                        \
+        BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(2, names), n),
+/**/
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/preprocessor/repetition/repeat.hpp>
+
+#define BOOST_PARAMETER_build_arg_list(n, make, param_spec, arg_type)        \
+    BOOST_PP_REPEAT(                                                         \
+        n, BOOST_PARAMETER_make_arg_list, (make)(param_spec)(arg_type)       \
+    )                                                                        \
+    ::boost::mpl::identity< ::boost::parameter::void_>                       \
+    BOOST_PP_REPEAT(n, BOOST_PARAMETER_right_angle, _)
+/**/
+
+#define BOOST_PARAMETER_make_deduced_list(z, n, names)                       \
+    BOOST_PP_SEQ_ELEM(0, names)<BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(1, names), n),
+/**/
+
+#define BOOST_PARAMETER_build_deduced_list(n, make, parameter_spec)          \
+    BOOST_PP_REPEAT(                                                         \
+        n, BOOST_PARAMETER_make_deduced_list, (make)(parameter_spec)         \
+    )                                                                        \
+    ::boost::mpl::identity< ::boost::parameter::void_>                       \
+    BOOST_PP_REPEAT(n, BOOST_PARAMETER_right_angle, _)
+/**/
+
+#define BOOST_PARAMETER_forward_typedef(z, n, names)                         \
+    typedef BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(0, names), n)                     \
+    BOOST_PP_CAT(BOOST_PP_SEQ_ELEM(1, names), n);
+/**/
+
+#define BOOST_PARAMETER_template_args(z, n, prefix)                          \
+    typename BOOST_PP_CAT(prefix, n) = ::boost::parameter::void_
+/**/
+
+#include <boost/mpl/pair.hpp>
+
+#if (0 < BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY)
+
+#include <boost/parameter/aux_/pack/item.hpp>
+#include <boost/preprocessor/control/iif.hpp>
+
+#define BOOST_PARAMETER_make_arg_items_R(r, prefix, i, elem)                 \
+    ::boost::parameter::aux::item<BOOST_PP_CAT(prefix, i),                   \
+    BOOST_PP_CAT(A, i) BOOST_PP_IIF(elem, &, const&),
+/**/
+
+#include <boost/parameter/aux_/pack/make_arg_list.hpp>
+#include <boost/parameter/aux_/pack/tag_keyword_arg.hpp>
+#include <boost/preprocessor/seq/for_each_i.hpp>
+#include <boost/preprocessor/seq/size.hpp>
+
+#define BOOST_PARAMETER_function_call_arg_list_R(r, seq)                     \
+    ::boost::parameter::aux::make_arg_list<                                  \
+        BOOST_PP_SEQ_FOR_EACH_I_R(                                           \
+            r, BOOST_PARAMETER_make_arg_items_R, PS, seq                     \
+        )                                                                    \
+        ::boost::parameter::void_                                            \
+        BOOST_PP_REPEAT(                                                     \
+            BOOST_PP_SEQ_SIZE(seq), BOOST_PARAMETER_right_angle, _           \
+        )                                                                    \
+      , deduced_list                                                         \
+      , ::boost::parameter::aux::tag_keyword_arg                             \
+    >
+/**/
+
+#include <boost/preprocessor/arithmetic/sub.hpp>
+
+#define BOOST_PARAMETER_function_call_arg_pack_init(z, n, limit)             \
+    BOOST_PP_CAT(a, BOOST_PP_SUB(limit, n))
+/**/
+
+#include <boost/parameter/aux_/preprocessor/binary_seq_to_args.hpp>
+#include <boost/preprocessor/arithmetic/dec.hpp>
+#include <boost/preprocessor/facilities/intercept.hpp>
+#include <boost/preprocessor/repetition/enum.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
+#include <boost/preprocessor/seq/seq.hpp>
+
+#define BOOST_PARAMETER_function_call_op_overload_R(r, seq)                  \
+    template <                                                               \
+        BOOST_PP_ENUM_PARAMS(                                                \
+            BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq))                             \
+          , typename A                                                       \
+        )                                                                    \
+    >                                                                        \
+    inline typename ::boost::mpl::first<                                     \
+        typename BOOST_PARAMETER_function_call_arg_list_R(                   \
+            r, BOOST_PP_SEQ_TAIL(seq)                                        \
+        )::type                                                              \
+    >::type                                                                  \
+        operator()(                                                          \
+            BOOST_PARAMETER_AUX_PP_BINARY_SEQ_TO_ARGS(                       \
+                BOOST_PP_SEQ_TAIL(seq), (A)(a)                               \
+            )                                                                \
+        ) const                                                              \
+    {                                                                        \
+        typedef typename BOOST_PARAMETER_function_call_arg_list_R(           \
+            r, BOOST_PP_SEQ_TAIL(seq)                                        \
+        )::type result;                                                      \
+        typedef typename ::boost::mpl::first<result>::type result_type;      \
+        typedef typename ::boost::mpl::second<result>::type error;           \
+        error();                                                             \
+        return result_type(                                                  \
+            BOOST_PP_ENUM(                                                   \
+                BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq))                         \
+              , BOOST_PARAMETER_function_call_arg_pack_init                  \
+              , BOOST_PP_DEC(BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq)))           \
+            )                                                                \
+            BOOST_PP_ENUM_TRAILING_PARAMS(                                   \
+                BOOST_PP_SUB(                                                \
+                    BOOST_PARAMETER_COMPOSE_MAX_ARITY                        \
+                  , BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq))                     \
+                )                                                            \
+              , ::boost::parameter::aux::void_reference() BOOST_PP_INTERCEPT \
+            )                                                                \
+        );                                                                   \
+    }
+/**/
+
+#endif  // exponential overloads
+
+#include <boost/parameter/aux_/pack/satisfies.hpp>
+#include <boost/mpl/eval_if.hpp>
+
+#define BOOST_PARAMETER_satisfies_begin(z, n, prefix)                        \
+    ::boost::mpl::eval_if<                                                   \
+        ::boost::parameter::aux::satisfies_requirements_of<                  \
+            typename ::boost::mpl::first<ArgumentPackAndError>::type         \
+          , BOOST_PP_CAT(prefix, n)                                          \
+        >,
+/**/
+

include/boost/parameter/aux_/preprocessor/no_perfect_forwarding_end.hpp

@@ -0,0 +1,24 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// No include guard.  This file is intended for multiple inclusion.
+
+#undef BOOST_PARAMETER_satisfies_begin
+#if (0 < BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY)
+#undef BOOST_PARAMETER_function_call_op_overload_R
+#undef BOOST_PARAMETER_function_call_arg_pack_init
+#undef BOOST_PARAMETER_function_call_arg_list_R
+#undef BOOST_PARAMETER_make_arg_items_R
+#endif
+#undef BOOST_PARAMETER_template_args
+#undef BOOST_PARAMETER_forward_typedef
+#undef BOOST_PARAMETER_build_deduced_list
+#undef BOOST_PARAMETER_make_deduced_list
+#undef BOOST_PARAMETER_build_arg_list
+#undef BOOST_PARAMETER_make_arg_list
+#undef BOOST_PARAMETER_satisfies_end
+#undef BOOST_PARAMETER_right_angle
+

include/boost/parameter/aux_/preprocessor/nullptr.hpp

@@ -0,0 +1,18 @@
+// Copyright Cromwell D. Enage 2019.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_NULLPTR_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_NULLPTR_HPP
+
+#include <boost/config.hpp>
+
+#if defined(BOOST_NO_CXX11_NULLPTR)
+#define BOOST_PARAMETER_AUX_PP_NULLPTR 0
+#else
+#define BOOST_PARAMETER_AUX_PP_NULLPTR nullptr
+#endif
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/overloads.hpp

@@ -0,0 +1,92 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// This file generates overloads in this format:
+//
+//     template <typename A0, typename A1>
+//     typename ::boost::mpl::apply_wrap1<
+//         ::boost::parameter::aux::make_arg_list<
+//             PS0,A0
+//           , ::boost::parameter::aux::make_arg_list<
+//                 PS1,A1
+//               , ::boost::mpl::identity<
+//                     ::boost::parameter::aux::empty_arg_list
+//                 >
+//             >
+//         >
+//      , unnamed_list
+//     >::type
+//         operator()(A0 const& a0, A1 const& a1) const
+//     {
+//         typedef typename ::boost::mpl::apply_wrap1<
+//             ::boost::parameter::aux::make_arg_list<
+//                 PS0,A0
+//               , ::boost::parameter::aux::make_arg_list<
+//                     PS1,A1
+//                   , ::boost::mpl::identity<
+//                         ::boost::parameter::aux::empty_arg_list
+//                     >
+//                 >
+//             >
+//         >::type arg_tuple;
+//
+//         return arg_tuple(
+//             a0
+//           , a1
+//           , ::boost::parameter::aux::void_()
+//             ...
+//         );
+//     }
+//
+
+#if !defined(BOOST_PP_IS_ITERATING)
+# error Boost.Parameters - do not include this file!
+#endif
+
+#define N BOOST_PP_ITERATION()
+
+#define BOOST_PARAMETER_open_list(z, n, text) \
+    ::boost::parameter::aux::item< \
+        BOOST_PP_CAT(PS, n), BOOST_PP_CAT(A, n)
+
+#define BOOST_PARAMETER_close_list(z, n, text) > 
+
+#define BOOST_PARAMETER_arg_list(n) \
+    ::boost::parameter::aux::make_arg_list< \
+        BOOST_PP_ENUM(N, BOOST_PARAMETER_open_list, _) \
+      , ::boost::parameter::void_ \
+        BOOST_PP_REPEAT(N, BOOST_PARAMETER_close_list, _) \
+      , deduced_list \
+      , ::boost::parameter::aux::tag_keyword_arg \
+    >
+
+#define BOOST_PARAMETER_arg_pack_init(z, n, limit) \
+    BOOST_PP_CAT(a, BOOST_PP_SUB(limit, n))
+
+template <BOOST_PP_ENUM_PARAMS(N, typename A)>
+typename ::boost::mpl::first<
+    typename BOOST_PARAMETER_arg_list(N)::type
+>::type
+    operator()(BOOST_PP_ENUM_BINARY_PARAMS(N, A, & a)) const
+{
+    typedef typename BOOST_PARAMETER_arg_list(N)::type result;
+    typedef typename ::boost::mpl::first<result>::type result_type;
+    typedef typename ::boost::mpl::second<result>::type error;
+    error();
+
+    return result_type(
+        BOOST_PP_ENUM(N, BOOST_PARAMETER_arg_pack_init, BOOST_PP_DEC(N))
+        BOOST_PP_ENUM_TRAILING_PARAMS(
+            BOOST_PP_SUB(BOOST_PARAMETER_COMPOSE_MAX_ARITY, N)
+          , ::boost::parameter::aux::void_reference() BOOST_PP_INTERCEPT
+        )
+    );
+}
+
+#undef BOOST_PARAMETER_arg_list
+#undef BOOST_PARAMETER_close_list
+#undef BOOST_PARAMETER_open_list
+#undef N
+

include/boost/parameter/aux_/preprocessor/qualifier.hpp

@@ -0,0 +1,88 @@
+// Copyright Daniel Wallin 2006.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_QUALIFIER_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_QUALIFIER_HPP
+
+#define BOOST_PARAMETER_QUALIFIER_EAT_in(x)
+#define BOOST_PARAMETER_QUALIFIER_EAT_out(x)
+#define BOOST_PARAMETER_QUALIFIER_EAT_in_out(x)
+#define BOOST_PARAMETER_QUALIFIER_EAT_consume(x)
+#define BOOST_PARAMETER_QUALIFIER_EAT_move_from(x)
+#define BOOST_PARAMETER_QUALIFIER_EAT_forward(x)
+
+#define BOOST_PARAMETER_GET_QUALIFIER_in(x) in_reference
+#define BOOST_PARAMETER_GET_QUALIFIER_out(x) out_reference
+#define BOOST_PARAMETER_GET_QUALIFIER_in_out(x) in_out_reference
+#define BOOST_PARAMETER_GET_QUALIFIER_consume(x) consume_reference
+#define BOOST_PARAMETER_GET_QUALIFIER_move_from(x) move_from_reference
+#define BOOST_PARAMETER_GET_QUALIFIER_forward(x) forward_reference
+
+#define BOOST_PARAMETER_STRIP_QUALIFIER_in(x) x
+#define BOOST_PARAMETER_STRIP_QUALIFIER_out(x) x
+#define BOOST_PARAMETER_STRIP_QUALIFIER_in_out(x) x
+#define BOOST_PARAMETER_STRIP_QUALIFIER_consume(x) x
+#define BOOST_PARAMETER_STRIP_QUALIFIER_move_from(x) x
+#define BOOST_PARAMETER_STRIP_QUALIFIER_forward(x) x
+
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_GET_QUALIFIER_GET(x) \
+    BOOST_PP_CAT(BOOST_PARAMETER_GET_QUALIFIER_, x)
+/**/
+
+#define BOOST_PARAMETER_GET_UNQUALIFIED(x) \
+    BOOST_PP_CAT(BOOST_PARAMETER_STRIP_QUALIFIER_, x)
+/**/
+
+#include <boost/preprocessor/facilities/is_empty.hpp>
+
+// Expands to 1 if x is either "in(k)", "out(k)", "in_out(k)", "consume(k)",
+// "move_from(k)", or "forward(k)"; expands to 0 otherwise.
+#define BOOST_PARAMETER_IS_QUALIFIER(x) \
+    BOOST_PP_IS_EMPTY(BOOST_PP_CAT(BOOST_PARAMETER_QUALIFIER_EAT_, x))
+/**/
+
+#include <boost/preprocessor/control/iif.hpp>
+
+// Expands to the qualifier of x,
+// where x is either a keyword qualifier or a keyword.
+//
+//   k => forward_reference
+//   in(k) => in_reference
+//   out(k) => out_reference
+//   in_out(k) => in_out_reference
+//   forward(k) => forward_reference
+//   consume(k) => consume_reference
+//   move_from(k) => move_from_reference
+#define BOOST_PARAMETER_GET_QUALIFIER(x) \
+    BOOST_PP_IIF( \
+        BOOST_PARAMETER_IS_QUALIFIER(x) \
+      , BOOST_PARAMETER_GET_QUALIFIER_GET(x) \
+      , forward_reference \
+    )
+/**/
+
+// Expands to the unqualified version of x,
+// where x is either a keyword qualifier or a keyword.
+//
+//   k => k
+//   in(k) => k
+//   out(k) => k
+//   in_out(k) => k
+//   forward(k) => k
+//   consume(k) => k
+//   move_from(k) => k
+#define BOOST_PARAMETER_UNQUALIFIED(x) \
+    BOOST_PP_IIF( \
+        BOOST_PARAMETER_IS_QUALIFIER(x) \
+      , BOOST_PARAMETER_GET_UNQUALIFIED(x) \
+      , x \
+    )
+/**/
+
+#endif  // include guard
+

include/boost/parameter/aux_/preprocessor/seq_enum.hpp

@@ -0,0 +1,26 @@
+// Copyright David Abrahams 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_SEQ_ENUM_HPP
+#define BOOST_PARAMETER_AUX_PREPROCESSOR_SEQ_ENUM_HPP
+
+#include <boost/preprocessor/seq/enum.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+#if BOOST_WORKAROUND(__MWERKS__, <= 0x3003)
+#include <boost/preprocessor/seq/size.hpp>
+// Temporary version of BOOST_PP_SEQ_ENUM
+// until Paul M. integrates the workaround.
+#define BOOST_PARAMETER_SEQ_ENUM_I(size, seq) \
+    BOOST_PP_CAT(BOOST_PP_SEQ_ENUM_, size) seq
+#define BOOST_PARAMETER_SEQ_ENUM(seq) \
+    BOOST_PARAMETER_SEQ_ENUM_I(BOOST_PP_SEQ_SIZE(seq), seq)
+#else
+#define BOOST_PARAMETER_SEQ_ENUM(seq) BOOST_PP_SEQ_ENUM(seq)
+#endif
+
+#endif  // include guard
+

include/boost/parameter/aux_/result_of0.hpp

@@ -1,36 +1,53 @@
-// Copyright David Abrahams 2005. Distributed under the Boost
-// Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+// Copyright David Abrahams 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
 #ifndef BOOST_PARAMETER_AUX_RESULT_OF0_DWA2005511_HPP
-# define BOOST_PARAMETER_AUX_RESULT_OF0_DWA2005511_HPP
+#define BOOST_PARAMETER_AUX_RESULT_OF0_DWA2005511_HPP
 
-# include <boost/utility/result_of.hpp>
-
-// A metafunction returning the result of invoking a nullary function
-// object of the given type.
-
-#ifndef BOOST_NO_RESULT_OF
-
-# include <boost/utility/result_of.hpp>
-namespace boost { namespace parameter { namespace aux { 
-template <class F>
-struct result_of0 : result_of<F()>
-{};
-
-}}} // namespace boost::parameter::aux_
+#include <boost/parameter/aux_/use_default_tag.hpp>
+#include <boost/parameter/config.hpp>
+#include <boost/utility/result_of.hpp>
 
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
 #else
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/is_void.hpp>
+#endif
 
-namespace boost { namespace parameter { namespace aux { 
-template <class F>
-struct result_of0
-{
-    typedef typename F::result_type type;
-};
+namespace boost { namespace parameter { namespace aux {
 
-}}} // namespace boost::parameter::aux_
+    // A metafunction returning the result of invoking
+    // a nullary function object of the given type.
+    template <typename F>
+    class result_of0
+    {
+#if defined(BOOST_NO_RESULT_OF)
+        typedef typename F::result_type result_of_F;
+#else
+        typedef typename ::boost::result_of<F()>::type result_of_F;
+#endif
 
-#endif 
+     public:
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_if<
+            ::std::is_void<result_of_F>
+#else
+        typedef typename ::boost::mpl::if_<
+            ::boost::is_void<result_of_F>
+#endif
+          , ::boost::parameter::aux::use_default_tag
+          , result_of_F
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        >;
+#else
+        >::type type;
+#endif
+    };
+}}} // namespace boost::parameter::aux
 
+#endif  // include guard
 
-#endif // BOOST_PARAMETER_AUX_RESULT_OF0_DWA2005511_HPP

include/boost/parameter/aux_/set.hpp

@@ -0,0 +1,118 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_SET_060912_HPP
+#define BOOST_PARAMETER_SET_060912_HPP
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/list.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    typedef ::boost::mp11::mp_list<> set0;
+}}} // namespace boost::parameter::aux
+
+#include <boost/mp11/algorithm.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename S, typename K>
+    struct insert_
+    {
+        using type = ::boost::mp11::mp_insert_c<S,0,K>;
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Set, typename K>
+    struct has_key_
+    {
+        using type = ::boost::mp11::mp_if<
+            ::boost::mp11::mp_empty<Set>
+          , ::boost::mp11::mp_false
+          , ::std::is_same<
+                ::boost::mp11::mp_find<Set,K>
+              , ::boost::mp11::mp_size<Set>
+            >
+        >;
+    };
+}}} // namespace boost::parameter::aux
+
+#elif BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+#include <boost/mpl/list.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    typedef ::boost::mpl::list0<> set0;
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/push_front.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Set, typename K>
+    struct insert_ : ::boost::mpl::push_front<Set,K>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/end.hpp>
+#include <boost/mpl/find.hpp>
+#include <boost/type_traits/is_same.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Set, typename K>
+    struct has_key_
+    {
+        typedef typename ::boost::mpl::find<Set,K>::type iter;
+        typedef typename ::boost::mpl::if_<
+            ::boost::is_same<iter,typename ::boost::mpl::end<Set>::type>
+          , ::boost::mpl::false_
+          , ::boost::mpl::true_
+        >::type type;
+    };
+}}} // namespace boost::parameter::aux
+
+#else   // !BOOST_PARAMETER_CAN_USE_MP11 && Borland workarounds not needed
+#include <boost/mpl/set/set0.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    typedef ::boost::mpl::set0<> set0;
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/insert.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Set, typename K>
+    struct insert_ : ::boost::mpl::insert<Set,K>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/mpl/has_key.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Set, typename K>
+    struct has_key_ : ::boost::mpl::has_key<Set,K>
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11 || Borland workarounds needed
+#endif  // include guard
+

include/boost/parameter/aux_/tag.hpp

@@ -1,38 +1,160 @@
-// Copyright David Abrahams 2005. Distributed under the Boost
-// Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-#ifndef BOOST_PARAMETER_AUX_TAG_DWA2005610_HPP
-# define BOOST_PARAMETER_AUX_TAG_DWA2005610_HPP
+// Copyright David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
 
-# include <boost/parameter/aux_/unwrap_cv_reference.hpp>
-# include <boost/parameter/aux_/tagged_argument.hpp>
+#ifndef BOOST_PARAMETER_AUX_TAG_DWA2005610_HPP
+#define BOOST_PARAMETER_AUX_TAG_DWA2005610_HPP
+
+#include <boost/parameter/aux_/unwrap_cv_reference.hpp>
+#include <boost/parameter/aux_/tagged_argument.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11) && \
+    !BOOST_WORKAROUND(BOOST_MSVC, >= 1910)
+// MSVC-14.1+ assigns rvalue references to tagged_argument instances
+// instead of tagged_argument_rref instances with this code.
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
 
 namespace boost { namespace parameter { namespace aux { 
 
-template <class Keyword, class ActualArg
-#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
-        , class = typename is_cv_reference_wrapper<ActualArg>::type
-#endif 
-          >
-struct tag
-{
-    typedef tagged_argument<
-        Keyword
-      , typename unwrap_cv_reference<ActualArg>::type
-    > type;
-};
+    template <typename Keyword, typename Arg>
+    struct tag_if_lvalue_reference
+    {
+        using type = ::boost::parameter::aux::tagged_argument_list_of_1<
+            ::boost::parameter::aux::tagged_argument<
+                Keyword
+              , typename ::boost::parameter::aux
+                ::unwrap_cv_reference<Arg>::type
+            >
+        >;
+    };
 
-#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
-template <class Keyword, class ActualArg>
-struct tag<Keyword,ActualArg,mpl::false_>
-{
-    typedef tagged_argument<
-        Keyword
-      , ActualArg
-    > type;
-};
-#endif 
+    template <typename Keyword, typename Arg>
+    struct tag_if_scalar
+    {
+        using type = ::boost::parameter::aux::tagged_argument_list_of_1<
+            ::boost::parameter::aux
+            ::tagged_argument<Keyword,typename ::std::add_const<Arg>::type>
+        >;
+    };
 
+    template <typename Keyword, typename Arg>
+    using tag_if_otherwise = ::boost::mp11::mp_if<
+        ::std::is_scalar<typename ::std::remove_const<Arg>::type>
+      , ::boost::parameter::aux::tag_if_scalar<Keyword,Arg>
+      , ::boost::mp11::mp_identity<
+            ::boost::parameter::aux::tagged_argument_list_of_1<
+                ::boost::parameter::aux::tagged_argument_rref<Keyword,Arg>
+            >
+        >
+    >;
+
+    template <typename Keyword, typename Arg>
+    using tag = ::boost::mp11::mp_if<
+        ::boost::mp11::mp_if<
+            ::std::is_lvalue_reference<Arg>
+          , ::boost::mp11::mp_true
+          , ::boost::parameter::aux::is_cv_reference_wrapper<Arg>
+        >
+      , ::boost::parameter::aux::tag_if_lvalue_reference<Keyword,Arg>
+      , ::boost::parameter::aux::tag_if_otherwise<Keyword,Arg>
+    >;
 }}} // namespace boost::parameter::aux_
 
-#endif // BOOST_PARAMETER_AUX_TAG_DWA2005610_HPP
+#elif defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/type_traits/add_const.hpp>
+#include <boost/type_traits/is_scalar.hpp>
+#include <boost/type_traits/is_lvalue_reference.hpp>
+#include <boost/type_traits/remove_const.hpp>
+
+namespace boost { namespace parameter { namespace aux { 
+
+    template <typename Keyword, typename ActualArg>
+    struct tag
+    {
+        typedef typename ::boost::parameter::aux
+        ::unwrap_cv_reference<ActualArg>::type Arg;
+        typedef typename ::boost::add_const<Arg>::type ConstArg;
+        typedef typename ::boost::remove_const<Arg>::type MutArg;
+        typedef typename ::boost::mpl::eval_if<
+            typename ::boost::mpl::if_<
+                ::boost::is_lvalue_reference<ActualArg>
+              , ::boost::mpl::true_
+              , ::boost::parameter::aux::is_cv_reference_wrapper<ActualArg>
+            >::type
+          , ::boost::mpl::identity<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+                ::boost::parameter::aux::tagged_argument_list_of_1<
+#endif
+                    ::boost::parameter::aux::tagged_argument<Keyword,Arg>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+                >
+#endif
+            >
+          , ::boost::mpl::if_<
+                ::boost::is_scalar<MutArg>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+              , ::boost::parameter::aux::tagged_argument_list_of_1<
+                    ::boost::parameter::aux::tagged_argument<Keyword,ConstArg>
+                >
+              , ::boost::parameter::aux::tagged_argument_list_of_1<
+                    ::boost::parameter::aux::tagged_argument_rref<Keyword,Arg>
+                >
+#else
+              , ::boost::parameter::aux::tagged_argument<Keyword,ConstArg>
+              , ::boost::parameter::aux::tagged_argument_rref<Keyword,Arg>
+#endif
+            >
+        >::type type;
+    };
+}}} // namespace boost::parameter::aux_
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+namespace boost { namespace parameter { namespace aux { 
+
+    template <
+        typename Keyword
+      , typename Arg
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+      , typename = typename ::boost::parameter::aux
+        ::is_cv_reference_wrapper<Arg>::type
+#endif
+    >
+    struct tag
+    {
+        typedef ::boost::parameter::aux::tagged_argument<
+            Keyword
+          , typename ::boost::parameter::aux::unwrap_cv_reference<Arg>::type
+        > type;
+    };
+}}} // namespace boost::parameter::aux_
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+#include <boost/mpl/bool.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
+namespace boost { namespace parameter { namespace aux { 
+
+    template <typename Keyword, typename Arg>
+    struct tag<Keyword,Arg,::boost::mpl::false_>
+    {
+        typedef ::boost::parameter::aux::tagged_argument<
+            Keyword
+          , typename ::boost::remove_reference<Arg>::type
+        > type;
+    };
+}}} // namespace boost::parameter::aux_
+
+#endif  // Borland workarounds needed.
+#endif  // MP11 or perfect forwarding support
+#endif  // include guard
+

include/boost/parameter/aux_/tagged_argument.hpp

@@ -1,60 +1,903 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef TAGGED_ARGUMENT_050328_HPP
-#define TAGGED_ARGUMENT_050328_HPP
-
-#include <boost/parameter/aux_/void.hpp>
-#include <boost/parameter/aux_/arg_list.hpp>
-#include <boost/detail/is_xxx.hpp>
+#ifndef BOOST_PARAMETER_TAGGED_ARGUMENT_050328_HPP
+#define BOOST_PARAMETER_TAGGED_ARGUMENT_050328_HPP
 
 namespace boost { namespace parameter { namespace aux {
 
-// Holds a reference to an argument of type Arg associated with
-// keyword Keyword
-    
-template <class Keyword, class Arg>
-struct tagged_argument
-{
-    typedef Keyword key_type;
-    typedef Arg value_type;
-    typedef Arg& reference;
-
-    tagged_argument(reference x) : value(x) {}
-
-    // Comma operator to compose argument list without using parameters<>.
-    // Useful for argument lists with undetermined length.
-    template <class Keyword2, class Arg2>
-    arg_list<
-        tagged_argument<Keyword, Arg>
-      , arg_list<tagged_argument<Keyword2, Arg2> > 
-    >
-    operator,(tagged_argument<Keyword2, Arg2> x) const
-    {
-        return arg_list<
-            tagged_argument<Keyword, Arg>
-          , arg_list<tagged_argument<Keyword2, Arg2> > 
-        >(
-            *this
-          , arg_list<tagged_argument<Keyword2, Arg2> >(x, empty_arg_list())
-        );
-    }
-    
-    reference value;
-#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
-    // warning suppression
- private:
-    void operator=(tagged_argument const&);
-#endif 
-};
-
-// Defines a metafunction, is_tagged_argument, that identifies
-// tagged_argument specializations.
-BOOST_DETAIL_IS_XXX_DEF(tagged_argument,tagged_argument,2)
-
+    struct error_const_lvalue_bound_to_out_parameter;
+    struct error_lvalue_bound_to_consume_parameter;
+    struct error_rvalue_bound_to_out_parameter;
 }}} // namespace boost::parameter::aux
 
-#endif // TAGGED_ARGUMENT_050328_HPP
+#include <boost/parameter/keyword_fwd.hpp>
+#include <boost/parameter/config.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/remove_const.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Keyword, typename Arg>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using tagged_argument_type = ::boost::mp11::mp_if<
+        ::boost::mp11::mp_if<
+            ::std::is_scalar<Arg>
+          , ::boost::mp11::mp_false
+          , ::std::is_same<
+                typename Keyword::qualifier
+              , ::boost::parameter::consume_reference
+            >
+        >
+      , ::boost::parameter::aux::error_lvalue_bound_to_consume_parameter
+      , ::boost::mp11::mp_if<
+            ::std::is_const<Arg>
+          , ::boost::mp11::mp_if<
+                ::std::is_same<
+                    typename Keyword::qualifier
+                  , ::boost::parameter::out_reference
+                >
+              , ::boost::parameter::aux
+                ::error_const_lvalue_bound_to_out_parameter
+              , ::std::remove_const<Arg>
+            >
+          , ::boost::mp11::mp_identity<Arg>
+        >
+    >;
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+    struct tagged_argument_type
+      : ::boost::mpl::eval_if<
+            ::boost::is_same<
+                typename Keyword::qualifier
+              , ::boost::parameter::out_reference
+            >
+          , ::boost::parameter::aux::error_const_lvalue_bound_to_out_parameter
+          , ::boost::remove_const<Arg>
+        >
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/aux_/tagged_argument_fwd.hpp>
+#include <boost/parameter/aux_/is_tagged_argument.hpp>
+#include <boost/parameter/aux_/default.hpp>
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/parameter/aux_/arg_list.hpp>
+#include <boost/parameter/aux_/result_of0.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/mpl/apply_wrap.hpp>
+#include <boost/type_traits/is_const.hpp>
+#include <boost/type_traits/is_function.hpp>
+#include <boost/type_traits/is_scalar.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
+#if defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
+#include <boost/function.hpp>
+#else
+#include <functional>
+#endif
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#include <boost/core/enable_if.hpp>
+#include <utility>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Holds an lvalue reference to an argument of type Arg associated with
+    // keyword Keyword
+    template <typename Keyword, typename Arg>
+    class tagged_argument
+      : public ::boost::parameter::aux::tagged_argument_base
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using arg_type = typename ::boost::parameter::aux
+        ::tagged_argument_type<Keyword,Arg>::type;
+#else
+        typedef typename ::boost::mpl::eval_if<
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<Arg>
+              , ::boost::mpl::false_
+              , ::boost::is_same<
+                    typename Keyword::qualifier
+                  , ::boost::parameter::consume_reference
+                >
+            >::type
+          , ::boost::parameter::aux::error_lvalue_bound_to_consume_parameter
+          , ::boost::mpl::eval_if<
+                ::boost::is_const<Arg>
+              , ::boost::parameter::aux::tagged_argument_type<Keyword,Arg>
+              , ::boost::mpl::identity<Arg>
+            >
+        >::type arg_type;
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+     public:
+        typedef Keyword key_type;
+
+        // Wrap plain (non-UDT) function objects in either
+        // a boost::function or a std::function. -- Cromwell D. Enage
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using value_type = ::boost::mp11::mp_if<
+            ::std::is_function<arg_type>
+          , ::std::function<arg_type>
+          , Arg
+        >;
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::boost::mpl::if_<
+            ::boost::is_function<arg_type>
+#if defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
+          , ::boost::function<arg_type>
+#else
+          , ::std::function<arg_type>
+#endif
+          , Arg
+        >::type value_type;
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+        // If Arg is void_, then this type will evaluate to void_&.  If the
+        // supplied argument is a plain function, then this type will evaluate
+        // to a reference-to-const function wrapper type.  If the supplied
+        // argument is an lvalue, then Arg will be deduced to the lvalue
+        // reference. -- Cromwell D. Enage
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using reference = ::boost::mp11::mp_if<
+            ::std::is_function<arg_type>
+          , value_type const&
+          , Arg&
+        >;
+#else
+        typedef typename ::boost::mpl::if_<
+            ::boost::is_function<arg_type>
+          , value_type const&
+          , Arg&
+        >::type reference;
+#endif
+
+     private:
+        // Store plain functions by value, everything else by reference.
+        // -- Cromwell D. Enage
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        ::boost::mp11::mp_if<
+            ::std::is_function<arg_type>
+          , value_type
+          , reference
+        > value;
+#else
+        typename ::boost::mpl::if_<
+            ::boost::is_function<arg_type>
+          , value_type
+          , reference
+        >::type value;
+#endif
+
+     public:
+        inline explicit BOOST_CONSTEXPR tagged_argument(reference x)
+          : value(x)
+        {
+        }
+
+        inline BOOST_CONSTEXPR tagged_argument(tagged_argument const& copy)
+          : value(copy.value)
+        {
+        }
+
+        // A metafunction class that, given a keyword and a default type,
+        // returns the appropriate result type for a keyword lookup given
+        // that default.
+        struct binding
+        {
+            template <typename KW, typename Default, typename Reference>
+            struct apply
+              : ::boost::mpl::eval_if<
+                    ::boost::is_same<KW,key_type>
+                  , ::boost::mpl::if_<Reference,reference,value_type>
+                  , ::boost::mpl::identity<Default>
+                >
+            {
+            };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            template <typename KW, typename Default, typename Reference>
+            using fn = ::boost::mp11::mp_if<
+                ::std::is_same<KW,key_type>
+              , ::boost::mp11::mp_if<Reference,reference,value_type>
+              , Default
+            >;
+#endif
+        };
+
+#if !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        // Comma operator to compose argument list without using parameters<>.
+        // Useful for argument lists with undetermined length.
+        template <typename Keyword2, typename Arg2>
+        inline BOOST_CONSTEXPR ::boost::parameter::aux::arg_list<
+            ::boost::parameter::aux::tagged_argument<Keyword,Arg>
+          , ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+            >
+        >
+            operator,(
+                ::boost::parameter::aux
+                ::tagged_argument<Keyword2,Arg2> const& x
+            ) const
+        {
+            return ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument<Keyword,Arg>
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+                >
+            >(
+                *this
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+                >(x, ::boost::parameter::aux::empty_arg_list())
+            );
+        }
+
+        template <typename Keyword2, typename Arg2>
+        inline BOOST_CONSTEXPR ::boost::parameter::aux::arg_list<
+            ::boost::parameter::aux::tagged_argument<Keyword,Arg>
+          , ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument_rref<Keyword2,Arg2>
+            >
+        >
+            operator,(
+                ::boost::parameter::aux
+                ::tagged_argument_rref<Keyword2,Arg2> const& x
+            ) const
+        {
+            return ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument<Keyword,Arg>
+              , boost::parameter::aux::arg_list<
+                    boost::parameter::aux::tagged_argument_rref<Keyword2,Arg2>
+                >
+            >(
+                *this
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux
+                    ::tagged_argument_rref<Keyword2,Arg2>
+                >(x, ::boost::parameter::aux::empty_arg_list())
+            );
+        }
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+        // Accessor interface.
+        inline BOOST_CONSTEXPR reference get_value() const
+        {
+            return this->value;
+        }
+
+        inline BOOST_CONSTEXPR reference
+            operator[](::boost::parameter::keyword<Keyword> const&) const
+        {
+            return this->get_value();
+        }
+
+        template <typename Default>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::default_<key_type,Default> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename Default>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::default_r_<key_type,Default> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename F>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::lazy_default<key_type,F> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename KW, typename Default>
+        inline BOOST_CONSTEXPR Default&
+            operator[](
+                ::boost::parameter::aux::default_<KW,Default> const& x
+            ) const
+        {
+            return x.value;
+        }
+
+        template <typename KW, typename Default>
+        inline BOOST_CONSTEXPR Default&&
+            operator[](
+                ::boost::parameter::aux::default_r_<KW,Default> const& x
+            ) const
+        {
+            return ::std::forward<Default>(x.value);
+        }
+
+        template <typename KW, typename F>
+        inline BOOST_CONSTEXPR
+        typename ::boost::parameter::aux::result_of0<F>::type
+            operator[](
+                ::boost::parameter::aux::lazy_default<KW,F> const& x
+            ) const
+        {
+            return x.compute_default();
+        }
+
+        template <typename ParameterRequirements>
+        static BOOST_CONSTEXPR typename ParameterRequirements::has_default
+            satisfies(ParameterRequirements*);
+
+        template <typename HasDefault, typename Predicate>
+        static BOOST_CONSTEXPR
+        typename ::boost::mpl::apply_wrap1<Predicate,value_type>::type
+            satisfies(
+                ::boost::parameter::aux::parameter_requirements<
+                    key_type
+                  , Predicate
+                  , HasDefault
+                >*
+            );
+
+        // MPL sequence support
+        // Convenience for users
+        typedef ::boost::parameter::aux::tagged_argument<Keyword,Arg> type;
+        // For the benefit of iterators
+        typedef ::boost::parameter::aux::empty_arg_list tail_type;
+        // For dispatching to sequence intrinsics
+        typedef ::boost::parameter::aux::arg_list_tag tag;
+    };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    template <typename Keyword>
+    using tagged_argument_rref_key = ::boost::mp11::mp_if<
+        ::std::is_same<
+            typename Keyword::qualifier
+          , ::boost::parameter::out_reference
+        >
+      , ::boost::parameter::aux::error_rvalue_bound_to_out_parameter
+      , ::boost::mp11::mp_identity<Keyword>
+    >;
+#endif
+
+    // Holds an rvalue reference to an argument of type Arg associated with
+    // keyword Keyword
+    template <typename Keyword, typename Arg>
+    struct tagged_argument_rref
+      : ::boost::parameter::aux::tagged_argument_base
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using key_type = typename ::boost::parameter::aux
+        ::tagged_argument_rref_key<Keyword>::type;
+#else
+        typedef typename ::boost::mpl::eval_if<
+            ::boost::is_same<
+                typename Keyword::qualifier
+              , ::boost::parameter::out_reference
+            >
+          , ::boost::parameter::aux::error_rvalue_bound_to_out_parameter
+          , ::boost::mpl::identity<Keyword>
+        >::type key_type;
+#endif
+        typedef Arg value_type;
+        typedef Arg&& reference;
+
+     private:
+        reference value;
+
+     public:
+        inline explicit BOOST_CONSTEXPR tagged_argument_rref(reference x)
+          : value(::std::forward<Arg>(x))
+        {
+        }
+
+        inline BOOST_CONSTEXPR tagged_argument_rref(
+            tagged_argument_rref const& copy
+        ) : value(::std::forward<Arg>(copy.value))
+        {
+        }
+
+        // A metafunction class that, given a keyword and a default type,
+        // returns the appropriate result type for a keyword lookup given
+        // that default.
+        struct binding
+        {
+            template <typename KW, typename Default, typename Reference>
+            struct apply
+            {
+                typedef typename ::boost::mpl::eval_if<
+                    ::boost::is_same<KW,key_type>
+                  , ::boost::mpl::if_<Reference,reference,value_type>
+                  , ::boost::mpl::identity<Default>
+                >::type type;
+            };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            template <typename KW, typename Default, typename Reference>
+            using fn = ::boost::mp11::mp_if<
+                ::std::is_same<KW,key_type>
+              , ::boost::mp11::mp_if<Reference,reference,value_type>
+              , Default
+            >;
+#endif
+        };
+
+#if !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        // Comma operator to compose argument list without using parameters<>.
+        // Useful for argument lists with undetermined length.
+        template <typename Keyword2, typename Arg2>
+        inline BOOST_CONSTEXPR ::boost::parameter::aux::arg_list<
+            ::boost::parameter::aux::tagged_argument_rref<Keyword,Arg>
+          , ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+            >
+        >
+            operator,(
+                ::boost::parameter::aux
+                ::tagged_argument<Keyword2,Arg2> const& x
+            ) const
+        {
+            return boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument_rref<Keyword,Arg>
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+                >
+            >(
+                *this
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+                >(x, ::boost::parameter::aux::empty_arg_list())
+            );
+        }
+
+        template <typename Keyword2, typename Arg2>
+        inline BOOST_CONSTEXPR ::boost::parameter::aux::arg_list<
+            ::boost::parameter::aux::tagged_argument_rref<Keyword,Arg>
+          , ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument_rref<Keyword2,Arg2>
+            >
+        >
+            operator,(
+                ::boost::parameter::aux
+                ::tagged_argument_rref<Keyword2,Arg2> const& x
+            ) const
+        {
+            return ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument_rref<Keyword,Arg>
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux
+                    ::tagged_argument_rref<Keyword2,Arg2>
+                >
+            >(
+                *this
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux::tagged_argument_rref<
+                        Keyword2
+                      , Arg2
+                    >
+                >(x, ::boost::parameter::aux::empty_arg_list())
+            );
+        }
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+        // Accessor interface.
+        inline BOOST_CONSTEXPR reference get_value() const
+        {
+            return ::std::forward<Arg>(this->value);
+        }
+
+        inline BOOST_CONSTEXPR reference
+            operator[](::boost::parameter::keyword<Keyword> const&) const
+        {
+            return this->get_value();
+        }
+
+        template <typename Default>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::default_<key_type,Default> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename Default>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::default_r_<key_type,Default> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename F>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::lazy_default<key_type,F> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename KW, typename Default>
+        inline BOOST_CONSTEXPR Default&
+            operator[](
+                ::boost::parameter::aux::default_<KW,Default> const& x
+            ) const
+        {
+            return x.value;
+        }
+
+        template <typename KW, typename Default>
+        inline BOOST_CONSTEXPR Default&&
+            operator[](
+                ::boost::parameter::aux::default_r_<KW,Default> const& x
+            ) const
+        {
+            return ::std::forward<Default>(x.value);
+        }
+
+        template <typename KW, typename F>
+        inline BOOST_CONSTEXPR
+        typename ::boost::parameter::aux::result_of0<F>::type
+            operator[](
+                ::boost::parameter::aux::lazy_default<KW,F> const& x
+            ) const
+        {
+            return x.compute_default();
+        }
+
+        template <typename ParameterRequirements>
+        static BOOST_CONSTEXPR typename ParameterRequirements::has_default
+            satisfies(ParameterRequirements*);
+
+        template <typename HasDefault, typename Predicate>
+        static BOOST_CONSTEXPR
+        typename ::boost::mpl::apply_wrap1<Predicate,value_type>::type
+            satisfies(
+                ::boost::parameter::aux::parameter_requirements<
+                    key_type
+                  , Predicate
+                  , HasDefault
+                >*
+            );
+
+        // MPL sequence support
+        // Convenience for users
+        typedef ::boost::parameter::aux
+        ::tagged_argument_rref<Keyword,Arg> type;
+        // For the benefit of iterators
+        typedef ::boost::parameter::aux::empty_arg_list tail_type;
+        // For dispatching to sequence intrinsics
+        typedef ::boost::parameter::aux::arg_list_tag tag;
+    };
+}}} // namespace boost::parameter::aux
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Holds an lvalue reference to an argument of type Arg associated with
+    // keyword Keyword
+    template <typename Keyword, typename Arg>
+    class tagged_argument
+      : public ::boost::parameter::aux::tagged_argument_base
+    {
+        typedef typename ::boost::remove_const<Arg>::type arg_type;
+
+     public:
+        typedef Keyword key_type;
+
+        // Wrap plain (non-UDT) function objects in either
+        // a boost::function or a std::function. -- Cromwell D. Enage
+        typedef typename ::boost::mpl::if_<
+            ::boost::is_function<arg_type>
+#if defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
+          , ::boost::function<arg_type>
+#else
+          , ::std::function<arg_type>
+#endif
+          , Arg
+        >::type value_type;
+
+        // If Arg is void_, then this type will evaluate to void_&.  If the
+        // supplied argument is a plain function, then this type will evaluate
+        // to a reference-to-const function wrapper type.  If the supplied
+        // argument is an lvalue, then Arg will be deduced to the lvalue
+        // reference. -- Cromwell D. Enage
+        typedef typename ::boost::mpl::if_<
+            ::boost::is_function<arg_type>
+          , value_type const&
+          , Arg&
+        >::type reference;
+
+     private:
+        // Store plain functions by value, everything else by reference.
+        // -- Cromwell D. Enage
+        typename ::boost::mpl::if_<
+            ::boost::is_function<arg_type>
+          , value_type
+          , reference
+        >::type value;
+
+     public:
+        inline explicit BOOST_CONSTEXPR tagged_argument(reference x)
+          : value(x)
+        {
+        }
+
+        inline BOOST_CONSTEXPR tagged_argument(tagged_argument const& copy)
+          : value(copy.value)
+        {
+        }
+
+        // A metafunction class that, given a keyword and a default type,
+        // returns the appropriate result type for a keyword lookup given
+        // that default.
+        struct binding
+        {
+            template <typename KW, typename Default, typename Reference>
+            struct apply
+            {
+                typedef typename ::boost::mpl::eval_if<
+                    ::boost::is_same<KW,key_type>
+                  , ::boost::mpl::if_<Reference,reference,value_type>
+                  , ::boost::mpl::identity<Default>
+                >::type type;
+            };
+        };
+
+        // Comma operator to compose argument list without using parameters<>.
+        // Useful for argument lists with undetermined length.
+        template <typename Keyword2, typename Arg2>
+        inline ::boost::parameter::aux::arg_list<
+            ::boost::parameter::aux::tagged_argument<Keyword,Arg>
+          , ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+            >
+        >
+            operator,(
+                ::boost::parameter::aux
+                ::tagged_argument<Keyword2,Arg2> const& x
+            ) const
+        {
+            return ::boost::parameter::aux::arg_list<
+                ::boost::parameter::aux::tagged_argument<Keyword,Arg>
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+                >
+            >(
+                *this
+              , ::boost::parameter::aux::arg_list<
+                    ::boost::parameter::aux::tagged_argument<Keyword2,Arg2>
+                >(x, ::boost::parameter::aux::empty_arg_list())
+            );
+        }
+
+        // Accessor interface.
+        inline BOOST_CONSTEXPR reference get_value() const
+        {
+            return this->value;
+        }
+
+        inline BOOST_CONSTEXPR reference
+            operator[](::boost::parameter::keyword<Keyword> const&) const
+        {
+            return this->get_value();
+        }
+
+#if defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING) || \
+    BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+        template <typename KW, typename Default>
+        inline BOOST_CONSTEXPR Default&
+            get_with_default(
+                ::boost::parameter::aux::default_<KW,Default> const& x
+              , int
+            ) const
+        {
+            return x.value;
+        }
+
+        template <typename Default>
+        inline BOOST_CONSTEXPR reference
+            get_with_default(
+                ::boost::parameter::aux::default_<key_type,Default> const&
+              , long
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename KW, typename Default>
+        inline BOOST_CONSTEXPR typename ::boost::mpl::apply_wrap3<
+            binding
+          , KW
+          , Default&
+          , ::boost::mpl::true_
+        >::type
+            operator[](
+                ::boost::parameter::aux::default_<KW,Default> const& x
+            ) const
+        {
+            return this->get_with_default(x, 0L);
+        }
+
+        template <typename KW, typename F>
+        inline BOOST_CONSTEXPR
+        typename ::boost::parameter::aux::result_of0<F>::type
+            get_with_lazy_default(
+                ::boost::parameter::aux::lazy_default<KW,F> const& x
+              , int
+            ) const
+        {
+            return x.compute_default();
+        }
+
+        template <typename F>
+        inline BOOST_CONSTEXPR reference
+            get_with_lazy_default(
+                ::boost::parameter::aux::lazy_default<key_type,F> const&
+              , long
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename KW, typename F>
+        inline BOOST_CONSTEXPR typename ::boost::mpl::apply_wrap3<
+            binding
+          , KW
+          , typename ::boost::parameter::aux::result_of0<F>::type
+          , ::boost::mpl::true_
+        >::type
+            operator[](
+                ::boost::parameter::aux::lazy_default<KW,F> const& x
+            ) const
+        {
+            return this->get_with_lazy_default(x, 0L);
+        }
+#else   // No function template ordering or Borland workarounds needed.
+        template <typename Default>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::default_<key_type,Default> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename F>
+        inline BOOST_CONSTEXPR reference
+            operator[](
+                ::boost::parameter::aux::lazy_default<key_type,F> const&
+            ) const
+        {
+            return this->get_value();
+        }
+
+        template <typename KW, typename Default>
+        inline BOOST_CONSTEXPR Default&
+            operator[](
+                ::boost::parameter::aux::default_<KW,Default> const& x
+            ) const
+        {
+            return x.value;
+        }
+
+        template <typename KW, typename F>
+        inline BOOST_CONSTEXPR
+        typename ::boost::parameter::aux::result_of0<F>::type
+            operator[](
+                ::boost::parameter::aux::lazy_default<KW,F> const& x
+            ) const
+        {
+            return x.compute_default();
+        }
+
+        template <typename ParameterRequirements>
+        static BOOST_CONSTEXPR typename ParameterRequirements::has_default
+            satisfies(ParameterRequirements*);
+
+        template <typename HasDefault, typename Predicate>
+        static BOOST_CONSTEXPR
+        typename ::boost::mpl::apply_wrap1<Predicate,value_type>::type
+            satisfies(
+                ::boost::parameter::aux::parameter_requirements<
+                    key_type
+                  , Predicate
+                  , HasDefault
+                >*
+            );
+#endif  // Function template ordering, Borland workarounds needed.
+
+        // MPL sequence support
+        // Convenience for users
+        typedef ::boost::parameter::aux::tagged_argument<Keyword,Arg> type;
+        // For the benefit of iterators
+        typedef ::boost::parameter::aux::empty_arg_list tail_type;
+        // For dispatching to sequence intrinsics
+        typedef ::boost::parameter::aux::arg_list_tag tag;
+
+#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
+        // warning suppression
+     private:
+        void operator=(type const&);
+#endif
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename TaggedArg>
+    struct tagged_argument_list_of_1 : public TaggedArg
+    {
+        using base_type = TaggedArg;
+
+        inline explicit BOOST_CONSTEXPR tagged_argument_list_of_1(
+            typename base_type::reference x
+        ) : base_type(static_cast<typename base_type::reference>(x))
+        {
+        }
+
+        inline BOOST_CONSTEXPR tagged_argument_list_of_1(
+            tagged_argument_list_of_1 const& copy
+        ) : base_type(static_cast<base_type const&>(copy))
+        {
+        }
+
+        using base_type::operator[];
+        using base_type::satisfies;
+
+        template <typename TA2>
+        inline BOOST_CONSTEXPR ::boost::parameter::aux::flat_like_arg_list<
+            ::boost::parameter::aux
+            ::flat_like_arg_tuple<typename TaggedArg::key_type,TaggedArg>
+          , ::boost::parameter::aux::flat_like_arg_tuple<
+                typename TA2::base_type::key_type
+              , typename TA2::base_type
+            >
+        >
+            operator,(TA2 const& x) const
+        {
+            return boost::parameter::aux::flat_like_arg_list<
+                ::boost::parameter::aux
+                ::flat_like_arg_tuple<typename TaggedArg::key_type,TaggedArg>
+              , ::boost::parameter::aux::flat_like_arg_tuple<
+                    typename TA2::base_type::key_type
+                  , typename TA2::base_type
+                >
+            >(
+                static_cast<base_type const&>(*this)
+              , ::boost::parameter::aux::arg_list<typename TA2::base_type>(
+                    static_cast<typename TA2::base_type const&>(x)
+                  , ::boost::parameter::aux::empty_arg_list()
+                )
+            );
+        }
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
 

include/boost/parameter/aux_/tagged_argument_fwd.hpp

@@ -0,0 +1,38 @@
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_TAGGED_ARGUMENT_FWD_HPP
+#define BOOST_PARAMETER_TAGGED_ARGUMENT_FWD_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Keyword, typename Arg>
+    class tagged_argument;
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename Keyword, typename Arg>
+    struct tagged_argument_rref;
+}}} // namespace boost::parameter::aux
+
+#endif
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename TaggedArg>
+    struct tagged_argument_list_of_1;
+}}} // namespace boost::parameter::aux
+
+#endif
+#endif  // include guard
+

include/boost/parameter/aux_/template_keyword.hpp

@@ -0,0 +1,89 @@
+// Copyright Daniel Wallin 2006.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_TEMPLATE_KEYWORD_060203_HPP
+#define BOOST_PARAMETER_TEMPLATE_KEYWORD_060203_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct template_keyword_base
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    using is_template_keyword = ::std::is_base_of<
+        ::boost::parameter::aux::template_keyword_base
+      , typename ::std::remove_const<
+            typename ::std::remove_reference<T>::type
+        >::type
+    >;
+}}} // namespace boost::parameter::aux
+
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/remove_const.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#include <boost/type_traits/is_base_of.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#else
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/is_lvalue_reference.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+#if !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+    template <typename T>
+    struct is_template_keyword_aux
+      : ::boost::mpl::if_<
+            ::boost::is_convertible<
+                T*
+              , ::boost::parameter::aux::template_keyword_base const*
+            >
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+
+    template <typename T>
+    struct is_template_keyword
+      : ::boost::mpl::if_<
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+            // Cannot use is_convertible<> to check if T is derived from
+            // template_keyword_base. -- Cromwell D. Enage
+            ::boost::is_base_of<
+                ::boost::parameter::aux::template_keyword_base
+              , typename ::boost::remove_const<
+                    typename ::boost::remove_reference<T>::type
+                >::type
+            >
+          , ::boost::mpl::true_
+          , ::boost::mpl::false_
+#else
+            ::boost::is_lvalue_reference<T>
+          , ::boost::mpl::false_
+          , ::boost::parameter::aux::is_template_keyword_aux<T>
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+        >::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
+

include/boost/parameter/aux_/unwrap_cv_reference.hpp

@@ -1,97 +1,174 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef UNWRAP_CV_REFERENCE_050328_HPP
-#define UNWRAP_CV_REFERENCE_050328_HPP
+#ifndef BOOST_PARAMETER_AUX_UNWRAP_CV_REFERENCE_HPP
+#define BOOST_PARAMETER_AUX_UNWRAP_CV_REFERENCE_HPP
+
+namespace boost {
+
+    template <typename T>
+    class reference_wrapper;
+} // namespace boost
 
 #include <boost/parameter/aux_/yesno.hpp>
-#include <boost/mpl/bool.hpp>
-#include <boost/mpl/identity.hpp>
-#include <boost/mpl/eval_if.hpp>
-
-namespace boost { template<class T> class reference_wrapper; }
 
 namespace boost { namespace parameter { namespace aux {
 
-//
-// reference_wrapper support -- because of the forwarding problem,
-// when passing arguments positionally by non-const reference, we
-// ask users of named parameter interfaces to use ref(x) to wrap
-// them.
-//
+    //
+    // reference_wrapper support -- if perfect forwarding is unsupported,
+    // then when passing arguments positionally by non-const reference,
+    // we ask users of named parameter interfaces to use ref(x) to wrap them.
+    //
 
-// is_cv_reference_wrapper returns mpl::true_ if T is of type
-// reference_wrapper<U> cv
-template <class U>
-yes_tag is_cv_reference_wrapper_check(reference_wrapper<U> const volatile*);
-no_tag is_cv_reference_wrapper_check(...);
-
-template <class T>
-struct is_cv_reference_wrapper
-{
-    BOOST_STATIC_CONSTANT(
-        bool, value = (
-            sizeof(is_cv_reference_wrapper_check((T*)0)) == sizeof(yes_tag)
-        )
-    );
-
-    typedef mpl::bool_<
-#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
-        is_cv_reference_wrapper::
-#endif 
-    value> type;
-};
-
-#if BOOST_WORKAROUND(MSVC, == 1200)
-template <>
-struct is_cv_reference_wrapper<int>
-  : mpl::false_ {};
-#endif
-
-// Needed for unwrap_cv_reference below. T might be const, so
-// eval_if might fail because of deriving from T const on EDG.
-template <class T>
-struct get_type
-{
-    typedef typename T::type type;
-};
-
-#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
-template <class T, class is_reference_wrapper = typename is_cv_reference_wrapper<T>::type>
-struct unwrap_cv_reference
-{
-    typedef T type;
-};
-
-template <class T>
-struct unwrap_cv_reference<T const, mpl::false_>
-{
-    typedef T const type;
-};
-
-template <class T>
-struct unwrap_cv_reference<T, mpl::true_>
-  : T
-{};
-
-#else 
-// Produces the unwrapped type to hold a reference to in named<>
-// Can't use boost::unwrap_reference<> here because it
-// doesn't handle the case where T = reference_wrapper<U> cv
-template <class T>
-struct unwrap_cv_reference
-{
-    typedef typename mpl::eval_if<
-        is_cv_reference_wrapper<T>
-      , get_type<T>
-      , mpl::identity<T>
-    >::type type;
-};
-#endif
+    template <typename U>
+    ::boost::parameter::aux::yes_tag
+        is_cv_reference_wrapper_check(
+            ::boost::reference_wrapper<U> const volatile*
+        );
 
+    ::boost::parameter::aux::no_tag is_cv_reference_wrapper_check(...);
 }}} // namespace boost::parameter::aux
 
-#endif // UNWRAP_CV_REFERENCE_050328_HPP
+#include <boost/parameter/config.hpp>
+
+#if !defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
+#include <functional>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // Support for std::ref(x) -- Cromwell D. Enage
+    template <typename U>
+    ::boost::parameter::aux::yes_tag
+        is_cv_reference_wrapper_check(
+            ::std::reference_wrapper<U> const volatile*
+        );
+}}} // namespace boost::parameter::aux
+#endif
+
+#include <boost/parameter/aux_/preprocessor/nullptr.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11) && !( \
+        BOOST_WORKAROUND(BOOST_MSVC, >= 1900) && \
+        BOOST_WORKAROUND(BOOST_MSVC, < 1910) \
+    )
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11) || MSVC-14.0
+#include <boost/mpl/bool.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564)) && \
+    !BOOST_WORKAROUND(BOOST_GCC, < 40000)
+#include <boost/mpl/eval_if.hpp>
+#endif
+#endif  // BOOST_PARAMETER_CAN_USE_MP11 && not MSVC-14.0
+
+namespace boost { namespace parameter { namespace aux {
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11) && !( \
+        BOOST_WORKAROUND(BOOST_MSVC, >= 1900) && \
+        BOOST_WORKAROUND(BOOST_MSVC, < 1910) \
+    )
+    // This metafunction returns mp11::mp_true if T is of type
+    // reference_wrapper<U> cv.
+    template <typename T>
+    using is_cv_reference_wrapper = ::boost::mp11::mp_bool<
+        sizeof(
+            ::boost::parameter::aux::is_cv_reference_wrapper_check(
+                static_cast<
+                    typename ::std::remove_reference<T>::type*
+                >(BOOST_PARAMETER_AUX_PP_NULLPTR)
+            )
+        ) == sizeof(::boost::parameter::aux::yes_tag)
+    >;
+
+    // Needed for unwrap_cv_reference below. T might be const, so
+    // mp_eval_if<> might fail because of deriving from T const on EDG.
+    template <typename T>
+    using unwrap_cv_reference_impl = typename ::std::remove_reference<T>::type;
+
+    // Produces the unwrapped type to hold a reference to in
+    // tagged_argument<>.  Can't use boost::unwrap_reference<> here
+    // because it doesn't handle the case where T = reference_wrapper<U> cv.
+    template <typename T>
+    using unwrap_cv_reference = ::boost::mp11::mp_eval_if<
+        ::boost::parameter::aux::is_cv_reference_wrapper<T>
+      , ::boost::parameter::aux::unwrap_cv_reference_impl<T>
+      , ::std::remove_reference
+      , T
+    >;
+#else  // !defined(BOOST_PARAMETER_CAN_USE_MP11) || MSVC-14.0
+    // This metafunction returns mpl::true_ if T is of type
+    // reference_wrapper<U> cv.
+    template <typename T>
+    struct is_cv_reference_wrapper
+    {
+        BOOST_STATIC_CONSTANT(
+            bool, value = (
+                sizeof(
+                    ::boost::parameter::aux::is_cv_reference_wrapper_check(
+                        static_cast<
+                            typename ::boost::remove_reference<T>::type*
+                        >(BOOST_PARAMETER_AUX_PP_NULLPTR)
+                    )
+                ) == sizeof(::boost::parameter::aux::yes_tag)
+            )
+        );
+
+        typedef boost::mpl::bool_<
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
+            is_cv_reference_wrapper::
+#endif 
+        value> type;
+    };
+
+#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564)) || \
+    BOOST_WORKAROUND(BOOST_GCC, < 40000)
+    template <
+        typename T
+      , typename = typename ::boost::parameter::aux
+        ::is_cv_reference_wrapper<T>::type
+    >
+    struct unwrap_cv_reference : ::boost::remove_reference<T>
+    {
+    };
+
+    template <typename T>
+    struct unwrap_cv_reference<T const,::boost::mpl::false_>
+    {
+        typedef T const type;
+    };
+
+    template <typename T>
+    struct unwrap_cv_reference<T,::boost::mpl::true_> : T
+    {
+    };
+#else   // no Borland or GCC 3- workarounds needed
+    // Needed for unwrap_cv_reference below. T might be const, so
+    // eval_if<> might fail because of deriving from T const on EDG.
+    template <typename T>
+    struct unwrap_cv_reference_impl : ::boost::remove_reference<T>::type
+    {
+    };
+
+    // Produces the unwrapped type to hold a reference to in
+    // tagged_argument<>.  Can't use boost::unwrap_reference<> here
+    // because it doesn't handle the case where T = reference_wrapper<U> cv.
+    template <typename T>
+    struct unwrap_cv_reference
+      : ::boost::mpl::eval_if<
+            ::boost::parameter::aux::is_cv_reference_wrapper<T>
+          , ::boost::parameter::aux::unwrap_cv_reference_impl<T>
+          , ::boost::remove_reference<T>
+        >
+    {
+    };
+#endif  // Borland or GCC 3- workarounds needed
+#endif  // BOOST_PARAMETER_CAN_USE_MP11 && not MSVC-14.0
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
 

include/boost/parameter/aux_/use_default.hpp

@@ -0,0 +1,17 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_AUX_USE_DEFAULT_HPP
+#define BOOST_PARAMETER_AUX_USE_DEFAULT_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct use_default
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/use_default_tag.hpp

@@ -0,0 +1,29 @@
+// Copyright Daniel Wallin 2006.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_USE_DEFAULT_TAG_HPP
+#define BOOST_PARAMETER_USE_DEFAULT_TAG_HPP
+
+#include <boost/config.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    struct use_default_tag
+    {
+        inline BOOST_CONSTEXPR BOOST_DEFAULTED_FUNCTION(use_default_tag(), {})
+
+        inline BOOST_CONSTEXPR BOOST_DEFAULTED_FUNCTION(
+            use_default_tag(use_default_tag const&), {}
+        )
+
+        inline BOOST_CONSTEXPR use_default_tag operator()() const
+        {
+            return *this;
+        }
+    };
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/aux_/void.hpp

@@ -1,18 +1,38 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef VOID_050329_HPP
-#define VOID_050329_HPP
+#ifndef BOOST_PARAMETER_VOID_050329_HPP
+#define BOOST_PARAMETER_VOID_050329_HPP
+
+namespace boost { namespace parameter { 
+
+    // A placemarker for "no argument passed."
+    // MAINTAINER NOTE: Do not make this into a metafunction
+    struct void_
+    {
+    };
+}} // namespace boost::parameter
 
 namespace boost { namespace parameter { namespace aux {
 
-// A placemarker for "no argument passed."
-// MAINTAINER NOTE: Do not make this into a metafunction
-struct void_ {}; 
-
+    inline ::boost::parameter::void_& void_reference()
+    {
+        static ::boost::parameter::void_ instance;
+        return instance;
+    }
 }}} // namespace boost::parameter::aux
 
-#endif // VOID_050329_HPP
+#include <boost/config/workaround.hpp>
+
+#if BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x580))
+
+namespace boost { namespace parameter { namespace aux {
+
+    typedef void* voidstar;
+}}} // namespace boost::parameter::aux
+
+#endif
+#endif  // include guard
 

include/boost/parameter/aux_/yesno.hpp

@@ -1,26 +1,42 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef YESNO_050328_HPP
-#define YESNO_050328_HPP
+#ifndef BOOST_PARAMETER_AUX_YESNO_HPP
+#define BOOST_PARAMETER_AUX_YESNO_HPP
+
+namespace boost { namespace parameter { namespace aux {
+
+    // types used with the "sizeof trick" to capture the results of
+    // overload resolution at compile-time.
+    typedef char yes_tag;
+    typedef char (&no_tag)[2];
+}}} // namespace boost::parameter::aux
 
 #include <boost/mpl/bool.hpp>
 
 namespace boost { namespace parameter { namespace aux {
 
-// types used with the "sizeof trick" to capture the results of
-// overload resolution at compile-time.
-typedef char yes_tag;
-typedef char (&no_tag)[2];
-
-// mpl::true_ and mpl::false_ are not distinguishable by sizeof(),
-// so we pass them through these functions to get a type that is.
-yes_tag to_yesno(mpl::true_);
-no_tag to_yesno(mpl::false_);
-
+    // mpl::true_ and mpl::false_ are not distinguishable by sizeof(),
+    // so we pass them through these functions to get a type that is.
+    ::boost::parameter::aux::yes_tag to_yesno(::boost::mpl::true_);
+    ::boost::parameter::aux::no_tag to_yesno(::boost::mpl::false_);
 }}} // namespace boost::parameter::aux
 
-#endif // YESNO_050328_HPP
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+    // mp11::mp_true and mp11::mp_false are not distinguishable by sizeof(),
+    // so we pass them through these functions to get a type that is.
+    ::boost::parameter::aux::yes_tag to_yesno(::boost::mp11::mp_true);
+    ::boost::parameter::aux::no_tag to_yesno(::boost::mp11::mp_false);
+}}} // namespace boost::parameter::aux
+
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+#endif  // include guard
 

include/boost/parameter/binding.hpp

@@ -1,57 +1,164 @@
-// Copyright David Abrahams 2005. Distributed under the Boost
-// Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+// Copyright David Abrahams 2005.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
 #ifndef BOOST_PARAMETER_BINDING_DWA200558_HPP
-# define BOOST_PARAMETER_BINDING_DWA200558_HPP
+#define BOOST_PARAMETER_BINDING_DWA200558_HPP
 
-# include <boost/mpl/apply.hpp>
-# include <boost/parameter/aux_/result_of0.hpp>
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/parameter/config.hpp>
 
-#  include <boost/parameter/aux_/void.hpp>
-
-# if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
-#  include <boost/parameter/aux_/void.hpp>
-#  include <boost/type_traits/is_same.hpp>
-# endif 
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/mpl/apply_wrap.hpp>
+#include <boost/mpl/assert.hpp>
+#include <boost/type_traits/is_same.hpp>
+#endif
 
 namespace boost { namespace parameter { 
 
-// A metafunction that, given an argument pack, returns the type of
-// the parameter identified by the given keyword.  If no such
-// parameter has been specified, returns Default
-# if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
-template <class Parameters, class Keyword, class Default = void>
-struct binding
-  : mpl::apply_wrap2<
-        typename Parameters::binding,Keyword,Default
-    >
-{};
-# else
-template <class Parameters, class Keyword, class Default = aux::void_>
-struct binding
-{
-    typedef typename mpl::apply_wrap2<
-        typename Parameters::binding,Keyword,
-        typename mpl::if_<is_same<Default,aux::void_>,void,Default>::type
-    >::type type;
-};
-# endif
+    // A metafunction that, given an argument pack, returns the reference type
+    // of the parameter identified by the given keyword.  If no such parameter
+    // has been specified, returns Default
 
-// A metafunction that, given an argument pack, returns the type of
-// the parameter identified by the given keyword.  If no such
-// parameter has been specified, returns the type returned by invoking
-// DefaultFn
-template <class Parameters, class Keyword, class DefaultFn>
-struct lazy_binding
-{
-  typedef typename mpl::apply_wrap2<
-      typename Parameters::binding
-    , Keyword
-    , typename aux::result_of0<DefaultFn>::type
-  >::type type;
-};
+    template <typename Parameters, typename Keyword, typename Default>
+    struct binding0
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_apply_q<
+            typename Parameters::binding
+          , ::boost::mp11::mp_list<Keyword,Default,::boost::mp11::mp_true>
+        >;
 
+        static_assert(
+            ::boost::mp11::mp_if<
+                ::std::is_same<Default,::boost::parameter::void_>
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<type,::boost::parameter::void_>
+                  , ::boost::mp11::mp_false
+                  , ::boost::mp11::mp_true
+                >
+              , ::boost::mp11::mp_true
+            >::value
+          , "required parameters must not result in void_ type"
+        );
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+        typedef typename ::boost::mpl::apply_wrap3<
+            typename Parameters::binding
+          , Keyword
+          , Default
+          , ::boost::mpl::true_
+        >::type type;
 
+        BOOST_MPL_ASSERT((
+            typename ::boost::mpl::eval_if<
+                ::boost::is_same<Default,::boost::parameter::void_>
+              , ::boost::mpl::if_<
+                    ::boost::is_same<type,::boost::parameter::void_>
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+              , ::boost::mpl::true_
+            >::type
+        ));
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+    };
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    template <typename Placeholder, typename Keyword, typename Default>
+    struct binding1
+    {
+        using type = ::boost::mp11::mp_apply_q<
+            Placeholder
+          , ::boost::mp11::mp_list<Keyword,Default,::boost::mp11::mp_true>
+        >;
+
+        static_assert(
+            ::boost::mp11::mp_if<
+                ::std::is_same<Default,::boost::parameter::void_>
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<type,::boost::parameter::void_>
+                  , ::boost::mp11::mp_false
+                  , ::boost::mp11::mp_true
+                >
+              , ::boost::mp11::mp_true
+            >::value
+          , "required parameters must not result in void_ type"
+        );
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
 }} // namespace boost::parameter
 
-#endif // BOOST_PARAMETER_BINDING_DWA200558_HPP
+#include <boost/parameter/aux_/is_placeholder.hpp>
+
+namespace boost { namespace parameter { 
+
+    template <
+        typename Parameters
+      , typename Keyword
+      , typename Default = ::boost::parameter::void_
+    >
+    struct binding
+#if !defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mpl::eval_if<
+            ::boost::parameter::aux::is_mpl_placeholder<Parameters>
+          , ::boost::mpl::identity<int>
+          , ::boost::parameter::binding0<Parameters,Keyword,Default>
+        >
+#endif
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = typename ::boost::mp11::mp_if<
+            ::boost::parameter::aux::is_mpl_placeholder<Parameters>
+          , ::boost::mp11::mp_identity<int>
+          , ::boost::mp11::mp_if<
+                ::boost::parameter::aux::is_mp11_placeholder<Parameters>
+              , ::boost::parameter::binding1<Parameters,Keyword,Default>
+              , ::boost::parameter::binding0<Parameters,Keyword,Default>
+            >
+        >::type;
+#endif
+    };
+}} // namespace boost::parameter
+
+#include <boost/parameter/aux_/result_of0.hpp>
+
+namespace boost { namespace parameter { 
+
+    // A metafunction that, given an argument pack, returns the reference type
+    // of the parameter identified by the given keyword.  If no such parameter
+    // has been specified, returns the type returned by invoking DefaultFn
+    template <typename Parameters, typename Keyword, typename DefaultFn>
+    struct lazy_binding
+    {
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+        using type = ::boost::mp11::mp_apply_q<
+            typename Parameters::binding
+          , ::boost::mp11::mp_list<
+                Keyword
+              , typename ::boost::parameter::aux::result_of0<DefaultFn>::type
+              , ::boost::mp11::mp_true
+            >
+        >;
+#else
+        typedef typename ::boost::mpl::apply_wrap3<
+            typename Parameters::binding
+          , Keyword
+          , typename ::boost::parameter::aux::result_of0<DefaultFn>::type
+          , ::boost::mpl::true_
+        >::type type;
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+    };
+}} // namespace boost::parameter
+
+#endif  // include guard
+

include/boost/parameter/compose.hpp

@@ -0,0 +1,210 @@
+// Copyright Cromwell D. Enage 2019.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_COMPOSE_HPP
+#define BOOST_PARAMETER_COMPOSE_HPP
+
+#include <boost/parameter/aux_/arg_list.hpp>
+
+namespace boost { namespace parameter {
+
+    inline BOOST_CONSTEXPR ::boost::parameter::aux::empty_arg_list compose()
+    {
+        return ::boost::parameter::aux::empty_arg_list();
+    }
+}} // namespace boost::parameter
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+namespace boost { namespace parameter { namespace aux {
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    template <typename ...TaggedArgs>
+    struct compose_arg_list
+    {
+        using type = ::boost::parameter::aux::flat_like_arg_list<
+            ::boost::parameter::aux::flat_like_arg_tuple<
+                typename TaggedArgs::base_type::key_type
+              , typename TaggedArgs::base_type
+            >...
+        >;
+    };
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+    template <typename TaggedArg0, typename ...TaggedArgs>
+    struct compose_arg_list;
+
+    template <typename TaggedArg0>
+    struct compose_arg_list<TaggedArg0>
+    {
+        typedef ::boost::parameter::aux::arg_list<TaggedArg0> type;
+    };
+
+    template <typename TaggedArg0, typename ...TaggedArgs>
+    struct compose_arg_list
+    {
+        typedef ::boost::parameter::aux::arg_list<
+            TaggedArg0
+          , typename ::boost::parameter::aux
+            ::compose_arg_list<TaggedArgs...>::type
+        > type;
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/are_tagged_arguments.hpp>
+#include <boost/core/enable_if.hpp>
+
+namespace boost { namespace parameter { namespace result_of {
+
+    template <typename ...TaggedArgs>
+    struct compose
+      : ::boost::lazy_enable_if<
+            ::boost::parameter::are_tagged_arguments<TaggedArgs...>
+          , ::boost::parameter::aux::compose_arg_list<TaggedArgs...>
+        >
+    {
+    };
+
+    template <>
+    struct compose<>
+    {
+        typedef ::boost::parameter::aux::empty_arg_list type;
+    };
+}}} // namespace boost::parameter::result_of
+
+namespace boost { namespace parameter {
+
+    template <typename TaggedArg0, typename ...TaggedArgs>
+    inline BOOST_CONSTEXPR typename ::boost::parameter::result_of
+    ::compose<TaggedArg0,TaggedArgs...>::type
+        compose(TaggedArg0 const& arg0, TaggedArgs const&... args)
+    {
+        return typename ::boost::parameter::aux
+        ::compose_arg_list<TaggedArg0,TaggedArgs...>::type(
+            ::boost::parameter::aux::value_type_is_not_void()
+          , arg0
+          , args...
+        );
+    }
+}} // namespace boost::parameter
+
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#define BOOST_PARAMETER_compose_arg_list_type_suffix(z, n, suffix) suffix
+
+#include <boost/preprocessor/cat.hpp>
+
+#define BOOST_PARAMETER_compose_arg_list_type_prefix(z, n, prefix)           \
+    ::boost::parameter::aux::arg_list<BOOST_PP_CAT(prefix, n)
+/**/
+
+#include <boost/preprocessor/facilities/intercept.hpp>
+#include <boost/preprocessor/repetition/enum.hpp>
+#include <boost/preprocessor/repetition/repeat.hpp>
+
+#define BOOST_PARAMETER_compose_arg_list_type(z, n, prefix)                  \
+    BOOST_PP_CAT(BOOST_PP_ENUM_, z)(                                         \
+        n, BOOST_PARAMETER_compose_arg_list_type_prefix, prefix              \
+    ) BOOST_PP_CAT(BOOST_PP_REPEAT_, z)(                                     \
+        n, BOOST_PARAMETER_compose_arg_list_type_suffix, >                   \
+    )
+/**/
+
+#include <boost/parameter/aux_/void.hpp>
+#include <boost/preprocessor/arithmetic/inc.hpp>
+#include <boost/preprocessor/arithmetic/sub.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
+
+#if defined(BOOST_NO_SFINAE)
+#define BOOST_PARAMETER_compose_arg_list_function_overload(z, n, prefix)     \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename prefix)>                 \
+    inline BOOST_CONSTEXPR                                                   \
+    BOOST_PARAMETER_compose_arg_list_type(z, n, prefix)                      \
+        compose(BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, prefix, const& a))       \
+    {                                                                        \
+        return BOOST_PARAMETER_compose_arg_list_type(z, n, prefix)(          \
+            BOOST_PP_ENUM_PARAMS_Z(z, n, a)                                  \
+            BOOST_PP_ENUM_TRAILING_PARAMS_Z(                                 \
+                z                                                            \
+              , BOOST_PP_SUB(BOOST_PARAMETER_COMPOSE_MAX_ARITY, n)           \
+              , ::boost::parameter::aux::void_reference() BOOST_PP_INTERCEPT \
+            )                                                                \
+        );                                                                   \
+    }
+/**/
+#else   // !defined(BOOST_NO_SFINAE)
+#include <boost/parameter/are_tagged_arguments.hpp>
+#include <boost/core/enable_if.hpp>
+
+namespace boost { namespace parameter { namespace result_of {
+
+    template <
+        BOOST_PP_ENUM_BINARY_PARAMS(
+            BOOST_PP_INC(BOOST_PARAMETER_COMPOSE_MAX_ARITY)
+          , typename TaggedArg
+          , = void BOOST_PP_INTERCEPT
+        )
+    >
+    struct compose;
+
+    template <>
+    struct compose<>
+    {
+        typedef ::boost::parameter::aux::empty_arg_list type;
+    };
+}}} // namespace boost::parameter::result_of
+
+#define BOOST_PARAMETER_compose_arg_list_function_overload(z, n, prefix)     \
+namespace boost { namespace parameter { namespace result_of {                \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename prefix)>                 \
+    struct compose<BOOST_PP_ENUM_PARAMS_Z(z, n, prefix)>                     \
+      : ::boost::enable_if<                                                  \
+            ::boost::parameter                                               \
+            ::are_tagged_arguments<BOOST_PP_ENUM_PARAMS_Z(z, n, prefix)>     \
+          , BOOST_PARAMETER_compose_arg_list_type(z, n, prefix)              \
+        >                                                                    \
+    {                                                                        \
+    };                                                                       \
+}}}                                                                          \
+namespace boost { namespace parameter {                                      \
+    template <BOOST_PP_ENUM_PARAMS_Z(z, n, typename prefix)>                 \
+    inline BOOST_CONSTEXPR typename ::boost::parameter::result_of            \
+    ::compose<BOOST_PP_ENUM_PARAMS_Z(z, n, prefix)>::type                    \
+        compose(BOOST_PP_ENUM_BINARY_PARAMS_Z(z, n, prefix, const& a))       \
+    {                                                                        \
+        return BOOST_PARAMETER_compose_arg_list_type(z, n, prefix)(          \
+            BOOST_PP_ENUM_PARAMS_Z(z, n, a)                                  \
+            BOOST_PP_ENUM_TRAILING_PARAMS_Z(                                 \
+                z                                                            \
+              , BOOST_PP_SUB(BOOST_PARAMETER_COMPOSE_MAX_ARITY, n)           \
+              , ::boost::parameter::aux::void_reference() BOOST_PP_INTERCEPT \
+            )                                                                \
+        );                                                                   \
+    }                                                                        \
+}}
+/**/
+#endif  // BOOST_NO_SFINAE
+
+#include <boost/preprocessor/repetition/repeat_from_to.hpp>
+
+BOOST_PP_REPEAT_FROM_TO(
+    1
+  , BOOST_PP_INC(BOOST_PARAMETER_COMPOSE_MAX_ARITY)
+  , BOOST_PARAMETER_compose_arg_list_function_overload
+  , TaggedArg
+)
+
+#undef BOOST_PARAMETER_compose_arg_list_function_overload
+#undef BOOST_PARAMETER_compose_arg_list_type
+#undef BOOST_PARAMETER_compose_arg_list_type_prefix
+#undef BOOST_PARAMETER_compose_arg_list_type_suffix
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
+

include/boost/parameter/config.hpp

@@ -1,14 +1,83 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
 #ifndef BOOST_PARAMETER_CONFIG_050403_HPP
 #define BOOST_PARAMETER_CONFIG_050403_HPP
 
-#ifndef BOOST_PARAMETER_MAX_ARITY
-# define BOOST_PARAMETER_MAX_ARITY 5
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+// Allow projects to #define BOOST_PARAMETER_DISABLE_PERFECT_FORWARDING to
+// turn off perfect forwarding as necessary.  Otherwise, also require correct
+// SFINAE support, needed explicitly by tagged_argument & keyword & cast;
+// correct function template ordering, needed by the code generation macros;
+// rvalue references, needed throughout; variadic templates, needed by
+// parameters; function template default arguments, needed by the code
+// generation macros; and the ability to handle multiple parameter packs,
+// needed by parameters.  Older versions of GCC either don't have the latter
+// ability or cannot disambiguate between keyword's overloaded
+// operators.  Older versions of Clang either fail to compile due to
+// differences in length between parameter packs 'Args' and 'args' or fail at
+// runtime due to segmentation faults.
+// -- Cromwell D. Enage
+#if !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING) && \
+    !defined(BOOST_PARAMETER_DISABLE_PERFECT_FORWARDING) && \
+    !defined(BOOST_NO_SFINAE) && \
+    !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING) && \
+    !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && \
+    !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && \
+    !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) && \
+    !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564)) && !( \
+        defined(BOOST_CLANG) && (1 == BOOST_CLANG) && ( \
+            (__clang_major__ < 3) || ( \
+                (3 == __clang_major__) && (__clang_minor__ < 2) \
+            ) \
+        ) \
+    ) && !BOOST_WORKAROUND(BOOST_GCC, < 40900)
+#define BOOST_PARAMETER_HAS_PERFECT_FORWARDING
 #endif
 
-#endif // BOOST_PARAMETER_CONFIG_050403_HPP
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#if !defined(BOOST_PARAMETER_CAN_USE_MP11) && \
+    !defined(BOOST_PARAMETER_DISABLE_MP11_USAGE) && \
+    !defined(BOOST_NO_CXX11_CONSTEXPR) && \
+    !defined(BOOST_NO_CXX11_DECLTYPE_N3276) && \
+    !defined(BOOST_NO_CXX11_AUTO_DECLARATIONS) && \
+    !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES) && \
+    !defined(BOOST_NO_CXX11_STATIC_ASSERT) && \
+    !defined(BOOST_NO_CXX11_HDR_TYPE_TRAITS) && \
+    !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST) && \
+    !defined(BOOST_NO_CXX11_HDR_TUPLE)
+// Boost.MP11 requires C++11. -- Cromwell D. Enage
+#define BOOST_PARAMETER_CAN_USE_MP11
+#endif
+#if !defined(BOOST_PARAMETER_MAX_ARITY)
+// Unlike the variadic MPL sequences provided by Boost.Fusion,
+// boost::mpl::vector has a size limit. -- Cromwell D. Enage
+#include <boost/mpl/limits/vector.hpp>
+#define BOOST_PARAMETER_MAX_ARITY BOOST_MPL_LIMIT_VECTOR_SIZE
+#endif
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#if !defined(BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY)
+#define BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY 0
+#endif
+#if !defined(BOOST_PARAMETER_COMPOSE_MAX_ARITY)
+#if BOOST_WORKAROUND(BOOST_MSVC, < 1800) || \
+    BOOST_WORKAROUND(BOOST_GCC, < 60000)
+// Some tests cause MSVC-11.0 and earlier to run out of heap space,
+// while some other tests cause GCC 5 and earlier to do the same,
+// if the value is set any higher. -- Cromwell D. Enage
+#define BOOST_PARAMETER_COMPOSE_MAX_ARITY 20
+#else
+#define BOOST_PARAMETER_COMPOSE_MAX_ARITY 64
+#endif
+#endif  // BOOST_PARAMETER_COMPOSE_MAX_ARITY
+#if !defined(BOOST_PARAMETER_MAX_ARITY)
+#define BOOST_PARAMETER_MAX_ARITY 8
+#endif
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+#endif  // include guard
 

include/boost/parameter/deduced.hpp

@@ -0,0 +1,132 @@
+// Copyright David Abrahams, Daniel Wallin 2003.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_DEDUCED_HPP
+#define BOOST_PARAMETER_DEDUCED_HPP
+
+#include <boost/parameter/aux_/use_default.hpp>
+
+namespace boost { namespace parameter {
+
+    // This metafunction can be used to describe the treatment of particular
+    // named parameters for the purposes of overload elimination with SFINAE,
+    // by placing specializations in the parameters<...> list.
+    //
+    // If a keyword k is specified with deduced<...>, that keyword
+    // will be automatically deduced from the argument list.
+    template <typename Tag>
+    struct deduced
+    {
+        typedef Tag key_type;
+    };
+}}
+
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#else
+#include <boost/mpl/bool.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    template <typename T>
+    struct is_deduced_aux
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_false
+#else
+      : ::boost::mpl::false_
+#endif
+    {
+    };
+
+    template <typename Tag>
+    struct is_deduced_aux< ::boost::parameter::deduced<Tag> >
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+      : ::boost::mp11::mp_true
+#else
+      : ::boost::mpl::true_
+#endif
+    {
+    };
+
+    template <typename T>
+    struct is_deduced0
+      : ::boost::parameter::aux::is_deduced_aux<typename T::key_type>::type
+    {
+    };
+}}} // namespace boost::parameter::aux
+
+#include <boost/parameter/required.hpp>
+#include <boost/parameter/optional.hpp>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/utility.hpp>
+#else
+#include <boost/mpl/if.hpp>
+#endif
+
+namespace boost { namespace parameter { namespace aux {
+
+    //
+    // tag_type, has_default, and predicate --
+    //
+    // These metafunctions accept a ParameterSpec and extract the
+    // keyword tag, whether or not a default is supplied for the
+    // parameter, and the predicate that the corresponding actual
+    // argument type is required match.
+    //
+    // a ParameterSpec is a specialization of either keyword<...>,
+    // required<...>, optional<...>
+    //
+
+    template <typename T>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using has_default = ::boost::mp11::mp_if<
+        ::boost::parameter::aux::is_required<T>
+      , ::boost::mp11::mp_false
+      , ::boost::mp11::mp_true
+    >;
+#else
+    struct has_default
+      : ::boost::mpl::if_<
+            ::boost::parameter::aux::is_required<T>
+          , ::boost::mpl::false_
+          , ::boost::mpl::true_
+        >::type
+    {
+    };
+#endif
+
+    template <typename T>
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+    using is_deduced = ::boost::mp11::mp_if<
+        ::boost::mp11::mp_if<
+            ::boost::parameter::aux::is_optional<T>
+          , ::boost::mp11::mp_true
+          , ::boost::parameter::aux::is_required<T>
+        >
+      , ::boost::parameter::aux::is_deduced0<T>
+      , ::boost::mp11::mp_false
+    >;
+#else
+    struct is_deduced
+      : ::boost::mpl::if_<
+            typename ::boost::mpl::if_<
+                ::boost::parameter::aux::is_optional<T>
+              , ::boost::mpl::true_
+              , ::boost::parameter::aux::is_required<T>
+            >::type
+          , ::boost::parameter::aux::is_deduced0<T>
+          , ::boost::mpl::false_
+        >::type
+    {
+    };
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+}}} // namespace boost::parameter::aux
+
+#endif  // include guard
+

include/boost/parameter/is_argument_pack.hpp

@@ -0,0 +1,29 @@
+// Copyright Cromwell D. Enage 2018.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_PARAMETER_IS_ARGUMENT_PACK_HPP
+#define BOOST_PARAMETER_IS_ARGUMENT_PACK_HPP
+
+#include <boost/parameter/aux_/is_tagged_argument.hpp>
+#include <boost/parameter/aux_/arg_list.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/is_base_of.hpp>
+
+namespace boost { namespace parameter {
+
+    template <typename T>
+    struct is_argument_pack
+      : ::boost::mpl::if_<
+            ::boost::is_base_of< ::boost::parameter::aux::empty_arg_list,T>
+          , ::boost::mpl::true_
+          , ::boost::parameter::aux::is_tagged_argument<T>
+        >::type
+    {
+    };
+}}
+
+#endif  // include guard
+

include/boost/parameter/keyword.hpp

@@ -1,134 +1,744 @@
-// Copyright Daniel Wallin, David Abrahams 2005. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2005.
+// Copyright Cromwell D. Enage 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef KEYWORD_050328_HPP
-#define KEYWORD_050328_HPP
+#ifndef BOOST_PARAMETER_KEYWORD_HPP
+#define BOOST_PARAMETER_KEYWORD_HPP
 
-#include <boost/parameter/aux_/unwrap_cv_reference.hpp>
 #include <boost/parameter/aux_/tag.hpp>
 #include <boost/parameter/aux_/default.hpp>
-#include <boost/noncopyable.hpp>
+#include <boost/parameter/keyword_fwd.hpp>
+#include <boost/parameter/config.hpp>
+
+#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+#include <boost/core/enable_if.hpp>
+#include <utility>
+
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#include <type_traits>
+#else
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/is_scalar.hpp>
+#include <boost/type_traits/is_const.hpp>
+#endif
 
 namespace boost { namespace parameter {
 
-// Instances of unique specializations of keyword<...> serve to
-// associate arguments with parameter names.  For example:
-//
-//    struct rate_;           // parameter names
-//    struct skew_;
-//    namespace
-//    {
-//      keyword<rate_> rate;  // keywords
-//      keyword<skew_> skew;
-//    }
-//
-//    ...
-//
-//    f(rate = 1, skew = 2.4);
-//
-template <class Tag>
-struct keyword : noncopyable
-{
-    template <class T>
-    typename aux::tag<Tag, T>::type
-    operator=(T& x) const
+    // Instances of unique specializations of keyword<...> serve to
+    // associate arguments with parameter names.  For example:
+    //
+    //     struct rate_;             // parameter names
+    //     struct skew_;
+    //
+    //     namespace
+    //     {
+    //         keyword<rate_> rate;  // keywords
+    //         keyword<skew_> skew;
+    //     }
+    //
+    //     ...
+    //
+    //     f(rate = 1, skew = 2.4);
+    template <typename Tag>
+    struct keyword
     {
-        typedef typename aux::tag<Tag, T>::type result;
-        return result(x);
-    }
+        typedef Tag tag;
 
-    template <class Default>
-    aux::default_<Tag, Default>
-    operator|(Default& default_) const
-    {
-        return aux::default_<Tag, Default>(default_);
-    }
+        inline BOOST_CONSTEXPR keyword()
+        {
+        }
 
-    template <class Default>
-    aux::lazy_default<Tag, Default>
-    operator||(Default& default_) const
-    {
-        return aux::lazy_default<Tag, Default>(default_);
-    }
+        template <typename T>
+        inline BOOST_CONSTEXPR typename ::boost::lazy_enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::std::is_scalar<T>
+              , ::boost::mp11::mp_true
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<T>
+              , ::boost::mpl::true_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::tag<Tag,T const&>
+        >::type
+            operator=(T const& x) const
+        {
+            typedef typename ::boost::parameter::aux
+            ::tag<Tag,T const&>::type result;
+            return result(x);
+        }
 
-#if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)  // avoid partial ordering bugs
-    template <class T>
-    typename aux::tag<Tag, T const>::type
-    operator=(T const& x) const
-    {
-        typedef typename aux::tag<Tag, T const>::type result;
-        return result(x);
-    }
-#endif 
+        template <typename Default>
+        inline BOOST_CONSTEXPR typename ::boost::enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::std::is_scalar<Default>
+              , ::boost::mp11::mp_true
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<Default>
+              , ::boost::mpl::true_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::default_<Tag,Default const>
+        >::type
+            operator|(Default const& d) const
+        {
+            return ::boost::parameter::aux::default_<Tag,Default const>(d);
+        }
 
-#if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)  // avoid partial ordering bugs
-    template <class Default>
-    aux::default_<Tag, const Default>
-    operator|(const Default& default_) const
-#if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
-        volatile
-#endif 
-    {
-        return aux::default_<Tag, const Default>(default_);
-    }
+        template <typename T>
+        inline BOOST_CONSTEXPR typename ::boost::lazy_enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::out_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+              , ::boost::mp11::mp_if<
+                    ::std::is_const<T>
+                  , ::boost::mp11::mp_false
+                  , ::boost::mp11::mp_true
+                >
+              , ::boost::mp11::mp_false
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                typename ::boost::mpl::if_<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::out_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >::type
+              , ::boost::mpl::if_<
+                    ::boost::is_const<T>
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+              , ::boost::mpl::false_
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::tag<Tag,T&>
+        >::type
+            operator=(T& x) const
+        {
+            typedef typename ::boost::parameter::aux
+            ::tag<Tag,T&>::type result;
+            return result(x);
+        }
 
-    template <class Default>
-    aux::lazy_default<Tag, Default>
-    operator||(Default const& default_) const
-#if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
-        volatile
-#endif 
-    {
-        return aux::lazy_default<Tag, Default>(default_);
-    }
-#endif
+        template <typename Default>
+        inline BOOST_CONSTEXPR typename ::boost::enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::out_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+              , ::boost::mp11::mp_if<
+                    ::std::is_const<Default>
+                  , ::boost::mp11::mp_false
+                  , ::boost::mp11::mp_true
+                >
+              , ::boost::mp11::mp_false
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                typename ::boost::mpl::if_<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::out_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >::type
+              , ::boost::mpl::if_<
+                    ::boost::is_const<Default>
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+              , ::boost::mpl::false_
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::default_<Tag,Default>
+        >::type
+            operator|(Default& d) const
+        {
+            return ::boost::parameter::aux::default_<Tag,Default>(d);
+        }
 
- public: // Insurance against ODR violations
-    
-    // People will need to define these keywords in header files.  To
-    // prevent ODR violations, it's important that the keyword used in
-    // every instantiation of a function template is the same object.
-    // We provide a reference to a common instance of each keyword
-    // object and prevent construction by users.
-    
-    static keyword<Tag>& get()
-    {
-        static keyword<Tag> result;
-        return result;
-    }
-    
- private:
-    keyword() {}
-};
+        template <typename Default>
+        inline BOOST_CONSTEXPR
+        ::boost::parameter::aux::lazy_default<Tag,Default const>
+            operator||(Default const& d) const
+        {
+            return ::boost::parameter::aux
+            ::lazy_default<Tag,Default const>(d);
+        }
 
-// Reduces boilerplate required to declare and initialize keywords
-// without violating ODR.  Declares a keyword tag type with the given
-// name in namespace tag_namespace, and declares and initializes a
-// reference in an anonymous namespace to a singleton instance of that
-// type.
+        template <typename Default>
+        inline BOOST_CONSTEXPR
+        ::boost::parameter::aux::lazy_default<Tag,Default>
+            operator||(Default& d) const
+        {
+            return ::boost::parameter::aux::lazy_default<Tag,Default>(d);
+        }
 
-#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
+        template <typename T>
+        inline BOOST_CONSTEXPR typename ::boost::lazy_enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::std::is_scalar<T>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<T>
+              , ::boost::mpl::false_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::tag<Tag,T const>
+        >::type
+            operator=(T const&& x) const
+        {
+            typedef typename ::boost::parameter::aux
+            ::tag<Tag,T const>::type result;
+            return result(::std::forward<T const>(x));
+        }
 
-# define BOOST_PARAMETER_KEYWORD(tag_namespace,name)                \
-    namespace tag_namespace { struct name; }                        \
-    static ::boost::parameter::keyword<tag_namespace::name>& name   \
-       = ::boost::parameter::keyword<tag_namespace::name>::get();
+        template <typename T>
+        inline BOOST_CONSTEXPR typename ::boost::lazy_enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::std::is_scalar<T>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::consume_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<T>
+              , ::boost::mpl::false_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::consume_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::tag<Tag,T>
+        >::type
+            operator=(T&& x) const
+        {
+            typedef typename ::boost::parameter::aux::tag<Tag,T>::type result;
+            return result(::std::forward<T>(x));
+        }
 
-#else
+        template <typename Default>
+        inline BOOST_CONSTEXPR typename ::boost::enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::std::is_scalar<Default>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<Default>
+              , ::boost::mpl::false_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::default_r_<Tag,Default const>
+        >::type
+            operator|(Default const&& d) const
+        {
+            return ::boost::parameter::aux::default_r_<Tag,Default const>(
+                ::std::forward<Default const>(d)
+            );
+        }
 
-#define BOOST_PARAMETER_KEYWORD(tag_namespace,name)                 \
-    namespace tag_namespace { struct name; }                        \
-    namespace                                                       \
-    {                                                               \
-       ::boost::parameter::keyword<tag_namespace::name>& name       \
-       = ::boost::parameter::keyword<tag_namespace::name>::get();   \
-    }
+        template <typename Default>
+        inline BOOST_CONSTEXPR typename ::boost::enable_if<
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+            ::boost::mp11::mp_if<
+                ::std::is_scalar<Default>
+              , ::boost::mp11::mp_false
+              , ::boost::mp11::mp_if<
+                    ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::consume_reference
+                    >
+                  , ::boost::mp11::mp_true
+                  , ::std::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >
+            >
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<Default>
+              , ::boost::mpl::false_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::consume_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+          , ::boost::parameter::aux::default_r_<Tag,Default>
+        >::type
+            operator|(Default&& d) const
+        {
+            return ::boost::parameter::aux
+            ::default_r_<Tag,Default>(::std::forward<Default>(d));
+        }
 
-#endif
+     public: // Insurance against ODR violations
+        // Users will need to define their keywords in header files.  To
+        // prevent ODR violations, it's important that the keyword used in
+        // every instantiation of a function template is the same object.
+        // We provide a reference to a common instance of each keyword
+        // object and prevent construction by users.
+        static ::boost::parameter::keyword<Tag> const instance;
 
+        // This interface is deprecated.
+        static ::boost::parameter::keyword<Tag>& get()
+        {
+            return const_cast< ::boost::parameter::keyword<Tag>&>(instance);
+        }
+    };
+
+    template <typename Tag>
+    ::boost::parameter::keyword<Tag> const ::boost::parameter
+    ::keyword<Tag>::instance = ::boost::parameter::keyword<Tag>();
 }} // namespace boost::parameter
 
-#endif // KEYWORD_050328_HPP
+#else   // !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
+
+#if !defined(BOOST_NO_SFINAE)
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/core/enable_if.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/is_scalar.hpp>
+#include <boost/type_traits/is_const.hpp>
+#endif  // BOOST_NO_SFINAE
+
+namespace boost { namespace parameter {
+
+    // Instances of unique specializations of keyword<...> serve to
+    // associate arguments with parameter names.  For example:
+    //
+    //     struct rate_;             // parameter names
+    //     struct skew_;
+    //
+    //     namespace
+    //     {
+    //         keyword<rate_> rate;  // keywords
+    //         keyword<skew_> skew;
+    //     }
+    //
+    //     ...
+    //
+    //     f(rate = 1, skew = 2.4);
+    template <typename Tag>
+    struct keyword
+    {
+        typedef Tag tag;
+
+        inline BOOST_CONSTEXPR keyword()
+        {
+        }
+
+        template <typename T>
+#if defined(BOOST_NO_SFINAE)
+        inline typename ::boost::parameter::aux::tag<Tag,T const&>::type
+#else
+        inline BOOST_CONSTEXPR typename ::boost::lazy_enable_if<
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<T>
+              , ::boost::mpl::true_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+          , ::boost::parameter::aux::tag<Tag,T const&>
+        >::type
+#endif  // BOOST_NO_SFINAE
+            operator=(T const& x) const
+        {
+            typedef typename ::boost::parameter::aux
+            ::tag<Tag,T const&>::type result;
+            return result(x);
+        }
+
+        template <typename Default>
+#if defined(BOOST_NO_SFINAE)
+        inline ::boost::parameter::aux::default_<Tag,Default const>
+#else
+        inline BOOST_CONSTEXPR typename ::boost::enable_if<
+            typename ::boost::mpl::eval_if<
+                ::boost::is_scalar<Default>
+              , ::boost::mpl::true_
+              , ::boost::mpl::eval_if<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::in_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::mpl::if_<
+                        ::boost::is_same<
+                            typename Tag::qualifier
+                          , ::boost::parameter::forward_reference
+                        >
+                      , ::boost::mpl::true_
+                      , ::boost::mpl::false_
+                    >
+                >
+            >::type
+          , ::boost::parameter::aux::default_<Tag,Default const>
+        >::type
+#endif  // BOOST_NO_SFINAE
+            operator|(Default const& d) const
+        {
+            return ::boost::parameter::aux::default_<Tag,Default const>(d);
+        }
+
+        template <typename T>
+#if defined(BOOST_NO_SFINAE)
+        inline typename ::boost::parameter::aux::tag<Tag,T&>::type
+#else
+        inline BOOST_CONSTEXPR typename ::boost::lazy_enable_if<
+            typename ::boost::mpl::eval_if<
+                typename ::boost::mpl::if_<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::out_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >::type
+              , ::boost::mpl::if_<
+                    ::boost::is_const<T>
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+              , ::boost::mpl::false_
+            >::type
+          , ::boost::parameter::aux::tag<Tag,T&>
+        >::type
+#endif  // BOOST_NO_SFINAE
+            operator=(T& x) const
+        {
+            typedef typename ::boost::parameter::aux
+            ::tag<Tag,T&>::type result;
+            return result(x);
+        }
+
+        template <typename Default>
+#if defined(BOOST_NO_SFINAE)
+        inline ::boost::parameter::aux::default_<Tag,Default>
+#else
+        inline BOOST_CONSTEXPR typename ::boost::enable_if<
+            typename ::boost::mpl::eval_if<
+                typename ::boost::mpl::if_<
+                    ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::out_reference
+                    >
+                  , ::boost::mpl::true_
+                  , ::boost::is_same<
+                        typename Tag::qualifier
+                      , ::boost::parameter::forward_reference
+                    >
+                >::type
+              , ::boost::mpl::if_<
+                    ::boost::is_const<Default>
+                  , ::boost::mpl::false_
+                  , ::boost::mpl::true_
+                >
+              , ::boost::mpl::false_
+            >::type
+          , ::boost::parameter::aux::default_<Tag,Default>
+        >::type
+#endif  // BOOST_NO_SFINAE
+            operator|(Default& d) const
+        {
+            return ::boost::parameter::aux::default_<Tag,Default>(d);
+        }
+
+        template <typename Default>
+        inline BOOST_CONSTEXPR
+        ::boost::parameter::aux::lazy_default<Tag,Default const>
+            operator||(Default const& d) const
+        {
+            return ::boost::parameter::aux
+            ::lazy_default<Tag,Default const>(d);
+        }
+
+        template <typename Default>
+        inline BOOST_CONSTEXPR
+        ::boost::parameter::aux::lazy_default<Tag,Default>
+            operator||(Default& d) const
+        {
+            return ::boost::parameter::aux::lazy_default<Tag,Default>(d);
+        }
+
+     public: // Insurance against ODR violations
+        // Users will need to define their keywords in header files.  To
+        // prevent ODR violations, it's important that the keyword used in
+        // every instantiation of a function template is the same object.
+        // We provide a reference to a common instance of each keyword
+        // object and prevent construction by users.
+        static ::boost::parameter::keyword<Tag> const instance;
+
+        // This interface is deprecated.
+        static ::boost::parameter::keyword<Tag>& get()
+        {
+            return const_cast< ::boost::parameter::keyword<Tag>&>(instance);
+        }
+    };
+
+    template <typename Tag>
+    ::boost::parameter::keyword<Tag> const ::boost::parameter
+    ::keyword<Tag>::instance = ::boost::parameter::keyword<Tag>();
+}} // namespace boost::parameter
+
+#endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
+
+#include <boost/parameter/aux_/name.hpp>
+#include <boost/preprocessor/stringize.hpp>
+
+// Reduces boilerplate required to declare and initialize keywords without
+// violating ODR.  Declares a keyword tag type with the given name in
+// namespace tag_namespace, and declares and initializes a reference in an
+// anonymous namespace to a singleton instance of that type.
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_KEYWORD(tag_namespace, name)                         \
+    namespace tag_namespace                                                  \
+    {                                                                        \
+        struct name                                                          \
+        {                                                                    \
+            static BOOST_CONSTEXPR char const* keyword_name()                \
+            {                                                                \
+                return BOOST_PP_STRINGIZE(name);                             \
+            }                                                                \
+            using _ = BOOST_PARAMETER_TAG_PLACEHOLDER_TYPE(name);            \
+            using _1 = _;                                                    \
+            BOOST_PARAMETER_TAG_MP11_PLACEHOLDER_BINDING(binding_fn, name);  \
+            BOOST_PARAMETER_TAG_MP11_PLACEHOLDER_VALUE(fn, name);            \
+            using qualifier = ::boost::parameter::forward_reference;         \
+        };                                                                   \
+    }                                                                        \
+    namespace                                                                \
+    {                                                                        \
+        ::boost::parameter::keyword<tag_namespace::name> const& name         \
+            = ::boost::parameter::keyword<tag_namespace::name>::instance;    \
+    }
+/**/
+#else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#define BOOST_PARAMETER_KEYWORD(tag_namespace, name)                         \
+    namespace tag_namespace                                                  \
+    {                                                                        \
+        struct name                                                          \
+        {                                                                    \
+            static BOOST_CONSTEXPR char const* keyword_name()                \
+            {                                                                \
+                return BOOST_PP_STRINGIZE(name);                             \
+            }                                                                \
+            typedef BOOST_PARAMETER_TAG_PLACEHOLDER_TYPE(name) _;            \
+            typedef BOOST_PARAMETER_TAG_PLACEHOLDER_TYPE(name) _1;           \
+            typedef ::boost::parameter::forward_reference qualifier;         \
+        };                                                                   \
+    }                                                                        \
+    namespace                                                                \
+    {                                                                        \
+        ::boost::parameter::keyword<tag_namespace::name> const& name         \
+            = ::boost::parameter::keyword<tag_namespace::name>::instance;    \
+    }
+/**/
+#endif  // BOOST_PARAMETER_CAN_USE_MP11
+
+#endif  // include guard