From 3dcc2f3cdcbc2d718d7d68d4b06a70173683a8ba Mon Sep 17 00:00:00 2001
From: Paul <pfultz2@yahoo.com>
Date: Fri, 8 Aug 2014 19:26:40 -0400
Subject: [PATCH] Add macros for delegating constructors

---
 fit/detail/delegate.h                         | 37 +++++++++++++++++++
 .../remove_rvalue_reference.h}                | 23 +++++++++---
 fit/fix.h                                     |  2 +-
 fit/lazy.h                                    |  2 +-
 fit/on.h                                      |  2 +-
 test/on.cpp                                   | 16 ++++----
 6 files changed, 65 insertions(+), 17 deletions(-)
 create mode 100644 fit/detail/delegate.h
 rename fit/{enable_if_convertible.h => detail/remove_rvalue_reference.h} (52%)

diff --git a/fit/detail/delegate.h b/fit/detail/delegate.h
new file mode 100644
index 0000000..d392c96
--- /dev/null
+++ b/fit/detail/delegate.h
@@ -0,0 +1,37 @@
+/*=============================================================================
+    Copyright (c) 2012 Paul Fultz II
+    delgate.h
+    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 FIT_GUARD_FUNCTION_DELGATE_H
+#define FIT_GUARD_FUNCTION_DELGATE_H
+
+#include <type_traits>
+#include <utility>
+
+#define FIT_ENABLE_IF_CONVERTIBLE(...) \
+    typename std::enable_if<std::is_convertible<__VA_ARGS__>::value, int>::type = 0
+
+#define FIT_ENABLE_IF_CONVERTIBLE_UNPACK(...) \
+    typename std::enable_if<std::is_convertible<__VA_ARGS__>::value..., int>::type = 0
+
+#define FIT_ENABLE_IF_CONSTRUCTIBLE(...) \
+    typename std::enable_if<std::is_constructible<__VA_ARGS__>::value, int>::type = 0
+
+#define FIT_DELGATE_CONSTRUCTOR(C, T, var) \
+    template<class... FitXs, FIT_ENABLE_IF_CONSTRUCTIBLE(T, FitXs&&...)> \
+    constexpr C(FitXs&&... fit_xs) : var(std::forward<FitXs>(fit_xs)...) {}
+
+// TODO: For compilers that support inheriting constructors replace with
+// `using Base::Base;`
+#define FIT_INHERIT_CONSTRUCTOR(Derived, Base) FIT_DELGATE_CONSTRUCTOR(Derived, Base, Base)
+
+namespace fit {
+namespace detail {
+
+}
+}
+
+#endif
\ No newline at end of file
diff --git a/fit/enable_if_convertible.h b/fit/detail/remove_rvalue_reference.h
similarity index 52%
rename from fit/enable_if_convertible.h
rename to fit/detail/remove_rvalue_reference.h
index 919740c..78cd7e0 100644
--- a/fit/enable_if_convertible.h
+++ b/fit/detail/remove_rvalue_reference.h
@@ -1,16 +1,27 @@
 /*=============================================================================
     Copyright (c) 2014 Paul Fultz II
-    enable_if_convertible.h
+    remove_rvalue_reference.h
     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 FIT_GUARD_FUNCTION_ENABLE_IF_CONVERTIBLE_H
-#define FIT_GUARD_FUNCTION_ENABLE_IF_CONVERTIBLE_H
+#ifndef FIT_GUARD_FUNCTION_REMOVE_RVALUE_REFERENCE_H
+#define FIT_GUARD_FUNCTION_REMOVE_RVALUE_REFERENCE_H
 
-#include <utility>
+namespace fit { namespace detail {
 
-#define FIT_ENABLE_IF_CONVERTIBLE(T, U) \
-	typename std::enable_if<std::is_convertible<T, U>::value, int>::type = 0
+template<class T>
+struct remove_rvalue_reference
+{
+    typedef T type;
+};
+
+template<class T>
+struct remove_rvalue_reference<T&&>
+{
+    typedef T type;
+};
+
+}}
 
 #endif
\ No newline at end of file
diff --git a/fit/fix.h b/fit/fix.h
index 5772a86..885a019 100644
--- a/fit/fix.h
+++ b/fit/fix.h
@@ -32,7 +32,7 @@
 
 #include <fit/always.h>
 #include <fit/returns.h>
-#include <fit/enable_if_convertible.h>
+#include <fit/detail/delegate.h>
 
 #ifndef FIT_FIX_HAS_CONSTEXPR
 #define FIT_FIX_HAS_CONSTEXPR 0
diff --git a/fit/lazy.h b/fit/lazy.h
index 91487f7..1967dee 100644
--- a/fit/lazy.h
+++ b/fit/lazy.h
@@ -44,7 +44,7 @@
 #include <fit/always.h>
 #include <fit/static.h>
 #include <fit/invoke.h>
-#include <fit/enable_if_convertible.h>
+#include <fit/detail/delegate.h>
 #include <tuple>
 #include <functional>
 #include <type_traits>
diff --git a/fit/on.h b/fit/on.h
index b756f74..ea02837 100644
--- a/fit/on.h
+++ b/fit/on.h
@@ -41,7 +41,7 @@
 
 #include <utility>
 #include <fit/always.h>
-#include <fit/enable_if_convertible.h>
+#include <fit/detail/delegate.h>
 #include <fit/returns.h>
 
 namespace fit {
diff --git a/test/on.cpp b/test/on.cpp
index a0751a6..4e8d6ab 100644
--- a/test/on.cpp
+++ b/test/on.cpp
@@ -4,20 +4,20 @@
 
 struct foo
 {
-	constexpr foo(int x) : x(x)
-	{}
-	int x;
+    constexpr foo(int x) : x(x)
+    {}
+    int x;
 };
 
 struct select_x
 {
-	template<class T>
-	constexpr auto operator()(T&& x) const FIT_RETURNS(x.x);
+    template<class T>
+    constexpr auto operator()(T&& x) const FIT_RETURNS(x.x);
 };
 
 FIT_TEST_CASE()
 {
-	constexpr auto add = fit::_ + fit::_;
-	static_assert(fit::on(select_x(), fit::_ + fit::_)(foo(1), foo(2)) == 3, "Constexpr projection failed");
-	FIT_TEST_CHECK(fit::on(std::mem_fn(&foo::x), fit::_ + fit::_)(foo(1), foo(2)) == 3);
+    constexpr auto add = fit::_ + fit::_;
+    static_assert(fit::on(select_x(), fit::_ + fit::_)(foo(1), foo(2)) == 3, "Constexpr projection failed");
+    FIT_TEST_CHECK(fit::on(std::mem_fn(&foo::x), fit::_ + fit::_)(foo(1), foo(2)) == 3);
 }