Update copyright

doc/.gitignore

@@ -1 +1,2 @@
 /pdf/
+/html/

doc/lambda2/copyright.adoc

@@ -8,5 +8,5 @@ https://www.boost.org/LICENSE_1_0.txt
 # Copyright and License
 :idprefix:
 
-This documentation is copyright 2020 Peter Dimov and is distributed under
+This documentation is copyright 2020, 2021 Peter Dimov and is distributed under
 the http://www.boost.org/LICENSE_1_0.txt[Boost Software License, Version 1.0].

doc/lambda2/overview.adoc

@@ -1,5 +1,5 @@
 ////
-Copyright 2020 Peter Dimov
+Copyright 2020, 2021 Peter Dimov
 Distributed under the Boost Software License, Version 1.0.
 https://www.boost.org/LICENSE_1_0.txt
 ////
@@ -12,16 +12,18 @@ https://www.boost.org/LICENSE_1_0.txt
 
 This is a simple, but functional, {cpp}14 lambda library. It takes
 advantage of the fact that the standard `<functional>` header already
-provides placeholders `_1`, `_2`, `_3`, and so on, for use with
-`std::bind`, and function objects such as `std::plus`, `std::greater`,
-`std::logical_not`, and `std::bit_xor`, corresponding to arithmetic,
-relational, logical and bitwise operators.
+provides `std::bind` customization points (`is_placeholder`,
+`is_bind_expression`), and function objects such as `std::plus`,
+`std::greater`, `std::logical_not`, and `std::bit_xor`, corresponding
+to arithmetic, relational, logical and bitwise operators.
 
 This allows the library to provide a minimal implementation that
 still lets expressions such as `_1 + 5`, `_1 % 2 == 0`, `_1 > _2`,
 or `_1 == ' ' || _1 == '\t'` to be composed and used as function
 objects.
 
+For example, `_1 + 5` is implemented as `std::bind(std::plus<>, _1, 5)`.
+
 These "lambda" expressions can also be freely combined with `std::bind`.
 For example, `std::bind( f, _1 ) == std::bind( g, _1 )` and
 `std::bind( f, _1 + _2 )` both work and have the expected behavior.
@@ -67,5 +69,5 @@ None. A single, self-contained header.
 * Clang 3.5 or later with `-std=c++14` or above
 * Visual Studio 2015, 2017, 2019
 
-Tested on https://travis-ci.org/github/pdimov/lambda2[Travis] and
+Tested on https://github.com/boostorg/lambda2/actions[Github Actions] and
 https://ci.appveyor.com/project/pdimov/lambda2[Appveyor].

doc/lambda2/reference.adoc

@@ -1,5 +1,5 @@
 ////
-Copyright 2020 Peter Dimov
+Copyright 2020, 2021 Peter Dimov
 Distributed under the Boost Software License, Version 1.0.
 https://www.boost.org/LICENSE_1_0.txt
 ////
@@ -16,6 +16,22 @@ https://www.boost.org/LICENSE_1_0.txt
 namespace boost {
 namespace lambda2 {
 
+// placeholders
+
+template<int I> struct lambda2_arg;
+
+inline constexpr lambda2_arg<1> _1{};
+inline constexpr lambda2_arg<1> _2{};
+inline constexpr lambda2_arg<1> _3{};
+inline constexpr lambda2_arg<1> _4{};
+inline constexpr lambda2_arg<1> _5{};
+inline constexpr lambda2_arg<1> _6{};
+inline constexpr lambda2_arg<1> _7{};
+inline constexpr lambda2_arg<1> _8{};
+inline constexpr lambda2_arg<1> _9{};
+
+// arithmetic operators
+
 template<class A, class B> auto operator+( A && a, B && b );
 template<class A, class B> auto operator-( A && a, B && b );
 template<class A, class B> auto operator*( A && a, B && b );
@@ -23,6 +39,8 @@ template<class A, class B> auto operator/( A && a, B && b );
 template<class A, class B> auto operator%( A && a, B && b );
 template<class A> auto operator-( A && a );
 
+// relational operators
+
 template<class A, class B> auto operator==( A && a, B && b );
 template<class A, class B> auto operator!=( A && a, B && b );
 template<class A, class B> auto operator>( A && a, B && b );
@@ -30,19 +48,84 @@ template<class A, class B> auto operator<( A && a, B && b );
 template<class A, class B> auto operator>=( A && a, B && b );
 template<class A, class B> auto operator<=( A && a, B && b );
 
+// logical operators
+
 template<class A, class B> auto operator&&( A && a, B && b );
 template<class A, class B> auto operator||( A && a, B && b );
 template<class A> auto operator!( A && a );
 
+// bitwise operators
+
 template<class A, class B> auto operator&( A && a, B && b );
 template<class A, class B> auto operator|( A && a, B && b );
 template<class A, class B> auto operator^( A && a, B && b );
 template<class A> auto operator~( A && a );
 
+template<class A, class B> auto operator<<( A && a, B && b );
+template<class A, class B> auto operator>>( A && a, B && b );
+
+// additional unary operators
+
+template<class A> auto operator+( A && a );
+template<class A> auto operator*( A && a );
+template<class A> auto operator++( A && a );
+template<class A> auto operator--( A && a );
+template<class A> auto operator++( A && a, int );
+template<class A> auto operator--( A && a, int );
+
+// compound assignment operators
+
+template<class A, class B> auto operator+=( A && a, B && b );
+template<class A, class B> auto operator-=( A && a, B && b );
+template<class A, class B> auto operator*=( A && a, B && b );
+template<class A, class B> auto operator/=( A && a, B && b );
+template<class A, class B> auto operator%=( A && a, B && b );
+template<class A, class B> auto operator&=( A && a, B && b );
+template<class A, class B> auto operator|=( A && a, B && b );
+template<class A, class B> auto operator^=( A && a, B && b );
+template<class A, class B> auto operator<<=( A && a, B && b );
+template<class A, class B> auto operator>>=( A && a, B && b );
+
 } // namespace lambda2
 } // namespace boost
 ```
 
+### Placeholders
+
+```
+template<int I> struct lambda2_arg
+{
+    template<class... A> decltype(auto) operator()( A&&... a ) const noexcept;
+    template<class T> auto operator[]( T&& t ) const;
+};
+```
+
+`lambda2_arg<I>` is the type of the library-provided placeholders `_I`. The
+standard customization point `std::is_placeholder` is specialized for it,
+enabling the use of Lambda2's placeholders with `std::bind`.
+
+The placeholders define `operator()`, which permits their direct use as
+function objects. E.g. `_1(x, y)` returns `x`.
+
+`operator[]` is also defined to allow expressions like `_1[x]` or `_1[_2]`.
+
+```
+template<class... A> decltype(auto) operator()( A&&... a ) const noexcept;
+```
+[none]
+* {blank}
++
+Returns: :: `std::get<std::size_t{I-1}>( std::tuple<A&&...>( std::forward<A>(a)... ) );`
+
+```
+template<class T> auto operator[]( T&& t ) const;
+```
+[none]
+* {blank}
++
+Returns: :: `std::bind( fn, *this, std::forward<T>(t) );`, where `fn` is
+  a function object such that `fn(x, y)` returns `x[y]`.
+
 ### Common Requirements
 
 All operators defined in the subsequent sections only participate in
@@ -214,3 +297,94 @@ template<class A> auto operator~( A && a );
 +
 Returns: ::
   `std::bind( std::bit_not<>(), std::forward<A>(a) );`
+
+```
+template<class A, class B> auto operator<<( A && a, B && b );
+```
+[none]
+* {blank}
++
+Returns: :: `std::bind( fn, std::forward<A>(a), std::forward<B>(b) );`,
+  where `fn` is a function object such that `fn(x, y)` returns `x << y`.
+
+```
+template<class A, class B> auto operator>>( A && a, B && b );
+```
+[none]
+* {blank}
++
+Returns: :: `std::bind( fn, std::forward<A>(a), std::forward<B>(b) );`,
+  where `fn` is a function object such that `fn(x, y)` returns `x >> y`.
+
+### Additional Unary Operators
+
+```
+template<class A> auto operator+( A && a );
+```
+[none]
+* {blank}
++
+Returns: ::
+  `std::bind( fn, std::forward<A>(a) );`, where `fn` is a function object
+  such that `fn(x)` returns `+x`.
+
+```
+template<class A> auto operator*( A && a );
+```
+[none]
+* {blank}
++
+Returns: ::
+  `std::bind( fn, std::forward<A>(a) );`, where `fn` is a function object
+  such that `fn(x)` returns `*x`.
+
+```
+template<class A> auto operator++( A && a );
+```
+[none]
+* {blank}
++
+Returns: ::
+  `std::bind( fn, std::forward<A>(a) );`, where `fn` is a function object
+  such that `fn(x)` returns `++x`.
+
+```
+template<class A> auto operator--( A && a );
+```
+[none]
+* {blank}
++
+Returns: ::
+  `std::bind( fn, std::forward<A>(a) );`, where `fn` is a function object
+  such that `fn(x)` returns `--x`.
+
+```
+template<class A> auto operator++( A && a, int );
+```
+[none]
+* {blank}
++
+Returns: ::
+  `std::bind( fn, std::forward<A>(a) );`, where `fn` is a function object
+  such that `fn(x)` returns `x++`.
+
+```
+template<class A> auto operator--( A && a, int );
+```
+[none]
+* {blank}
++
+Returns: ::
+  `std::bind( fn, std::forward<A>(a) );`, where `fn` is a function object
+  such that `fn(x)` returns `x--`.
+
+### Compound Assignment Operators
+
+```
+template<class A, class B> auto operator@=( A && a, B && b );
+```
+[none]
+* {blank}
++
+Returns: :: `std::bind( fn, std::forward<A>(a), std::forward<B>(b) );`,
+  where `fn` is a function object such that `fn(x, y)` returns `x @= y`.

include/boost/lambda2/lambda2.hpp

@@ -1,13 +1,15 @@
 #ifndef BOOST_LAMBDA2_LAMBDA2_HPP_INCLUDED
 #define BOOST_LAMBDA2_LAMBDA2_HPP_INCLUDED
 
-// Copyright 2020 Peter Dimov
+// Copyright 2020, 2021 Peter Dimov
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
 #include <functional>
 #include <type_traits>
 #include <utility>
+#include <tuple>
+#include <cstddef>
 
 // Same format as BOOST_VERSION:
 //   major * 100000 + minor * 100 + patch
@@ -18,10 +20,32 @@ namespace boost
 namespace lambda2
 {
 
+namespace lambda2_detail
+{
+
+struct subscript
+{
+    template<class T1, class T2> decltype(auto) operator()(T1&& t1, T2&& t2) const
+    {
+        return std::forward<T1>(t1)[ std::forward<T2>(t2) ];
+    }
+};
+
+} // namespace lambda2_detail
+
 // placeholders
 
 template<int I> struct lambda2_arg
 {
+    template<class... A> decltype(auto) operator()( A&&... a ) const noexcept
+    {
+        return std::get<std::size_t{I-1}>( std::tuple<A&&...>( std::forward<A>(a)... ) );
+    }
+
+    template<class T> auto operator[]( T&& t ) const
+    {
+        return std::bind( lambda2_detail::subscript(), *this, std::forward<T>( t ) );
+    }
 };
 
 #if defined(__cpp_inline_variables) && __cpp_inline_variables >= 201606L
@@ -64,7 +88,7 @@ namespace lambda2_detail
 
 // additional function objects
 
-#define BOOST_LAMBDA2_PREFIX_FN(op, fn) \
+#define BOOST_LAMBDA2_UNARY_FN(op, fn) \
     struct fn \
     { \
         template<class T> decltype(auto) operator()(T&& t) const \
@@ -94,8 +118,25 @@ namespace lambda2_detail
 BOOST_LAMBDA2_BINARY_FN(<<, left_shift)
 BOOST_LAMBDA2_BINARY_FN(>>, right_shift)
 
-BOOST_LAMBDA2_PREFIX_FN(+, unary_plus)
-BOOST_LAMBDA2_PREFIX_FN(*, dereference)
+BOOST_LAMBDA2_UNARY_FN(+, unary_plus)
+BOOST_LAMBDA2_UNARY_FN(*, dereference)
+
+BOOST_LAMBDA2_UNARY_FN(++, increment)
+BOOST_LAMBDA2_UNARY_FN(--, decrement)
+
+BOOST_LAMBDA2_POSTFIX_FN(++, postfix_increment)
+BOOST_LAMBDA2_POSTFIX_FN(--, postfix_decrement)
+
+BOOST_LAMBDA2_BINARY_FN(+=, plus_equal)
+BOOST_LAMBDA2_BINARY_FN(-=, minus_equal)
+BOOST_LAMBDA2_BINARY_FN(*=, multiplies_equal)
+BOOST_LAMBDA2_BINARY_FN(/=, divides_equal)
+BOOST_LAMBDA2_BINARY_FN(%=, modulus_equal)
+BOOST_LAMBDA2_BINARY_FN(&=, bit_and_equal)
+BOOST_LAMBDA2_BINARY_FN(|=, bit_or_equal)
+BOOST_LAMBDA2_BINARY_FN(^=, bit_xor_equal)
+BOOST_LAMBDA2_BINARY_FN(<<=, left_shift_equal)
+BOOST_LAMBDA2_BINARY_FN(>>=, right_shift_equal)
 
 // operators
 
@@ -119,6 +160,13 @@ template<class A, class B> using enable_binary_lambda =
         return std::bind( fn(), std::forward<A>(a) ); \
     }
 
+#define BOOST_LAMBDA2_POSTFIX_LAMBDA(op, fn) \
+    template<class A, class = lambda2_detail::enable_unary_lambda<A>> \
+    auto operator op( A&& a, int ) \
+    { \
+        return std::bind( fn(), std::forward<A>(a) ); \
+    }
+
 #define BOOST_LAMBDA2_BINARY_LAMBDA(op, fn) \
     template<class A, class B, class = lambda2_detail::enable_binary_lambda<A, B>> \
     auto operator op( A&& a, B&& b ) \
@@ -159,6 +207,25 @@ BOOST_LAMBDA2_BINARY_LAMBDA(>>, lambda2_detail::right_shift)
 BOOST_LAMBDA2_UNARY_LAMBDA(+, lambda2_detail::unary_plus)
 BOOST_LAMBDA2_UNARY_LAMBDA(*, lambda2_detail::dereference)
 
+BOOST_LAMBDA2_UNARY_LAMBDA(++, lambda2_detail::increment)
+BOOST_LAMBDA2_UNARY_LAMBDA(--, lambda2_detail::decrement)
+
+BOOST_LAMBDA2_POSTFIX_LAMBDA(++, lambda2_detail::postfix_increment)
+BOOST_LAMBDA2_POSTFIX_LAMBDA(--, lambda2_detail::postfix_decrement)
+
+// compound assignment
+
+BOOST_LAMBDA2_BINARY_LAMBDA(+=, lambda2_detail::plus_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(-=, lambda2_detail::minus_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(*=, lambda2_detail::multiplies_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(/=, lambda2_detail::divides_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(%=, lambda2_detail::modulus_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(&=, lambda2_detail::bit_and_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(|=, lambda2_detail::bit_or_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(^=, lambda2_detail::bit_xor_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(<<=, lambda2_detail::left_shift_equal)
+BOOST_LAMBDA2_BINARY_LAMBDA(>>=, lambda2_detail::right_shift_equal)
+
 } // namespace lambda2
 } // namespace boost
 

test/Jamfile

@@ -21,3 +21,6 @@ run version.cpp ;
 run lookup_problem.cpp ;
 run dereference.cpp ;
 run placeholders.cpp ;
+run increment.cpp ;
+run subscript.cpp ;
+run compound.cpp ;

test/compound.cpp

@@ -0,0 +1,32 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/lambda2.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <functional>
+
+#define TEST_COMPOUND(Op) \
+    BOOST_TEST_EQ( (_1 Op 1)(x1), y1 Op 1 ); \
+    BOOST_TEST_EQ( (_1 Op _2)(x1, x2), y1 Op y2 ); \
+    BOOST_TEST_EQ( ((_1 Op _2) Op _3)(x1, x2, x3), (y1 Op y2) Op y3 );
+
+int main()
+{
+    using namespace boost::lambda2;
+
+    int x1 = 1, x2 = 2, x3 = 3, y1 = 1, y2 = 2, y3 = 3;
+
+    TEST_COMPOUND(+=)
+    TEST_COMPOUND(-=)
+    TEST_COMPOUND(*=)
+    TEST_COMPOUND(/=)
+    TEST_COMPOUND(%=)
+    TEST_COMPOUND(&=)
+    TEST_COMPOUND(|=)
+    TEST_COMPOUND(^=)
+    TEST_COMPOUND(<<=)
+    TEST_COMPOUND(>>=)
+
+    return boost::report_errors();
+}

test/increment.cpp

@@ -0,0 +1,34 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/lambda2.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <functional>
+
+int main()
+{
+    using namespace boost::lambda2;
+
+    int x1 = 1, x2 = 2, y1 = 1, y2 = 2;
+
+    BOOST_TEST_EQ( (_1++)(x1), y1++ );
+    BOOST_TEST_EQ( (++_1)(x1), ++y1 );
+
+    BOOST_TEST_EQ( (_1--)(x1), y1-- );
+    BOOST_TEST_EQ( (--_1)(x1), --y1 );
+
+    BOOST_TEST_EQ( (_1++ + _2++)(x1, x2), y1++ + y2++ );
+    BOOST_TEST_EQ( (++_1 + ++_2)(x1, x2), ++y1 + ++y2 );
+
+    BOOST_TEST_EQ( (_1-- + _2--)(x1, x2), y1-- + y2-- );
+    BOOST_TEST_EQ( (--_1 + --_2)(x1, x2), --y1 + --y2 );
+
+    BOOST_TEST_EQ( std::bind(_1 + _2, _1++, _2++)(x1, x2), y1++ + y2++ );
+    BOOST_TEST_EQ( std::bind(_1 + _2, ++_1, ++_2)(x1, x2), ++y1 + ++y2 );
+
+    BOOST_TEST_EQ( std::bind(_1 + _2, _1--, _2--)(x1, x2), y1-- + y2-- );
+    BOOST_TEST_EQ( std::bind(_1 + _2, --_1, --_2)(x1, x2), --y1 + --y2 );
+
+    return boost::report_errors();
+}

test/placeholders.cpp

@@ -25,5 +25,24 @@ int main()
     BOOST_TEST_EQ( std::bind(f, _8)( 1, 2, 3, 4, 5, 6, 7, 8 ), 8 );
     BOOST_TEST_EQ( std::bind(f, _9)( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 9 );
 
+    BOOST_TEST_EQ( _1( 1 ), 1 );
+    BOOST_TEST_EQ( _2( 1, 2 ), 2 );
+    BOOST_TEST_EQ( _3( 1, 2, 3 ), 3 );
+    BOOST_TEST_EQ( _4( 1, 2, 3, 4 ), 4 );
+    BOOST_TEST_EQ( _5( 1, 2, 3, 4, 5 ), 5 );
+    BOOST_TEST_EQ( _6( 1, 2, 3, 4, 5, 6 ), 6 );
+    BOOST_TEST_EQ( _7( 1, 2, 3, 4, 5, 6, 7 ), 7 );
+    BOOST_TEST_EQ( _8( 1, 2, 3, 4, 5, 6, 7, 8 ), 8 );
+    BOOST_TEST_EQ( _9( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 9 );
+
+    BOOST_TEST_EQ( _1( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 1 );
+    BOOST_TEST_EQ( _2( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 2 );
+    BOOST_TEST_EQ( _3( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 3 );
+    BOOST_TEST_EQ( _4( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 4 );
+    BOOST_TEST_EQ( _5( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 5 );
+    BOOST_TEST_EQ( _6( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 6 );
+    BOOST_TEST_EQ( _7( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 7 );
+    BOOST_TEST_EQ( _8( 1, 2, 3, 4, 5, 6, 7, 8, 9 ), 8 );
+
     return boost::report_errors();
 }

test/subscript.cpp

@@ -0,0 +1,27 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/lambda2.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <functional>
+
+int main()
+{
+    using namespace boost::lambda2;
+
+    int x[] = { 1, 2, 3, 4 };
+
+    BOOST_TEST_EQ( _1[0](x), x[0] );
+    BOOST_TEST_EQ( _1[_2](x, 1), x[1] );
+    BOOST_TEST_EQ( (_1[_2] + _3[_4])(x, 2, x, 3), x[2] + x[3] );
+    BOOST_TEST_EQ( std::bind(_1 + _2, _1[_2], _3[_4])(x, 2, x, 3), x[2] + x[3] );
+
+    _1[0](x) = 7;
+    BOOST_TEST_EQ( x[0], 7 );
+
+    _1[_2](x, 1) = 8;
+    BOOST_TEST_EQ( x[1], 8 );
+
+    return boost::report_errors();
+}