Add tuple_apply

doc/html/mp11.html

@@ -591,6 +591,7 @@ body.book #toc,body.book #preamble,body.book h1.sect0,body.book .sect1>h2{page-b
 </li>
 <li><a href="#tuple">Tuple Operations, &lt;boost/mp11/tuple.hpp&gt;</a>
 <ul class="sectlevel3">
+<li><a href="#tuple_apply_f_tp">tuple_apply(f, tp)</a></li>
 <li><a href="#tuple_for_each_tp_f">tuple_for_each(tp, f)</a></li>
 </ul>
 </li>
@@ -2809,6 +2810,18 @@ of <code>U&#8230;&#8203;</code> and the <code>mp_bind</code> expressions replace
 <div class="sect2">
 <h3 id="tuple">Tuple Operations, &lt;boost/mp11/tuple.hpp&gt;</h3>
 <div class="sect3">
+<h4 id="tuple_apply_f_tp">tuple_apply(f, tp)</h4>
+<div class="literalblock">
+<div class="content">
+<pre>template&lt;class F, class Tp&gt; constexpr /*...*/ tuple_apply(F&amp;&amp; f, Tp&amp;&amp; tp);</pre>
+</div>
+</div>
+<div class="paragraph">
+<p><code>tuple_apply(f, tp)</code> returns <code>std::forward&lt;F&gt;(f)(std::get&lt;J&gt;(std::forward&lt;Tp&gt;(tp))&#8230;&#8203;)</code> for <code>J</code> in 0..<code>N-1</code>,
+where <code>N</code> is <code>std::tuple_size&lt;typename std::remove_reference&lt;Tp&gt;::type&gt;::value</code>. Same as <code>std::apply</code> in C++17.</p>
+</div>
+</div>
+<div class="sect3">
 <h4 id="tuple_for_each_tp_f">tuple_for_each(tp, f)</h4>
 <div class="literalblock">
 <div class="content">

doc/mp11/tuple.adoc

@@ -9,8 +9,17 @@ http://www.boost.org/LICENSE_1_0.txt
 
 [#tuple]
 # Tuple Operations, <boost/mp11/tuple.hpp>
+:toc:
+:toc-title:
 :idprefix:
 
+## tuple_apply(f, tp)
+
+    template<class F, class Tp> constexpr /*...*/ tuple_apply(F&& f, Tp&& tp);
+
+`tuple_apply(f, tp)` returns `std::forward<F>(f)(std::get<J>(std::forward<Tp>(tp))...)` for `J` in 0..`N-1`,
+where `N` is `std::tuple_size<typename std::remove_reference<Tp>::type>::value`. Same as `std::apply` in C++17.
+
 ## tuple_for_each(tp, f)
 
     template<class Tp, class F> constexpr F tuple_for_each(Tp&& tp, F&& f);

include/boost/mp11/tuple.hpp

@@ -21,6 +21,26 @@ namespace boost
 namespace mp11
 {
 
+// tuple_apply
+namespace detail
+{
+
+template<class F, class Tp, std::size_t... J> BOOST_CONSTEXPR auto tuple_apply_impl( F && f, Tp && tp, integer_sequence<std::size_t, J...> )
+    -> decltype( std::forward<F>(f)( std::get<J>(std::forward<Tp>(tp))... ) )
+{
+    return std::forward<F>(f)( std::get<J>(std::forward<Tp>(tp))... );
+}
+
+} // namespace detail
+
+template<class F, class Tp,
+    class Seq = make_index_sequence<std::tuple_size<typename std::remove_reference<Tp>::type>::value>>
+BOOST_CONSTEXPR auto tuple_apply( F && f, Tp && tp )
+    -> decltype( detail::tuple_apply_impl( std::forward<F>(f), std::forward<Tp>(tp), Seq() ) )
+{
+    return detail::tuple_apply_impl( std::forward<F>(f), std::forward<Tp>(tp), Seq() );
+}
+
 // tuple_for_each
 namespace detail
 {

include/boost/mp11_single.hpp

@@ -2675,6 +2675,26 @@ namespace boost
 namespace mp11
 {
 
+// tuple_apply
+namespace detail
+{
+
+template<class F, class Tp, std::size_t... J> BOOST_CONSTEXPR auto tuple_apply_impl( F && f, Tp && tp, integer_sequence<std::size_t, J...> )
+    -> decltype( std::forward<F>(f)( std::get<J>(std::forward<Tp>(tp))... ) )
+{
+    return std::forward<F>(f)( std::get<J>(std::forward<Tp>(tp))... );
+}
+
+} // namespace detail
+
+template<class F, class Tp,
+    class Seq = make_index_sequence<std::tuple_size<typename std::remove_reference<Tp>::type>::value>>
+BOOST_CONSTEXPR auto tuple_apply( F && f, Tp && tp )
+    -> decltype( detail::tuple_apply_impl( std::forward<F>(f), std::forward<Tp>(tp), Seq() ) )
+{
+    return detail::tuple_apply_impl( std::forward<F>(f), std::forward<Tp>(tp), Seq() );
+}
+
 // tuple_for_each
 namespace detail
 {

test/Jamfile

@@ -93,9 +93,11 @@ run mp_invoke_sf.cpp : : : $(REQ) ;
 # integer_sequence
 run integer_sequence.cpp : : : $(REQ) ;
 
-# tuple_for_each
+# tuple
 run tuple_for_each.cpp : : : $(REQ) ;
 run tuple_for_each_cx.cpp : : : $(REQ) ;
+run tuple_apply.cpp : : : $(REQ) ;
+run tuple_apply_cx.cpp : : : $(REQ) ;
 
 # set
 run mp_set_contains.cpp : : : $(REQ) ;

test/tuple_apply.cpp

@@ -0,0 +1,132 @@
+
+// Copyright 2015, 2017 Peter Dimov.
+//
+// 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/mp11/tuple.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <tuple>
+#include <memory>
+#include <utility>
+#include <array>
+
+int main()
+{
+    using boost::mp11::tuple_apply;
+
+    {
+        std::tuple<int, short, char> tp{ 1, 2, 3 };
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, tp );
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, std::move(tp) );
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
+    {
+        std::tuple<int, short, char> const tp{ 1, 2, 3 };
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, tp );
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, std::move(tp) );
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
+#if defined( __clang_major__ ) && __clang_major__ == 3 && __clang_minor__ < 8
+#else
+
+    {
+        std::tuple<std::unique_ptr<int>, std::unique_ptr<int>, std::unique_ptr<int>> tp{ std::unique_ptr<int>(new int(1)), std::unique_ptr<int>(new int(2)), std::unique_ptr<int>(new int(3)) };
+
+        int s = tuple_apply( [&]( std::unique_ptr<int> px, std::unique_ptr<int> py, std::unique_ptr<int> pz ){ return 100 * *px + 10 * *py + *pz; }, std::move(tp) );
+        BOOST_TEST_EQ( s, 123 );
+    }
+
+#endif
+
+    {
+        std::pair<int, short> tp{ 1, 2 };
+
+        {
+            int s = tuple_apply( [&]( int x, int y ){ return 10 * x + y; }, tp );
+            BOOST_TEST_EQ( s, 12 );
+        }
+
+        {
+            int s = tuple_apply( [&]( int x, int y ){ return 10 * x + y; }, std::move(tp) );
+            BOOST_TEST_EQ( s, 12 );
+        }
+    }
+
+    {
+        std::pair<int, short> const tp{ 1, 2 };
+
+        {
+            int s = tuple_apply( [&]( int x, int y ){ return 10 * x + y; }, tp );
+            BOOST_TEST_EQ( s, 12 );
+        }
+
+        {
+            int s = tuple_apply( [&]( int x, int y ){ return 10 * x + y; }, std::move(tp) );
+            BOOST_TEST_EQ( s, 12 );
+        }
+    }
+
+    {
+        std::array<int, 3> tp{{ 1, 2, 3 }};
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, tp );
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, std::move(tp) );
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
+    {
+        std::array<int, 3> const tp{{ 1, 2, 3 }};
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, tp );
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = tuple_apply( [&]( int x, int y, int z ){ return 100 * x + 10 * y + z; }, std::move(tp) );
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
+    {
+        std::tuple<> tp;
+
+        BOOST_TEST_EQ( tuple_apply( []{ return 11; }, tp ), 11 );
+        BOOST_TEST_EQ( tuple_apply( []{ return 12; }, std::move( tp ) ), 12 );
+    }
+
+    {
+        std::array<int, 0> tp;
+
+        BOOST_TEST_EQ( tuple_apply( []{ return 11; }, tp ), 11 );
+        BOOST_TEST_EQ( tuple_apply( []{ return 12; }, std::move( tp ) ), 12 );
+    }
+
+    return boost::report_errors();
+}

test/tuple_apply_cx.cpp

@@ -0,0 +1,66 @@
+
+//  Copyright 2015 Peter Dimov.
+//
+// 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/mp11/tuple.hpp>
+#include <boost/config.hpp>
+
+// Technically std::tuple isn't constexpr enabled in C++11, but it works with libstdc++
+
+#if defined( BOOST_NO_CXX11_CONSTEXPR ) || ( defined( _LIBCPP_VERSION ) && __cplusplus < 201400L )
+
+int main() {}
+
+#else
+
+#include <tuple>
+#include <array>
+#include <utility>
+
+constexpr int f( int x, int y, int z )
+{
+    return x * 100 + y * 10 + z;
+}
+
+constexpr int g( int x, int y )
+{
+    return x * 10 + y;
+}
+
+constexpr int h()
+{
+    return 11;
+}
+
+int main()
+{
+    {
+        constexpr std::tuple<int, short, char> tp{ 1, 2, 3 };
+        constexpr auto r = boost::mp11::tuple_apply( f, tp );
+        static_assert( r == 123, "r == 123" );
+    }
+
+    {
+        constexpr std::pair<short, char> tp{ 1, 2 };
+        constexpr auto r = boost::mp11::tuple_apply( g, tp );
+        static_assert( r == 12, "r == 12" );
+    }
+
+    {
+        constexpr std::array<short, 3> tp{{ 1, 2, 3 }};
+        constexpr auto r = boost::mp11::tuple_apply( f, tp );
+        static_assert( r == 123, "r == 123" );
+    }
+
+    {
+        constexpr std::tuple<> tp;
+        constexpr auto r = boost::mp11::tuple_apply( h, tp );
+        static_assert( r == 11, "r == 11" );
+    }
+}
+
+#endif

test/tuple_for_each.cpp

@@ -38,6 +38,26 @@ int main()
         }
     }
 
+    {
+        std::tuple<int, short, char> const tp{ 1, 2, 3 };
+
+        {
+            int s = 0;
+
+            tuple_for_each( tp, [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = 0;
+
+            tuple_for_each( std::move(tp), [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
 #if defined( __clang_major__ ) && __clang_major__ == 3 && __clang_minor__ < 8
 #else
 
@@ -73,6 +93,26 @@ int main()
         }
     }
 
+    {
+        std::pair<int, short> const tp{ 1, 2 };
+
+        {
+            int s = 0;
+
+            tuple_for_each( tp, [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 12 );
+        }
+
+        {
+            int s = 0;
+
+            tuple_for_each( std::move(tp), [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 12 );
+        }
+    }
+
     {
         std::array<int, 3> tp{{ 1, 2, 3 }};
 
@@ -93,6 +133,26 @@ int main()
         }
     }
 
+    {
+        std::array<int, 3> const tp{{ 1, 2, 3 }};
+
+        {
+            int s = 0;
+
+            tuple_for_each( tp, [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+
+        {
+            int s = 0;
+
+            tuple_for_each( std::move(tp), [&]( int x ){ s = s * 10 + x; } );
+
+            BOOST_TEST_EQ( s, 123 );
+        }
+    }
+
     {
         std::tuple<> tp;