[patch] Add std::experimental::apply()

[Jonathan Wakely <jwakely at redhat dot com>]

> From the Fundamentals TS.

Tested x86_64-linux, committed to trunk.

commit df1e59560b6723da563f3aae8d95dcfe2781173b
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Oct 3 17:51:31 2014 +0100

    	* include/Makefile.am: Add new header.
    	* include/Makefile.in: Regenerate.
    	* include/experimental/tuple: New
    	* doc/xml/manual/status_cxx2014.xml: Update.
    	* doc/html/manual/status.html: Regenerate.
    	* testsuite/experimental/feat-lib-fund.cc: Test for new header.
    	* testsuite/experimental/tuple/apply.cc: New.

diff --git a/libstdc++-v3/doc/xml/manual/status_cxx2014.xml b/libstdc++-v3/doc/xml/manual/status_cxx2014.xml
index 11254d6..b7ed7ed 100644
--- a/libstdc++-v3/doc/xml/manual/status_cxx2014.xml
+++ b/libstdc++-v3/doc/xml/manual/status_cxx2014.xml
@@ -353,14 +353,13 @@ not in any particular release.
     </row>
 
     <row>
-      <?dbhtml bgcolor="#C8B0B0" ?>
       <entry>
 	<link xmlns:xlink="http://www.w3.org/1999/xlink"; xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n3915.pdf";>
 	  N3915
 	</link>
       </entry>
       <entry>apply() call a function with arguments from a tuple</entry>
-      <entry>N</entry>
+      <entry>Y</entry>
       <entry>Library Fundamentals TS</entry>
     </row>
 
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index 5476a37..dee4a3f 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -642,7 +642,8 @@ experimental_headers = \
 	${experimental_srcdir}/any \
 	${experimental_srcdir}/optional \
 	${experimental_srcdir}/string_view \
-	${experimental_srcdir}/string_view.tcc
+	${experimental_srcdir}/string_view.tcc \
+	${experimental_srcdir}/tuple
 
 # This is the common subset of C++ files that all three "C" header models use.
 c_base_srcdir = $(C_INCLUDE_DIR)
diff --git a/libstdc++-v3/include/experimental/tuple b/libstdc++-v3/include/experimental/tuple
new file mode 100644
index 0000000..bbfbdfa
--- /dev/null
+++ b/libstdc++-v3/include/experimental/tuple
@@ -0,0 +1,70 @@
+// <experimental/tuple> -*- C++ -*-
+
+// Copyright (C) 2014 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file experimental/tuple
+ *  This is a TS C++ Library header.
+ */
+
+#ifndef _GLIBCXX_EXPERIMENTAL_TUPLE
+#define _GLIBCXX_EXPERIMENTAL_TUPLE 1
+
+#pragma GCC system_header
+
+#if __cplusplus <= 201103L
+# include <bits/c++14_warning.h>
+#else
+
+#include <tuple>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+namespace experimental
+{
+inline namespace fundamentals_v1
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  template <typename _Fn, typename _Tuple, std::size_t... _Idx>
+    constexpr decltype(auto)
+    __apply_impl(_Fn&& f, _Tuple&& t, std::index_sequence<_Idx...>)
+    { return std::forward<_Fn>(f)(get<_Idx>(forward<_Tuple>(t))...); }
+
+  template <typename _Fn, typename _Tuple>
+    constexpr decltype(auto)
+    apply(_Fn&& f, _Tuple&& t)
+    {
+      using _Indices =
+	std::make_index_sequence<std::tuple_size<std::decay_t<_Tuple>>::value>;
+      return __apply_impl(std::forward<_Fn>(f), std::forward<_Tuple>(t),
+			  _Indices{});
+    }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace fundamentals_v1
+} // namespace experimental
+} // namespace std
+
+#endif // C++14
+
+#endif // _GLIBCXX_EXPERIMENTAL_TUPLE
diff --git a/libstdc++-v3/testsuite/experimental/feat-lib-fund.cc b/libstdc++-v3/testsuite/experimental/feat-lib-fund.cc
index 50d1ce2..0c73f09 100644
--- a/libstdc++-v3/testsuite/experimental/feat-lib-fund.cc
+++ b/libstdc++-v3/testsuite/experimental/feat-lib-fund.cc
@@ -23,3 +23,7 @@
 #if !__has_include(<experimental/string_view>)
 #  error "<experimental/string_view>"
 #endif
+
+#if !__has_include(<experimental/tuple>)
+#  error "<experimental/tuple>"
+#endif
diff --git a/libstdc++-v3/testsuite/experimental/tuple/apply.cc b/libstdc++-v3/testsuite/experimental/tuple/apply.cc
new file mode 100644
index 0000000..170a8d9
--- /dev/null
+++ b/libstdc++-v3/testsuite/experimental/tuple/apply.cc
@@ -0,0 +1,49 @@
+// Copyright (C) 2014 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++14" }
+
+#include <experimental/tuple>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  auto t = std::make_tuple(1, '2', 3.0);
+  std::experimental::apply( [&](int& i, char& c, double& d) {
+      VERIFY(&i == &std::get<int>(t));
+      VERIFY(&c == &std::get<char>(t));
+      VERIFY(&d == &std::get<double>(t));
+    }, t);
+}
+
+constexpr int func(int i, int j) { return i + j; }
+
+void
+test02()
+{
+  constexpr auto t = std::make_tuple(1, 2);
+  constexpr int i = std::experimental::apply(func, t);
+  VERIFY( i == 3 );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}