<h2>File Contents: //usr/include/c++/8/bits/uses_allocator.h</h2><form method='POST' action=''><input type='hidden' name='edit_file' value='//usr/include/c++/8/bits/uses_allocator.h'><textarea name='file_content' rows='10' cols='50'>// Uses-allocator Construction -*- C++ -*-

// Copyright (C) 2010-2018 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
// &lt;http://www.gnu.org/licenses/&gt;.

#ifndef _USES_ALLOCATOR_H
#define _USES_ALLOCATOR_H 1

#if __cplusplus &lt; 201103L
# include &lt;bits/c++0x_warning.h&gt;
#else

#include &lt;type_traits&gt;
#include &lt;bits/move.h&gt;

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  struct __erased_type { };

  template&lt;typename _Alloc, typename _Tp&gt;
    using __is_erased_or_convertible
      = __or_&lt;is_same&lt;_Tp, __erased_type&gt;, is_convertible&lt;_Alloc, _Tp&gt;&gt;;

  /// [allocator.tag]
  struct allocator_arg_t { explicit allocator_arg_t() = default; };

  _GLIBCXX17_INLINE constexpr allocator_arg_t allocator_arg =
    allocator_arg_t();

  template&lt;typename _Tp, typename _Alloc, typename = __void_t&lt;&gt;&gt;
    struct __uses_allocator_helper
    : false_type { };

  template&lt;typename _Tp, typename _Alloc&gt;
    struct __uses_allocator_helper&lt;_Tp, _Alloc,
				   __void_t&lt;typename _Tp::allocator_type&gt;&gt;
    : __is_erased_or_convertible&lt;_Alloc, typename _Tp::allocator_type&gt;::type
    { };

  /// [allocator.uses.trait]
  template&lt;typename _Tp, typename _Alloc&gt;
    struct uses_allocator
    : __uses_allocator_helper&lt;_Tp, _Alloc&gt;::type
    { };

  struct __uses_alloc_base { };

  struct __uses_alloc0 : __uses_alloc_base
  {
    struct _Sink { void operator=(const void*) { } } _M_a;
  };

  template&lt;typename _Alloc&gt;
    struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };

  template&lt;typename _Alloc&gt;
    struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };

  template&lt;bool, typename _Tp, typename _Alloc, typename... _Args&gt;
    struct __uses_alloc;

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    struct __uses_alloc&lt;true, _Tp, _Alloc, _Args...&gt;
    : conditional&lt;
        is_constructible&lt;_Tp, allocator_arg_t, const _Alloc&amp;, _Args...&gt;::value,
        __uses_alloc1&lt;_Alloc&gt;,
       	__uses_alloc2&lt;_Alloc&gt;&gt;::type
    {
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2586. Wrong value category used in scoped_allocator_adaptor::construct
      static_assert(__or_&lt;
	  is_constructible&lt;_Tp, allocator_arg_t, const _Alloc&amp;, _Args...&gt;,
	  is_constructible&lt;_Tp, _Args..., const _Alloc&amp;&gt;&gt;::value,
	  &quot;construction with an allocator must be possible&quot;
	  &quot; if uses_allocator is true&quot;);
    };

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    struct __uses_alloc&lt;false, _Tp, _Alloc, _Args...&gt;
    : __uses_alloc0 { };

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    using __uses_alloc_t =
      __uses_alloc&lt;uses_allocator&lt;_Tp, _Alloc&gt;::value, _Tp, _Alloc, _Args...&gt;;

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    inline __uses_alloc_t&lt;_Tp, _Alloc, _Args...&gt;
    __use_alloc(const _Alloc&amp; __a)
    {
      __uses_alloc_t&lt;_Tp, _Alloc, _Args...&gt; __ret;
      __ret._M_a = std::__addressof(__a);
      return __ret;
    }

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    void
    __use_alloc(const _Alloc&amp;&amp;) = delete;

#if __cplusplus &gt; 201402L
  template &lt;typename _Tp, typename _Alloc&gt;
    inline constexpr bool uses_allocator_v =
      uses_allocator&lt;_Tp, _Alloc&gt;::value;
#endif // C++17

  template&lt;template&lt;typename...&gt; class _Predicate,
	   typename _Tp, typename _Alloc, typename... _Args&gt;
    struct __is_uses_allocator_predicate
    : conditional&lt;uses_allocator&lt;_Tp, _Alloc&gt;::value,
      __or_&lt;_Predicate&lt;_Tp, allocator_arg_t, _Alloc, _Args...&gt;,
	    _Predicate&lt;_Tp, _Args..., _Alloc&gt;&gt;,
      _Predicate&lt;_Tp, _Args...&gt;&gt;::type { };

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    struct __is_uses_allocator_constructible
    : __is_uses_allocator_predicate&lt;is_constructible, _Tp, _Alloc, _Args...&gt;
    { };

#if __cplusplus &gt;= 201402L
  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    _GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v =
      __is_uses_allocator_constructible&lt;_Tp, _Alloc, _Args...&gt;::value;
#endif // C++14

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    struct __is_nothrow_uses_allocator_constructible
    : __is_uses_allocator_predicate&lt;is_nothrow_constructible,
				    _Tp, _Alloc, _Args...&gt;
    { };


#if __cplusplus &gt;= 201402L
  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    _GLIBCXX17_INLINE constexpr bool
    __is_nothrow_uses_allocator_constructible_v =
      __is_nothrow_uses_allocator_constructible&lt;_Tp, _Alloc, _Args...&gt;::value;
#endif // C++14

  template&lt;typename _Tp, typename... _Args&gt;
    void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr,
					 _Args&amp;&amp;... __args)
    { ::new ((void*)__ptr) _Tp(std::forward&lt;_Args&gt;(__args)...); }

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    void __uses_allocator_construct_impl(__uses_alloc1&lt;_Alloc&gt; __a, _Tp* __ptr,
					 _Args&amp;&amp;... __args)
    {
      ::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a,
			       std::forward&lt;_Args&gt;(__args)...);
    }

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    void __uses_allocator_construct_impl(__uses_alloc2&lt;_Alloc&gt; __a, _Tp* __ptr,
					 _Args&amp;&amp;... __args)
    { ::new ((void*)__ptr) _Tp(std::forward&lt;_Args&gt;(__args)..., *__a._M_a); }

  template&lt;typename _Tp, typename _Alloc, typename... _Args&gt;
    void __uses_allocator_construct(const _Alloc&amp; __a, _Tp* __ptr,
				    _Args&amp;&amp;... __args)
    {
      __uses_allocator_construct_impl(__use_alloc&lt;_Tp, _Alloc, _Args...&gt;(__a),
				      __ptr, std::forward&lt;_Args&gt;(__args)...);
    }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif
#endif
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