libstdc++-v3/include/bits/uses_allocator.h

   1 // Uses-allocator Construction -*- C++ -*-
   2
   3 // Copyright (C) 2010-2015 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #ifndef _USES_ALLOCATOR_H
  26 #define _USES_ALLOCATOR_H 1
  27
  28 #if __cplusplus < 201103L
  29 # include <bits/c++0x_warning.h>
  30 #else
  31
  32 #include <type_traits>
  33
  34 namespace std _GLIBCXX_VISIBILITY(default)
  35 {
  36 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  37
  38   /// [allocator.tag]
  39   struct allocator_arg_t { };
  40
  41   constexpr allocator_arg_t allocator_arg = allocator_arg_t();
  42
  43   template<typename _Tp, typename _Alloc, typename = __void_t<>>
  44     struct __uses_allocator_helper
  45     : false_type { };
  46
  47   template<typename _Tp, typename _Alloc>
  48     struct __uses_allocator_helper<_Tp, _Alloc,
  49                                    __void_t<typename _Tp::allocator_type>>
  50     : is_convertible<_Alloc, typename _Tp::allocator_type>::type
  51     { };
  52
  53   /// [allocator.uses.trait]
  54   template<typename _Tp, typename _Alloc>
  55     struct uses_allocator
  56     : __uses_allocator_helper<_Tp, _Alloc>::type
  57     { };
  58
  59   struct __uses_alloc_base { };
  60
  61   struct __uses_alloc0 : __uses_alloc_base
  62   {
  63     struct _Sink { void operator=(const void*) { } } _M_a;
  64   };
  65
  66   template<typename _Alloc>
  67     struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };
  68
  69   template<typename _Alloc>
  70     struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };
  71
  72   template<bool, typename _Tp, typename _Alloc, typename... _Args>
  73     struct __uses_alloc;
  74
  75   template<typename _Tp, typename _Alloc, typename... _Args>
  76     struct __uses_alloc<true, _Tp, _Alloc, _Args...>
  77     : conditional<
  78         is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value,
  79         __uses_alloc1<_Alloc>,
  80         __uses_alloc2<_Alloc>>::type
  81     { };
  82
  83   template<typename _Tp, typename _Alloc, typename... _Args>
  84     struct __uses_alloc<false, _Tp, _Alloc, _Args...>
  85     : __uses_alloc0 { };
  86
  87   template<typename _Tp, typename _Alloc, typename... _Args>
  88     using __uses_alloc_t =
  89       __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>;
  90
  91   template<typename _Tp, typename _Alloc, typename... _Args>
  92     inline __uses_alloc_t<_Tp, _Alloc, _Args...>
  93     __use_alloc(const _Alloc& __a)
  94     {
  95       __uses_alloc_t<_Tp, _Alloc, _Args...> __ret;
  96       __ret._M_a = &__a;
  97       return __ret;
  98     }
  99
 100 _GLIBCXX_END_NAMESPACE_VERSION
 101 } // namespace std
 102
 103 #endif
 104 #endif