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/usr/include/c++/11/scoped_allocator


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     1	// <scoped_allocator> -*- C++ -*-
     2	
     3	// Copyright (C) 2011-2021 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	/** @file include/scoped_allocator
    26	 *  This is a Standard C++ Library header.
    27	 *  @ingroup allocators
    28	 */
    29	
    30	#ifndef _SCOPED_ALLOCATOR
    31	#define _SCOPED_ALLOCATOR 1
    32	
    33	#pragma GCC system_header
    34	
    35	#if __cplusplus < 201103L
    36	# include <bits/c++0x_warning.h>
    37	#else
    38	
    39	#include <tuple>
    40	#include <bits/alloc_traits.h>
    41	#include <bits/stl_pair.h>
    42	#include <bits/uses_allocator.h>
    43	#if __cplusplus > 201703L
    44	# include <bits/uses_allocator_args.h>
    45	#endif
    46	
    47	namespace std _GLIBCXX_VISIBILITY(default)
    48	{
    49	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    50	
    51	  /**
    52	   * @addtogroup allocators
    53	   * @{
    54	   */
    55	
    56	  template<typename _OuterAlloc, typename... _InnerAllocs>
    57	    class scoped_allocator_adaptor;
    58	
    59	  /// @cond undocumented
    60	
    61	  template<typename _Alloc>
    62	    using __outer_allocator_t
    63	      = decltype(std::declval<_Alloc>().outer_allocator());
    64	
    65	  template<typename _Alloc, typename = void>
    66	    struct __outermost_type
    67	    {
    68	      using type = _Alloc;
    69	      static type& _S_outermost(_Alloc& __a) { return __a; }
    70	    };
    71	
    72	  template<typename _Alloc>
    73	    struct __outermost_type<_Alloc, __void_t<__outer_allocator_t<_Alloc>>>
    74	    : __outermost_type<
    75	      typename remove_reference<__outer_allocator_t<_Alloc>>::type
    76	    >
    77	    {
    78	      using __base = __outermost_type<
    79	        typename remove_reference<__outer_allocator_t<_Alloc>>::type
    80	      >;
    81	
    82	      static typename __base::type&
    83	      _S_outermost(_Alloc& __a)
    84	      { return __base::_S_outermost(__a.outer_allocator()); }
    85	    };
    86	
    87	  // Implementation of the OUTERMOST pseudofunction
    88	  template<typename _Alloc>
    89	    inline typename __outermost_type<_Alloc>::type&
    90	    __outermost(_Alloc& __a)
    91	    { return __outermost_type<_Alloc>::_S_outermost(__a); }
    92	
    93	  template<typename...>
    94	    struct __inner_type_impl;
    95	
    96	  template<typename _Outer>
    97	    struct __inner_type_impl<_Outer>
    98	    {
    99	      typedef scoped_allocator_adaptor<_Outer> __type;
   100	
   101	      __inner_type_impl() = default;
   102	      __inner_type_impl(const __inner_type_impl&) = default;
   103	      __inner_type_impl(__inner_type_impl&&) = default;
   104	      __inner_type_impl& operator=(const __inner_type_impl&) = default;
   105	      __inner_type_impl& operator=(__inner_type_impl&&) = default;
   106	
   107	      template<typename _Alloc>
   108	      __inner_type_impl(const __inner_type_impl<_Alloc>& __other)
   109	      { }
   110	
   111	      template<typename _Alloc>
   112	      __inner_type_impl(__inner_type_impl<_Alloc>&& __other)
   113	      { }
   114	
   115	      __type&
   116	      _M_get(__type* __p) noexcept { return *__p; }
   117	
   118	      const __type&
   119	      _M_get(const __type* __p) const noexcept { return *__p; }
   120	
   121	      tuple<>
   122	      _M_tie() const noexcept { return tuple<>(); }
   123	
   124	      bool
   125	      operator==(const __inner_type_impl&) const noexcept
   126	      { return true; }
   127	    };
   128	
   129	  template<typename _Outer, typename _InnerHead, typename... _InnerTail>
   130	    struct __inner_type_impl<_Outer, _InnerHead, _InnerTail...>
   131	    {
   132	      typedef scoped_allocator_adaptor<_InnerHead, _InnerTail...> __type;
   133	
   134	      __inner_type_impl() = default;
   135	      __inner_type_impl(const __inner_type_impl&) = default;
   136	      __inner_type_impl(__inner_type_impl&&) = default;
   137	      __inner_type_impl& operator=(const __inner_type_impl&) = default;
   138	      __inner_type_impl& operator=(__inner_type_impl&&) = default;
   139	
   140	      template<typename... _Allocs>
   141	      __inner_type_impl(const __inner_type_impl<_Allocs...>& __other)
   142	      : _M_inner(__other._M_inner) { }
   143	
   144	      template<typename... _Allocs>
   145	      __inner_type_impl(__inner_type_impl<_Allocs...>&& __other)
   146	      : _M_inner(std::move(__other._M_inner)) { }
   147	
   148	    template<typename... _Args>
   149	      explicit
   150	      __inner_type_impl(_Args&&... __args)
   151	      : _M_inner(std::forward<_Args>(__args)...) { }
   152	
   153	      __type&
   154	      _M_get(void*) noexcept { return _M_inner; }
   155	
   156	      const __type&
   157	      _M_get(const void*) const noexcept { return _M_inner; }
   158	
   159	      tuple<const _InnerHead&, const _InnerTail&...>
   160	      _M_tie() const noexcept
   161	      { return _M_inner._M_tie(); }
   162	
   163	      bool
   164	      operator==(const __inner_type_impl& __other) const noexcept
   165	      { return _M_inner == __other._M_inner; }
   166	
   167	    private:
   168	      template<typename...> friend class __inner_type_impl;
   169	      template<typename, typename...> friend class scoped_allocator_adaptor;
   170	
   171	      __type _M_inner;
   172	    };
   173	
   174	  /// @endcond
   175	
   176	  /// An adaptor to recursively pass an allocator to the objects it constructs
   177	  template<typename _OuterAlloc, typename... _InnerAllocs>
   178	    class scoped_allocator_adaptor
   179	    : public _OuterAlloc
   180	    {
   181	      typedef allocator_traits<_OuterAlloc> __traits;
   182	
   183	      typedef __inner_type_impl<_OuterAlloc, _InnerAllocs...> __inner_type;
   184	      __inner_type _M_inner;
   185	
   186	      template<typename _Outer, typename... _Inner>
   187	        friend class scoped_allocator_adaptor;
   188	
   189	      template<typename...>
   190	        friend class __inner_type_impl;
   191	
   192	      tuple<const _OuterAlloc&, const _InnerAllocs&...>
   193	      _M_tie() const noexcept
   194	      { return std::tuple_cat(std::tie(outer_allocator()), _M_inner._M_tie()); }
   195	
   196	      template<typename _Alloc>
   197		using __outermost_alloc_traits
   198		  = allocator_traits<typename __outermost_type<_Alloc>::type>;
   199	
   200	#if ! __cpp_lib_make_obj_using_allocator
   201	      template<typename _Tp, typename... _Args>
   202	        void
   203	        _M_construct(__uses_alloc0, _Tp* __p, _Args&&... __args)
   204	        {
   205		  typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
   206		  _O_traits::construct(__outermost(*this), __p,
   207				       std::forward<_Args>(__args)...);
   208	        }
   209	
   210	      typedef __uses_alloc1<typename __inner_type::__type> __uses_alloc1_;
   211	      typedef __uses_alloc2<typename __inner_type::__type> __uses_alloc2_;
   212	
   213	      template<typename _Tp, typename... _Args>
   214	        void
   215	        _M_construct(__uses_alloc1_, _Tp* __p, _Args&&... __args)
   216	        {
   217		  typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
   218		  _O_traits::construct(__outermost(*this), __p,
   219				       allocator_arg, inner_allocator(),
   220				       std::forward<_Args>(__args)...);
   221	        }
   222	
   223	      template<typename _Tp, typename... _Args>
   224	        void
   225	        _M_construct(__uses_alloc2_, _Tp* __p, _Args&&... __args)
   226	        {
   227		  typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
   228		  _O_traits::construct(__outermost(*this), __p,
   229				       std::forward<_Args>(__args)...,
   230				       inner_allocator());
   231	        }
   232	#endif // ! make_obj_using_allocator
   233	
   234	      template<typename _Alloc>
   235	        static _Alloc
   236	        _S_select_on_copy(const _Alloc& __a)
   237	        {
   238	          typedef allocator_traits<_Alloc> __a_traits;
   239	          return __a_traits::select_on_container_copy_construction(__a);
   240	        }
   241	
   242	      template<std::size_t... _Indices>
   243	        scoped_allocator_adaptor(tuple<const _OuterAlloc&,
   244	                                       const _InnerAllocs&...> __refs,
   245	                                 _Index_tuple<_Indices...>)
   246	        : _OuterAlloc(_S_select_on_copy(std::get<0>(__refs))),
   247	          _M_inner(_S_select_on_copy(std::get<_Indices+1>(__refs))...)
   248	        { }
   249	
   250	      // Used to constrain constructors to disallow invalid conversions.
   251	      template<typename _Alloc>
   252	        using _Constructible = typename enable_if<
   253	            is_constructible<_OuterAlloc, _Alloc>::value
   254	          >::type;
   255	
   256	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
   257	      // 2975. Missing case for pair construction in scoped [...] allocators
   258	      template<typename _Tp>
   259		struct __not_pair { using type = void; };
   260	
   261	      template<typename _Tp, typename _Up>
   262		struct __not_pair<pair<_Tp, _Up>> { };
   263	
   264	    public:
   265	      typedef _OuterAlloc                       outer_allocator_type;
   266	      typedef typename __inner_type::__type     inner_allocator_type;
   267	
   268	      typedef typename __traits::value_type             value_type;
   269	      typedef typename __traits::size_type              size_type;
   270	      typedef typename __traits::difference_type        difference_type;
   271	      typedef typename __traits::pointer                pointer;
   272	      typedef typename __traits::const_pointer          const_pointer;
   273	      typedef typename __traits::void_pointer           void_pointer;
   274	      typedef typename __traits::const_void_pointer     const_void_pointer;
   275	
   276	      typedef typename __or_<
   277		typename __traits::propagate_on_container_copy_assignment,
   278		typename allocator_traits<_InnerAllocs>::
   279		  propagate_on_container_copy_assignment...>::type
   280		  propagate_on_container_copy_assignment;
   281	
   282	      typedef typename __or_<
   283		typename __traits::propagate_on_container_move_assignment,
   284		typename allocator_traits<_InnerAllocs>::
   285		  propagate_on_container_move_assignment...>::type
   286		  propagate_on_container_move_assignment;
   287	
   288	      typedef typename __or_<
   289		typename __traits::propagate_on_container_swap,
   290		typename allocator_traits<_InnerAllocs>::
   291		  propagate_on_container_swap...>::type
   292		  propagate_on_container_swap;
   293	
   294	      typedef typename __and_<
   295		typename __traits::is_always_equal,
   296		typename allocator_traits<_InnerAllocs>::is_always_equal...>::type
   297		  is_always_equal;
   298	
   299	      template <class _Tp>
   300	        struct rebind
   301	        {
   302	          typedef scoped_allocator_adaptor<
   303	            typename __traits::template rebind_alloc<_Tp>,
   304	            _InnerAllocs...> other;
   305	        };
   306	
   307	      scoped_allocator_adaptor() : _OuterAlloc(), _M_inner() { }
   308	
   309	      template<typename _Outer2, typename = _Constructible<_Outer2>>
   310	        scoped_allocator_adaptor(_Outer2&& __outer,
   311	                                 const _InnerAllocs&... __inner)
   312	        : _OuterAlloc(std::forward<_Outer2>(__outer)),
   313	          _M_inner(__inner...)
   314	        { }
   315	
   316	      scoped_allocator_adaptor(const scoped_allocator_adaptor& __other)
   317	      : _OuterAlloc(__other.outer_allocator()),
   318		_M_inner(__other._M_inner)
   319	      { }
   320	
   321	      scoped_allocator_adaptor(scoped_allocator_adaptor&& __other)
   322	      : _OuterAlloc(std::move(__other.outer_allocator())),
   323		_M_inner(std::move(__other._M_inner))
   324	      { }
   325	
   326	      template<typename _Outer2, typename = _Constructible<const _Outer2&>>
   327	        scoped_allocator_adaptor(
   328	            const scoped_allocator_adaptor<_Outer2, _InnerAllocs...>& __other)
   329	        : _OuterAlloc(__other.outer_allocator()),
   330	          _M_inner(__other._M_inner)
   331	        { }
   332	
   333	      template<typename _Outer2, typename = _Constructible<_Outer2>>
   334	        scoped_allocator_adaptor(
   335	            scoped_allocator_adaptor<_Outer2, _InnerAllocs...>&& __other)
   336	        : _OuterAlloc(std::move(__other.outer_allocator())),
   337	          _M_inner(std::move(__other._M_inner))
   338	        { }
   339	
   340	      scoped_allocator_adaptor&
   341	      operator=(const scoped_allocator_adaptor&) = default;
   342	
   343	      scoped_allocator_adaptor&
   344	      operator=(scoped_allocator_adaptor&&) = default;
   345	
   346	      inner_allocator_type& inner_allocator() noexcept
   347	      { return _M_inner._M_get(this); }
   348	
   349	      const inner_allocator_type& inner_allocator() const noexcept
   350	      { return _M_inner._M_get(this); }
   351	
   352	      outer_allocator_type& outer_allocator() noexcept
   353	      { return static_cast<_OuterAlloc&>(*this); }
   354	
   355	      const outer_allocator_type& outer_allocator() const noexcept
   356	      { return static_cast<const _OuterAlloc&>(*this); }
   357	
   358	      _GLIBCXX_NODISCARD pointer allocate(size_type __n)
   359	      { return __traits::allocate(outer_allocator(), __n); }
   360	
   361	      _GLIBCXX_NODISCARD pointer allocate(size_type __n, const_void_pointer __hint)
   362	      { return __traits::allocate(outer_allocator(), __n, __hint); }
   363	
   364	      void deallocate(pointer __p, size_type __n)
   365	      { return __traits::deallocate(outer_allocator(), __p, __n); }
   366	
   367	      size_type max_size() const
   368	      { return __traits::max_size(outer_allocator()); }
   369	
   370	#if ! __cpp_lib_make_obj_using_allocator
   371	      template<typename _Tp, typename... _Args>
   372		typename __not_pair<_Tp>::type
   373		construct(_Tp* __p, _Args&&... __args)
   374		{
   375		  auto& __inner = inner_allocator();
   376		  auto __use_tag
   377		    = std::__use_alloc<_Tp, inner_allocator_type, _Args...>(__inner);
   378		  _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
   379		}
   380	
   381	      template<typename _T1, typename _T2, typename... _Args1,
   382		       typename... _Args2>
   383		void
   384		construct(pair<_T1, _T2>* __p, piecewise_construct_t,
   385			  tuple<_Args1...> __x, tuple<_Args2...> __y)
   386		{
   387		  // _GLIBCXX_RESOLVE_LIB_DEFECTS
   388		  // 2203.  wrong argument types for piecewise construction
   389		  auto& __inner = inner_allocator();
   390		  auto __x_use_tag
   391		    = std::__use_alloc<_T1, inner_allocator_type, _Args1...>(__inner);
   392		  auto __y_use_tag
   393		    = std::__use_alloc<_T2, inner_allocator_type, _Args2...>(__inner);
   394		  typename _Build_index_tuple<sizeof...(_Args1)>::__type __x_indices;
   395		  typename _Build_index_tuple<sizeof...(_Args2)>::__type __y_indices;
   396		  typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
   397		  _O_traits::construct(__outermost(*this), __p, piecewise_construct,
   398				       _M_construct_p(__x_use_tag, __x_indices, __x),
   399				       _M_construct_p(__y_use_tag, __y_indices, __y));
   400		}
   401	
   402	      template<typename _T1, typename _T2>
   403		void
   404		construct(pair<_T1, _T2>* __p)
   405		{ construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
   406	
   407	      template<typename _T1, typename _T2, typename _Up, typename _Vp>
   408		void
   409		construct(pair<_T1, _T2>* __p, _Up&& __u, _Vp&& __v)
   410		{
   411		  construct(__p, piecewise_construct,
   412			    std::forward_as_tuple(std::forward<_Up>(__u)),
   413			    std::forward_as_tuple(std::forward<_Vp>(__v)));
   414		}
   415	
   416	      template<typename _T1, typename _T2, typename _Up, typename _Vp>
   417		void
   418		construct(pair<_T1, _T2>* __p, const pair<_Up, _Vp>& __x)
   419		{
   420		  construct(__p, piecewise_construct,
   421			    std::forward_as_tuple(__x.first),
   422			    std::forward_as_tuple(__x.second));
   423		}
   424	
   425	      template<typename _T1, typename _T2, typename _Up, typename _Vp>
   426		void
   427		construct(pair<_T1, _T2>* __p, pair<_Up, _Vp>&& __x)
   428		{
   429		  construct(__p, piecewise_construct,
   430			    std::forward_as_tuple(std::forward<_Up>(__x.first)),
   431			    std::forward_as_tuple(std::forward<_Vp>(__x.second)));
   432		}
   433	#else // make_obj_using_allocator
   434	      template<typename _Tp, typename... _Args>
   435		__attribute__((__nonnull__))
   436		void
   437		construct(_Tp* __p, _Args&&... __args)
   438		{
   439		  typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
   440		  std::apply([__p, this](auto&&... __newargs) {
   441		      _O_traits::construct(__outermost(*this), __p,
   442			  std::forward<decltype(__newargs)>(__newargs)...);
   443		  },
   444		  uses_allocator_construction_args<_Tp>(inner_allocator(),
   445		    std::forward<_Args>(__args)...));
   446		}
   447	#endif
   448	
   449	      template<typename _Tp>
   450	        void destroy(_Tp* __p)
   451	        {
   452		  typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
   453		  _O_traits::destroy(__outermost(*this), __p);
   454		}
   455	
   456	      scoped_allocator_adaptor
   457	      select_on_container_copy_construction() const
   458	      {
   459	        typedef typename _Build_index_tuple<sizeof...(_InnerAllocs)>::__type
   460		    _Indices;
   461	        return scoped_allocator_adaptor(_M_tie(), _Indices());
   462	      }
   463	
   464	      template <typename _OutA1, typename _OutA2, typename... _InA>
   465	      friend bool
   466	      operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
   467	                 const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept;
   468	
   469	    private:
   470	#if ! __cpp_lib_make_obj_using_allocator
   471	      template<typename _Ind, typename... _Args>
   472		tuple<_Args&&...>
   473		_M_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t)
   474		{ return std::move(__t); }
   475	
   476	      template<size_t... _Ind, typename... _Args>
   477		tuple<allocator_arg_t, inner_allocator_type&, _Args&&...>
   478		_M_construct_p(__uses_alloc1_, _Index_tuple<_Ind...>,
   479			       tuple<_Args...>& __t)
   480		{
   481		  return { allocator_arg, inner_allocator(),
   482		      std::get<_Ind>(std::move(__t))...
   483		  };
   484		}
   485	
   486	      template<size_t... _Ind, typename... _Args>
   487		tuple<_Args&&..., inner_allocator_type&>
   488		_M_construct_p(__uses_alloc2_, _Index_tuple<_Ind...>,
   489			       tuple<_Args...>& __t)
   490		{
   491		  return { std::get<_Ind>(std::move(__t))..., inner_allocator() };
   492		}
   493	#endif // ! make_obj_using_allocator
   494	    };
   495	
   496	  /// @related std::scoped_allocator_adaptor
   497	  template <typename _OutA1, typename _OutA2, typename... _InA>
   498	    inline bool
   499	    operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
   500	               const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept
   501	    {
   502	      return __a.outer_allocator() == __b.outer_allocator()
   503	          && __a._M_inner == __b._M_inner;
   504	    }
   505	
   506	#if __cpp_impl_three_way_comparison < 201907L
   507	  /// @related std::scoped_allocator_adaptor
   508	  template <typename _OutA1, typename _OutA2, typename... _InA>
   509	    inline bool
   510	    operator!=(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
   511	               const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept
   512	    { return !(__a == __b); }
   513	#endif
   514	
   515	  /// @}
   516	
   517	_GLIBCXX_END_NAMESPACE_VERSION
   518	} // namespace
   519	
   520	#endif // C++11
   521	
   522	#endif // _SCOPED_ALLOCATOR