libstdc++-v3/include/ext/alloc_traits.h

// Allocator traits -*- C++ -*-

// Copyright (C) 2011-2025 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 ext/alloc_traits.h
 *  This file is a GNU extension to the Standard C++ Library.
 */

#ifndef _EXT_ALLOC_TRAITS_H
#define _EXT_ALLOC_TRAITS_H 1

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

# include <bits/alloc_traits.h>

namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

/**
 * @brief  Uniform interface to C++98 and C++11 allocators.
 * @ingroup allocators
*/
template<typename _Alloc, typename = typename _Alloc::value_type>
  struct __alloc_traits
#if __cplusplus >= 201103L
  : std::allocator_traits<_Alloc>
#endif
  {
    typedef _Alloc allocator_type;
#if __cplusplus >= 201103L
    typedef std::allocator_traits<_Alloc>           _Base_type;
    typedef typename _Base_type::value_type         value_type;
    typedef typename _Base_type::pointer            pointer;
    typedef typename _Base_type::const_pointer      const_pointer;
    typedef typename _Base_type::size_type          size_type;
    typedef typename _Base_type::difference_type    difference_type;
    // C++11 allocators do not define reference or const_reference
    typedef value_type&                             reference;
    typedef const value_type&                       const_reference;
    using _Base_type::allocate;
    using _Base_type::deallocate;
    using _Base_type::construct;
    using _Base_type::destroy;
    using _Base_type::max_size;

  private:
    template<typename _Ptr>
      using __is_custom_pointer
	= std::__and_<std::is_same<pointer, _Ptr>,
		      std::__not_<std::is_pointer<_Ptr>>>;

  public:
    // overload construct for non-standard pointer types
    template<typename _Ptr, typename... _Args>
      [[__gnu__::__always_inline__]]
      static _GLIBCXX14_CONSTEXPR
      std::__enable_if_t<__is_custom_pointer<_Ptr>::value>
      construct(_Alloc& __a, _Ptr __p, _Args&&... __args)
      noexcept(noexcept(_Base_type::construct(__a, std::__to_address(__p),
					      std::forward<_Args>(__args)...)))
      {
	_Base_type::construct(__a, std::__to_address(__p),
			      std::forward<_Args>(__args)...);
      }

    // overload destroy for non-standard pointer types
    template<typename _Ptr>
      [[__gnu__::__always_inline__]]
      static _GLIBCXX14_CONSTEXPR
      std::__enable_if_t<__is_custom_pointer<_Ptr>::value>
      destroy(_Alloc& __a, _Ptr __p)
      noexcept(noexcept(_Base_type::destroy(__a, std::__to_address(__p))))
      { _Base_type::destroy(__a, std::__to_address(__p)); }

    [[__gnu__::__always_inline__]]
    static constexpr _Alloc _S_select_on_copy(const _Alloc& __a)
    { return _Base_type::select_on_container_copy_construction(__a); }

    [[__gnu__::__always_inline__]]
    static _GLIBCXX14_CONSTEXPR void _S_on_swap(_Alloc& __a, _Alloc& __b)
    { std::__alloc_on_swap(__a, __b); }

    [[__gnu__::__always_inline__]]
    static constexpr bool _S_propagate_on_copy_assign()
    { return _Base_type::propagate_on_container_copy_assignment::value; }

    [[__gnu__::__always_inline__]]
    static constexpr bool _S_propagate_on_move_assign()
    { return _Base_type::propagate_on_container_move_assignment::value; }

    [[__gnu__::__always_inline__]]
    static constexpr bool _S_propagate_on_swap()
    { return _Base_type::propagate_on_container_swap::value; }

    [[__gnu__::__always_inline__]]
    static constexpr bool _S_always_equal()
    { return _Base_type::is_always_equal::value; }

    __attribute__((__always_inline__))
    static constexpr bool _S_nothrow_move()
    { return _S_propagate_on_move_assign() || _S_always_equal(); }

    template<typename _Tp>
      struct rebind
      { typedef typename _Base_type::template rebind_alloc<_Tp> other; };
#else // ! C++11

    typedef typename _Alloc::pointer                pointer;
    typedef typename _Alloc::const_pointer          const_pointer;
    typedef typename _Alloc::value_type             value_type;
    typedef typename _Alloc::reference              reference;
    typedef typename _Alloc::const_reference        const_reference;
    typedef typename _Alloc::size_type              size_type;
    typedef typename _Alloc::difference_type        difference_type;

    __attribute__((__always_inline__)) _GLIBCXX_NODISCARD
    static pointer
    allocate(_Alloc& __a, size_type __n)
    { return __a.allocate(__n); }

    template<typename _Hint>
      __attribute__((__always_inline__)) _GLIBCXX_NODISCARD
      static pointer
      allocate(_Alloc& __a, size_type __n, _Hint __hint)
      { return __a.allocate(__n, __hint); }

    __attribute__((__always_inline__))
    static void deallocate(_Alloc& __a, pointer __p, size_type __n)
    { __a.deallocate(__p, __n); }

    template<typename _Tp>
      __attribute__((__always_inline__))
      static void construct(_Alloc& __a, pointer __p, const _Tp& __arg)
      { __a.construct(__p, __arg); }

    __attribute__((__always_inline__))
    static void destroy(_Alloc& __a, pointer __p)
    { __a.destroy(__p); }

    __attribute__((__always_inline__))
    static size_type max_size(const _Alloc& __a)
    { return __a.max_size(); }

    __attribute__((__always_inline__))
    static const _Alloc& _S_select_on_copy(const _Alloc& __a) { return __a; }

    __attribute__((__always_inline__))
    static void _S_on_swap(_Alloc& __a, _Alloc& __b)
    {
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 431. Swapping containers with unequal allocators.
      std::__alloc_swap<_Alloc>::_S_do_it(__a, __b);
    }

    template<typename _Tp>
      struct rebind
      { typedef typename _Alloc::template rebind<_Tp>::other other; };
#endif // C++11
  };

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace __gnu_cxx

#endif