safe_container.h

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// Safe container implementation  -*- C++ -*-
 
// Copyright (C) 2014-2025 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 debug/safe_container.h
 *  This file is a GNU debug extension to the Standard C++ Library.
 */
 
#ifndef _GLIBCXX_DEBUG_SAFE_CONTAINER_H
#define _GLIBCXX_DEBUG_SAFE_CONTAINER_H 1
 
#include <ext/alloc_traits.h>
 
namespace __gnu_debug
{
  /// Safe class dealing with some allocator dependent operations.
  template<typename _SafeContainer,
           typename _Alloc,
           template<typename> class _SafeBase,
           bool _IsCxx11AllocatorAware = true>
    class _Safe_container
    : public _SafeBase<_SafeContainer>
    {
      typedef _SafeBase<_SafeContainer> _Base;
 
      _GLIBCXX20_CONSTEXPR
      const _SafeContainer&
      _M_cont() const _GLIBCXX_NOEXCEPT
      { return *static_cast<const _SafeContainer*>(this); }
 
    protected:
#if __cplusplus >= 201103L
      _Safe_container() = default;
      _Safe_container(const _Safe_container&) = default;
      _Safe_container(_Safe_container&&) = default;
 
    private:
      _GLIBCXX20_CONSTEXPR
      void
      _M_swap_base(const _Safe_container& __x) const noexcept
      { _Base::_M_swap(__x); }
 
      _GLIBCXX20_CONSTEXPR
      _Safe_container(_Safe_container&& __x, const _Alloc&, std::true_type)
      : _Safe_container(std::move(__x))
      { }
 
      _GLIBCXX20_CONSTEXPR
      _Safe_container(_Safe_container&& __x, const _Alloc& __a, std::false_type)
      : _Safe_container()
      {
        if (!std::__is_constant_evaluated())
          {
            if (__x._M_cont().get_allocator() == __a)
              _M_swap_base(__x);
            else
              __x._M_invalidate_all();
          }
      }
 
    protected:
      _GLIBCXX20_CONSTEXPR
      _Safe_container(_Safe_container&& __x, const _Alloc& __a)
      : _Safe_container(std::move(__x), __a,
                      typename std::allocator_traits<_Alloc>::is_always_equal{})
      { }
#endif
 
      // Copy assignment invalidate all iterators.
      _GLIBCXX20_CONSTEXPR
      _Safe_container&
      operator=(const _Safe_container&) _GLIBCXX_NOEXCEPT
      {
        if (!std::__is_constant_evaluated())
          this->_M_invalidate_all();
        return *this;
      }
 
#if __cplusplus >= 201103L
      _GLIBCXX20_CONSTEXPR
      _Safe_container&
      operator=(_Safe_container&& __x) noexcept
      {
        if (std::__is_constant_evaluated())
          return *this;
 
        if (std::__addressof(__x) == this)
          {
            // Standard containers have a valid but unspecified value after
            // self-move, so we invalidate all debug iterators even if the
            // underlying container happens to preserve its contents.
            this->_M_invalidate_all();
            return *this;
          }
 
        if (_IsCxx11AllocatorAware)
          {
            typedef __gnu_cxx::__alloc_traits<_Alloc> _Alloc_traits;
 
            bool __xfer_memory = _Alloc_traits::_S_propagate_on_move_assign()
              || _M_cont().get_allocator() == __x._M_cont().get_allocator();
            if (__xfer_memory)
              _M_swap_base(__x);
            else
              this->_M_invalidate_all();
          }
        else
          _M_swap_base(__x);
 
        __x._M_invalidate_all();
        return *this;
      }
 
      _GLIBCXX20_CONSTEXPR
      void
      _M_swap(const _Safe_container& __x) const noexcept
      {
        if (_IsCxx11AllocatorAware)
          {
            typedef __gnu_cxx::__alloc_traits<_Alloc> _Alloc_traits;
 
            if (!_Alloc_traits::_S_propagate_on_swap())
              __glibcxx_check_equal_allocs(this->_M_cont()._M_base(),
                                           __x._M_cont()._M_base());
          }
 
        _M_swap_base(__x);
      }
#else
      void
      _M_swap(const _Safe_container& __x) const throw()
      { _Base::_M_swap(__x); }
#endif
    };
 
} // namespace __gnu_debug
 
#endif