safe_unordered_container.h

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// Safe container implementation  -*- 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 debug/safe_unordered_container.h
 *  This file is a GNU debug extension to the Standard C++ Library.
 */
 
#ifndef _GLIBCXX_DEBUG_SAFE_UNORDERED_CONTAINER_H
#define _GLIBCXX_DEBUG_SAFE_UNORDERED_CONTAINER_H 1
 
#include <debug/assertions.h>
#include <debug/macros.h>
#include <debug/functions.h>
#include <debug/safe_unordered_base.h>
 
namespace __gnu_debug
{
  /**
   * @brief Base class for constructing a @a safe unordered container type
   * that tracks iterators that reference it.
   *
   * The class template %_Safe_unordered_container simplifies the
   * construction of @a safe unordered containers that track the iterators
   * that reference the container, so that the iterators are notified of
   * changes in the container that may affect their operation, e.g., if
   * the container invalidates its iterators or is destructed. This class
   * template may only be used by deriving from it and passing the name
   * of the derived class as its template parameter via the curiously
   * recurring template pattern. The derived class must have @c
   * iterator and @c const_iterator types that are instantiations of
   * class template _Safe_iterator for this container and @c local_iterator
   * and @c const_local_iterator types that are instantiations of class
   * template _Safe_local_iterator for this container. Iterators will
   * then be tracked automatically.
   */
  template<typename _Container>
    class _Safe_unordered_container : public _Safe_unordered_container_base
    {
    private:
      _Container&
      _M_cont() noexcept
      { return *static_cast<_Container*>(this); }
 
      const _Safe_unordered_container*
      _M_self() const
      { return this; }
 
    protected:
      void
      _M_invalidate_locals()
      {
        auto __local_end = _M_cont()._M_base().cend(0);
        this->_M_invalidate_local_if(
                [__local_end](__decltype(__local_end) __it)
                { return __it != __local_end; });
      }
 
#if __cplusplus > 201402L
      template<typename _ExtractKey, typename _Source>
        struct _UContInvalidatePred
        {
          template<typename _Iterator>
            bool
            operator()(_Iterator __it) const
            { return _M_source.count(_ExtractKey{}(*__it)) == 0; }
 
          const _Source& _M_source;
        };
 
      template<typename _ExtractKey, typename _Source>
        struct _UMContInvalidatePred
        {
          template<typename _Iterator>
            bool
            operator()(_Iterator __it) const
            {
              auto __rng =
                _M_source._M_base().equal_range(_ExtractKey{}(*__it));
              for (auto __rit = __rng.first;
                   __rit != __rng.second; ++__rit)
                {
                  if (__it == __rit)
                    return false;
                }
 
              return true;
            }
 
          const _Source& _M_source;
        };
 
      template<typename _Source, typename _InvalidatePred>
        struct _UContMergeGuard
        {
          _UContMergeGuard(_Source& __src) noexcept
          : _M_source(__src), _M_size(__src.size()), _M_pred { __src }
          { }
 
          _UContMergeGuard(const _UContMergeGuard&) = delete;
 
          ~_UContMergeGuard()
          {
            const std::size_t __size = _M_source.size();
            if (__size == _M_size)
              return;
 
            __try
              {
                if (__size == 0)
                  _M_source._M_invalidate_all();
                else
                  {
                    _M_source._M_invalidate_if(_M_pred);
                    _M_source._M_invalidate_local_if(_M_pred);
                  }
              }
            __catch(...)
              {
                _M_source._M_invalidate_all();
              }
          }
 
          _Source& _M_source;
          const std::size_t _M_size;
          _InvalidatePred _M_pred;
        };
 
      template<typename _ExtractKey, typename _Source>
        static _UContMergeGuard<_Source,
                                _UContInvalidatePred<_ExtractKey, _Source>>
        _S_uc_guard(_ExtractKey, _Source& __src)
        {
          typedef _UContInvalidatePred<_ExtractKey, _Source> _InvalidatePred;
          return _UContMergeGuard<_Source, _InvalidatePred>(__src);
        }
 
      template<typename _ExtractKey, typename _Source>
        static _UContMergeGuard<_Source,
                                _UMContInvalidatePred<_ExtractKey, _Source>>
        _S_umc_guard(_ExtractKey, _Source& __src)
        {
          typedef _UMContInvalidatePred<_ExtractKey, _Source> _InvalidatePred;
          return _UContMergeGuard<_Source, _InvalidatePred>(__src);
        }
#endif // C++17
 
    public:
      void
      _M_invalidate_all()
      {
        auto __end = _M_cont()._M_base().cend();
        this->_M_invalidate_if([__end](__decltype(__end) __it)
                               { return __it != __end; });
        _M_invalidate_locals();
      }
 
      /** Invalidates all iterators @c x that reference this container,
          are not singular, and for which @c __pred(x) returns @c
          true. @c __pred will be invoked with the normal iterators nested
          in the safe ones. */
      template<typename _Predicate>
        void
        _M_invalidate_if(_Predicate __pred);
 
      /** Invalidates all local iterators @c x that reference this container,
          are not singular, and for which @c __pred(x) returns @c
          true. @c __pred will be invoked with the normal local iterators
          nested in the safe ones. */
      template<typename _Predicate>
        void
        _M_invalidate_local_if(_Predicate __pred);
    };
} // namespace __gnu_debug
 
#include <debug/safe_unordered_container.tcc>
 
#endif