libstdc++-v3/include/debug/safe_unordered_container.h

// 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); }

    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