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- // Node handles for containers -*- C++ -*-
- // Copyright (C) 2016-2022 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 bits/node_handle.h
- * This is an internal header file, included by other library headers.
- * Do not attempt to use it directly.
- * @headername{map,set,unordered_map,unordered_set}
- */
- #ifndef _NODE_HANDLE
- #define _NODE_HANDLE 1
- #pragma GCC system_header
- #if __cplusplus >= 201703L
- # define __cpp_lib_node_extract 201606L
- #include <new>
- #include <bits/alloc_traits.h>
- #include <bits/ptr_traits.h>
- namespace std _GLIBCXX_VISIBILITY(default)
- {
- _GLIBCXX_BEGIN_NAMESPACE_VERSION
- /**
- * @defgroup node_handles Node handles
- * @ingroup associative_containers
- * @since C++17
- *
- * The associative containers (`map`, `set`, `multimap` and `multiset`)
- * support extracting and re-inserting nodes from the container. Those
- * operations use the container's `node_handle` type, which is an alias
- * for a `_Node_handle<...>` type. You should always use the container's
- * `node_handle` type (e.g. `std::set<int>::node_handle`) to refer to
- * these types, not the non-standard internal `_Node_handle` names.
- *
- * @{
- */
- /// Base class for node handle types of maps and sets.
- template<typename _Val, typename _NodeAlloc>
- class _Node_handle_common
- {
- using _AllocTraits = allocator_traits<_NodeAlloc>;
- public:
- using allocator_type = __alloc_rebind<_NodeAlloc, _Val>;
- allocator_type
- get_allocator() const noexcept
- {
- __glibcxx_assert(!this->empty());
- return allocator_type(_M_alloc._M_alloc);
- }
- explicit operator bool() const noexcept { return _M_ptr != nullptr; }
- [[nodiscard]] bool empty() const noexcept { return _M_ptr == nullptr; }
- /// @cond undocumented
- protected:
- constexpr _Node_handle_common() noexcept : _M_ptr() { }
- ~_Node_handle_common()
- {
- if (!empty())
- _M_reset();
- }
- _Node_handle_common(_Node_handle_common&& __nh) noexcept
- : _M_ptr(__nh._M_ptr)
- {
- if (_M_ptr)
- _M_move(std::move(__nh));
- }
- _Node_handle_common&
- operator=(_Node_handle_common&& __nh) noexcept
- {
- if (empty())
- {
- if (!__nh.empty())
- _M_move(std::move(__nh));
- }
- else if (__nh.empty())
- _M_reset();
- else
- {
- // Free the current node before replacing the allocator.
- _AllocTraits::destroy(*_M_alloc, _M_ptr->_M_valptr());
- _AllocTraits::deallocate(*_M_alloc, _M_ptr, 1);
- _M_alloc = __nh._M_alloc.release(); // assigns if POCMA
- _M_ptr = __nh._M_ptr;
- __nh._M_ptr = nullptr;
- }
- return *this;
- }
- _Node_handle_common(typename _AllocTraits::pointer __ptr,
- const _NodeAlloc& __alloc)
- : _M_ptr(__ptr), _M_alloc(__alloc)
- {
- __glibcxx_assert(__ptr != nullptr);
- }
- void
- _M_swap(_Node_handle_common& __nh) noexcept
- {
- if (empty())
- {
- if (!__nh.empty())
- _M_move(std::move(__nh));
- }
- else if (__nh.empty())
- __nh._M_move(std::move(*this));
- else
- {
- using std::swap;
- swap(_M_ptr, __nh._M_ptr);
- _M_alloc.swap(__nh._M_alloc); // swaps if POCS
- }
- }
- private:
- // Moves the pointer and allocator from __nh to *this.
- // Precondition: empty() && !__nh.empty()
- // Postcondition: !empty() && __nh.empty()
- void
- _M_move(_Node_handle_common&& __nh) noexcept
- {
- ::new (std::__addressof(_M_alloc)) _NodeAlloc(__nh._M_alloc.release());
- _M_ptr = __nh._M_ptr;
- __nh._M_ptr = nullptr;
- }
- // Deallocates the node, destroys the allocator.
- // Precondition: !empty()
- // Postcondition: empty()
- void
- _M_reset() noexcept
- {
- _NodeAlloc __alloc = _M_alloc.release();
- _AllocTraits::destroy(__alloc, _M_ptr->_M_valptr());
- _AllocTraits::deallocate(__alloc, _M_ptr, 1);
- _M_ptr = nullptr;
- }
- protected:
- typename _AllocTraits::pointer _M_ptr;
- private:
- // A simplified, non-copyable std::optional<_NodeAlloc>.
- // Call release() before destruction iff the allocator member is active.
- union _Optional_alloc
- {
- _Optional_alloc() { }
- ~_Optional_alloc() { }
- _Optional_alloc(_Optional_alloc&&) = delete;
- _Optional_alloc& operator=(_Optional_alloc&&) = delete;
- _Optional_alloc(const _NodeAlloc& __alloc) noexcept
- : _M_alloc(__alloc)
- { }
- // Precondition: _M_alloc is the active member of the union.
- void
- operator=(_NodeAlloc&& __alloc) noexcept
- {
- using _ATr = _AllocTraits;
- if constexpr (_ATr::propagate_on_container_move_assignment::value)
- _M_alloc = std::move(__alloc);
- else if constexpr (!_AllocTraits::is_always_equal::value)
- __glibcxx_assert(_M_alloc == __alloc);
- }
- // Precondition: _M_alloc is the active member of both unions.
- void
- swap(_Optional_alloc& __other) noexcept
- {
- using std::swap;
- if constexpr (_AllocTraits::propagate_on_container_swap::value)
- swap(_M_alloc, __other._M_alloc);
- else if constexpr (!_AllocTraits::is_always_equal::value)
- __glibcxx_assert(_M_alloc == __other._M_alloc);
- }
- // Precondition: _M_alloc is the active member of the union.
- _NodeAlloc& operator*() noexcept { return _M_alloc; }
- // Precondition: _M_alloc is the active member of the union.
- _NodeAlloc release() noexcept
- {
- _NodeAlloc __tmp = std::move(_M_alloc);
- _M_alloc.~_NodeAlloc();
- return __tmp;
- }
- struct _Empty { };
- [[__no_unique_address__]] _Empty _M_empty;
- [[__no_unique_address__]] _NodeAlloc _M_alloc;
- };
- [[__no_unique_address__]] _Optional_alloc _M_alloc;
- template<typename _Key2, typename _Value2, typename _KeyOfValue,
- typename _Compare, typename _ValueAlloc>
- friend class _Rb_tree;
- /// @endcond
- };
- /// Node handle type for maps.
- template<typename _Key, typename _Value, typename _NodeAlloc>
- class _Node_handle : public _Node_handle_common<_Value, _NodeAlloc>
- {
- public:
- constexpr _Node_handle() noexcept = default;
- ~_Node_handle() = default;
- _Node_handle(_Node_handle&&) noexcept = default;
- _Node_handle&
- operator=(_Node_handle&&) noexcept = default;
- using key_type = _Key;
- using mapped_type = typename _Value::second_type;
- key_type&
- key() const noexcept
- {
- __glibcxx_assert(!this->empty());
- return *_M_pkey;
- }
- mapped_type&
- mapped() const noexcept
- {
- __glibcxx_assert(!this->empty());
- return *_M_pmapped;
- }
- void
- swap(_Node_handle& __nh) noexcept
- {
- this->_M_swap(__nh);
- using std::swap;
- swap(_M_pkey, __nh._M_pkey);
- swap(_M_pmapped, __nh._M_pmapped);
- }
- friend void
- swap(_Node_handle& __x, _Node_handle& __y)
- noexcept(noexcept(__x.swap(__y)))
- { __x.swap(__y); }
- private:
- using _AllocTraits = allocator_traits<_NodeAlloc>;
- _Node_handle(typename _AllocTraits::pointer __ptr,
- const _NodeAlloc& __alloc)
- : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc)
- {
- if (__ptr)
- {
- auto& __key = const_cast<_Key&>(__ptr->_M_valptr()->first);
- _M_pkey = _S_pointer_to(__key);
- _M_pmapped = _S_pointer_to(__ptr->_M_valptr()->second);
- }
- else
- {
- _M_pkey = nullptr;
- _M_pmapped = nullptr;
- }
- }
- template<typename _Tp>
- using __pointer
- = __ptr_rebind<typename _AllocTraits::pointer,
- remove_reference_t<_Tp>>;
- __pointer<_Key> _M_pkey = nullptr;
- __pointer<typename _Value::second_type> _M_pmapped = nullptr;
- template<typename _Tp>
- __pointer<_Tp>
- _S_pointer_to(_Tp& __obj)
- { return pointer_traits<__pointer<_Tp>>::pointer_to(__obj); }
- const key_type&
- _M_key() const noexcept { return key(); }
- template<typename _Key2, typename _Value2, typename _KeyOfValue,
- typename _Compare, typename _ValueAlloc>
- friend class _Rb_tree;
- template<typename _Key2, typename _Value2, typename _ValueAlloc,
- typename _ExtractKey, typename _Equal,
- typename _Hash, typename _RangeHash, typename _Unused,
- typename _RehashPolicy, typename _Traits>
- friend class _Hashtable;
- };
- /// Node handle type for sets.
- template<typename _Value, typename _NodeAlloc>
- class _Node_handle<_Value, _Value, _NodeAlloc>
- : public _Node_handle_common<_Value, _NodeAlloc>
- {
- public:
- constexpr _Node_handle() noexcept = default;
- ~_Node_handle() = default;
- _Node_handle(_Node_handle&&) noexcept = default;
- _Node_handle&
- operator=(_Node_handle&&) noexcept = default;
- using value_type = _Value;
- value_type&
- value() const noexcept
- {
- __glibcxx_assert(!this->empty());
- return *this->_M_ptr->_M_valptr();
- }
- void
- swap(_Node_handle& __nh) noexcept
- { this->_M_swap(__nh); }
- friend void
- swap(_Node_handle& __x, _Node_handle& __y)
- noexcept(noexcept(__x.swap(__y)))
- { __x.swap(__y); }
- private:
- using _AllocTraits = allocator_traits<_NodeAlloc>;
- _Node_handle(typename _AllocTraits::pointer __ptr,
- const _NodeAlloc& __alloc)
- : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) { }
- const value_type&
- _M_key() const noexcept { return value(); }
- template<typename _Key, typename _Val, typename _KeyOfValue,
- typename _Compare, typename _Alloc>
- friend class _Rb_tree;
- template<typename _Key2, typename _Value2, typename _ValueAlloc,
- typename _ExtractKey, typename _Equal,
- typename _Hash, typename _RangeHash, typename _Unused,
- typename _RehashPolicy, typename _Traits>
- friend class _Hashtable;
- };
- /// Return type of insert(node_handle&&) on unique maps/sets.
- template<typename _Iterator, typename _NodeHandle>
- struct _Node_insert_return
- {
- _Iterator position = _Iterator();
- bool inserted = false;
- _NodeHandle node;
- };
- /// @}
- _GLIBCXX_END_NAMESPACE_VERSION
- } // namespace std
- #endif // C++17
- #endif
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