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375 lines
10 KiB
C++
375 lines
10 KiB
C++
// Node handles for containers -*- C++ -*-
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// Copyright (C) 2016-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file bits/node_handle.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly.
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* @headername{map,set,unordered_map,unordered_set}
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*/
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#ifndef _NODE_HANDLE
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#define _NODE_HANDLE 1
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#pragma GCC system_header
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#if __cplusplus >= 201703L
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# define __cpp_lib_node_extract 201606
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#include <new>
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#include <bits/alloc_traits.h>
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#include <bits/ptr_traits.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/// Base class for node handle types of maps and sets.
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template<typename _Val, typename _NodeAlloc>
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class _Node_handle_common
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{
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using _AllocTraits = allocator_traits<_NodeAlloc>;
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public:
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using allocator_type = __alloc_rebind<_NodeAlloc, _Val>;
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allocator_type
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get_allocator() const noexcept
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{
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__glibcxx_assert(!this->empty());
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return allocator_type(_M_alloc._M_alloc);
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}
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explicit operator bool() const noexcept { return _M_ptr != nullptr; }
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[[nodiscard]] bool empty() const noexcept { return _M_ptr == nullptr; }
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protected:
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constexpr _Node_handle_common() noexcept : _M_ptr() { }
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~_Node_handle_common()
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{
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if (!empty())
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_M_reset();
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}
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_Node_handle_common(_Node_handle_common&& __nh) noexcept
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: _M_ptr(__nh._M_ptr)
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{
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if (_M_ptr)
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_M_move(std::move(__nh));
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}
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_Node_handle_common&
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operator=(_Node_handle_common&& __nh) noexcept
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{
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if (empty())
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{
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if (!__nh.empty())
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_M_move(std::move(__nh));
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}
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else if (__nh.empty())
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_M_reset();
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else
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{
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// Free the current node before replacing the allocator.
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_AllocTraits::destroy(*_M_alloc, _M_ptr->_M_valptr());
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_AllocTraits::deallocate(*_M_alloc, _M_ptr, 1);
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_M_alloc = __nh._M_alloc.release(); // assigns if POCMA
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_M_ptr = __nh._M_ptr;
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__nh._M_ptr = nullptr;
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}
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return *this;
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}
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_Node_handle_common(typename _AllocTraits::pointer __ptr,
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const _NodeAlloc& __alloc)
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: _M_ptr(__ptr), _M_alloc(__alloc)
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{
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__glibcxx_assert(__ptr != nullptr);
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}
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void
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_M_swap(_Node_handle_common& __nh) noexcept
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{
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if (empty())
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{
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if (!__nh.empty())
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_M_move(std::move(__nh));
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}
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else if (__nh.empty())
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__nh._M_move(std::move(*this));
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else
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{
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using std::swap;
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swap(_M_ptr, __nh._M_ptr);
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_M_alloc.swap(__nh._M_alloc); // swaps if POCS
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}
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}
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private:
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// Moves the pointer and allocator from __nh to *this.
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// Precondition: empty() && !__nh.empty()
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// Postcondition: !empty() && __nh.empty()
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void
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_M_move(_Node_handle_common&& __nh) noexcept
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{
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::new (std::__addressof(_M_alloc)) _NodeAlloc(__nh._M_alloc.release());
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_M_ptr = __nh._M_ptr;
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__nh._M_ptr = nullptr;
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}
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// Deallocates the node, destroys the allocator.
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// Precondition: !empty()
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// Postcondition: empty()
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void
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_M_reset() noexcept
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{
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_NodeAlloc __alloc = _M_alloc.release();
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_AllocTraits::destroy(__alloc, _M_ptr->_M_valptr());
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_AllocTraits::deallocate(__alloc, _M_ptr, 1);
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_M_ptr = nullptr;
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}
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protected:
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typename _AllocTraits::pointer _M_ptr;
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private:
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// A simplified, non-copyable std::optional<_NodeAlloc>.
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// Call release() before destruction iff the allocator member is active.
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union _Optional_alloc
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{
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_Optional_alloc() { }
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~_Optional_alloc() { }
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_Optional_alloc(_Optional_alloc&&) = delete;
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_Optional_alloc& operator=(_Optional_alloc&&) = delete;
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_Optional_alloc(const _NodeAlloc& __alloc) noexcept
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: _M_alloc(__alloc)
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{ }
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// Precondition: _M_alloc is the active member of the union.
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void
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operator=(_NodeAlloc&& __alloc) noexcept
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{
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using _ATr = _AllocTraits;
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if constexpr (_ATr::propagate_on_container_move_assignment::value)
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_M_alloc = std::move(__alloc);
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else if constexpr (!_AllocTraits::is_always_equal::value)
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__glibcxx_assert(_M_alloc == __alloc);
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}
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// Precondition: _M_alloc is the active member of both unions.
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void
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swap(_Optional_alloc& __other) noexcept
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{
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using std::swap;
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if constexpr (_AllocTraits::propagate_on_container_swap::value)
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swap(_M_alloc, __other._M_alloc);
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else if constexpr (!_AllocTraits::is_always_equal::value)
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__glibcxx_assert(_M_alloc == __other._M_alloc);
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}
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// Precondition: _M_alloc is the active member of the union.
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_NodeAlloc& operator*() noexcept { return _M_alloc; }
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// Precondition: _M_alloc is the active member of the union.
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_NodeAlloc release() noexcept
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{
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_NodeAlloc __tmp = std::move(_M_alloc);
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_M_alloc.~_NodeAlloc();
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return __tmp;
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}
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struct _Empty { };
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[[__no_unique_address__]] _Empty _M_empty;
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[[__no_unique_address__]] _NodeAlloc _M_alloc;
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};
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[[__no_unique_address__]] _Optional_alloc _M_alloc;
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template<typename _Key2, typename _Value2, typename _KeyOfValue,
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typename _Compare, typename _ValueAlloc>
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friend class _Rb_tree;
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};
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/// Node handle type for maps.
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template<typename _Key, typename _Value, typename _NodeAlloc>
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class _Node_handle : public _Node_handle_common<_Value, _NodeAlloc>
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{
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public:
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constexpr _Node_handle() noexcept = default;
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~_Node_handle() = default;
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_Node_handle(_Node_handle&&) noexcept = default;
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_Node_handle&
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operator=(_Node_handle&&) noexcept = default;
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using key_type = _Key;
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using mapped_type = typename _Value::second_type;
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key_type&
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key() const noexcept
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{
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__glibcxx_assert(!this->empty());
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return *_M_pkey;
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}
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mapped_type&
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mapped() const noexcept
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{
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__glibcxx_assert(!this->empty());
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return *_M_pmapped;
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}
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void
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swap(_Node_handle& __nh) noexcept
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{
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this->_M_swap(__nh);
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using std::swap;
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swap(_M_pkey, __nh._M_pkey);
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swap(_M_pmapped, __nh._M_pmapped);
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}
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friend void
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swap(_Node_handle& __x, _Node_handle& __y)
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noexcept(noexcept(__x.swap(__y)))
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{ __x.swap(__y); }
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private:
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using _AllocTraits = allocator_traits<_NodeAlloc>;
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_Node_handle(typename _AllocTraits::pointer __ptr,
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const _NodeAlloc& __alloc)
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: _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc)
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{
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if (__ptr)
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{
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auto& __key = const_cast<_Key&>(__ptr->_M_valptr()->first);
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_M_pkey = _S_pointer_to(__key);
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_M_pmapped = _S_pointer_to(__ptr->_M_valptr()->second);
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}
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else
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{
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_M_pkey = nullptr;
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_M_pmapped = nullptr;
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}
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}
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template<typename _Tp>
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using __pointer
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= __ptr_rebind<typename _AllocTraits::pointer,
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remove_reference_t<_Tp>>;
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__pointer<_Key> _M_pkey = nullptr;
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__pointer<typename _Value::second_type> _M_pmapped = nullptr;
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template<typename _Tp>
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__pointer<_Tp>
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_S_pointer_to(_Tp& __obj)
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{ return pointer_traits<__pointer<_Tp>>::pointer_to(__obj); }
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const key_type&
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_M_key() const noexcept { return key(); }
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template<typename _Key2, typename _Value2, typename _KeyOfValue,
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typename _Compare, typename _ValueAlloc>
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friend class _Rb_tree;
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template<typename _Key2, typename _Value2, typename _ValueAlloc,
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typename _ExtractKey, typename _Equal,
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typename _Hash, typename _RangeHash, typename _Unused,
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typename _RehashPolicy, typename _Traits>
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friend class _Hashtable;
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};
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/// Node handle type for sets.
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template<typename _Value, typename _NodeAlloc>
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class _Node_handle<_Value, _Value, _NodeAlloc>
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: public _Node_handle_common<_Value, _NodeAlloc>
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{
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public:
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constexpr _Node_handle() noexcept = default;
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~_Node_handle() = default;
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_Node_handle(_Node_handle&&) noexcept = default;
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_Node_handle&
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operator=(_Node_handle&&) noexcept = default;
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using value_type = _Value;
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value_type&
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value() const noexcept
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{
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__glibcxx_assert(!this->empty());
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return *this->_M_ptr->_M_valptr();
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}
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void
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swap(_Node_handle& __nh) noexcept
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{ this->_M_swap(__nh); }
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friend void
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swap(_Node_handle& __x, _Node_handle& __y)
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noexcept(noexcept(__x.swap(__y)))
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{ __x.swap(__y); }
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private:
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using _AllocTraits = allocator_traits<_NodeAlloc>;
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_Node_handle(typename _AllocTraits::pointer __ptr,
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const _NodeAlloc& __alloc)
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: _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) { }
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const value_type&
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_M_key() const noexcept { return value(); }
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template<typename _Key, typename _Val, typename _KeyOfValue,
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typename _Compare, typename _Alloc>
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friend class _Rb_tree;
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template<typename _Key2, typename _Value2, typename _ValueAlloc,
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typename _ExtractKey, typename _Equal,
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typename _Hash, typename _RangeHash, typename _Unused,
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typename _RehashPolicy, typename _Traits>
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friend class _Hashtable;
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};
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/// Return type of insert(node_handle&&) on unique maps/sets.
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template<typename _Iterator, typename _NodeHandle>
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struct _Node_insert_return
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{
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_Iterator position = _Iterator();
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bool inserted = false;
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_NodeHandle node;
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};
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif // C++17
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#endif
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