libstdc++
node_handle.h
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00001 // Node handles for containers -*- C++ -*-
00002 
00003 // Copyright (C) 2016-2017 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file bits/node_handle.h
00026  *  This is an internal header file, included by other library headers.
00027  *  Do not attempt to use it directly.
00028  *  @headername{map,set,unordered_map,unordered_set}
00029  */
00030 
00031 #ifndef _NODE_HANDLE
00032 #define _NODE_HANDLE 1
00033 
00034 #pragma GCC system_header
00035 
00036 #if __cplusplus > 201402L
00037 # define __cpp_lib_node_extract 201606
00038 
00039 #include <optional>
00040 #include <tuple>
00041 #include <bits/alloc_traits.h>
00042 #include <bits/ptr_traits.h>
00043 
00044 namespace std _GLIBCXX_VISIBILITY(default)
00045 {
00046 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00047 
00048   /// Base class for node handle types of maps and sets.
00049   template<typename _Val, typename _NodeAlloc>
00050     class _Node_handle_common
00051     {
00052       using _AllocTraits = allocator_traits<_NodeAlloc>;
00053 
00054     public:
00055       using allocator_type = __alloc_rebind<_NodeAlloc, _Val>;
00056 
00057       allocator_type
00058       get_allocator() const noexcept
00059       {
00060         __glibcxx_assert(!this->empty());
00061         return allocator_type(*_M_alloc);
00062       }
00063 
00064       explicit operator bool() const noexcept { return _M_ptr != nullptr; }
00065 
00066       bool empty() const noexcept { return _M_ptr == nullptr; }
00067 
00068     protected:
00069       constexpr _Node_handle_common() noexcept : _M_ptr(), _M_alloc() {}
00070 
00071       ~_Node_handle_common() { _M_destroy(); }
00072 
00073       _Node_handle_common(_Node_handle_common&& __nh) noexcept
00074       : _M_ptr(__nh._M_ptr), _M_alloc(std::move(__nh._M_alloc))
00075       {
00076         __nh._M_ptr = nullptr;
00077         __nh._M_alloc = nullopt;
00078       }
00079 
00080       _Node_handle_common&
00081       operator=(_Node_handle_common&& __nh) noexcept
00082       {
00083         _M_destroy();
00084         _M_ptr = __nh._M_ptr;
00085         if constexpr (is_move_assignable_v<_NodeAlloc>)
00086           {
00087             if (_AllocTraits::propagate_on_container_move_assignment::value
00088                 || !this->_M_alloc)
00089               this->_M_alloc = std::move(__nh._M_alloc);
00090             else
00091               __glibcxx_assert(this->_M_alloc == __nh._M_alloc);
00092           }
00093         else
00094           __glibcxx_assert(_M_alloc);
00095         __nh._M_ptr = nullptr;
00096         __nh._M_alloc = nullopt;
00097         return *this;
00098       }
00099 
00100       _Node_handle_common(typename _AllocTraits::pointer __ptr,
00101                           const _NodeAlloc& __alloc)
00102       : _M_ptr(__ptr), _M_alloc(__alloc) { }
00103 
00104       void
00105       _M_swap(_Node_handle_common& __nh) noexcept
00106       {
00107         using std::swap;
00108         swap(_M_ptr, __nh._M_ptr);
00109         if (_AllocTraits::propagate_on_container_swap
00110             || !_M_alloc || !__nh._M_alloc)
00111           _M_alloc.swap(__nh._M_alloc);
00112         else
00113           __glibcxx_assert(_M_alloc == __nh._M_alloc);
00114       }
00115 
00116     private:
00117       void
00118       _M_destroy() noexcept
00119       {
00120         if (_M_ptr != nullptr)
00121           {
00122             allocator_type __alloc(*_M_alloc);
00123             allocator_traits<allocator_type>::destroy(__alloc,
00124                                                       _M_ptr->_M_valptr());
00125             _AllocTraits::deallocate(*_M_alloc, _M_ptr, 1);
00126           }
00127       }
00128 
00129     protected:
00130       typename _AllocTraits::pointer    _M_ptr;
00131     private:
00132       optional<_NodeAlloc>              _M_alloc;
00133 
00134       template<typename _Key2, typename _Value2, typename _KeyOfValue,
00135                typename _Compare, typename _ValueAlloc>
00136         friend class _Rb_tree;
00137     };
00138 
00139   /// Node handle type for maps.
00140   template<typename _Key, typename _Value, typename _NodeAlloc>
00141     class _Node_handle : public _Node_handle_common<_Value, _NodeAlloc>
00142     {
00143     public:
00144       constexpr _Node_handle() noexcept = default;
00145       ~_Node_handle() = default;
00146       _Node_handle(_Node_handle&&) noexcept = default;
00147 
00148       _Node_handle&
00149       operator=(_Node_handle&&) noexcept = default;
00150 
00151       using key_type = _Key;
00152       using mapped_type = typename _Value::second_type;
00153 
00154       key_type&
00155       key() const noexcept
00156       {
00157         __glibcxx_assert(!this->empty());
00158         return *_M_pkey;
00159       }
00160 
00161       mapped_type&
00162       mapped() const noexcept
00163       {
00164         __glibcxx_assert(!this->empty());
00165         return *_M_pmapped;
00166       }
00167 
00168       void
00169       swap(_Node_handle& __nh) noexcept
00170       {
00171         this->_M_swap(__nh);
00172         using std::swap;
00173         swap(_M_pkey, __nh._M_pkey);
00174         swap(_M_pmapped, __nh._M_pmapped);
00175       }
00176 
00177       friend void
00178       swap(_Node_handle& __x, _Node_handle& __y)
00179       noexcept(noexcept(__x.swap(__y)))
00180       { __x.swap(__y); }
00181 
00182     private:
00183       using _AllocTraits = allocator_traits<_NodeAlloc>;
00184 
00185       _Node_handle(typename _AllocTraits::pointer __ptr,
00186                    const _NodeAlloc& __alloc)
00187       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc)
00188       {
00189         if (__ptr)
00190           {
00191             auto& __key = const_cast<_Key&>(__ptr->_M_valptr()->first);
00192             _M_pkey = _S_pointer_to(__key);
00193             _M_pmapped = _S_pointer_to(__ptr->_M_valptr()->second);
00194           }
00195         else
00196           {
00197             _M_pkey = nullptr;
00198             _M_pmapped = nullptr;
00199           }
00200       }
00201 
00202       template<typename _Tp>
00203         using __pointer = __ptr_rebind<typename _AllocTraits::pointer, _Tp>;
00204 
00205       __pointer<_Key>                           _M_pkey = nullptr;
00206       __pointer<typename _Value::second_type>   _M_pmapped = nullptr;
00207 
00208       template<typename _Tp>
00209         __pointer<_Tp>
00210         _S_pointer_to(_Tp& __obj)
00211         { return pointer_traits<__pointer<_Tp>>::pointer_to(__obj); }
00212 
00213       const key_type&
00214       _M_key() const noexcept { return key(); }
00215 
00216       template<typename _Key2, typename _Value2, typename _KeyOfValue,
00217                typename _Compare, typename _ValueAlloc>
00218         friend class _Rb_tree;
00219 
00220       template<typename _Key2, typename _Value2, typename _ValueAlloc,
00221                typename _ExtractKey, typename _Equal,
00222                typename _H1, typename _H2, typename _Hash,
00223                typename _RehashPolicy, typename _Traits>
00224         friend class _Hashtable;
00225     };
00226 
00227   /// Node handle type for sets.
00228   template<typename _Value, typename _NodeAlloc>
00229     class _Node_handle<_Value, _Value, _NodeAlloc>
00230     : public _Node_handle_common<_Value, _NodeAlloc>
00231     {
00232     public:
00233       constexpr _Node_handle() noexcept = default;
00234       ~_Node_handle() = default;
00235       _Node_handle(_Node_handle&&) noexcept = default;
00236 
00237       _Node_handle&
00238       operator=(_Node_handle&&) noexcept = default;
00239 
00240       using value_type = _Value;
00241 
00242       value_type&
00243       value() const noexcept
00244       {
00245         __glibcxx_assert(!this->empty());
00246         return *this->_M_ptr->_M_valptr();
00247       }
00248 
00249       void
00250       swap(_Node_handle& __nh) noexcept
00251       { this->_M_swap(__nh); }
00252 
00253       friend void
00254       swap(_Node_handle& __x, _Node_handle& __y)
00255       noexcept(noexcept(__x.swap(__y)))
00256       { __x.swap(__y); }
00257 
00258     private:
00259       using _AllocTraits = allocator_traits<_NodeAlloc>;
00260 
00261       _Node_handle(typename _AllocTraits::pointer __ptr,
00262                    const _NodeAlloc& __alloc)
00263       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) { }
00264 
00265       const value_type&
00266       _M_key() const noexcept { return value(); }
00267 
00268       template<typename _Key, typename _Val, typename _KeyOfValue,
00269                typename _Compare, typename _Alloc>
00270         friend class _Rb_tree;
00271 
00272       template<typename _Key2, typename _Value2, typename _ValueAlloc,
00273                typename _ExtractKey, typename _Equal,
00274                typename _H1, typename _H2, typename _Hash,
00275                typename _RehashPolicy, typename _Traits>
00276         friend class _Hashtable;
00277     };
00278 
00279   /// Return type of insert(node_handle&&) on unique maps/sets.
00280   template<typename _Iterator, typename _NodeHandle>
00281     struct _Node_insert_return
00282     {
00283       _Iterator         position = _Iterator();
00284       bool              inserted = false;
00285       _NodeHandle       node;
00286 
00287       template<size_t _Idx>
00288         decltype(auto) get() &
00289         { return std::get<_Idx>(std::tie(inserted, position, node)); }
00290 
00291       template<size_t _Idx>
00292         decltype(auto) get() const &
00293         { return std::get<_Idx>(std::tie(inserted, position, node)); }
00294 
00295       template<size_t _Idx>
00296         decltype(auto) get() &&
00297         {
00298           return std::move(std::get<_Idx>(std::tie(inserted, position, node)));
00299         }
00300 
00301       template<size_t _Idx>
00302         decltype(auto) get() const &&
00303         {
00304           return std::move(std::get<_Idx>(std::tie(inserted, position, node)));
00305         }
00306     };
00307 
00308 _GLIBCXX_END_NAMESPACE_VERSION
00309 } // namespace std
00310 
00311 #endif // C++17
00312 #endif