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 <bits/alloc_traits.h>
00041 #include <bits/ptr_traits.h>
00042 
00043 namespace std _GLIBCXX_VISIBILITY(default)
00044 {
00045 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00046 
00047   /// Base class for node handle types of maps and sets.
00048   template<typename _Val, typename _NodeAlloc>
00049     class _Node_handle_common
00050     {
00051       using _AllocTraits = allocator_traits<_NodeAlloc>;
00052 
00053     public:
00054       using allocator_type = __alloc_rebind<_NodeAlloc, _Val>;
00055 
00056       allocator_type
00057       get_allocator() const noexcept
00058       {
00059         __glibcxx_assert(!this->empty());
00060         return allocator_type(*_M_alloc);
00061       }
00062 
00063       explicit operator bool() const noexcept { return _M_ptr != nullptr; }
00064 
00065       bool empty() const noexcept { return _M_ptr == nullptr; }
00066 
00067     protected:
00068       constexpr _Node_handle_common() noexcept : _M_ptr(), _M_alloc() {}
00069 
00070       ~_Node_handle_common() { _M_destroy(); }
00071 
00072       _Node_handle_common(_Node_handle_common&& __nh) noexcept
00073       : _M_ptr(__nh._M_ptr), _M_alloc(std::move(__nh._M_alloc))
00074       {
00075         __nh._M_ptr = nullptr;
00076         __nh._M_alloc = nullopt;
00077       }
00078 
00079       _Node_handle_common&
00080       operator=(_Node_handle_common&& __nh) noexcept
00081       {
00082         _M_destroy();
00083         _M_ptr = __nh._M_ptr;
00084         if constexpr (is_move_assignable_v<_NodeAlloc>)
00085           {
00086             if (_AllocTraits::propagate_on_container_move_assignment::value
00087                 || !this->_M_alloc)
00088               this->_M_alloc = std::move(__nh._M_alloc);
00089             else
00090               __glibcxx_assert(this->_M_alloc == __nh._M_alloc);
00091           }
00092         else
00093           __glibcxx_assert(_M_alloc);
00094         __nh._M_ptr = nullptr;
00095         __nh._M_alloc = nullopt;
00096         return *this;
00097       }
00098 
00099       _Node_handle_common(typename _AllocTraits::pointer __ptr,
00100                           const _NodeAlloc& __alloc)
00101       : _M_ptr(__ptr), _M_alloc(__alloc) { }
00102 
00103       void
00104       _M_swap(_Node_handle_common& __nh) noexcept
00105       {
00106         using std::swap;
00107         swap(_M_ptr, __nh._M_ptr);
00108         if (_AllocTraits::propagate_on_container_swap
00109             || !_M_alloc || !__nh._M_alloc)
00110           _M_alloc.swap(__nh._M_alloc);
00111         else
00112           __glibcxx_assert(_M_alloc == __nh._M_alloc);
00113       }
00114 
00115     private:
00116       void
00117       _M_destroy() noexcept
00118       {
00119         if (_M_ptr != nullptr)
00120           {
00121             allocator_type __alloc(*_M_alloc);
00122             allocator_traits<allocator_type>::destroy(__alloc,
00123                                                       _M_ptr->_M_valptr());
00124             _AllocTraits::deallocate(*_M_alloc, _M_ptr, 1);
00125           }
00126       }
00127 
00128     protected:
00129       typename _AllocTraits::pointer    _M_ptr;
00130     private:
00131       optional<_NodeAlloc>              _M_alloc;
00132 
00133       template<typename _Key2, typename _Value2, typename _KeyOfValue,
00134                typename _Compare, typename _ValueAlloc>
00135         friend class _Rb_tree;
00136     };
00137 
00138   /// Node handle type for maps.
00139   template<typename _Key, typename _Value, typename _NodeAlloc>
00140     class _Node_handle : public _Node_handle_common<_Value, _NodeAlloc>
00141     {
00142     public:
00143       constexpr _Node_handle() noexcept = default;
00144       ~_Node_handle() = default;
00145       _Node_handle(_Node_handle&&) noexcept = default;
00146 
00147       _Node_handle&
00148       operator=(_Node_handle&&) noexcept = default;
00149 
00150       using key_type = _Key;
00151       using mapped_type = typename _Value::second_type;
00152 
00153       key_type&
00154       key() const noexcept
00155       {
00156         __glibcxx_assert(!this->empty());
00157         return *_M_pkey;
00158       }
00159 
00160       mapped_type&
00161       mapped() const noexcept
00162       {
00163         __glibcxx_assert(!this->empty());
00164         return *_M_pmapped;
00165       }
00166 
00167       void
00168       swap(_Node_handle& __nh) noexcept
00169       {
00170         this->_M_swap(__nh);
00171         using std::swap;
00172         swap(_M_pkey, __nh._M_pkey);
00173         swap(_M_pmapped, __nh._M_pmapped);
00174       }
00175 
00176       friend void
00177       swap(_Node_handle& __x, _Node_handle& __y)
00178       noexcept(noexcept(__x.swap(__y)))
00179       { __x.swap(__y); }
00180 
00181     private:
00182       using _AllocTraits = allocator_traits<_NodeAlloc>;
00183 
00184       _Node_handle(typename _AllocTraits::pointer __ptr,
00185                    const _NodeAlloc& __alloc)
00186       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc)
00187       {
00188         if (__ptr)
00189           {
00190             auto& __key = const_cast<_Key&>(__ptr->_M_valptr()->first);
00191             _M_pkey = _S_pointer_to(__key);
00192             _M_pmapped = _S_pointer_to(__ptr->_M_valptr()->second);
00193           }
00194         else
00195           {
00196             _M_pkey = nullptr;
00197             _M_pmapped = nullptr;
00198           }
00199       }
00200 
00201       template<typename _Tp>
00202         using __pointer
00203           = __ptr_rebind<typename _AllocTraits::pointer,
00204                          remove_reference_t<_Tp>>;
00205 
00206       __pointer<_Key>                           _M_pkey = nullptr;
00207       __pointer<typename _Value::second_type>   _M_pmapped = nullptr;
00208 
00209       template<typename _Tp>
00210         __pointer<_Tp>
00211         _S_pointer_to(_Tp& __obj)
00212         { return pointer_traits<__pointer<_Tp>>::pointer_to(__obj); }
00213 
00214       const key_type&
00215       _M_key() const noexcept { return key(); }
00216 
00217       template<typename _Key2, typename _Value2, typename _KeyOfValue,
00218                typename _Compare, typename _ValueAlloc>
00219         friend class _Rb_tree;
00220 
00221       template<typename _Key2, typename _Value2, typename _ValueAlloc,
00222                typename _ExtractKey, typename _Equal,
00223                typename _H1, typename _H2, typename _Hash,
00224                typename _RehashPolicy, typename _Traits>
00225         friend class _Hashtable;
00226     };
00227 
00228   /// Node handle type for sets.
00229   template<typename _Value, typename _NodeAlloc>
00230     class _Node_handle<_Value, _Value, _NodeAlloc>
00231     : public _Node_handle_common<_Value, _NodeAlloc>
00232     {
00233     public:
00234       constexpr _Node_handle() noexcept = default;
00235       ~_Node_handle() = default;
00236       _Node_handle(_Node_handle&&) noexcept = default;
00237 
00238       _Node_handle&
00239       operator=(_Node_handle&&) noexcept = default;
00240 
00241       using value_type = _Value;
00242 
00243       value_type&
00244       value() const noexcept
00245       {
00246         __glibcxx_assert(!this->empty());
00247         return *this->_M_ptr->_M_valptr();
00248       }
00249 
00250       void
00251       swap(_Node_handle& __nh) noexcept
00252       { this->_M_swap(__nh); }
00253 
00254       friend void
00255       swap(_Node_handle& __x, _Node_handle& __y)
00256       noexcept(noexcept(__x.swap(__y)))
00257       { __x.swap(__y); }
00258 
00259     private:
00260       using _AllocTraits = allocator_traits<_NodeAlloc>;
00261 
00262       _Node_handle(typename _AllocTraits::pointer __ptr,
00263                    const _NodeAlloc& __alloc)
00264       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) { }
00265 
00266       const value_type&
00267       _M_key() const noexcept { return value(); }
00268 
00269       template<typename _Key, typename _Val, typename _KeyOfValue,
00270                typename _Compare, typename _Alloc>
00271         friend class _Rb_tree;
00272 
00273       template<typename _Key2, typename _Value2, typename _ValueAlloc,
00274                typename _ExtractKey, typename _Equal,
00275                typename _H1, typename _H2, typename _Hash,
00276                typename _RehashPolicy, typename _Traits>
00277         friend class _Hashtable;
00278     };
00279 
00280   /// Return type of insert(node_handle&&) on unique maps/sets.
00281   template<typename _Iterator, typename _NodeHandle>
00282     struct _Node_insert_return
00283     {
00284       _Iterator         position = _Iterator();
00285       bool              inserted = false;
00286       _NodeHandle       node;
00287     };
00288 
00289 _GLIBCXX_END_NAMESPACE_VERSION
00290 } // namespace std
00291 
00292 #endif // C++17
00293 #endif