1// Node handles for containers -*- C++ -*- 
2 
3// Copyright (C) 2016-2019 Free Software Foundation, Inc. 
4// 
5// This file is part of the GNU ISO C++ Library. This library is free 
6// software; you can redistribute it and/or modify it under the 
7// terms of the GNU General Public License as published by the 
8// Free Software Foundation; either version 3, or (at your option) 
9// any later version. 
10 
11// This library is distributed in the hope that it will be useful, 
12// but WITHOUT ANY WARRANTY; without even the implied warranty of 
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
14// GNU General Public License for more details. 
15 
16// Under Section 7 of GPL version 3, you are granted additional 
17// permissions described in the GCC Runtime Library Exception, version 
18// 3.1, as published by the Free Software Foundation. 
19 
20// You should have received a copy of the GNU General Public License and 
21// a copy of the GCC Runtime Library Exception along with this program; 
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 
23// <http://www.gnu.org/licenses/>. 
24 
25/** @file bits/node_handle.h 
26 * This is an internal header file, included by other library headers. 
27 * Do not attempt to use it directly. 
28 * @headername{map,set,unordered_map,unordered_set} 
29 */ 
30 
31#ifndef _NODE_HANDLE 
32#define _NODE_HANDLE 1 
33 
34#pragma GCC system_header 
35 
36#if __cplusplus > 201402L 
37# define __cpp_lib_node_extract 201606 
38 
39#include <optional> 
40#include <bits/alloc_traits.h> 
41#include <bits/ptr_traits.h> 
42 
43namespace std _GLIBCXX_VISIBILITY(default) 
44{ 
45_GLIBCXX_BEGIN_NAMESPACE_VERSION 
46 
47 /// Base class for node handle types of maps and sets. 
48 template<typename _Val, typename _NodeAlloc> 
49 class _Node_handle_common 
50 { 
51 using _AllocTraits = allocator_traits<_NodeAlloc>; 
52 
53 public: 
54 using allocator_type = __alloc_rebind<_NodeAlloc, _Val>; 
55 
56 allocator_type 
57 get_allocator() const noexcept 
58 { 
59 __glibcxx_assert(!this->empty()); 
60 return allocator_type(*_M_alloc); 
61 } 
62 
63 explicit operator bool() const noexcept { return _M_ptr != nullptr; } 
64 
65 [[nodiscard]] bool empty() const noexcept { return _M_ptr == nullptr; } 
66 
67 protected: 
68 constexpr _Node_handle_common() noexcept : _M_ptr(), _M_alloc() {} 
69 
70 ~_Node_handle_common() { _M_destroy(); } 
71 
72 _Node_handle_common(_Node_handle_common&& __nh) noexcept 
73 : _M_ptr(__nh._M_ptr), _M_alloc(std::move(__nh._M_alloc)) 
74 { 
75 __nh._M_ptr = nullptr; 
76 __nh._M_alloc = nullopt; 
77 } 
78 
79 _Node_handle_common& 
80 operator=(_Node_handle_common&& __nh) noexcept 
81 { 
82 _M_destroy(); 
83 _M_ptr = __nh._M_ptr; 
84 if constexpr (is_move_assignable_v<_NodeAlloc>) 
85 { 
86 if (_AllocTraits::propagate_on_container_move_assignment::value 
87 || !this->_M_alloc) 
88 this->_M_alloc = std::move(__nh._M_alloc); 
89 else 
90 { 
91 __glibcxx_assert(this->_M_alloc == __nh._M_alloc); 
92 } 
93 } 
94 else 
95 { 
96 __glibcxx_assert(_M_alloc); 
97 } 
98 __nh._M_ptr = nullptr; 
99 __nh._M_alloc = nullopt; 
100 return *this; 
101 } 
102 
103 _Node_handle_common(typename _AllocTraits::pointer __ptr, 
104 const _NodeAlloc& __alloc) 
105 : _M_ptr(__ptr), _M_alloc(__alloc) { } 
106 
107 void 
108 _M_swap(_Node_handle_common& __nh) noexcept 
109 { 
110 using std::swap; 
111 swap(_M_ptr, __nh._M_ptr); 
112 if (_AllocTraits::propagate_on_container_swap::value 
113 || !_M_alloc || !__nh._M_alloc) 
114 _M_alloc.swap(__nh._M_alloc); 
115 else 
116 { 
117 __glibcxx_assert(_M_alloc == __nh._M_alloc); 
118 } 
119 } 
120 
121 private: 
122 void 
123 _M_destroy() noexcept 
124 { 
125 if (_M_ptr != nullptr) 
126 { 
127 allocator_type __alloc(*_M_alloc); 
128 allocator_traits<allocator_type>::destroy(__alloc, 
129 _M_ptr->_M_valptr()); 
130 _AllocTraits::deallocate(*_M_alloc, _M_ptr, 1); 
131 } 
132 } 
133 
134 protected: 
135 typename _AllocTraits::pointer _M_ptr; 
136 private: 
137 optional<_NodeAlloc> _M_alloc; 
138 
139 template<typename _Key2, typename _Value2, typename _KeyOfValue, 
140 typename _Compare, typename _ValueAlloc> 
141 friend class _Rb_tree; 
142 }; 
143 
144 /// Node handle type for maps. 
145 template<typename _Key, typename _Value, typename _NodeAlloc> 
146 class _Node_handle : public _Node_handle_common<_Value, _NodeAlloc> 
147 { 
148 public: 
149 constexpr _Node_handle() noexcept = default; 
150 ~_Node_handle() = default; 
151 _Node_handle(_Node_handle&&) noexcept = default; 
152 
153 _Node_handle& 
154 operator=(_Node_handle&&) noexcept = default; 
155 
156 using key_type = _Key; 
157 using mapped_type = typename _Value::second_type; 
158 
159 key_type& 
160 key() const noexcept 
161 { 
162 __glibcxx_assert(!this->empty()); 
163 return *_M_pkey; 
164 } 
165 
166 mapped_type& 
167 mapped() const noexcept 
168 { 
169 __glibcxx_assert(!this->empty()); 
170 return *_M_pmapped; 
171 } 
172 
173 void 
174 swap(_Node_handle& __nh) noexcept 
175 { 
176 this->_M_swap(__nh); 
177 using std::swap; 
178 swap(_M_pkey, __nh._M_pkey); 
179 swap(_M_pmapped, __nh._M_pmapped); 
180 } 
181 
182 friend void 
183 swap(_Node_handle& __x, _Node_handle& __y) 
184 noexcept(noexcept(__x.swap(__y))) 
185 { __x.swap(__y); } 
186 
187 private: 
188 using _AllocTraits = allocator_traits<_NodeAlloc>; 
189 
190 _Node_handle(typename _AllocTraits::pointer __ptr, 
191 const _NodeAlloc& __alloc) 
192 : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) 
193 { 
194 if (__ptr) 
195 { 
196 auto& __key = const_cast<_Key&>(__ptr->_M_valptr()->first); 
197 _M_pkey = _S_pointer_to(__key); 
198 _M_pmapped = _S_pointer_to(__ptr->_M_valptr()->second); 
199 } 
200 else 
201 { 
202 _M_pkey = nullptr; 
203 _M_pmapped = nullptr; 
204 } 
205 } 
206 
207 template<typename _Tp> 
208 using __pointer 
209 = __ptr_rebind<typename _AllocTraits::pointer, 
210 remove_reference_t<_Tp>>; 
211 
212 __pointer<_Key> _M_pkey = nullptr; 
213 __pointer<typename _Value::second_type> _M_pmapped = nullptr; 
214 
215 template<typename _Tp> 
216 __pointer<_Tp> 
217 _S_pointer_to(_Tp& __obj) 
218 { return pointer_traits<__pointer<_Tp>>::pointer_to(__obj); } 
219 
220 const key_type& 
221 _M_key() const noexcept { return key(); } 
222 
223 template<typename _Key2, typename _Value2, typename _KeyOfValue, 
224 typename _Compare, typename _ValueAlloc> 
225 friend class _Rb_tree; 
226 
227 template<typename _Key2, typename _Value2, typename _ValueAlloc, 
228 typename _ExtractKey, typename _Equal, 
229 typename _H1, typename _H2, typename _Hash, 
230 typename _RehashPolicy, typename _Traits> 
231 friend class _Hashtable; 
232 }; 
233 
234 /// Node handle type for sets. 
235 template<typename _Value, typename _NodeAlloc> 
236 class _Node_handle<_Value, _Value, _NodeAlloc> 
237 : public _Node_handle_common<_Value, _NodeAlloc> 
238 { 
239 public: 
240 constexpr _Node_handle() noexcept = default; 
241 ~_Node_handle() = default; 
242 _Node_handle(_Node_handle&&) noexcept = default; 
243 
244 _Node_handle& 
245 operator=(_Node_handle&&) noexcept = default; 
246 
247 using value_type = _Value; 
248 
249 value_type& 
250 value() const noexcept 
251 { 
252 __glibcxx_assert(!this->empty()); 
253 return *this->_M_ptr->_M_valptr(); 
254 } 
255 
256 void 
257 swap(_Node_handle& __nh) noexcept 
258 { this->_M_swap(__nh); } 
259 
260 friend void 
261 swap(_Node_handle& __x, _Node_handle& __y) 
262 noexcept(noexcept(__x.swap(__y))) 
263 { __x.swap(__y); } 
264 
265 private: 
266 using _AllocTraits = allocator_traits<_NodeAlloc>; 
267 
268 _Node_handle(typename _AllocTraits::pointer __ptr, 
269 const _NodeAlloc& __alloc) 
270 : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) { } 
271 
272 const value_type& 
273 _M_key() const noexcept { return value(); } 
274 
275 template<typename _Key, typename _Val, typename _KeyOfValue, 
276 typename _Compare, typename _Alloc> 
277 friend class _Rb_tree; 
278 
279 template<typename _Key2, typename _Value2, typename _ValueAlloc, 
280 typename _ExtractKey, typename _Equal, 
281 typename _H1, typename _H2, typename _Hash, 
282 typename _RehashPolicy, typename _Traits> 
283 friend class _Hashtable; 
284 }; 
285 
286 /// Return type of insert(node_handle&&) on unique maps/sets. 
287 template<typename _Iterator, typename _NodeHandle> 
288 struct _Node_insert_return 
289 { 
290 _Iterator position = _Iterator(); 
291 bool inserted = false; 
292 _NodeHandle node; 
293 }; 
294 
295_GLIBCXX_END_NAMESPACE_VERSION 
296} // namespace std 
297 
298#endif // C++17 
299#endif 
300