1 // Node handles for containers -*- C++ -*-
2 
3 // Copyright (C) 2016-2018 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 
43 namespace 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
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