libstdc++
node_handle.h
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1 // Node handles for containers -*- C++ -*-
2 
3 // Copyright (C) 2016-2020 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::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);
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
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:101
constexpr nullopt_t nullopt
Tag to disengage optional objects.
ISO C++ entities toplevel namespace is std.
typename pointer_traits< _Ptr >::template rebind< _Tp > __ptr_rebind
Convenience alias for rebinding pointers.
Definition: ptr_traits.h:152
static constexpr void destroy(_Alloc &__a, _Tp *__p) noexcept(noexcept(_S_destroy(__a, __p, 0)))
Destroy an object of type _Tp.