libstdc++
utility
Go to the documentation of this file.
1 // <utility> -*- C++ -*-
2 
3 // Copyright (C) 2001-2018 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 /*
26  *
27  * Copyright (c) 1994
28  * Hewlett-Packard Company
29  *
30  * Permission to use, copy, modify, distribute and sell this software
31  * and its documentation for any purpose is hereby granted without fee,
32  * provided that the above copyright notice appear in all copies and
33  * that both that copyright notice and this permission notice appear
34  * in supporting documentation. Hewlett-Packard Company makes no
35  * representations about the suitability of this software for any
36  * purpose. It is provided "as is" without express or implied warranty.
37  *
38  *
39  * Copyright (c) 1996,1997
40  * Silicon Graphics Computer Systems, Inc.
41  *
42  * Permission to use, copy, modify, distribute and sell this software
43  * and its documentation for any purpose is hereby granted without fee,
44  * provided that the above copyright notice appear in all copies and
45  * that both that copyright notice and this permission notice appear
46  * in supporting documentation. Silicon Graphics makes no
47  * representations about the suitability of this software for any
48  * purpose. It is provided "as is" without express or implied warranty.
49  */
50 
51 /** @file include/utility
52  * This is a Standard C++ Library header.
53  */
54 
55 #ifndef _GLIBCXX_UTILITY
56 #define _GLIBCXX_UTILITY 1
57 
58 #pragma GCC system_header
59 
60 /**
61  * @defgroup utilities Utilities
62  *
63  * Components deemed generally useful. Includes pair, tuple,
64  * forward/move helpers, ratio, function object, metaprogramming and
65  * type traits, time, date, and memory functions.
66  */
67 
68 #include <bits/c++config.h>
69 #include <bits/stl_relops.h>
70 #include <bits/stl_pair.h>
71 
72 #if __cplusplus >= 201103L
73 
74 #include <type_traits>
75 #include <bits/move.h>
76 #include <initializer_list>
77 
78 #if __cplusplus > 201402L
79 #include <exception>
80 #endif
81 
82 namespace std _GLIBCXX_VISIBILITY(default)
83 {
84 _GLIBCXX_BEGIN_NAMESPACE_VERSION
85 
86  /// Finds the size of a given tuple type.
87  template<typename _Tp>
88  struct tuple_size;
89 
90  // _GLIBCXX_RESOLVE_LIB_DEFECTS
91  // 2313. tuple_size should always derive from integral_constant<size_t, N>
92  // 2770. tuple_size<const T> specialization is not SFINAE compatible
93 
94  template<typename _Tp,
95  typename _Up = typename remove_cv<_Tp>::type,
96  typename = typename enable_if<is_same<_Tp, _Up>::value>::type,
97  size_t = tuple_size<_Tp>::value>
98  using __enable_if_has_tuple_size = _Tp;
99 
100  template<typename _Tp>
101  struct tuple_size<const __enable_if_has_tuple_size<_Tp>>
102  : public tuple_size<_Tp> { };
103 
104  template<typename _Tp>
105  struct tuple_size<volatile __enable_if_has_tuple_size<_Tp>>
106  : public tuple_size<_Tp> { };
107 
108  template<typename _Tp>
109  struct tuple_size<const volatile __enable_if_has_tuple_size<_Tp>>
110  : public tuple_size<_Tp> { };
111 
112  /// Gives the type of the ith element of a given tuple type.
113  template<std::size_t __i, typename _Tp>
114  struct tuple_element;
115 
116  // Duplicate of C++14's tuple_element_t for internal use in C++11 mode
117  template<std::size_t __i, typename _Tp>
118  using __tuple_element_t = typename tuple_element<__i, _Tp>::type;
119 
120  template<std::size_t __i, typename _Tp>
121  struct tuple_element<__i, const _Tp>
122  {
123  typedef typename add_const<__tuple_element_t<__i, _Tp>>::type type;
124  };
125 
126  template<std::size_t __i, typename _Tp>
127  struct tuple_element<__i, volatile _Tp>
128  {
129  typedef typename add_volatile<__tuple_element_t<__i, _Tp>>::type type;
130  };
131 
132  template<std::size_t __i, typename _Tp>
133  struct tuple_element<__i, const volatile _Tp>
134  {
135  typedef typename add_cv<__tuple_element_t<__i, _Tp>>::type type;
136  };
137 
138 #if __cplusplus > 201103L
139 #define __cpp_lib_tuple_element_t 201402
140 
141  template<std::size_t __i, typename _Tp>
142  using tuple_element_t = typename tuple_element<__i, _Tp>::type;
143 #endif
144 
145  // Various functions which give std::pair a tuple-like interface.
146 
147  /// Partial specialization for std::pair
148  template<typename _T1, typename _T2>
149  struct __is_tuple_like_impl<std::pair<_T1, _T2>> : true_type
150  { };
151 
152  /// Partial specialization for std::pair
153  template<class _Tp1, class _Tp2>
154  struct tuple_size<std::pair<_Tp1, _Tp2>>
155  : public integral_constant<std::size_t, 2> { };
156 
157  /// Partial specialization for std::pair
158  template<class _Tp1, class _Tp2>
159  struct tuple_element<0, std::pair<_Tp1, _Tp2>>
160  { typedef _Tp1 type; };
161 
162  /// Partial specialization for std::pair
163  template<class _Tp1, class _Tp2>
164  struct tuple_element<1, std::pair<_Tp1, _Tp2>>
165  { typedef _Tp2 type; };
166 
167  template<std::size_t _Int>
168  struct __pair_get;
169 
170  template<>
171  struct __pair_get<0>
172  {
173  template<typename _Tp1, typename _Tp2>
174  static constexpr _Tp1&
175  __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
176  { return __pair.first; }
177 
178  template<typename _Tp1, typename _Tp2>
179  static constexpr _Tp1&&
180  __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
181  { return std::forward<_Tp1>(__pair.first); }
182 
183  template<typename _Tp1, typename _Tp2>
184  static constexpr const _Tp1&
185  __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
186  { return __pair.first; }
187 
188  template<typename _Tp1, typename _Tp2>
189  static constexpr const _Tp1&&
190  __const_move_get(const std::pair<_Tp1, _Tp2>&& __pair) noexcept
191  { return std::forward<const _Tp1>(__pair.first); }
192  };
193 
194  template<>
195  struct __pair_get<1>
196  {
197  template<typename _Tp1, typename _Tp2>
198  static constexpr _Tp2&
199  __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
200  { return __pair.second; }
201 
202  template<typename _Tp1, typename _Tp2>
203  static constexpr _Tp2&&
204  __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
205  { return std::forward<_Tp2>(__pair.second); }
206 
207  template<typename _Tp1, typename _Tp2>
208  static constexpr const _Tp2&
209  __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
210  { return __pair.second; }
211 
212  template<typename _Tp1, typename _Tp2>
213  static constexpr const _Tp2&&
214  __const_move_get(const std::pair<_Tp1, _Tp2>&& __pair) noexcept
215  { return std::forward<const _Tp2>(__pair.second); }
216  };
217 
218  template<std::size_t _Int, class _Tp1, class _Tp2>
219  constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
220  get(std::pair<_Tp1, _Tp2>& __in) noexcept
221  { return __pair_get<_Int>::__get(__in); }
222 
223  template<std::size_t _Int, class _Tp1, class _Tp2>
224  constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&&
225  get(std::pair<_Tp1, _Tp2>&& __in) noexcept
226  { return __pair_get<_Int>::__move_get(std::move(__in)); }
227 
228  template<std::size_t _Int, class _Tp1, class _Tp2>
229  constexpr const typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
230  get(const std::pair<_Tp1, _Tp2>& __in) noexcept
231  { return __pair_get<_Int>::__const_get(__in); }
232 
233  template<std::size_t _Int, class _Tp1, class _Tp2>
234  constexpr const typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&&
235  get(const std::pair<_Tp1, _Tp2>&& __in) noexcept
236  { return __pair_get<_Int>::__const_move_get(std::move(__in)); }
237 
238 #if __cplusplus > 201103L
239 
240 #define __cpp_lib_tuples_by_type 201304
241 
242  template <typename _Tp, typename _Up>
243  constexpr _Tp&
244  get(pair<_Tp, _Up>& __p) noexcept
245  { return __p.first; }
246 
247  template <typename _Tp, typename _Up>
248  constexpr const _Tp&
249  get(const pair<_Tp, _Up>& __p) noexcept
250  { return __p.first; }
251 
252  template <typename _Tp, typename _Up>
253  constexpr _Tp&&
254  get(pair<_Tp, _Up>&& __p) noexcept
255  { return std::move(__p.first); }
256 
257  template <typename _Tp, typename _Up>
258  constexpr const _Tp&&
259  get(const pair<_Tp, _Up>&& __p) noexcept
260  { return std::move(__p.first); }
261 
262  template <typename _Tp, typename _Up>
263  constexpr _Tp&
264  get(pair<_Up, _Tp>& __p) noexcept
265  { return __p.second; }
266 
267  template <typename _Tp, typename _Up>
268  constexpr const _Tp&
269  get(const pair<_Up, _Tp>& __p) noexcept
270  { return __p.second; }
271 
272  template <typename _Tp, typename _Up>
273  constexpr _Tp&&
274  get(pair<_Up, _Tp>&& __p) noexcept
275  { return std::move(__p.second); }
276 
277  template <typename _Tp, typename _Up>
278  constexpr const _Tp&&
279  get(const pair<_Up, _Tp>&& __p) noexcept
280  { return std::move(__p.second); }
281 
282 #define __cpp_lib_exchange_function 201304
283 
284  /// Assign @p __new_val to @p __obj and return its previous value.
285  template <typename _Tp, typename _Up = _Tp>
286  inline _Tp
287  exchange(_Tp& __obj, _Up&& __new_val)
288  { return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
289 #endif
290 
291  // Stores a tuple of indices. Used by tuple and pair, and by bind() to
292  // extract the elements in a tuple.
293  template<size_t... _Indexes> struct _Index_tuple { };
294 
295 #ifdef __has_builtin
296 # if __has_builtin(__make_integer_seq)
297 # define _GLIBCXX_USE_MAKE_INTEGER_SEQ 1
298 # endif
299 #endif
300 
301  // Builds an _Index_tuple<0, 1, 2, ..., _Num-1>.
302  template<size_t _Num>
303  struct _Build_index_tuple
304  {
305 #if _GLIBCXX_USE_MAKE_INTEGER_SEQ
306  template<typename, size_t... _Indices>
307  using _IdxTuple = _Index_tuple<_Indices...>;
308 
309  using __type = __make_integer_seq<_IdxTuple, size_t, _Num>;
310 #else
311  using __type = _Index_tuple<__integer_pack(_Num)...>;
312 #endif
313  };
314 
315 #if __cplusplus > 201103L
316 
317 #define __cpp_lib_integer_sequence 201304
318 
319  /// Class template integer_sequence
320  template<typename _Tp, _Tp... _Idx>
321  struct integer_sequence
322  {
323  typedef _Tp value_type;
324  static constexpr size_t size() noexcept { return sizeof...(_Idx); }
325  };
326 
327  /// Alias template make_integer_sequence
328  template<typename _Tp, _Tp _Num>
329  using make_integer_sequence
330 #if _GLIBCXX_USE_MAKE_INTEGER_SEQ
331  = __make_integer_seq<integer_sequence, _Tp, _Num>;
332 #else
333  = integer_sequence<_Tp, __integer_pack(_Num)...>;
334 #endif
335 
336 #undef _GLIBCXX_USE_MAKE_INTEGER_SEQ
337 
338  /// Alias template index_sequence
339  template<size_t... _Idx>
340  using index_sequence = integer_sequence<size_t, _Idx...>;
341 
342  /// Alias template make_index_sequence
343  template<size_t _Num>
344  using make_index_sequence = make_integer_sequence<size_t, _Num>;
345 
346  /// Alias template index_sequence_for
347  template<typename... _Types>
348  using index_sequence_for = make_index_sequence<sizeof...(_Types)>;
349 #endif
350 
351 #if __cplusplus > 201402L
352 
353  struct in_place_t {
354  explicit in_place_t() = default;
355  };
356 
357  inline constexpr in_place_t in_place{};
358 
359  template<typename _Tp> struct in_place_type_t
360  {
361  explicit in_place_type_t() = default;
362  };
363 
364  template<typename _Tp>
365  inline constexpr in_place_type_t<_Tp> in_place_type{};
366 
367  template<size_t _Idx> struct in_place_index_t
368  {
369  explicit in_place_index_t() = default;
370  };
371 
372  template<size_t _Idx>
373  inline constexpr in_place_index_t<_Idx> in_place_index{};
374 
375  template<typename>
376  struct __is_in_place_type_impl : false_type
377  { };
378 
379  template<typename _Tp>
380  struct __is_in_place_type_impl<in_place_type_t<_Tp>> : true_type
381  { };
382 
383  template<typename _Tp>
384  struct __is_in_place_type
385  : public __is_in_place_type_impl<_Tp>
386  { };
387 
388 #define __cpp_lib_as_const 201510
389  template<typename _Tp>
390  constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
391 
392  template<typename _Tp>
393  void as_const(const _Tp&&) = delete;
394 
395 #endif // C++17
396 
397 _GLIBCXX_END_NAMESPACE_VERSION
398 } // namespace
399 
400 #endif
401 
402 #endif /* _GLIBCXX_UTILITY */