libstdc++
utility
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1 // <utility> -*- C++ -*-
2 
3 // Copyright (C) 2001-2017 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 namespace std _GLIBCXX_VISIBILITY(default)
79 {
80 _GLIBCXX_BEGIN_NAMESPACE_VERSION
81 
82  /// Finds the size of a given tuple type.
83  template<typename _Tp>
84  struct tuple_size;
85 
86  // _GLIBCXX_RESOLVE_LIB_DEFECTS
87  // 2770. tuple_size<const T> specialization is not SFINAE compatible
88 
89 #if __cplusplus <= 201402L
90  template<typename _Tp, typename = void>
91  struct __tuple_size_cv_impl { };
92 
93  template<typename _Tp>
94  struct __tuple_size_cv_impl<_Tp, __void_t<decltype(tuple_size<_Tp>::value)>>
95  : integral_constant<size_t, tuple_size<_Tp>::value> { };
96 
97  // _GLIBCXX_RESOLVE_LIB_DEFECTS
98  // 2313. tuple_size should always derive from integral_constant<size_t, N>
99  template<typename _Tp>
100  struct tuple_size<const _Tp> : __tuple_size_cv_impl<_Tp> { };
101 
102  template<typename _Tp>
103  struct tuple_size<volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
104 
105  template<typename _Tp>
106  struct tuple_size<const volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
107 #else
108  template<typename _Tp,
109  typename _Up = typename remove_cv<_Tp>::type,
110  typename = typename enable_if<is_same<_Tp, _Up>::value>::type,
111  size_t = tuple_size<_Tp>::value>
112  using __enable_if_has_tuple_size = _Tp;
113 
114  template<typename _Tp>
115  struct tuple_size<const __enable_if_has_tuple_size<_Tp>>
116  : public tuple_size<_Tp> { };
117 
118  template<typename _Tp>
119  struct tuple_size<volatile __enable_if_has_tuple_size<_Tp>>
120  : public tuple_size<_Tp> { };
121 
122  template<typename _Tp>
123  struct tuple_size<const volatile __enable_if_has_tuple_size<_Tp>>
124  : public tuple_size<_Tp> { };
125 #endif
126 
127  /// Gives the type of the ith element of a given tuple type.
128  template<std::size_t __i, typename _Tp>
129  struct tuple_element;
130 
131  // Duplicate of C++14's tuple_element_t for internal use in C++11 mode
132  template<std::size_t __i, typename _Tp>
133  using __tuple_element_t = typename tuple_element<__i, _Tp>::type;
134 
135  template<std::size_t __i, typename _Tp>
136  struct tuple_element<__i, const _Tp>
137  {
138  typedef typename add_const<__tuple_element_t<__i, _Tp>>::type type;
139  };
140 
141  template<std::size_t __i, typename _Tp>
142  struct tuple_element<__i, volatile _Tp>
143  {
144  typedef typename add_volatile<__tuple_element_t<__i, _Tp>>::type type;
145  };
146 
147  template<std::size_t __i, typename _Tp>
148  struct tuple_element<__i, const volatile _Tp>
149  {
150  typedef typename add_cv<__tuple_element_t<__i, _Tp>>::type type;
151  };
152 
153 #if __cplusplus > 201103L
154 #define __cpp_lib_tuple_element_t 201402
155 
156  template<std::size_t __i, typename _Tp>
157  using tuple_element_t = typename tuple_element<__i, _Tp>::type;
158 #endif
159 
160  // Various functions which give std::pair a tuple-like interface.
161 
162  /// Partial specialization for std::pair
163  template<typename _T1, typename _T2>
164  struct __is_tuple_like_impl<std::pair<_T1, _T2>> : true_type
165  { };
166 
167  /// Partial specialization for std::pair
168  template<class _Tp1, class _Tp2>
169  struct tuple_size<std::pair<_Tp1, _Tp2>>
170  : public integral_constant<std::size_t, 2> { };
171 
172  /// Partial specialization for std::pair
173  template<class _Tp1, class _Tp2>
174  struct tuple_element<0, std::pair<_Tp1, _Tp2>>
175  { typedef _Tp1 type; };
176 
177  /// Partial specialization for std::pair
178  template<class _Tp1, class _Tp2>
179  struct tuple_element<1, std::pair<_Tp1, _Tp2>>
180  { typedef _Tp2 type; };
181 
182  template<std::size_t _Int>
183  struct __pair_get;
184 
185  template<>
186  struct __pair_get<0>
187  {
188  template<typename _Tp1, typename _Tp2>
189  static constexpr _Tp1&
190  __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
191  { return __pair.first; }
192 
193  template<typename _Tp1, typename _Tp2>
194  static constexpr _Tp1&&
195  __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
196  { return std::forward<_Tp1>(__pair.first); }
197 
198  template<typename _Tp1, typename _Tp2>
199  static constexpr const _Tp1&
200  __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
201  { return __pair.first; }
202  };
203 
204  template<>
205  struct __pair_get<1>
206  {
207  template<typename _Tp1, typename _Tp2>
208  static constexpr _Tp2&
209  __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
210  { return __pair.second; }
211 
212  template<typename _Tp1, typename _Tp2>
213  static constexpr _Tp2&&
214  __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
215  { return std::forward<_Tp2>(__pair.second); }
216 
217  template<typename _Tp1, typename _Tp2>
218  static constexpr const _Tp2&
219  __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
220  { return __pair.second; }
221  };
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>::__get(__in); }
227 
228  template<std::size_t _Int, class _Tp1, class _Tp2>
229  constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&&
230  get(std::pair<_Tp1, _Tp2>&& __in) noexcept
231  { return __pair_get<_Int>::__move_get(std::move(__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_get(__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 _Tp&
259  get(pair<_Up, _Tp>& __p) noexcept
260  { return __p.second; }
261 
262  template <typename _Tp, typename _Up>
263  constexpr const _Tp&
264  get(const pair<_Up, _Tp>& __p) noexcept
265  { return __p.second; }
266 
267  template <typename _Tp, typename _Up>
268  constexpr _Tp&&
269  get(pair<_Up, _Tp>&& __p) noexcept
270  { return std::move(__p.second); }
271 
272 #define __cpp_lib_exchange_function 201304
273 
274  /// Assign @p __new_val to @p __obj and return its previous value.
275  template <typename _Tp, typename _Up = _Tp>
276  inline _Tp
277  exchange(_Tp& __obj, _Up&& __new_val)
278  { return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
279 #endif
280 
281  // Stores a tuple of indices. Used by tuple and pair, and by bind() to
282  // extract the elements in a tuple.
283  template<size_t... _Indexes> struct _Index_tuple { };
284 
285  // Concatenates two _Index_tuples.
286  template<typename _Itup1, typename _Itup2> struct _Itup_cat;
287 
288  template<size_t... _Ind1, size_t... _Ind2>
289  struct _Itup_cat<_Index_tuple<_Ind1...>, _Index_tuple<_Ind2...>>
290  {
291  using __type = _Index_tuple<_Ind1..., (_Ind2 + sizeof...(_Ind1))...>;
292  };
293 
294  // Builds an _Index_tuple<0, 1, 2, ..., _Num-1>.
295  template<size_t _Num>
296  struct _Build_index_tuple
297  : _Itup_cat<typename _Build_index_tuple<_Num / 2>::__type,
298  typename _Build_index_tuple<_Num - _Num / 2>::__type>
299  { };
300 
301  template<>
302  struct _Build_index_tuple<1>
303  {
304  typedef _Index_tuple<0> __type;
305  };
306 
307  template<>
308  struct _Build_index_tuple<0>
309  {
310  typedef _Index_tuple<> __type;
311  };
312 
313 #if __cplusplus > 201103L
314 
315 #define __cpp_lib_integer_sequence 201304
316 
317  /// Class template integer_sequence
318  template<typename _Tp, _Tp... _Idx>
319  struct integer_sequence
320  {
321  typedef _Tp value_type;
322  static constexpr size_t size() noexcept { return sizeof...(_Idx); }
323  };
324 
325  template<typename _Tp, _Tp _Num,
326  typename _ISeq = typename _Build_index_tuple<_Num>::__type>
327  struct _Make_integer_sequence;
328 
329  template<typename _Tp, _Tp _Num, size_t... _Idx>
330  struct _Make_integer_sequence<_Tp, _Num, _Index_tuple<_Idx...>>
331  {
332  static_assert( _Num >= 0,
333  "Cannot make integer sequence of negative length" );
334 
335  typedef integer_sequence<_Tp, static_cast<_Tp>(_Idx)...> __type;
336  };
337 
338  /// Alias template make_integer_sequence
339  template<typename _Tp, _Tp _Num>
340  using make_integer_sequence
341  = typename _Make_integer_sequence<_Tp, _Num>::__type;
342 
343  /// Alias template index_sequence
344  template<size_t... _Idx>
345  using index_sequence = integer_sequence<size_t, _Idx...>;
346 
347  /// Alias template make_index_sequence
348  template<size_t _Num>
349  using make_index_sequence = make_integer_sequence<size_t, _Num>;
350 
351  /// Alias template index_sequence_for
352  template<typename... _Types>
353  using index_sequence_for = make_index_sequence<sizeof...(_Types)>;
354 #endif
355 
356 #if __cplusplus > 201402L
357 
358  struct in_place_t {
359  explicit in_place_t() = default;
360  };
361 
362  inline constexpr in_place_t in_place{};
363 
364  template<typename _Tp> struct in_place_type_t
365  {
366  explicit in_place_type_t() = default;
367  };
368 
369  template<typename _Tp>
370  inline constexpr in_place_type_t<_Tp> in_place_type{};
371 
372  template<size_t _Idx> struct in_place_index_t
373  {
374  explicit in_place_index_t() = default;
375  };
376 
377  template<size_t _Idx>
378  inline constexpr in_place_index_t<_Idx> in_place_index{};
379 
380  template<typename>
381  struct __is_in_place_type_impl : false_type
382  { };
383 
384  template<typename _Tp>
385  struct __is_in_place_type_impl<in_place_type_t<_Tp>> : true_type
386  { };
387 
388  template<typename _Tp>
389  struct __is_in_place_type
390  : public __is_in_place_type_impl<_Tp>
391  { };
392 
393 #define __cpp_lib_as_const 201510
394  template<typename _Tp>
395  constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
396 
397  template<typename _Tp>
398  void as_const(const _Tp&&) = delete;
399 
400 #endif // C++17
401 
402 _GLIBCXX_END_NAMESPACE_VERSION
403 } // namespace
404 
405 #endif
406 
407 #endif /* _GLIBCXX_UTILITY */