libstdc++
utility
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1 // <utility> -*- C++ -*-
2 
3 // Copyright (C) 2001-2021 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 > 201703L
79 #include <ext/numeric_traits.h>
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<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<size_t __i, typename _Tp>
118  using __tuple_element_t = typename tuple_element<__i, _Tp>::type;
119 
120  template<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<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<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 >= 201402L
139 // The standard says this macro and alias template should be in <tuple>
140 // but we define them here, to be available when the partial specializations
141 // of tuple_element<pair<T,U>> and tuple_element<array<T,N>> are defined.
142 #define __cpp_lib_tuple_element_t 201402L
143 
144  template<size_t __i, typename _Tp>
145  using tuple_element_t = typename tuple_element<__i, _Tp>::type;
146 #endif
147 
148  // Various functions which give std::pair a tuple-like interface.
149 
150  /// Partial specialization for std::pair
151  template<typename _T1, typename _T2>
152  struct __is_tuple_like_impl<pair<_T1, _T2>> : true_type
153  { };
154 
155  /// Partial specialization for std::pair
156  template<class _Tp1, class _Tp2>
157  struct tuple_size<pair<_Tp1, _Tp2>>
158  : public integral_constant<size_t, 2> { };
159 
160  /// Partial specialization for std::pair
161  template<class _Tp1, class _Tp2>
162  struct tuple_element<0, pair<_Tp1, _Tp2>>
163  { typedef _Tp1 type; };
164 
165  /// Partial specialization for std::pair
166  template<class _Tp1, class _Tp2>
167  struct tuple_element<1, pair<_Tp1, _Tp2>>
168  { typedef _Tp2 type; };
169 
170  template<size_t _Int>
171  struct __pair_get;
172 
173  template<>
174  struct __pair_get<0>
175  {
176  template<typename _Tp1, typename _Tp2>
177  static constexpr _Tp1&
178  __get(pair<_Tp1, _Tp2>& __pair) noexcept
179  { return __pair.first; }
180 
181  template<typename _Tp1, typename _Tp2>
182  static constexpr _Tp1&&
183  __move_get(pair<_Tp1, _Tp2>&& __pair) noexcept
184  { return std::forward<_Tp1>(__pair.first); }
185 
186  template<typename _Tp1, typename _Tp2>
187  static constexpr const _Tp1&
188  __const_get(const pair<_Tp1, _Tp2>& __pair) noexcept
189  { return __pair.first; }
190 
191  template<typename _Tp1, typename _Tp2>
192  static constexpr const _Tp1&&
193  __const_move_get(const pair<_Tp1, _Tp2>&& __pair) noexcept
194  { return std::forward<const _Tp1>(__pair.first); }
195  };
196 
197  template<>
198  struct __pair_get<1>
199  {
200  template<typename _Tp1, typename _Tp2>
201  static constexpr _Tp2&
202  __get(pair<_Tp1, _Tp2>& __pair) noexcept
203  { return __pair.second; }
204 
205  template<typename _Tp1, typename _Tp2>
206  static constexpr _Tp2&&
207  __move_get(pair<_Tp1, _Tp2>&& __pair) noexcept
208  { return std::forward<_Tp2>(__pair.second); }
209 
210  template<typename _Tp1, typename _Tp2>
211  static constexpr const _Tp2&
212  __const_get(const pair<_Tp1, _Tp2>& __pair) noexcept
213  { return __pair.second; }
214 
215  template<typename _Tp1, typename _Tp2>
216  static constexpr const _Tp2&&
217  __const_move_get(const pair<_Tp1, _Tp2>&& __pair) noexcept
218  { return std::forward<const _Tp2>(__pair.second); }
219  };
220 
221  template<size_t _Int, class _Tp1, class _Tp2>
222  constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
223  get(pair<_Tp1, _Tp2>& __in) noexcept
224  { return __pair_get<_Int>::__get(__in); }
225 
226  template<size_t _Int, class _Tp1, class _Tp2>
227  constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
228  get(pair<_Tp1, _Tp2>&& __in) noexcept
229  { return __pair_get<_Int>::__move_get(std::move(__in)); }
230 
231  template<size_t _Int, class _Tp1, class _Tp2>
232  constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
233  get(const pair<_Tp1, _Tp2>& __in) noexcept
234  { return __pair_get<_Int>::__const_get(__in); }
235 
236  template<size_t _Int, class _Tp1, class _Tp2>
237  constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
238  get(const pair<_Tp1, _Tp2>&& __in) noexcept
239  { return __pair_get<_Int>::__const_move_get(std::move(__in)); }
240 
241 #if __cplusplus >= 201402L
242 
243 #define __cpp_lib_tuples_by_type 201304
244 
245  template <typename _Tp, typename _Up>
246  constexpr _Tp&
247  get(pair<_Tp, _Up>& __p) noexcept
248  { return __p.first; }
249 
250  template <typename _Tp, typename _Up>
251  constexpr const _Tp&
252  get(const pair<_Tp, _Up>& __p) noexcept
253  { return __p.first; }
254 
255  template <typename _Tp, typename _Up>
256  constexpr _Tp&&
257  get(pair<_Tp, _Up>&& __p) noexcept
258  { return std::move(__p.first); }
259 
260  template <typename _Tp, typename _Up>
261  constexpr const _Tp&&
262  get(const pair<_Tp, _Up>&& __p) noexcept
263  { return std::move(__p.first); }
264 
265  template <typename _Tp, typename _Up>
266  constexpr _Tp&
267  get(pair<_Up, _Tp>& __p) noexcept
268  { return __p.second; }
269 
270  template <typename _Tp, typename _Up>
271  constexpr const _Tp&
272  get(const pair<_Up, _Tp>& __p) noexcept
273  { return __p.second; }
274 
275  template <typename _Tp, typename _Up>
276  constexpr _Tp&&
277  get(pair<_Up, _Tp>&& __p) noexcept
278  { return std::move(__p.second); }
279 
280  template <typename _Tp, typename _Up>
281  constexpr const _Tp&&
282  get(const pair<_Up, _Tp>&& __p) noexcept
283  { return std::move(__p.second); }
284 
285 #define __cpp_lib_exchange_function 201304
286 
287  /// Assign @p __new_val to @p __obj and return its previous value.
288  template <typename _Tp, typename _Up = _Tp>
289  _GLIBCXX20_CONSTEXPR
290  inline _Tp
291  exchange(_Tp& __obj, _Up&& __new_val)
292  { return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
293 
294 #endif // C++14
295 
296  // Stores a tuple of indices. Used by tuple and pair, and by bind() to
297  // extract the elements in a tuple.
298  template<size_t... _Indexes> struct _Index_tuple { };
299 
300  // Builds an _Index_tuple<0, 1, 2, ..., _Num-1>.
301  template<size_t _Num>
302  struct _Build_index_tuple
303  {
304 #if __has_builtin(__make_integer_seq)
305  template<typename, size_t... _Indices>
306  using _IdxTuple = _Index_tuple<_Indices...>;
307 
308  // Clang defines __make_integer_seq for this purpose.
309  using __type = __make_integer_seq<_IdxTuple, size_t, _Num>;
310 #else
311  // For GCC and other compilers, use __integer_pack instead.
312  using __type = _Index_tuple<__integer_pack(_Num)...>;
313 #endif
314  };
315 
316 #if __cplusplus >= 201402L
317 
318 #define __cpp_lib_integer_sequence 201304
319 
320  /// Class template integer_sequence
321  template<typename _Tp, _Tp... _Idx>
323  {
324  typedef _Tp value_type;
325  static constexpr size_t size() noexcept { return sizeof...(_Idx); }
326  };
327 
328  /// Alias template make_integer_sequence
329  template<typename _Tp, _Tp _Num>
331 #if __has_builtin(__make_integer_seq)
332  = __make_integer_seq<integer_sequence, _Tp, _Num>;
333 #else
334  = integer_sequence<_Tp, __integer_pack(_Num)...>;
335 #endif
336 
337  /// Alias template index_sequence
338  template<size_t... _Idx>
339  using index_sequence = integer_sequence<size_t, _Idx...>;
340 
341  /// Alias template make_index_sequence
342  template<size_t _Num>
344 
345  /// Alias template index_sequence_for
346  template<typename... _Types>
347  using index_sequence_for = make_index_sequence<sizeof...(_Types)>;
348 #endif
349 
350 #if __cplusplus > 201402L
351 
352  struct in_place_t {
353  explicit in_place_t() = default;
354  };
355 
356  inline constexpr in_place_t in_place{};
357 
358  template<typename _Tp> struct in_place_type_t
359  {
360  explicit in_place_type_t() = default;
361  };
362 
363  template<typename _Tp>
364  inline constexpr in_place_type_t<_Tp> in_place_type{};
365 
366  template<size_t _Idx> struct in_place_index_t
367  {
368  explicit in_place_index_t() = default;
369  };
370 
371  template<size_t _Idx>
372  inline constexpr in_place_index_t<_Idx> in_place_index{};
373 
374  template<typename>
375  struct __is_in_place_type_impl : false_type
376  { };
377 
378  template<typename _Tp>
379  struct __is_in_place_type_impl<in_place_type_t<_Tp>> : true_type
380  { };
381 
382  template<typename _Tp>
383  struct __is_in_place_type
384  : public __is_in_place_type_impl<_Tp>
385  { };
386 
387 #define __cpp_lib_as_const 201510
388  template<typename _Tp>
389  [[nodiscard]]
390  constexpr add_const_t<_Tp>&
391  as_const(_Tp& __t) noexcept
392  { return __t; }
393 
394  template<typename _Tp>
395  void as_const(const _Tp&&) = delete;
396 
397 #if __cplusplus > 201703L
398 #define __cpp_lib_integer_comparison_functions 202002L
399 
400  template<typename _Tp, typename _Up>
401  constexpr bool
402  cmp_equal(_Tp __t, _Up __u) noexcept
403  {
404  static_assert(__is_standard_integer<_Tp>::value);
405  static_assert(__is_standard_integer<_Up>::value);
406 
407  if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
408  return __t == __u;
409  else if constexpr (is_signed_v<_Tp>)
410  return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u;
411  else
412  return __u >= 0 && __t == make_unsigned_t<_Up>(__u);
413  }
414 
415  template<typename _Tp, typename _Up>
416  constexpr bool
417  cmp_not_equal(_Tp __t, _Up __u) noexcept
418  { return !std::cmp_equal(__t, __u); }
419 
420  template<typename _Tp, typename _Up>
421  constexpr bool
422  cmp_less(_Tp __t, _Up __u) noexcept
423  {
424  static_assert(__is_standard_integer<_Tp>::value);
425  static_assert(__is_standard_integer<_Up>::value);
426 
427  if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
428  return __t < __u;
429  else if constexpr (is_signed_v<_Tp>)
430  return __t < 0 || make_unsigned_t<_Tp>(__t) < __u;
431  else
432  return __u >= 0 && __t < make_unsigned_t<_Up>(__u);
433  }
434 
435  template<typename _Tp, typename _Up>
436  constexpr bool
437  cmp_greater(_Tp __t, _Up __u) noexcept
438  { return std::cmp_less(__u, __t); }
439 
440  template<typename _Tp, typename _Up>
441  constexpr bool
442  cmp_less_equal(_Tp __t, _Up __u) noexcept
443  { return !std::cmp_less(__u, __t); }
444 
445  template<typename _Tp, typename _Up>
446  constexpr bool
447  cmp_greater_equal(_Tp __t, _Up __u) noexcept
448  { return !std::cmp_less(__t, __u); }
449 
450  template<typename _Up, typename _Tp>
451  constexpr bool
452  in_range(_Tp __t) noexcept
453  {
454  static_assert(__is_standard_integer<_Up>::value);
455  static_assert(__is_standard_integer<_Tp>::value);
457 
458  if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
459  return __int_traits<_Up>::__min <= __t
460  && __t <= __int_traits<_Up>::__max;
461  else if constexpr (is_signed_v<_Tp>)
462  return __t >= 0
463  && make_unsigned_t<_Tp>(__t) <= __int_traits<_Up>::__max;
464  else
465  return __t <= make_unsigned_t<_Up>(__int_traits<_Up>::__max);
466  }
467 
468 #if __cplusplus > 202002L
469 #define __cpp_lib_to_underlying 202102L
470  /// Convert an object of enumeration type to its underlying type.
471  template<typename _Tp>
472  [[nodiscard]]
473  constexpr underlying_type_t<_Tp>
474  to_underlying(_Tp __value) noexcept
475  { return static_cast<underlying_type_t<_Tp>>(__value); }
476 #endif // C++23
477 #endif // C++20
478 #endif // C++17
479 
480 _GLIBCXX_END_NAMESPACE_VERSION
481 } // namespace
482 
483 #endif
484 
485 #endif /* _GLIBCXX_UTILITY */
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:83
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:86
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
ISO C++ entities toplevel namespace is std.
constexpr _Tp exchange(_Tp &__obj, _Up &&__new_val)
Assign __new_val to __obj and return its previous value.
Definition: utility:291
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
tuple_size
Definition: array:433
tuple_element
Definition: array:442
integral_constant
Definition: type_traits:66
Class template integer_sequence.
Definition: utility:323
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:202