libstdc++
utility
Go to the documentation of this file.
1 // <utility> -*- C++ -*-
2 
3 // Copyright (C) 2001-2016 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  // 2313. tuple_size should always derive from integral_constant<size_t, N>
88  template<typename _Tp>
89  struct tuple_size<const _Tp>
90  : integral_constant<size_t, tuple_size<_Tp>::value> { };
91 
92  template<typename _Tp>
93  struct tuple_size<volatile _Tp>
94  : integral_constant<size_t, tuple_size<_Tp>::value> { };
95 
96  template<typename _Tp>
97  struct tuple_size<const volatile _Tp>
98  : integral_constant<size_t, tuple_size<_Tp>::value> { };
99 
100  /// Gives the type of the ith element of a given tuple type.
101  template<std::size_t __i, typename _Tp>
102  struct tuple_element;
103 
104  // Duplicate of C++14's tuple_element_t for internal use in C++11 mode
105  template<std::size_t __i, typename _Tp>
106  using __tuple_element_t = typename tuple_element<__i, _Tp>::type;
107 
108  template<std::size_t __i, typename _Tp>
109  struct tuple_element<__i, const _Tp>
110  {
111  typedef typename add_const<__tuple_element_t<__i, _Tp>>::type type;
112  };
113 
114  template<std::size_t __i, typename _Tp>
115  struct tuple_element<__i, volatile _Tp>
116  {
117  typedef typename add_volatile<__tuple_element_t<__i, _Tp>>::type type;
118  };
119 
120  template<std::size_t __i, typename _Tp>
121  struct tuple_element<__i, const volatile _Tp>
122  {
123  typedef typename add_cv<__tuple_element_t<__i, _Tp>>::type type;
124  };
125 
126 #if __cplusplus > 201103L
127 #define __cpp_lib_tuple_element_t 201402
128 
129  template<std::size_t __i, typename _Tp>
130  using tuple_element_t = typename tuple_element<__i, _Tp>::type;
131 #endif
132 
133  template<typename>
134  struct __is_tuple_like_impl : false_type
135  { };
136 
137  // Various functions which give std::pair a tuple-like interface.
138 
139  /// Partial specialization for std::pair
140  template<typename _T1, typename _T2>
141  struct __is_tuple_like_impl<std::pair<_T1, _T2>> : true_type
142  { };
143 
144  /// Partial specialization for std::pair
145  template<class _Tp1, class _Tp2>
146  struct tuple_size<std::pair<_Tp1, _Tp2>>
147  : public integral_constant<std::size_t, 2> { };
148 
149  /// Partial specialization for std::pair
150  template<class _Tp1, class _Tp2>
151  struct tuple_element<0, std::pair<_Tp1, _Tp2>>
152  { typedef _Tp1 type; };
153 
154  /// Partial specialization for std::pair
155  template<class _Tp1, class _Tp2>
156  struct tuple_element<1, std::pair<_Tp1, _Tp2>>
157  { typedef _Tp2 type; };
158 
159  template<std::size_t _Int>
160  struct __pair_get;
161 
162  template<>
163  struct __pair_get<0>
164  {
165  template<typename _Tp1, typename _Tp2>
166  static constexpr _Tp1&
167  __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
168  { return __pair.first; }
169 
170  template<typename _Tp1, typename _Tp2>
171  static constexpr _Tp1&&
172  __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
173  { return std::forward<_Tp1>(__pair.first); }
174 
175  template<typename _Tp1, typename _Tp2>
176  static constexpr const _Tp1&
177  __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
178  { return __pair.first; }
179  };
180 
181  template<>
182  struct __pair_get<1>
183  {
184  template<typename _Tp1, typename _Tp2>
185  static constexpr _Tp2&
186  __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
187  { return __pair.second; }
188 
189  template<typename _Tp1, typename _Tp2>
190  static constexpr _Tp2&&
191  __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
192  { return std::forward<_Tp2>(__pair.second); }
193 
194  template<typename _Tp1, typename _Tp2>
195  static constexpr const _Tp2&
196  __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
197  { return __pair.second; }
198  };
199 
200  template<std::size_t _Int, class _Tp1, class _Tp2>
201  constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
202  get(std::pair<_Tp1, _Tp2>& __in) noexcept
203  { return __pair_get<_Int>::__get(__in); }
204 
205  template<std::size_t _Int, class _Tp1, class _Tp2>
206  constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&&
207  get(std::pair<_Tp1, _Tp2>&& __in) noexcept
208  { return __pair_get<_Int>::__move_get(std::move(__in)); }
209 
210  template<std::size_t _Int, class _Tp1, class _Tp2>
211  constexpr const typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
212  get(const std::pair<_Tp1, _Tp2>& __in) noexcept
213  { return __pair_get<_Int>::__const_get(__in); }
214 
215 #if __cplusplus > 201103L
216 
217 #define __cpp_lib_tuples_by_type 201304
218 
219  template <typename _Tp, typename _Up>
220  constexpr _Tp&
221  get(pair<_Tp, _Up>& __p) noexcept
222  { return __p.first; }
223 
224  template <typename _Tp, typename _Up>
225  constexpr const _Tp&
226  get(const pair<_Tp, _Up>& __p) noexcept
227  { return __p.first; }
228 
229  template <typename _Tp, typename _Up>
230  constexpr _Tp&&
231  get(pair<_Tp, _Up>&& __p) noexcept
232  { return std::move(__p.first); }
233 
234  template <typename _Tp, typename _Up>
235  constexpr _Tp&
236  get(pair<_Up, _Tp>& __p) noexcept
237  { return __p.second; }
238 
239  template <typename _Tp, typename _Up>
240  constexpr const _Tp&
241  get(const pair<_Up, _Tp>& __p) noexcept
242  { return __p.second; }
243 
244  template <typename _Tp, typename _Up>
245  constexpr _Tp&&
246  get(pair<_Up, _Tp>&& __p) noexcept
247  { return std::move(__p.second); }
248 
249 #define __cpp_lib_exchange_function 201304
250 
251  /// Assign @p __new_val to @p __obj and return its previous value.
252  template <typename _Tp, typename _Up = _Tp>
253  inline _Tp
254  exchange(_Tp& __obj, _Up&& __new_val)
255  { return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
256 #endif
257 
258  // Stores a tuple of indices. Used by tuple and pair, and by bind() to
259  // extract the elements in a tuple.
260  template<size_t... _Indexes> struct _Index_tuple { };
261 
262  // Concatenates two _Index_tuples.
263  template<typename _Itup1, typename _Itup2> struct _Itup_cat;
264 
265  template<size_t... _Ind1, size_t... _Ind2>
266  struct _Itup_cat<_Index_tuple<_Ind1...>, _Index_tuple<_Ind2...>>
267  {
268  using __type = _Index_tuple<_Ind1..., (_Ind2 + sizeof...(_Ind1))...>;
269  };
270 
271  // Builds an _Index_tuple<0, 1, 2, ..., _Num-1>.
272  template<size_t _Num>
273  struct _Build_index_tuple
274  : _Itup_cat<typename _Build_index_tuple<_Num / 2>::__type,
275  typename _Build_index_tuple<_Num - _Num / 2>::__type>
276  { };
277 
278  template<>
279  struct _Build_index_tuple<1>
280  {
281  typedef _Index_tuple<0> __type;
282  };
283 
284  template<>
285  struct _Build_index_tuple<0>
286  {
287  typedef _Index_tuple<> __type;
288  };
289 
290 #if __cplusplus > 201103L
291 
292 #define __cpp_lib_integer_sequence 201304
293 
294  /// Class template integer_sequence
295  template<typename _Tp, _Tp... _Idx>
296  struct integer_sequence
297  {
298  typedef _Tp value_type;
299  static constexpr size_t size() { return sizeof...(_Idx); }
300  };
301 
302  template<typename _Tp, _Tp _Num,
303  typename _ISeq = typename _Build_index_tuple<_Num>::__type>
304  struct _Make_integer_sequence;
305 
306  template<typename _Tp, _Tp _Num, size_t... _Idx>
307  struct _Make_integer_sequence<_Tp, _Num, _Index_tuple<_Idx...>>
308  {
309  static_assert( _Num >= 0,
310  "Cannot make integer sequence of negative length" );
311 
312  typedef integer_sequence<_Tp, static_cast<_Tp>(_Idx)...> __type;
313  };
314 
315  /// Alias template make_integer_sequence
316  template<typename _Tp, _Tp _Num>
317  using make_integer_sequence
318  = typename _Make_integer_sequence<_Tp, _Num>::__type;
319 
320  /// Alias template index_sequence
321  template<size_t... _Idx>
322  using index_sequence = integer_sequence<size_t, _Idx...>;
323 
324  /// Alias template make_index_sequence
325  template<size_t _Num>
326  using make_index_sequence = make_integer_sequence<size_t, _Num>;
327 
328  /// Alias template index_sequence_for
329  template<typename... _Types>
330  using index_sequence_for = make_index_sequence<sizeof...(_Types)>;
331 #endif
332 
333 _GLIBCXX_END_NAMESPACE_VERSION
334 } // namespace
335 
336 #endif
337 
338 #endif /* _GLIBCXX_UTILITY */