1 // <utility> -*- C++ -*-
3 // Copyright (C) 2001-2017 Free Software Foundation, Inc.
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
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13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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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.
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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/>.
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39 * Copyright (c) 1996,1997
40 * Silicon Graphics Computer Systems, Inc.
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51 /** @file include/utility
52 * This is a Standard C++ Library header.
55 #ifndef _GLIBCXX_UTILITY
56 #define _GLIBCXX_UTILITY 1
58 #pragma GCC system_header
61 * @defgroup utilities Utilities
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.
68 #include <bits/c++config.h>
69 #include <bits/stl_relops.h>
70 #include <bits/stl_pair.h>
72 #if __cplusplus >= 201103L
74 #include <type_traits>
75 #include <bits/move.h>
76 #include <initializer_list>
78 #if __cplusplus > 201402L
82 namespace std _GLIBCXX_VISIBILITY(default)
84 _GLIBCXX_BEGIN_NAMESPACE_VERSION
86 /// Finds the size of a given tuple type.
87 template<typename _Tp>
90 // _GLIBCXX_RESOLVE_LIB_DEFECTS
91 // 2770. tuple_size<const T> specialization is not SFINAE compatible
93 #if __cplusplus <= 201402L
94 template<typename _Tp, typename = void>
95 struct __tuple_size_cv_impl { };
97 template<typename _Tp>
98 struct __tuple_size_cv_impl<_Tp, __void_t<decltype(tuple_size<_Tp>::value)>>
99 : integral_constant<size_t, tuple_size<_Tp>::value> { };
101 // _GLIBCXX_RESOLVE_LIB_DEFECTS
102 // 2313. tuple_size should always derive from integral_constant<size_t, N>
103 template<typename _Tp>
104 struct tuple_size<const _Tp> : __tuple_size_cv_impl<_Tp> { };
106 template<typename _Tp>
107 struct tuple_size<volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
109 template<typename _Tp>
110 struct tuple_size<const volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
112 template<typename _Tp,
113 typename _Up = typename remove_cv<_Tp>::type,
114 typename = typename enable_if<is_same<_Tp, _Up>::value>::type,
115 size_t = tuple_size<_Tp>::value>
116 using __enable_if_has_tuple_size = _Tp;
118 template<typename _Tp>
119 struct tuple_size<const __enable_if_has_tuple_size<_Tp>>
120 : public tuple_size<_Tp> { };
122 template<typename _Tp>
123 struct tuple_size<volatile __enable_if_has_tuple_size<_Tp>>
124 : public tuple_size<_Tp> { };
126 template<typename _Tp>
127 struct tuple_size<const volatile __enable_if_has_tuple_size<_Tp>>
128 : public tuple_size<_Tp> { };
131 /// Gives the type of the ith element of a given tuple type.
132 template<std::size_t __i, typename _Tp>
133 struct tuple_element;
135 // Duplicate of C++14's tuple_element_t for internal use in C++11 mode
136 template<std::size_t __i, typename _Tp>
137 using __tuple_element_t = typename tuple_element<__i, _Tp>::type;
139 template<std::size_t __i, typename _Tp>
140 struct tuple_element<__i, const _Tp>
142 typedef typename add_const<__tuple_element_t<__i, _Tp>>::type type;
145 template<std::size_t __i, typename _Tp>
146 struct tuple_element<__i, volatile _Tp>
148 typedef typename add_volatile<__tuple_element_t<__i, _Tp>>::type type;
151 template<std::size_t __i, typename _Tp>
152 struct tuple_element<__i, const volatile _Tp>
154 typedef typename add_cv<__tuple_element_t<__i, _Tp>>::type type;
157 #if __cplusplus > 201103L
158 #define __cpp_lib_tuple_element_t 201402
160 template<std::size_t __i, typename _Tp>
161 using tuple_element_t = typename tuple_element<__i, _Tp>::type;
164 // Various functions which give std::pair a tuple-like interface.
166 /// Partial specialization for std::pair
167 template<typename _T1, typename _T2>
168 struct __is_tuple_like_impl<std::pair<_T1, _T2>> : true_type
171 /// Partial specialization for std::pair
172 template<class _Tp1, class _Tp2>
173 struct tuple_size<std::pair<_Tp1, _Tp2>>
174 : public integral_constant<std::size_t, 2> { };
176 /// Partial specialization for std::pair
177 template<class _Tp1, class _Tp2>
178 struct tuple_element<0, std::pair<_Tp1, _Tp2>>
179 { typedef _Tp1 type; };
181 /// Partial specialization for std::pair
182 template<class _Tp1, class _Tp2>
183 struct tuple_element<1, std::pair<_Tp1, _Tp2>>
184 { typedef _Tp2 type; };
186 template<std::size_t _Int>
192 template<typename _Tp1, typename _Tp2>
193 static constexpr _Tp1&
194 __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
195 { return __pair.first; }
197 template<typename _Tp1, typename _Tp2>
198 static constexpr _Tp1&&
199 __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
200 { return std::forward<_Tp1>(__pair.first); }
202 template<typename _Tp1, typename _Tp2>
203 static constexpr const _Tp1&
204 __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
205 { return __pair.first; }
211 template<typename _Tp1, typename _Tp2>
212 static constexpr _Tp2&
213 __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
214 { return __pair.second; }
216 template<typename _Tp1, typename _Tp2>
217 static constexpr _Tp2&&
218 __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
219 { return std::forward<_Tp2>(__pair.second); }
221 template<typename _Tp1, typename _Tp2>
222 static constexpr const _Tp2&
223 __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
224 { return __pair.second; }
227 template<std::size_t _Int, class _Tp1, class _Tp2>
228 constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
229 get(std::pair<_Tp1, _Tp2>& __in) noexcept
230 { return __pair_get<_Int>::__get(__in); }
232 template<std::size_t _Int, class _Tp1, class _Tp2>
233 constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&&
234 get(std::pair<_Tp1, _Tp2>&& __in) noexcept
235 { return __pair_get<_Int>::__move_get(std::move(__in)); }
237 template<std::size_t _Int, class _Tp1, class _Tp2>
238 constexpr const typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
239 get(const std::pair<_Tp1, _Tp2>& __in) noexcept
240 { return __pair_get<_Int>::__const_get(__in); }
242 #if __cplusplus > 201103L
244 #define __cpp_lib_tuples_by_type 201304
246 template <typename _Tp, typename _Up>
248 get(pair<_Tp, _Up>& __p) noexcept
249 { return __p.first; }
251 template <typename _Tp, typename _Up>
253 get(const pair<_Tp, _Up>& __p) noexcept
254 { return __p.first; }
256 template <typename _Tp, typename _Up>
258 get(pair<_Tp, _Up>&& __p) noexcept
259 { return std::move(__p.first); }
261 template <typename _Tp, typename _Up>
263 get(pair<_Up, _Tp>& __p) noexcept
264 { return __p.second; }
266 template <typename _Tp, typename _Up>
268 get(const pair<_Up, _Tp>& __p) noexcept
269 { return __p.second; }
271 template <typename _Tp, typename _Up>
273 get(pair<_Up, _Tp>&& __p) noexcept
274 { return std::move(__p.second); }
276 #define __cpp_lib_exchange_function 201304
278 /// Assign @p __new_val to @p __obj and return its previous value.
279 template <typename _Tp, typename _Up = _Tp>
281 exchange(_Tp& __obj, _Up&& __new_val)
282 { return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
285 // Stores a tuple of indices. Used by tuple and pair, and by bind() to
286 // extract the elements in a tuple.
287 template<size_t... _Indexes> struct _Index_tuple { };
289 // Concatenates two _Index_tuples.
290 template<typename _Itup1, typename _Itup2> struct _Itup_cat;
292 template<size_t... _Ind1, size_t... _Ind2>
293 struct _Itup_cat<_Index_tuple<_Ind1...>, _Index_tuple<_Ind2...>>
295 using __type = _Index_tuple<_Ind1..., (_Ind2 + sizeof...(_Ind1))...>;
298 // Builds an _Index_tuple<0, 1, 2, ..., _Num-1>.
299 template<size_t _Num>
300 struct _Build_index_tuple
301 : _Itup_cat<typename _Build_index_tuple<_Num / 2>::__type,
302 typename _Build_index_tuple<_Num - _Num / 2>::__type>
306 struct _Build_index_tuple<1>
308 typedef _Index_tuple<0> __type;
312 struct _Build_index_tuple<0>
314 typedef _Index_tuple<> __type;
317 #if __cplusplus > 201103L
319 #define __cpp_lib_integer_sequence 201304
321 /// Class template integer_sequence
322 template<typename _Tp, _Tp... _Idx>
323 struct integer_sequence
325 typedef _Tp value_type;
326 static constexpr size_t size() { return sizeof...(_Idx); }
329 template<typename _Tp, _Tp _Num,
330 typename _ISeq = typename _Build_index_tuple<_Num>::__type>
331 struct _Make_integer_sequence;
333 template<typename _Tp, _Tp _Num, size_t... _Idx>
334 struct _Make_integer_sequence<_Tp, _Num, _Index_tuple<_Idx...>>
336 static_assert( _Num >= 0,
337 "Cannot make integer sequence of negative length" );
339 typedef integer_sequence<_Tp, static_cast<_Tp>(_Idx)...> __type;
342 /// Alias template make_integer_sequence
343 template<typename _Tp, _Tp _Num>
344 using make_integer_sequence
345 = typename _Make_integer_sequence<_Tp, _Num>::__type;
347 /// Alias template index_sequence
348 template<size_t... _Idx>
349 using index_sequence = integer_sequence<size_t, _Idx...>;
351 /// Alias template make_index_sequence
352 template<size_t _Num>
353 using make_index_sequence = make_integer_sequence<size_t, _Num>;
355 /// Alias template index_sequence_for
356 template<typename... _Types>
357 using index_sequence_for = make_index_sequence<sizeof...(_Types)>;
360 #if __cplusplus > 201402L
363 explicit in_place_t() = default;
366 inline constexpr in_place_t in_place{};
368 template<typename _Tp> struct in_place_type_t
370 explicit in_place_type_t() = default;
373 template<typename _Tp>
374 inline constexpr in_place_type_t<_Tp> in_place_type{};
376 template<size_t _Idx> struct in_place_index_t
378 explicit in_place_index_t() = default;
381 template<size_t _Idx>
382 inline constexpr in_place_index_t<_Idx> in_place_index{};
385 struct __is_in_place_type_impl : false_type
388 template<typename _Tp>
389 struct __is_in_place_type_impl<in_place_type_t<_Tp>> : true_type
392 template<typename _Tp>
393 struct __is_in_place_type
394 : public __is_in_place_type_impl<_Tp>
397 #define __cpp_lib_as_const 201510
398 template<typename _Tp>
399 constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
401 template<typename _Tp>
402 void as_const(const _Tp&&) = delete;
406 _GLIBCXX_END_NAMESPACE_VERSION
411 #endif /* _GLIBCXX_UTILITY */