libstdc++
utility
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00001 // <utility> -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2017 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /*
00026  *
00027  * Copyright (c) 1994
00028  * Hewlett-Packard Company
00029  *
00030  * Permission to use, copy, modify, distribute and sell this software
00031  * and its documentation for any purpose is hereby granted without fee,
00032  * provided that the above copyright notice appear in all copies and
00033  * that both that copyright notice and this permission notice appear
00034  * in supporting documentation.  Hewlett-Packard Company makes no
00035  * representations about the suitability of this software for any
00036  * purpose.  It is provided "as is" without express or implied warranty.
00037  *
00038  *
00039  * Copyright (c) 1996,1997
00040  * Silicon Graphics Computer Systems, Inc.
00041  *
00042  * Permission to use, copy, modify, distribute and sell this software
00043  * and its documentation for any purpose is hereby granted without fee,
00044  * provided that the above copyright notice appear in all copies and
00045  * that both that copyright notice and this permission notice appear
00046  * in supporting documentation.  Silicon Graphics makes no
00047  * representations about the suitability of this software for any
00048  * purpose.  It is provided "as is" without express or implied warranty.
00049  */
00050 
00051 /** @file include/utility
00052  *  This is a Standard C++ Library header.
00053  */
00054 
00055 #ifndef _GLIBCXX_UTILITY
00056 #define _GLIBCXX_UTILITY 1
00057 
00058 #pragma GCC system_header
00059 
00060 /**
00061  * @defgroup utilities Utilities
00062  *
00063  * Components deemed generally useful. Includes pair, tuple,
00064  * forward/move helpers, ratio, function object, metaprogramming and
00065  * type traits, time, date, and memory functions.
00066  */
00067 
00068 #include <bits/c++config.h>
00069 #include <bits/stl_relops.h>
00070 #include <bits/stl_pair.h>
00071 
00072 #if __cplusplus >= 201103L
00073 
00074 #include <type_traits>
00075 #include <bits/move.h>
00076 #include <initializer_list>
00077 
00078 #if __cplusplus > 201402L
00079 #include <exception>
00080 #endif
00081 
00082 namespace std _GLIBCXX_VISIBILITY(default)
00083 {
00084 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00085 
00086   /// Finds the size of a given tuple type.
00087   template<typename _Tp>
00088     struct tuple_size;
00089 
00090   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00091   // 2770. tuple_size<const T> specialization is not SFINAE compatible
00092 
00093 #if __cplusplus <= 201402L
00094   template<typename _Tp, typename = void>
00095     struct __tuple_size_cv_impl { };
00096 
00097   template<typename _Tp>
00098     struct __tuple_size_cv_impl<_Tp, __void_t<decltype(tuple_size<_Tp>::value)>>
00099     : integral_constant<size_t, tuple_size<_Tp>::value> { };
00100 
00101   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00102   // 2313. tuple_size should always derive from integral_constant<size_t, N>
00103   template<typename _Tp>
00104     struct tuple_size<const _Tp> : __tuple_size_cv_impl<_Tp> { };
00105 
00106   template<typename _Tp>
00107     struct tuple_size<volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
00108 
00109   template<typename _Tp>
00110     struct tuple_size<const volatile _Tp> : __tuple_size_cv_impl<_Tp> { };
00111 #else
00112   template<typename _Tp,
00113            typename _Up = typename remove_cv<_Tp>::type,
00114            typename = typename enable_if<is_same<_Tp, _Up>::value>::type,
00115            size_t = tuple_size<_Tp>::value>
00116     using __enable_if_has_tuple_size = _Tp;
00117 
00118   template<typename _Tp>
00119     struct tuple_size<const __enable_if_has_tuple_size<_Tp>>
00120     : public tuple_size<_Tp> { };
00121 
00122   template<typename _Tp>
00123     struct tuple_size<volatile __enable_if_has_tuple_size<_Tp>>
00124     : public tuple_size<_Tp> { };
00125 
00126   template<typename _Tp>
00127     struct tuple_size<const volatile __enable_if_has_tuple_size<_Tp>>
00128     : public tuple_size<_Tp> { };
00129 #endif
00130 
00131   /// Gives the type of the ith element of a given tuple type.
00132   template<std::size_t __i, typename _Tp>
00133     struct tuple_element;
00134 
00135   // Duplicate of C++14's tuple_element_t for internal use in C++11 mode
00136   template<std::size_t __i, typename _Tp>
00137     using __tuple_element_t = typename tuple_element<__i, _Tp>::type;
00138 
00139   template<std::size_t __i, typename _Tp>
00140     struct tuple_element<__i, const _Tp>
00141     {
00142       typedef typename add_const<__tuple_element_t<__i, _Tp>>::type type;
00143     };
00144 
00145   template<std::size_t __i, typename _Tp>
00146     struct tuple_element<__i, volatile _Tp>
00147     {
00148       typedef typename add_volatile<__tuple_element_t<__i, _Tp>>::type type;
00149     };
00150 
00151   template<std::size_t __i, typename _Tp>
00152     struct tuple_element<__i, const volatile _Tp>
00153     {
00154       typedef typename add_cv<__tuple_element_t<__i, _Tp>>::type type;
00155     };
00156 
00157 #if __cplusplus > 201103L
00158 #define __cpp_lib_tuple_element_t 201402
00159 
00160   template<std::size_t __i, typename _Tp>
00161     using tuple_element_t = typename tuple_element<__i, _Tp>::type;
00162 #endif
00163 
00164   // Various functions which give std::pair a tuple-like interface.
00165 
00166   /// Partial specialization for std::pair
00167   template<typename _T1, typename _T2>
00168     struct __is_tuple_like_impl<std::pair<_T1, _T2>> : true_type
00169     { };
00170 
00171   /// Partial specialization for std::pair
00172   template<class _Tp1, class _Tp2>
00173     struct tuple_size<std::pair<_Tp1, _Tp2>>
00174     : public integral_constant<std::size_t, 2> { };
00175 
00176   /// Partial specialization for std::pair
00177   template<class _Tp1, class _Tp2>
00178     struct tuple_element<0, std::pair<_Tp1, _Tp2>>
00179     { typedef _Tp1 type; };
00180 
00181   /// Partial specialization for std::pair
00182   template<class _Tp1, class _Tp2>
00183     struct tuple_element<1, std::pair<_Tp1, _Tp2>>
00184     { typedef _Tp2 type; };
00185 
00186   template<std::size_t _Int>
00187     struct __pair_get;
00188 
00189   template<>
00190     struct __pair_get<0>
00191     {
00192       template<typename _Tp1, typename _Tp2>
00193         static constexpr _Tp1&
00194         __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
00195         { return __pair.first; }
00196 
00197       template<typename _Tp1, typename _Tp2>
00198         static constexpr _Tp1&&
00199         __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
00200         { return std::forward<_Tp1>(__pair.first); }
00201 
00202       template<typename _Tp1, typename _Tp2>
00203         static constexpr const _Tp1&
00204         __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
00205         { return __pair.first; }
00206     };
00207 
00208   template<>
00209     struct __pair_get<1>
00210     {
00211       template<typename _Tp1, typename _Tp2>
00212         static constexpr _Tp2&
00213         __get(std::pair<_Tp1, _Tp2>& __pair) noexcept
00214         { return __pair.second; }
00215 
00216       template<typename _Tp1, typename _Tp2>
00217         static constexpr _Tp2&&
00218         __move_get(std::pair<_Tp1, _Tp2>&& __pair) noexcept
00219         { return std::forward<_Tp2>(__pair.second); }
00220 
00221       template<typename _Tp1, typename _Tp2>
00222         static constexpr const _Tp2&
00223         __const_get(const std::pair<_Tp1, _Tp2>& __pair) noexcept
00224         { return __pair.second; }
00225     };
00226 
00227   template<std::size_t _Int, class _Tp1, class _Tp2>
00228     constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
00229     get(std::pair<_Tp1, _Tp2>& __in) noexcept
00230     { return __pair_get<_Int>::__get(__in); }
00231 
00232   template<std::size_t _Int, class _Tp1, class _Tp2>
00233     constexpr typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&&
00234     get(std::pair<_Tp1, _Tp2>&& __in) noexcept
00235     { return __pair_get<_Int>::__move_get(std::move(__in)); }
00236 
00237   template<std::size_t _Int, class _Tp1, class _Tp2>
00238     constexpr const typename tuple_element<_Int, std::pair<_Tp1, _Tp2>>::type&
00239     get(const std::pair<_Tp1, _Tp2>& __in) noexcept
00240     { return __pair_get<_Int>::__const_get(__in); }
00241 
00242 #if __cplusplus > 201103L
00243 
00244 #define __cpp_lib_tuples_by_type 201304
00245 
00246   template <typename _Tp, typename _Up>
00247     constexpr _Tp&
00248     get(pair<_Tp, _Up>& __p) noexcept
00249     { return __p.first; }
00250 
00251   template <typename _Tp, typename _Up>
00252     constexpr const _Tp&
00253     get(const pair<_Tp, _Up>& __p) noexcept
00254     { return __p.first; }
00255 
00256   template <typename _Tp, typename _Up>
00257     constexpr _Tp&&
00258     get(pair<_Tp, _Up>&& __p) noexcept
00259     { return std::move(__p.first); }
00260 
00261   template <typename _Tp, typename _Up>
00262     constexpr _Tp&
00263     get(pair<_Up, _Tp>& __p) noexcept
00264     { return __p.second; }
00265 
00266   template <typename _Tp, typename _Up>
00267     constexpr const _Tp&
00268     get(const pair<_Up, _Tp>& __p) noexcept
00269     { return __p.second; }
00270 
00271   template <typename _Tp, typename _Up>
00272     constexpr _Tp&&
00273     get(pair<_Up, _Tp>&& __p) noexcept
00274     { return std::move(__p.second); }
00275 
00276 #define __cpp_lib_exchange_function 201304
00277 
00278   /// Assign @p __new_val to @p __obj and return its previous value.
00279   template <typename _Tp, typename _Up = _Tp>
00280     inline _Tp
00281     exchange(_Tp& __obj, _Up&& __new_val)
00282     { return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
00283 #endif
00284 
00285   // Stores a tuple of indices.  Used by tuple and pair, and by bind() to
00286   // extract the elements in a tuple.
00287   template<size_t... _Indexes> struct _Index_tuple { };
00288 
00289   // Concatenates two _Index_tuples.
00290   template<typename _Itup1, typename _Itup2> struct _Itup_cat;
00291 
00292   template<size_t... _Ind1, size_t... _Ind2>
00293     struct _Itup_cat<_Index_tuple<_Ind1...>, _Index_tuple<_Ind2...>>
00294     {
00295       using __type = _Index_tuple<_Ind1..., (_Ind2 + sizeof...(_Ind1))...>;
00296     };
00297 
00298   // Builds an _Index_tuple<0, 1, 2, ..., _Num-1>.
00299   template<size_t _Num>
00300     struct _Build_index_tuple
00301     : _Itup_cat<typename _Build_index_tuple<_Num / 2>::__type,
00302                 typename _Build_index_tuple<_Num - _Num / 2>::__type>
00303     { };
00304 
00305   template<>
00306     struct _Build_index_tuple<1>
00307     {
00308       typedef _Index_tuple<0> __type;
00309     };
00310 
00311   template<>
00312     struct _Build_index_tuple<0>
00313     {
00314       typedef _Index_tuple<> __type;
00315     };
00316 
00317 #if __cplusplus > 201103L
00318 
00319 #define __cpp_lib_integer_sequence 201304
00320 
00321   /// Class template integer_sequence
00322   template<typename _Tp, _Tp... _Idx>
00323     struct integer_sequence
00324     {
00325       typedef _Tp value_type;
00326       static constexpr size_t size() { return sizeof...(_Idx); }
00327     };
00328 
00329   template<typename _Tp, _Tp _Num,
00330            typename _ISeq = typename _Build_index_tuple<_Num>::__type>
00331     struct _Make_integer_sequence;
00332 
00333   template<typename _Tp, _Tp _Num,  size_t... _Idx>
00334     struct _Make_integer_sequence<_Tp, _Num, _Index_tuple<_Idx...>>
00335     {
00336       static_assert( _Num >= 0,
00337                      "Cannot make integer sequence of negative length" );
00338 
00339       typedef integer_sequence<_Tp, static_cast<_Tp>(_Idx)...> __type;
00340     };
00341 
00342   /// Alias template make_integer_sequence
00343   template<typename _Tp, _Tp _Num>
00344     using make_integer_sequence
00345       = typename _Make_integer_sequence<_Tp, _Num>::__type;
00346 
00347   /// Alias template index_sequence
00348   template<size_t... _Idx>
00349     using index_sequence = integer_sequence<size_t, _Idx...>;
00350 
00351   /// Alias template make_index_sequence
00352   template<size_t _Num>
00353     using make_index_sequence = make_integer_sequence<size_t, _Num>;
00354 
00355   /// Alias template index_sequence_for
00356   template<typename... _Types>
00357     using index_sequence_for = make_index_sequence<sizeof...(_Types)>;
00358 #endif
00359 
00360 #if __cplusplus > 201402L
00361 
00362   struct in_place_t {
00363     explicit in_place_t() = default;
00364   };
00365 
00366   inline constexpr in_place_t in_place{};
00367 
00368   template<typename _Tp> struct in_place_type_t
00369   {
00370     explicit in_place_type_t() = default;
00371   };
00372 
00373   template<typename _Tp>
00374     inline constexpr in_place_type_t<_Tp> in_place_type{};
00375 
00376   template<size_t _Idx> struct in_place_index_t
00377   {
00378     explicit in_place_index_t() = default;
00379   };
00380 
00381   template<size_t _Idx>
00382     inline constexpr in_place_index_t<_Idx> in_place_index{};
00383 
00384   template<typename>
00385     struct __is_in_place_type_impl : false_type
00386     { };
00387 
00388   template<typename _Tp>
00389     struct __is_in_place_type_impl<in_place_type_t<_Tp>> : true_type
00390     { };
00391 
00392   template<typename _Tp>
00393     struct __is_in_place_type
00394       : public __is_in_place_type_impl<_Tp>
00395     { };
00396 
00397 #define  __cpp_lib_as_const 201510
00398   template<typename _Tp>
00399     constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
00400 
00401   template<typename _Tp>
00402     void as_const(const _Tp&&) = delete;
00403 
00404 #endif // C++17
00405 
00406 _GLIBCXX_END_NAMESPACE_VERSION
00407 } // namespace
00408 
00409 #endif
00410 
00411 #endif /* _GLIBCXX_UTILITY */