1 // Pair implementation -*- C++ -*- 2 3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 4 // Free Software Foundation, Inc. 5 // 6 // This file is part of the GNU ISO C++ Library. This library is free 7 // software; you can redistribute it and/or modify it under the 8 // terms of the GNU General Public License as published by the 9 // Free Software Foundation; either version 3, or (at your option) 10 // any later version. 11 12 // This library is distributed in the hope that it will be useful, 13 // but WITHOUT ANY WARRANTY; without even the implied warranty of 14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 // GNU General Public License for more details. 16 17 // Under Section 7 of GPL version 3, you are granted additional 18 // permissions described in the GCC Runtime Library Exception, version 19 // 3.1, as published by the Free Software Foundation. 20 21 // You should have received a copy of the GNU General Public License and 22 // a copy of the GCC Runtime Library Exception along with this program; 23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 // <http://www.gnu.org/licenses/>. 25 26 /* 27 * 28 * Copyright (c) 1994 29 * Hewlett-Packard Company 30 * 31 * Permission to use, copy, modify, distribute and sell this software 32 * and its documentation for any purpose is hereby granted without fee, 33 * provided that the above copyright notice appear in all copies and 34 * that both that copyright notice and this permission notice appear 35 * in supporting documentation. Hewlett-Packard Company makes no 36 * representations about the suitability of this software for any 37 * purpose. It is provided "as is" without express or implied warranty. 38 * 39 * 40 * Copyright (c) 1996,1997 41 * Silicon Graphics Computer Systems, Inc. 42 * 43 * Permission to use, copy, modify, distribute and sell this software 44 * and its documentation for any purpose is hereby granted without fee, 45 * provided that the above copyright notice appear in all copies and 46 * that both that copyright notice and this permission notice appear 47 * in supporting documentation. Silicon Graphics makes no 48 * representations about the suitability of this software for any 49 * purpose. It is provided "as is" without express or implied warranty. 50 */ 51 52 /** @file stl_pair.h 53 * This is an internal header file, included by other library headers. 54 * You should not attempt to use it directly. 55 */ 56 57 #ifndef _STL_PAIR_H 58 #define _STL_PAIR_H 1 59 60 #include <bits/move.h> // for std::move / std::forward, std::decay, and 61 // std::swap 62 63 _GLIBCXX_BEGIN_NAMESPACE(std) 64 65 /// pair holds two objects of arbitrary type. 66 template<class _T1, class _T2> 67 struct pair 68 { 69 typedef _T1 first_type; ///< @c first_type is the first bound type 70 typedef _T2 second_type; ///< @c second_type is the second bound type 71 72 _T1 first; ///< @c first is a copy of the first object 73 _T2 second; ///< @c second is a copy of the second object 74 75 // _GLIBCXX_RESOLVE_LIB_DEFECTS 76 // 265. std::pair::pair() effects overly restrictive 77 /** The default constructor creates @c first and @c second using their 78 * respective default constructors. */ 79 pair() 80 : first(), second() { } 81 82 /** Two objects may be passed to a @c pair constructor to be copied. */ 83 pair(const _T1& __a, const _T2& __b) 84 : first(__a), second(__b) { } 85 86 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 87 template<class _U1, class = typename 88 std::enable_if<std::is_convertible<_U1, _T1>::value>::type> 89 pair(_U1&& __x, const _T2& __y) 90 : first(std::forward<_U1>(__x)), second(__y) { } 91 92 template<class _U2, class = typename 93 std::enable_if<std::is_convertible<_U2, _T2>::value>::type> 94 pair(const _T1& __x, _U2&& __y) 95 : first(__x), second(std::forward<_U2>(__y)) { } 96 97 template<class _U1, class _U2, class = typename 98 std::enable_if<std::is_convertible<_U1, _T1>::value 99 && std::is_convertible<_U2, _T2>::value>::type> 100 pair(_U1&& __x, _U2&& __y) 101 : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { } 102 103 pair(pair&& __p) 104 : first(std::move(__p.first)), 105 second(std::move(__p.second)) { } 106 #endif 107 108 /** There is also a templated copy ctor for the @c pair class itself. */ 109 template<class _U1, class _U2> 110 pair(const pair<_U1, _U2>& __p) 111 : first(__p.first), 112 second(__p.second) { } 113 114 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 115 template<class _U1, class _U2> 116 pair(pair<_U1, _U2>&& __p) 117 : first(std::move(__p.first)), 118 second(std::move(__p.second)) { } 119 120 // http://gcc.gnu.org/ml/libstdc++/2007-08/msg00052.html 121 122 #if 0 123 // This constructor is incompatible with libstdc++-4.6, and it 124 // interferes with passing NULL pointers to the 2-argument 125 // constructors, so we disable it. map::emplace isn't 126 // implemented in libstdc++-4.4 anyway, and that's what this 127 // constructor was here for. 128 template<class _U1, class _Arg0, class... _Args> 129 pair(_U1&& __x, _Arg0&& __arg0, _Args&&... __args) 130 : first(std::forward<_U1>(__x)), 131 second(std::forward<_Arg0>(__arg0), 132 std::forward<_Args>(__args)...) { } 133 #endif 134 135 pair& 136 operator=(pair&& __p) 137 { 138 first = std::move(__p.first); 139 second = std::move(__p.second); 140 return *this; 141 } 142 143 template<class _U1, class _U2> 144 pair& 145 operator=(pair<_U1, _U2>&& __p) 146 { 147 first = std::move(__p.first); 148 second = std::move(__p.second); 149 return *this; 150 } 151 152 void 153 swap(pair& __p) 154 { 155 using std::swap; 156 swap(first, __p.first); 157 swap(second, __p.second); 158 } 159 #endif 160 }; 161 162 /// Two pairs of the same type are equal iff their members are equal. 163 template<class _T1, class _T2> 164 inline bool 165 operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) 166 { return __x.first == __y.first && __x.second == __y.second; } 167 168 /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html> 169 template<class _T1, class _T2> 170 inline bool 171 operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) 172 { return __x.first < __y.first 173 || (!(__y.first < __x.first) && __x.second < __y.second); } 174 175 /// Uses @c operator== to find the result. 176 template<class _T1, class _T2> 177 inline bool 178 operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) 179 { return !(__x == __y); } 180 181 /// Uses @c operator< to find the result. 182 template<class _T1, class _T2> 183 inline bool 184 operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) 185 { return __y < __x; } 186 187 /// Uses @c operator< to find the result. 188 template<class _T1, class _T2> 189 inline bool 190 operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) 191 { return !(__y < __x); } 192 193 /// Uses @c operator< to find the result. 194 template<class _T1, class _T2> 195 inline bool 196 operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) 197 { return !(__x < __y); } 198 199 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 200 /// See std::pair::swap(). 201 // Note: no std::swap overloads in C++03 mode, this has performance 202 // implications, see, eg, libstdc++/38466. 203 template<class _T1, class _T2> 204 inline void 205 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y) 206 { __x.swap(__y); } 207 208 template<class _T1, class _T2> 209 inline void 210 swap(pair<_T1, _T2>&& __x, pair<_T1, _T2>& __y) 211 { __x.swap(__y); } 212 213 template<class _T1, class _T2> 214 inline void 215 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>&& __y) 216 { __x.swap(__y); } 217 #endif 218 219 /** 220 * @brief A convenience wrapper for creating a pair from two objects. 221 * @param x The first object. 222 * @param y The second object. 223 * @return A newly-constructed pair<> object of the appropriate type. 224 * 225 * The standard requires that the objects be passed by reference-to-const, 226 * but LWG issue #181 says they should be passed by const value. We follow 227 * the LWG by default. 228 */ 229 // _GLIBCXX_RESOLVE_LIB_DEFECTS 230 // 181. make_pair() unintended behavior 231 #ifndef __GXX_EXPERIMENTAL_CXX0X__ 232 template<class _T1, class _T2> 233 inline pair<_T1, _T2> 234 make_pair(_T1 __x, _T2 __y) 235 { return pair<_T1, _T2>(__x, __y); } 236 #else 237 template<typename _Tp> 238 class reference_wrapper; 239 240 // Helper which adds a reference to a type when given a reference_wrapper 241 template<typename _Tp> 242 struct __strip_reference_wrapper 243 { 244 typedef _Tp __type; 245 }; 246 247 template<typename _Tp> 248 struct __strip_reference_wrapper<reference_wrapper<_Tp> > 249 { 250 typedef _Tp& __type; 251 }; 252 253 template<typename _Tp> 254 struct __strip_reference_wrapper<const reference_wrapper<_Tp> > 255 { 256 typedef _Tp& __type; 257 }; 258 259 template<typename _Tp> 260 struct __decay_and_strip 261 { 262 typedef typename __strip_reference_wrapper< 263 typename decay<_Tp>::type>::__type __type; 264 }; 265 266 // NB: DR 706. 267 template<class _T1, class _T2> 268 inline pair<typename __decay_and_strip<_T1>::__type, 269 typename __decay_and_strip<_T2>::__type> 270 make_pair(_T1&& __x, _T2&& __y) 271 { 272 return pair<typename __decay_and_strip<_T1>::__type, 273 typename __decay_and_strip<_T2>::__type> 274 (std::forward<_T1>(__x), std::forward<_T2>(__y)); 275 } 276 #endif 277 278 _GLIBCXX_END_NAMESPACE 279 280 #endif /* _STL_PAIR_H */ 281
