1 // Pair implementation -*- C++ -*- 2 3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 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 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 64 #include <type_traits> 65 #endif 66 67 _GLIBCXX_BEGIN_NAMESPACE(std) 68 69 /// pair holds two objects of arbitrary type. 70 template<class _T1, class _T2> 71 struct pair 72 { 73 typedef _T1 first_type; ///< @c first_type is the first bound type 74 typedef _T2 second_type; ///< @c second_type is the second bound type 75 76 _T1 first; ///< @c first is a copy of the first object 77 _T2 second; ///< @c second is a copy of the second object 78 79 // _GLIBCXX_RESOLVE_LIB_DEFECTS 80 // 265. std::pair::pair() effects overly restrictive 81 /** The default constructor creates @c first and @c second using their 82 * respective default constructors. */ 83 pair() 84 : first(), second() { } 85 86 /** Two objects may be passed to a @c pair constructor to be copied. */ 87 pair(const _T1& __a, const _T2& __b) 88 : first(__a), second(__b) { } 89 90 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 91 // DR 811. 92 template<class _U1, class = typename 93 std::enable_if<std::is_convertible<_U1, _T1>::value>::type> 94 pair(_U1&& __x, const _T2& __y) 95 : first(std::forward<_U1>(__x)), 96 second(__y) { } 97 98 template<class _U2, class = typename 99 std::enable_if<std::is_convertible<_U2, _T2>::value>::type> 100 pair(const _T1& __x, _U2&& __y) 101 : first(__x), 102 second(std::forward<_U2>(__y)) { } 103 104 template<class _U1, class _U2, class = typename 105 std::enable_if<std::is_convertible<_U1, _T1>::value 106 && std::is_convertible<_U2, _T2>::value>::type> 107 pair(_U1&& __x, _U2&& __y) 108 : first(std::forward<_U1>(__x)), 109 second(std::forward<_U2>(__y)) { } 110 111 pair(const pair &) = default; 112 pair(pair &&) = default; 113 #endif 114 115 /** There is also a templated copy ctor for the @c pair class itself. */ 116 template<class _U1, class _U2> 117 pair(const pair<_U1, _U2>& __p) 118 : first(__p.first), 119 second(__p.second) { } 120 121 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 122 template<class _U1, class _U2> 123 pair(pair<_U1, _U2>&& __p) 124 : first(std::forward<_U1>(__p.first)), 125 second(std::forward<_U2>(__p.second)) { } 126 127 pair& 128 operator=(const pair& __p) 129 { 130 first = __p.first; 131 second = __p.second; 132 return *this; 133 } 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 #endif 208 209 /** 210 * @brief A convenience wrapper for creating a pair from two objects. 211 * @param x The first object. 212 * @param y The second object. 213 * @return A newly-constructed pair<> object of the appropriate type. 214 * 215 * The standard requires that the objects be passed by reference-to-const, 216 * but LWG issue #181 says they should be passed by const value. We follow 217 * the LWG by default. 218 */ 219 // _GLIBCXX_RESOLVE_LIB_DEFECTS 220 // 181. make_pair() unintended behavior 221 #ifndef __GXX_EXPERIMENTAL_CXX0X__ 222 template<class _T1, class _T2> 223 inline pair<_T1, _T2> 224 make_pair(_T1 __x, _T2 __y) 225 { return pair<_T1, _T2>(__x, __y); } 226 #else 227 template<typename _Tp> 228 class reference_wrapper; 229 230 // Helper which adds a reference to a type when given a reference_wrapper 231 template<typename _Tp> 232 struct __strip_reference_wrapper 233 { 234 typedef _Tp __type; 235 }; 236 237 template<typename _Tp> 238 struct __strip_reference_wrapper<reference_wrapper<_Tp> > 239 { 240 typedef _Tp& __type; 241 }; 242 243 template<typename _Tp> 244 struct __strip_reference_wrapper<const reference_wrapper<_Tp> > 245 { 246 typedef _Tp& __type; 247 }; 248 249 template<typename _Tp> 250 struct __decay_and_strip 251 { 252 typedef typename __strip_reference_wrapper< 253 typename decay<_Tp>::type>::__type __type; 254 }; 255 256 // NB: DR 706. 257 template<class _T1, class _T2> 258 inline pair<typename __decay_and_strip<_T1>::__type, 259 typename __decay_and_strip<_T2>::__type> 260 make_pair(_T1&& __x, _T2&& __y) 261 { 262 return pair<typename __decay_and_strip<_T1>::__type, 263 typename __decay_and_strip<_T2>::__type> 264 (std::forward<_T1>(__x), std::forward<_T2>(__y)); 265 } 266 #endif 267 268 _GLIBCXX_END_NAMESPACE 269 270 #endif /* _STL_PAIR_H */ 271