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 bits/stl_pair.h
53 : * This is an internal header file, included by other library headers.
54 : * Do not attempt to use it directly. @headername{utility}
55 : */
56 :
57 : #ifndef _STL_PAIR_H
58 : #define _STL_PAIR_H 1
59 :
60 : #include <bits/move.h> // for std::move / std::forward, and std::swap
61 :
62 : #ifdef __GXX_EXPERIMENTAL_CXX0X__
63 : #include <type_traits> // for std::__decay_and_strip too
64 : #endif
65 :
66 : namespace std _GLIBCXX_VISIBILITY(default)
67 : {
68 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
69 :
70 : #ifdef __GXX_EXPERIMENTAL_CXX0X__
71 : /// piecewise_construct_t
72 : struct piecewise_construct_t { };
73 :
74 : /// piecewise_construct
75 : constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
76 :
77 : // Forward declarations.
78 : template<typename...>
79 : class tuple;
80 :
81 : template<int...>
82 : struct _Index_tuple;
83 : #endif
84 :
85 : /// Struct holding two objects of arbitrary type.
86 : template<class _T1, class _T2>
87 1894 : struct pair
88 : {
89 : typedef _T1 first_type; /// @c first_type is the first bound type
90 : typedef _T2 second_type; /// @c second_type is the second bound type
91 :
92 : _T1 first; /// @c first is a copy of the first object
93 : _T2 second; /// @c second is a copy of the second object
94 :
95 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
96 : // 265. std::pair::pair() effects overly restrictive
97 : /** The default constructor creates @c first and @c second using their
98 : * respective default constructors. */
99 2 : _GLIBCXX_CONSTEXPR pair()
100 2 : : first(), second() { }
101 :
102 : /** Two objects may be passed to a @c pair constructor to be copied. */
103 3981 : _GLIBCXX_CONSTEXPR pair(const _T1& __a, const _T2& __b)
104 3981 : : first(__a), second(__b) { }
105 :
106 : /** There is also a templated copy ctor for the @c pair class itself. */
107 : template<class _U1, class _U2>
108 : _GLIBCXX_CONSTEXPR pair(const pair<_U1, _U2>& __p)
109 : : first(__p.first), second(__p.second) { }
110 :
111 : #ifdef __GXX_EXPERIMENTAL_CXX0X__
112 : constexpr pair(const pair&) = default;
113 :
114 : // Implicit.
115 : // pair(pair&&) = default;
116 :
117 : // DR 811.
118 : template<class _U1, class = typename
119 : std::enable_if<std::is_convertible<_U1, _T1>::value>::type>
120 : pair(_U1&& __x, const _T2& __y)
121 : : first(std::forward<_U1>(__x)), second(__y) { }
122 :
123 : template<class _U2, class = typename
124 : std::enable_if<std::is_convertible<_U2, _T2>::value>::type>
125 : pair(const _T1& __x, _U2&& __y)
126 : : first(__x), second(std::forward<_U2>(__y)) { }
127 :
128 : template<class _U1, class _U2, class = typename
129 : std::enable_if<std::is_convertible<_U1, _T1>::value
130 : && std::is_convertible<_U2, _T2>::value>::type>
131 : pair(_U1&& __x, _U2&& __y)
132 : : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
133 :
134 : template<class _U1, class _U2>
135 : pair(pair<_U1, _U2>&& __p)
136 : : first(std::forward<_U1>(__p.first)),
137 : second(std::forward<_U2>(__p.second)) { }
138 :
139 : template<class... _Args1, class... _Args2>
140 : pair(piecewise_construct_t,
141 : tuple<_Args1...> __first, tuple<_Args2...> __second)
142 : : first(__cons<first_type>(std::move(__first))),
143 : second(__cons<second_type>(std::move(__second))) { }
144 :
145 : pair&
146 : operator=(const pair& __p)
147 : {
148 : first = __p.first;
149 : second = __p.second;
150 : return *this;
151 : }
152 :
153 : pair&
154 : operator=(pair&& __p)
155 : {
156 : first = std::move(__p.first);
157 : second = std::move(__p.second);
158 : return *this;
159 : }
160 :
161 : template<class _U1, class _U2>
162 : pair&
163 : operator=(const pair<_U1, _U2>& __p)
164 : {
165 : first = __p.first;
166 : second = __p.second;
167 : return *this;
168 : }
169 :
170 : template<class _U1, class _U2>
171 : pair&
172 : operator=(pair<_U1, _U2>&& __p)
173 : {
174 : first = std::move(__p.first);
175 : second = std::move(__p.second);
176 : return *this;
177 : }
178 :
179 : void
180 : swap(pair& __p)
181 : {
182 : using std::swap;
183 : swap(first, __p.first);
184 : swap(second, __p.second);
185 : }
186 :
187 : private:
188 : template<typename _Tp, typename... _Args>
189 : static _Tp
190 : __cons(tuple<_Args...>&&);
191 :
192 : template<typename _Tp, typename... _Args, int... _Indexes>
193 : static _Tp
194 : __do_cons(tuple<_Args...>&&, const _Index_tuple<_Indexes...>&);
195 : #endif
196 : };
197 :
198 : /// Two pairs of the same type are equal iff their members are equal.
199 : template<class _T1, class _T2>
200 : inline _GLIBCXX_CONSTEXPR bool
201 : operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
202 : { return __x.first == __y.first && __x.second == __y.second; }
203 :
204 : /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
205 : template<class _T1, class _T2>
206 : inline _GLIBCXX_CONSTEXPR bool
207 : operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
208 : { return __x.first < __y.first
209 : || (!(__y.first < __x.first) && __x.second < __y.second); }
210 :
211 : /// Uses @c operator== to find the result.
212 : template<class _T1, class _T2>
213 : inline _GLIBCXX_CONSTEXPR bool
214 : operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
215 : { return !(__x == __y); }
216 :
217 : /// Uses @c operator< to find the result.
218 : template<class _T1, class _T2>
219 : inline _GLIBCXX_CONSTEXPR bool
220 : operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
221 : { return __y < __x; }
222 :
223 : /// Uses @c operator< to find the result.
224 : template<class _T1, class _T2>
225 : inline _GLIBCXX_CONSTEXPR bool
226 : operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
227 : { return !(__y < __x); }
228 :
229 : /// Uses @c operator< to find the result.
230 : template<class _T1, class _T2>
231 : inline _GLIBCXX_CONSTEXPR bool
232 : operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
233 : { return !(__x < __y); }
234 :
235 : #ifdef __GXX_EXPERIMENTAL_CXX0X__
236 : /// See std::pair::swap().
237 : // Note: no std::swap overloads in C++03 mode, this has performance
238 : // implications, see, eg, libstdc++/38466.
239 : template<class _T1, class _T2>
240 : inline void
241 : swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
242 : { __x.swap(__y); }
243 : #endif
244 :
245 : /**
246 : * @brief A convenience wrapper for creating a pair from two objects.
247 : * @param x The first object.
248 : * @param y The second object.
249 : * @return A newly-constructed pair<> object of the appropriate type.
250 : *
251 : * The standard requires that the objects be passed by reference-to-const,
252 : * but LWG issue #181 says they should be passed by const value. We follow
253 : * the LWG by default.
254 : */
255 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
256 : // 181. make_pair() unintended behavior
257 : #ifdef __GXX_EXPERIMENTAL_CXX0X__
258 : // NB: DR 706.
259 : template<class _T1, class _T2>
260 : inline pair<typename __decay_and_strip<_T1>::__type,
261 : typename __decay_and_strip<_T2>::__type>
262 : make_pair(_T1&& __x, _T2&& __y)
263 : {
264 : typedef typename __decay_and_strip<_T1>::__type __ds_type1;
265 : typedef typename __decay_and_strip<_T2>::__type __ds_type2;
266 : typedef pair<__ds_type1, __ds_type2> __pair_type;
267 : return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
268 : }
269 : #else
270 : template<class _T1, class _T2>
271 : inline pair<_T1, _T2>
272 : make_pair(_T1 __x, _T2 __y)
273 : { return pair<_T1, _T2>(__x, __y); }
274 : #endif
275 :
276 : _GLIBCXX_END_NAMESPACE_VERSION
277 : } // namespace
278 :
279 : #endif /* _STL_PAIR_H */
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