libstdc++
stl_pair.h
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1 // Pair implementation -*- C++ -*-
2 
3 // Copyright (C) 2001-2015 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
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7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
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.
19 
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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
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24 
25 /*
26  *
27  * Copyright (c) 1994
28  * Hewlett-Packard Company
29  *
30  * Permission to use, copy, modify, distribute and sell this software
31  * and its documentation for any purpose is hereby granted without fee,
32  * provided that the above copyright notice appear in all copies and
33  * that both that copyright notice and this permission notice appear
34  * in supporting documentation. Hewlett-Packard Company makes no
35  * representations about the suitability of this software for any
36  * purpose. It is provided "as is" without express or implied warranty.
37  *
38  *
39  * Copyright (c) 1996,1997
40  * Silicon Graphics Computer Systems, Inc.
41  *
42  * Permission to use, copy, modify, distribute and sell this software
43  * and its documentation for any purpose is hereby granted without fee,
44  * provided that the above copyright notice appear in all copies and
45  * that both that copyright notice and this permission notice appear
46  * in supporting documentation. Silicon Graphics makes no
47  * representations about the suitability of this software for any
48  * purpose. It is provided "as is" without express or implied warranty.
49  */
50 
51 /** @file bits/stl_pair.h
52  * This is an internal header file, included by other library headers.
53  * Do not attempt to use it directly. @headername{utility}
54  */
55 
56 #ifndef _STL_PAIR_H
57 #define _STL_PAIR_H 1
58 
59 #include <bits/move.h> // for std::move / std::forward, and std::swap
60 
61 #if __cplusplus >= 201103L
62 #include <type_traits> // for std::__decay_and_strip too
63 #endif
64 
65 namespace std _GLIBCXX_VISIBILITY(default)
66 {
67 _GLIBCXX_BEGIN_NAMESPACE_VERSION
68 
69  /**
70  * @addtogroup utilities
71  * @{
72  */
73 
74 #if __cplusplus >= 201103L
75  /// piecewise_construct_t
77 
78  /// piecewise_construct
80 
81  // Forward declarations.
82  template<typename...>
83  class tuple;
84 
85  template<std::size_t...>
86  struct _Index_tuple;
87 #endif
88 
89  /**
90  * @brief Struct holding two objects of arbitrary type.
91  *
92  * @tparam _T1 Type of first object.
93  * @tparam _T2 Type of second object.
94  */
95  template<class _T1, class _T2>
96  struct pair
97  {
98  typedef _T1 first_type; /// @c first_type is the first bound type
99  typedef _T2 second_type; /// @c second_type is the second bound type
100 
101  _T1 first; /// @c first is a copy of the first object
102  _T2 second; /// @c second is a copy of the second object
103 
104  // _GLIBCXX_RESOLVE_LIB_DEFECTS
105  // 265. std::pair::pair() effects overly restrictive
106  /** The default constructor creates @c first and @c second using their
107  * respective default constructors. */
108  _GLIBCXX_CONSTEXPR pair()
109  : first(), second() { }
110 
111  /** Two objects may be passed to a @c pair constructor to be copied. */
112  _GLIBCXX_CONSTEXPR pair(const _T1& __a, const _T2& __b)
113  : first(__a), second(__b) { }
114 
115  /** There is also a templated copy ctor for the @c pair class itself. */
116 #if __cplusplus < 201103L
117  template<class _U1, class _U2>
118  pair(const pair<_U1, _U2>& __p)
119  : first(__p.first), second(__p.second) { }
120 #else
121  template<class _U1, class _U2, class = typename
122  enable_if<__and_<is_convertible<const _U1&, _T1>,
123  is_convertible<const _U2&, _T2>>::value>::type>
124  constexpr pair(const pair<_U1, _U2>& __p)
125  : first(__p.first), second(__p.second) { }
126 
127  constexpr pair(const pair&) = default;
128  constexpr pair(pair&&) = default;
129 
130  // DR 811.
131  template<class _U1, class = typename
132  enable_if<is_convertible<_U1, _T1>::value>::type>
133  constexpr pair(_U1&& __x, const _T2& __y)
134  : first(std::forward<_U1>(__x)), second(__y) { }
135 
136  template<class _U2, class = typename
137  enable_if<is_convertible<_U2, _T2>::value>::type>
138  constexpr pair(const _T1& __x, _U2&& __y)
139  : first(__x), second(std::forward<_U2>(__y)) { }
140 
141  template<class _U1, class _U2, class = typename
142  enable_if<__and_<is_convertible<_U1, _T1>,
143  is_convertible<_U2, _T2>>::value>::type>
144  constexpr pair(_U1&& __x, _U2&& __y)
145  : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
146 
147  template<class _U1, class _U2, class = typename
148  enable_if<__and_<is_convertible<_U1, _T1>,
149  is_convertible<_U2, _T2>>::value>::type>
150  constexpr pair(pair<_U1, _U2>&& __p)
151  : first(std::forward<_U1>(__p.first)),
152  second(std::forward<_U2>(__p.second)) { }
153 
154  template<typename... _Args1, typename... _Args2>
156 
157  pair&
158  operator=(const pair& __p)
159  {
160  first = __p.first;
161  second = __p.second;
162  return *this;
163  }
164 
165  pair&
166  operator=(pair&& __p)
167  noexcept(__and_<is_nothrow_move_assignable<_T1>,
168  is_nothrow_move_assignable<_T2>>::value)
169  {
170  first = std::forward<first_type>(__p.first);
171  second = std::forward<second_type>(__p.second);
172  return *this;
173  }
174 
175  template<class _U1, class _U2>
176  pair&
177  operator=(const pair<_U1, _U2>& __p)
178  {
179  first = __p.first;
180  second = __p.second;
181  return *this;
182  }
183 
184  template<class _U1, class _U2>
185  pair&
186  operator=(pair<_U1, _U2>&& __p)
187  {
188  first = std::forward<_U1>(__p.first);
189  second = std::forward<_U2>(__p.second);
190  return *this;
191  }
192 
193  void
194  swap(pair& __p)
195  noexcept(noexcept(swap(first, __p.first))
196  && noexcept(swap(second, __p.second)))
197  {
198  using std::swap;
199  swap(first, __p.first);
200  swap(second, __p.second);
201  }
202 
203  private:
204  template<typename... _Args1, std::size_t... _Indexes1,
205  typename... _Args2, std::size_t... _Indexes2>
207  _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
208 #endif
209  };
210 
211  /// Two pairs of the same type are equal iff their members are equal.
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.first == __y.first && __x.second == __y.second; }
216 
217  /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
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 __x.first < __y.first
222  || (!(__y.first < __x.first) && __x.second < __y.second); }
223 
224  /// Uses @c operator== to find the result.
225  template<class _T1, class _T2>
226  inline _GLIBCXX_CONSTEXPR bool
227  operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
228  { return !(__x == __y); }
229 
230  /// Uses @c operator< to find the result.
231  template<class _T1, class _T2>
232  inline _GLIBCXX_CONSTEXPR bool
233  operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
234  { return __y < __x; }
235 
236  /// Uses @c operator< to find the result.
237  template<class _T1, class _T2>
238  inline _GLIBCXX_CONSTEXPR bool
239  operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
240  { return !(__y < __x); }
241 
242  /// Uses @c operator< to find the result.
243  template<class _T1, class _T2>
244  inline _GLIBCXX_CONSTEXPR bool
245  operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
246  { return !(__x < __y); }
247 
248 #if __cplusplus >= 201103L
249  /// See std::pair::swap().
250  // Note: no std::swap overloads in C++03 mode, this has performance
251  // implications, see, eg, libstdc++/38466.
252  template<class _T1, class _T2>
253  inline void
255  noexcept(noexcept(__x.swap(__y)))
256  { __x.swap(__y); }
257 #endif
258 
259  /**
260  * @brief A convenience wrapper for creating a pair from two objects.
261  * @param __x The first object.
262  * @param __y The second object.
263  * @return A newly-constructed pair<> object of the appropriate type.
264  *
265  * The standard requires that the objects be passed by reference-to-const,
266  * but LWG issue #181 says they should be passed by const value. We follow
267  * the LWG by default.
268  */
269  // _GLIBCXX_RESOLVE_LIB_DEFECTS
270  // 181. make_pair() unintended behavior
271 #if __cplusplus >= 201103L
272  // NB: DR 706.
273  template<class _T1, class _T2>
275  typename __decay_and_strip<_T2>::__type>
276  make_pair(_T1&& __x, _T2&& __y)
277  {
278  typedef typename __decay_and_strip<_T1>::__type __ds_type1;
279  typedef typename __decay_and_strip<_T2>::__type __ds_type2;
280  typedef pair<__ds_type1, __ds_type2> __pair_type;
281  return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
282  }
283 #else
284  template<class _T1, class _T2>
285  inline pair<_T1, _T2>
286  make_pair(_T1 __x, _T2 __y)
287  { return pair<_T1, _T2>(__x, __y); }
288 #endif
289 
290  /// @}
291 
292 _GLIBCXX_END_NAMESPACE_VERSION
293 } // namespace std
294 
295 #endif /* _STL_PAIR_H */
constexpr pair(const pair< _U1, _U2 > &__p)
Definition: stl_pair.h:124
Primary class template, tuple.
Definition: tuple:463
constexpr pair< typename __decay_and_strip< _T1 >::__type, typename __decay_and_strip< _T2 >::__type > make_pair(_T1 &&__x, _T2 &&__y)
A convenience wrapper for creating a pair from two objects.
Definition: stl_pair.h:276
constexpr piecewise_construct_t piecewise_construct
piecewise_construct
Definition: stl_pair.h:79
constexpr pair()
second is a copy of the second object
Definition: stl_pair.h:108
constexpr pair(const _T1 &__a, const _T2 &__b)
Definition: stl_pair.h:112
_T2 second
first is a copy of the first object
Definition: stl_pair.h:102
piecewise_construct_t
Definition: stl_pair.h:76
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:96
_T1 first
second_type is the second bound type
Definition: stl_pair.h:101
ISO C++ entities toplevel namespace is std.
_T2 second_type
first_type is the first bound type
Definition: stl_pair.h:99