1// Pair implementation -*- C++ -*-
2
3// Copyright (C) 2001, 2004, 2005 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 2, 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// You should have received a copy of the GNU General Public License along
17// with this library; see the file COPYING.  If not, write to the Free
18// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
19// USA.
20
21// As a special exception, you may use this file as part of a free software
22// library without restriction.  Specifically, if other files instantiate
23// templates or use macros or inline functions from this file, or you compile
24// this file and link it with other files to produce an executable, this
25// file does not by itself cause the resulting executable to be covered by
26// the GNU General Public License.  This exception does not however
27// invalidate any other reasons why the executable file might be covered by
28// the GNU General Public License.
29
30/*
31 *
32 * Copyright (c) 1994
33 * Hewlett-Packard Company
34 *
35 * Permission to use, copy, modify, distribute and sell this software
36 * and its documentation for any purpose is hereby granted without fee,
37 * provided that the above copyright notice appear in all copies and
38 * that both that copyright notice and this permission notice appear
39 * in supporting documentation.  Hewlett-Packard Company makes no
40 * representations about the suitability of this software for any
41 * purpose.  It is provided "as is" without express or implied warranty.
42 *
43 *
44 * Copyright (c) 1996,1997
45 * Silicon Graphics Computer Systems, Inc.
46 *
47 * Permission to use, copy, modify, distribute and sell this software
48 * and its documentation for any purpose is hereby granted without fee,
49 * provided that the above copyright notice appear in all copies and
50 * that both that copyright notice and this permission notice appear
51 * in supporting documentation.  Silicon Graphics makes no
52 * representations about the suitability of this software for any
53 * purpose.  It is provided "as is" without express or implied warranty.
54 */
55
56/** @file stl_pair.h
57 *  This is an internal header file, included by other library headers.
58 *  You should not attempt to use it directly.
59 */
60
61#ifndef _PAIR_H
62#define _PAIR_H 1
63
64_GLIBCXX_BEGIN_NAMESPACE(std)
65
66  /// pair holds two objects of arbitrary type.
67  template<class _T1, class _T2>
68    struct pair
69    {
70      typedef _T1 first_type;    ///<  @c first_type is the first bound type
71      typedef _T2 second_type;   ///<  @c second_type is the second bound type
72
73      _T1 first;                 ///< @c first is a copy of the first object
74      _T2 second;                ///< @c second is a copy of the second object
75
76      // _GLIBCXX_RESOLVE_LIB_DEFECTS
77      // 265.  std::pair::pair() effects overly restrictive
78      /** The default constructor creates @c first and @c second using their
79       *  respective default constructors.  */
80      pair()
81      : first(), second() { }
82
83      /** Two objects may be passed to a @c pair constructor to be copied.  */
84      pair(const _T1& __a, const _T2& __b)
85      : first(__a), second(__b) { }
86
87      /** There is also a templated copy ctor for the @c pair class itself.  */
88      template<class _U1, class _U2>
89        pair(const pair<_U1, _U2>& __p)
90	: first(__p.first), second(__p.second) { }
91    };
92
93  /// Two pairs of the same type are equal iff their members are equal.
94  template<class _T1, class _T2>
95    inline bool
96    operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
97    { return __x.first == __y.first && __x.second == __y.second; }
98
99  /// <http://gcc.gnu.org/onlinedocs/libstdc++/20_util/howto.html#pairlt>
100  template<class _T1, class _T2>
101    inline bool
102    operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
103    { return __x.first < __y.first
104	     || (!(__y.first < __x.first) && __x.second < __y.second); }
105
106  /// Uses @c operator== to find the result.
107  template<class _T1, class _T2>
108    inline bool
109    operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
110    { return !(__x == __y); }
111
112  /// Uses @c operator< to find the result.
113  template<class _T1, class _T2>
114    inline bool
115    operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
116    { return __y < __x; }
117
118  /// Uses @c operator< to find the result.
119  template<class _T1, class _T2>
120    inline bool
121    operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
122    { return !(__y < __x); }
123
124  /// Uses @c operator< to find the result.
125  template<class _T1, class _T2>
126    inline bool
127    operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
128    { return !(__x < __y); }
129
130  /**
131   *  @brief A convenience wrapper for creating a pair from two objects.
132   *  @param  x  The first object.
133   *  @param  y  The second object.
134   *  @return   A newly-constructed pair<> object of the appropriate type.
135   *
136   *  The standard requires that the objects be passed by reference-to-const,
137   *  but LWG issue #181 says they should be passed by const value.  We follow
138   *  the LWG by default.
139   */
140  // _GLIBCXX_RESOLVE_LIB_DEFECTS
141  // 181.  make_pair() unintended behavior
142  template<class _T1, class _T2>
143    inline pair<_T1, _T2>
144    make_pair(_T1 __x, _T2 __y)
145    { return pair<_T1, _T2>(__x, __y); }
146
147_GLIBCXX_END_NAMESPACE
148
149#endif /* _PAIR_H */
150