libstdc++-v3/include/bits/stl_pair.h

   1 // Pair implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  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 namespace std
  65 {
  66
  67 /// pair holds two objects of arbitrary type.
  68 template <class _T1, class _T2>
  69 struct pair {
  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   // _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() : first(), second() {}
  80
  81   /** Two objects may be passed to a @c pair constructor to be copied.  */
  82   pair(const _T1& __a, const _T2& __b) : first(__a), second(__b) {}
  83
  84   /** There is also a templated copy ctor for the @c pair class itself.  */
  85   template <class _U1, class _U2>
  86   pair(const pair<_U1, _U2>& __p) : first(__p.first), second(__p.second) {}
  87 };
  88
  89 /// Two pairs of the same type are equal iff their members are equal.
  90 template <class _T1, class _T2>
  91 inline bool operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
  92 {
  93   return __x.first == __y.first && __x.second == __y.second;
  94 }
  95
  96 /// <http://gcc.gnu.org/onlinedocs/libstdc++/20_util/howto.html#pairlt>
  97 template <class _T1, class _T2>
  98 inline bool operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
  99 {
 100   return __x.first < __y.first ||
 101          (!(__y.first < __x.first) && __x.second < __y.second);
 102 }
 103
 104 /// Uses @c operator== to find the result.
 105 template <class _T1, class _T2>
 106 inline bool operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
 107   return !(__x == __y);
 108 }
 109
 110 /// Uses @c operator< to find the result.
 111 template <class _T1, class _T2>
 112 inline bool operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
 113   return __y < __x;
 114 }
 115
 116 /// Uses @c operator< to find the result.
 117 template <class _T1, class _T2>
 118 inline bool operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
 119   return !(__y < __x);
 120 }
 121
 122 /// Uses @c operator< to find the result.
 123 template <class _T1, class _T2>
 124 inline bool operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
 125   return !(__x < __y);
 126 }
 127
 128 /**
 129  *  @brief A convenience wrapper for creating a pair from two objects.
 130  *  @param  x  The first object.
 131  *  @param  y  The second object.
 132  *  @return   A newly-constructed pair<> object of the appropriate type.
 133  *
 134  *  The standard requires that the objects be passed by reference-to-const,
 135  *  but LWG issue #181 says they should be passed by const value.  We follow
 136  *  the LWG by default.
 137 */
 138 template <class _T1, class _T2>
 139 // _GLIBCXX_RESOLVE_LIB_DEFECTS
 140 // 181.  make_pair() unintended behavior
 141 inline pair<_T1, _T2> make_pair(_T1 __x, _T2 __y)
 142 {
 143   return pair<_T1, _T2>(__x, __y);
 144 }
 145
 146 } // namespace std
 147
 148 #endif /* _PAIR_H */
 149
 150 // Local Variables:
 151 // mode:C++
 152 // End: