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

   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 */