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

   1 // Pair implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
   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 2, 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 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING.  If not, write to the Free
  19 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  20 // USA.
  21
  22 // As a special exception, you may use this file as part of a free software
  23 // library without restriction.  Specifically, if other files instantiate
  24 // templates or use macros or inline functions from this file, or you compile
  25 // this file and link it with other files to produce an executable, this
  26 // file does not by itself cause the resulting executable to be covered by
  27 // the GNU General Public License.  This exception does not however
  28 // invalidate any other reasons why the executable file might be covered by
  29 // the GNU General Public License.
  30
  31 /*
  32  *
  33  * Copyright (c) 1994
  34  * Hewlett-Packard Company
  35  *
  36  * Permission to use, copy, modify, distribute and sell this software
  37  * and its documentation for any purpose is hereby granted without fee,
  38  * provided that the above copyright notice appear in all copies and
  39  * that both that copyright notice and this permission notice appear
  40  * in supporting documentation.  Hewlett-Packard Company makes no
  41  * representations about the suitability of this software for any
  42  * purpose.  It is provided "as is" without express or implied warranty.
  43  *
  44  *
  45  * Copyright (c) 1996,1997
  46  * Silicon Graphics Computer Systems, Inc.
  47  *
  48  * Permission to use, copy, modify, distribute and sell this software
  49  * and its documentation for any purpose is hereby granted without fee,
  50  * provided that the above copyright notice appear in all copies and
  51  * that both that copyright notice and this permission notice appear
  52  * in supporting documentation.  Silicon Graphics makes no
  53  * representations about the suitability of this software for any
  54  * purpose.  It is provided "as is" without express or implied warranty.
  55  */
  56
  57 /** @file stl_pair.h
  58  *  This is an internal header file, included by other library headers.
  59  *  You should not attempt to use it directly.
  60  */
  61
  62 #ifndef _STL_PAIR_H
  63 #define _STL_PAIR_H 1
  64
  65 #include <bits/stl_move.h> // for std::move / std::forward, std::decay, and
  66                            // std::swap
  67
  68 _GLIBCXX_BEGIN_NAMESPACE(std)
  69
  70   /// pair holds two objects of arbitrary type.
  71   template<class _T1, class _T2>
  72     struct pair
  73     {
  74       typedef _T1 first_type;    ///<  @c first_type is the first bound type
  75       typedef _T2 second_type;   ///<  @c second_type is the second bound type
  76
  77       _T1 first;                 ///< @c first is a copy of the first object
  78       _T2 second;                ///< @c second is a copy of the second object
  79
  80       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  81       // 265.  std::pair::pair() effects overly restrictive
  82       /** The default constructor creates @c first and @c second using their
  83        *  respective default constructors.  */
  84       pair()
  85       : first(), second() { }
  86
  87       /** Two objects may be passed to a @c pair constructor to be copied.  */
  88       pair(const _T1& __a, const _T2& __b)
  89       : first(__a), second(__b) { }
  90
  91 #ifdef __GXX_EXPERIMENTAL_CXX0X__
  92       template<class _U1, class _U2>
  93         pair(_U1&& __x, _U2&& __y)
  94         : first(std::forward<_U1>(__x)),
  95           second(std::forward<_U2>(__y)) { }
  96
  97       pair(pair&& __p)
  98       : first(std::move(__p.first)),
  99         second(std::move(__p.second)) { }
 100 #endif
 101
 102       /** There is also a templated copy ctor for the @c pair class itself.  */
 103       template<class _U1, class _U2>
 104         pair(const pair<_U1, _U2>& __p)
 105         : first(__p.first),
 106           second(__p.second) { }
 107
 108 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 109       template<class _U1, class _U2>
 110         pair(pair<_U1, _U2>&& __p)
 111         : first(std::move(__p.first)),
 112           second(std::move(__p.second)) { }
 113
 114       // http://gcc.gnu.org/ml/libstdc++/2007-08/msg00052.html
 115       template<class _U1, class _Arg0, class... _Args>
 116         pair(_U1&& __x, _Arg0&& __arg0, _Args&&... __args)
 117         : first(std::forward<_U1>(__x)),
 118           second(std::forward<_Arg0>(__arg0),
 119                  std::forward<_Args>(__args)...) { }
 120
 121       pair&
 122       operator=(pair&& __p)
 123       {
 124         first = std::move(__p.first);
 125         second = std::move(__p.second);
 126         return *this;
 127       }
 128
 129       template<class _U1, class _U2>
 130         pair&
 131         operator=(pair<_U1, _U2>&& __p)
 132         {
 133           first = std::move(__p.first);
 134           second = std::move(__p.second);
 135           return *this;
 136         }
 137
 138       void
 139       swap(pair&& __p)
 140       {
 141         using std::swap;
 142         swap(first, __p.first);
 143         swap(second, __p.second);
 144       }
 145 #endif
 146     };
 147
 148   /// Two pairs of the same type are equal iff their members are equal.
 149   template<class _T1, class _T2>
 150     inline bool
 151     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 152     { return __x.first == __y.first && __x.second == __y.second; }
 153
 154   /// <http://gcc.gnu.org/onlinedocs/libstdc++/20_util/howto.html#pairlt>
 155   template<class _T1, class _T2>
 156     inline bool
 157     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 158     { return __x.first < __y.first
 159              || (!(__y.first < __x.first) && __x.second < __y.second); }
 160
 161   /// Uses @c operator== to find the result.
 162   template<class _T1, class _T2>
 163     inline bool
 164     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 165     { return !(__x == __y); }
 166
 167   /// Uses @c operator< to find the result.
 168   template<class _T1, class _T2>
 169     inline bool
 170     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 171     { return __y < __x; }
 172
 173   /// Uses @c operator< to find the result.
 174   template<class _T1, class _T2>
 175     inline bool
 176     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 177     { return !(__y < __x); }
 178
 179   /// Uses @c operator< to find the result.
 180   template<class _T1, class _T2>
 181     inline bool
 182     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 183     { return !(__x < __y); }
 184
 185 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 186   /// See std::pair::swap().
 187   template<class _T1, class _T2>
 188     inline void
 189     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
 190     { __x.swap(__y); }
 191
 192   template<class _T1, class _T2>
 193     inline void
 194     swap(pair<_T1, _T2>&& __x, pair<_T1, _T2>& __y)
 195     { __x.swap(__y); }
 196
 197   template<class _T1, class _T2>
 198     inline void
 199     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>&& __y)
 200     { __x.swap(__y); }
 201 #endif
 202
 203   /**
 204    *  @brief A convenience wrapper for creating a pair from two objects.
 205    *  @param  x  The first object.
 206    *  @param  y  The second object.
 207    *  @return   A newly-constructed pair<> object of the appropriate type.
 208    *
 209    *  The standard requires that the objects be passed by reference-to-const,
 210    *  but LWG issue #181 says they should be passed by const value.  We follow
 211    *  the LWG by default.
 212    */
 213   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 214   // 181.  make_pair() unintended behavior
 215 #ifndef __GXX_EXPERIMENTAL_CXX0X__
 216   template<class _T1, class _T2>
 217     inline pair<_T1, _T2>
 218     make_pair(_T1 __x, _T2 __y)
 219     { return pair<_T1, _T2>(__x, __y); }
 220 #else
 221   template<typename _Tp>
 222     class reference_wrapper;
 223
 224   // Helper which adds a reference to a type when given a reference_wrapper
 225   template<typename _Tp>
 226     struct __strip_reference_wrapper
 227     {
 228       typedef _Tp __type;
 229     };
 230
 231   template<typename _Tp>
 232     struct __strip_reference_wrapper<reference_wrapper<_Tp> >
 233     {
 234       typedef _Tp& __type;
 235     };
 236
 237   template<typename _Tp>
 238     struct __strip_reference_wrapper<const reference_wrapper<_Tp> >
 239     {
 240       typedef _Tp& __type;
 241     };
 242
 243   template<typename _Tp>
 244     struct __decay_and_strip
 245     {
 246       typedef typename __strip_reference_wrapper<
 247         typename decay<_Tp>::type>::__type __type;
 248     };
 249
 250   // NB: DR 706.
 251   template<class _T1, class _T2>
 252     inline pair<typename __decay_and_strip<_T1>::__type,
 253                 typename __decay_and_strip<_T2>::__type>
 254     make_pair(_T1&& __x, _T2&& __y)
 255     {
 256       return pair<typename __decay_and_strip<_T1>::__type,
 257                   typename __decay_and_strip<_T2>::__type>
 258         (std::forward<_T1>(__x), std::forward<_T2>(__y));
 259     }
 260 #endif
 261
 262 _GLIBCXX_END_NAMESPACE
 263
 264 #endif /* _STL_PAIR_H */