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

   1 // Pair implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 /*
  27  *
  28  * Copyright (c) 1994
  29  * Hewlett-Packard Company
  30  *
  31  * Permission to use, copy, modify, distribute and sell this software
  32  * and its documentation for any purpose is hereby granted without fee,
  33  * provided that the above copyright notice appear in all copies and
  34  * that both that copyright notice and this permission notice appear
  35  * in supporting documentation.  Hewlett-Packard Company makes no
  36  * representations about the suitability of this software for any
  37  * purpose.  It is provided "as is" without express or implied warranty.
  38  *
  39  *
  40  * Copyright (c) 1996,1997
  41  * Silicon Graphics Computer Systems, Inc.
  42  *
  43  * Permission to use, copy, modify, distribute and sell this software
  44  * and its documentation for any purpose is hereby granted without fee,
  45  * provided that the above copyright notice appear in all copies and
  46  * that both that copyright notice and this permission notice appear
  47  * in supporting documentation.  Silicon Graphics makes no
  48  * representations about the suitability of this software for any
  49  * purpose.  It is provided "as is" without express or implied warranty.
  50  */
  51
  52 /** @file bits/stl_pair.h
  53  *  This is an internal header file, included by other library headers.
  54  *  Do not attempt to use it directly. @headername{utility}
  55  */
  56
  57 #ifndef _STL_PAIR_H
  58 #define _STL_PAIR_H 1
  59
  60 #include <bits/move.h> // for std::move / std::forward, and std::swap
  61
  62 #ifdef __GXX_EXPERIMENTAL_CXX0X__
  63 #include <type_traits> // for std::__decay_and_strip too
  64 #endif
  65
  66 _GLIBCXX_BEGIN_NAMESPACE(std)
  67
  68 #ifdef __GXX_EXPERIMENTAL_CXX0X__
  69   /// piecewise_construct_t
  70   struct piecewise_construct_t { };
  71
  72   /// piecewise_construct
  73   constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
  74
  75   // Forward declarations.
  76   template<typename...>
  77     class tuple;
  78
  79   template<int...>
  80     struct _Index_tuple;
  81 #endif
  82
  83   /// Struct holding two objects of arbitrary type.
  84   template<class _T1, class _T2>
  85     struct pair
  86     {
  87       typedef _T1 first_type;    /// @c first_type is the first bound type
  88       typedef _T2 second_type;   /// @c second_type is the second bound type
  89
  90       _T1 first;                 /// @c first is a copy of the first object
  91       _T2 second;                /// @c second is a copy of the second object
  92
  93       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  94       // 265.  std::pair::pair() effects overly restrictive
  95       /** The default constructor creates @c first and @c second using their
  96        *  respective default constructors.  */
  97       _GLIBCXX_CONSTEXPR pair()
  98       : first(), second() { }
  99
 100       /** Two objects may be passed to a @c pair constructor to be copied.  */
 101       _GLIBCXX_CONSTEXPR pair(const _T1& __a, const _T2& __b)
 102       : first(__a), second(__b) { }
 103
 104       /** There is also a templated copy ctor for the @c pair class itself.  */
 105       template<class _U1, class _U2>
 106         _GLIBCXX_CONSTEXPR pair(const pair<_U1, _U2>& __p)
 107         : first(__p.first), second(__p.second) { }
 108
 109 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 110       constexpr pair(const pair&) = default;
 111
 112       // Implicit.
 113       // pair(pair&&) = default;
 114
 115       // DR 811.
 116       template<class _U1, class = typename
 117                std::enable_if<std::is_convertible<_U1, _T1>::value>::type>
 118         pair(_U1&& __x, const _T2& __y)
 119         : first(std::forward<_U1>(__x)), second(__y) { }
 120
 121       template<class _U2, class = typename
 122                std::enable_if<std::is_convertible<_U2, _T2>::value>::type>
 123         pair(const _T1& __x, _U2&& __y)
 124         : first(__x), second(std::forward<_U2>(__y)) { }
 125
 126       template<class _U1, class _U2, class = typename
 127                std::enable_if<std::is_convertible<_U1, _T1>::value
 128                               && std::is_convertible<_U2, _T2>::value>::type>
 129         pair(_U1&& __x, _U2&& __y)
 130         : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
 131
 132       template<class _U1, class _U2>
 133         pair(pair<_U1, _U2>&& __p)
 134         : first(std::forward<_U1>(__p.first)),
 135           second(std::forward<_U2>(__p.second)) { }
 136
 137       template<class... _Args1, class... _Args2>
 138         pair(piecewise_construct_t,
 139              tuple<_Args1...> __first, tuple<_Args2...> __second)
 140         : first(__cons<first_type>(std::move(__first))),
 141           second(__cons<second_type>(std::move(__second))) { }
 142
 143       pair&
 144       operator=(const pair& __p)
 145       {
 146         first = __p.first;
 147         second = __p.second;
 148         return *this;
 149       }
 150
 151       pair&
 152       operator=(pair&& __p)
 153       {
 154         first = std::move(__p.first);
 155         second = std::move(__p.second);
 156         return *this;
 157       }
 158
 159       template<class _U1, class _U2>
 160         pair&
 161         operator=(const pair<_U1, _U2>& __p)
 162         {
 163           first = __p.first;
 164           second = __p.second;
 165           return *this;
 166         }
 167
 168       template<class _U1, class _U2>
 169         pair&
 170         operator=(pair<_U1, _U2>&& __p)
 171         {
 172           first = std::move(__p.first);
 173           second = std::move(__p.second);
 174           return *this;
 175         }
 176
 177       void
 178       swap(pair& __p)
 179       {
 180         using std::swap;
 181         swap(first, __p.first);
 182         swap(second, __p.second);
 183       }
 184
 185     private:
 186       template<typename _Tp, typename... _Args>
 187         static _Tp
 188         __cons(tuple<_Args...>&&);
 189
 190       template<typename _Tp, typename... _Args, int... _Indexes>
 191         static _Tp
 192         __do_cons(tuple<_Args...>&&, const _Index_tuple<_Indexes...>&);
 193 #endif
 194     };
 195
 196   /// Two pairs of the same type are equal iff their members are equal.
 197   template<class _T1, class _T2>
 198     inline _GLIBCXX_CONSTEXPR bool
 199     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 200     { return __x.first == __y.first && __x.second == __y.second; }
 201
 202   /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
 203   template<class _T1, class _T2>
 204     inline _GLIBCXX_CONSTEXPR bool
 205     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 206     { return __x.first < __y.first
 207              || (!(__y.first < __x.first) && __x.second < __y.second); }
 208
 209   /// Uses @c operator== to find the result.
 210   template<class _T1, class _T2>
 211     inline _GLIBCXX_CONSTEXPR bool
 212     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 213     { return !(__x == __y); }
 214
 215   /// Uses @c operator< to find the result.
 216   template<class _T1, class _T2>
 217     inline _GLIBCXX_CONSTEXPR bool
 218     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 219     { return __y < __x; }
 220
 221   /// Uses @c operator< to find the result.
 222   template<class _T1, class _T2>
 223     inline _GLIBCXX_CONSTEXPR bool
 224     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 225     { return !(__y < __x); }
 226
 227   /// Uses @c operator< to find the result.
 228   template<class _T1, class _T2>
 229     inline _GLIBCXX_CONSTEXPR bool
 230     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 231     { return !(__x < __y); }
 232
 233 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 234   /// See std::pair::swap().
 235   // Note:  no std::swap overloads in C++03 mode, this has performance
 236   //        implications, see, eg, libstdc++/38466.
 237   template<class _T1, class _T2>
 238     inline void
 239     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
 240     { __x.swap(__y); }
 241 #endif
 242
 243   /**
 244    *  @brief A convenience wrapper for creating a pair from two objects.
 245    *  @param  x  The first object.
 246    *  @param  y  The second object.
 247    *  @return   A newly-constructed pair<> object of the appropriate type.
 248    *
 249    *  The standard requires that the objects be passed by reference-to-const,
 250    *  but LWG issue #181 says they should be passed by const value.  We follow
 251    *  the LWG by default.
 252    */
 253   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 254   // 181.  make_pair() unintended behavior
 255 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 256   // NB: DR 706.
 257   template<class _T1, class _T2>
 258     inline pair<typename __decay_and_strip<_T1>::__type,
 259                 typename __decay_and_strip<_T2>::__type>
 260     make_pair(_T1&& __x, _T2&& __y)
 261     {
 262       typedef typename __decay_and_strip<_T1>::__type __ds_type1;
 263       typedef typename __decay_and_strip<_T2>::__type __ds_type2;
 264       typedef pair<__ds_type1, __ds_type2>            __pair_type;
 265       return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
 266     }
 267 #else
 268   template<class _T1, class _T2>
 269     inline pair<_T1, _T2>
 270     make_pair(_T1 __x, _T2 __y)
 271     { return pair<_T1, _T2>(__x, __y); }
 272 #endif
 273
 274 _GLIBCXX_END_NAMESPACE
 275
 276 #endif /* _STL_PAIR_H */