# stl_pair.h

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    00001 // Pair implementation -*- C++ -*-
    00002
    00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
    00004 // Free Software Foundation, Inc.
    00005 //
    00006 // This file is part of the GNU ISO C++ Library.  This library is free
    00007 // software; you can redistribute it and/or modify it under the
    00008 // terms of the GNU General Public License as published by the
    00009 // Free Software Foundation; either version 2, or (at your option)
    00010 // any later version.
    00011
    00012 // This library is distributed in the hope that it will be useful,
    00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
    00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00015 // GNU General Public License for more details.
    00016
    00017 // You should have received a copy of the GNU General Public License along
    00018 // with this library; see the file COPYING.  If not, write to the Free
    00019 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
    00020 // USA.
    00021
    00022 // As a special exception, you may use this file as part of a free software
    00023 // library without restriction.  Specifically, if other files instantiate
    00024 // templates or use macros or inline functions from this file, or you compile
    00025 // this file and link it with other files to produce an executable, this
    00026 // file does not by itself cause the resulting executable to be covered by
    00027 // the GNU General Public License.  This exception does not however
    00028 // invalidate any other reasons why the executable file might be covered by
    00029 // the GNU General Public License.
    00030
    00031 /*
    00032  *
    00033  * Copyright (c) 1994
    00034  * Hewlett-Packard Company
    00035  *
    00036  * Permission to use, copy, modify, distribute and sell this software
    00037  * and its documentation for any purpose is hereby granted without fee,
    00038  * provided that the above copyright notice appear in all copies and
    00039  * that both that copyright notice and this permission notice appear
    00040  * in supporting documentation.  Hewlett-Packard Company makes no
    00041  * representations about the suitability of this software for any
    00042  * purpose.  It is provided "as is" without express or implied warranty.
    00043  *
    00044  *
    00045  * Copyright (c) 1996,1997
    00046  * Silicon Graphics Computer Systems, Inc.
    00047  *
    00048  * Permission to use, copy, modify, distribute and sell this software
    00049  * and its documentation for any purpose is hereby granted without fee,
    00050  * provided that the above copyright notice appear in all copies and
    00051  * that both that copyright notice and this permission notice appear
    00052  * in supporting documentation.  Silicon Graphics makes no
    00053  * representations about the suitability of this software for any
    00054  * purpose.  It is provided "as is" without express or implied warranty.
    00055  */
    00056
    00057 /** @file stl_pair.h
    00058  *  This is an internal header file, included by other library headers.
    00059  *  You should not attempt to use it directly.
    00060  */
    00061
    00062 #ifndef _STL_PAIR_H
    00063 #define _STL_PAIR_H 1
    00064
    00065 #include <bits/stl_move.h> // for std::move / std::forward, std::decay, and
    00066                            // std::swap
    00067
    00068 _GLIBCXX_BEGIN_NAMESPACE(std)
    00069
    00070   /// pair holds two objects of arbitrary type.
    00071   template<class _T1, class _T2>
    00072     struct pair
    00073     {
    00074       typedef _T1 first_type;    ///<  @c first_type is the first bound type
    00075       typedef _T2 second_type;   ///<  @c second_type is the second bound type
    00076
    00077       _T1 first;                 ///< @c first is a copy of the first object
    00078       _T2 second;                ///< @c second is a copy of the second object
    00079
    00080       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    00081       // 265.  std::pair::pair() effects overly restrictive
    00082       /** The default constructor creates @c first and @c second using their
    00083        *  respective default constructors.  */
    00084       pair()
    00085       : first(), second() { }
    00086
    00087       /** Two objects may be passed to a @c pair constructor to be copied.  */
    00088       pair(const _T1& __a, const _T2& __b)
    00089       : first(__a), second(__b) { }
    00090
    00091 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    00092       template<class _U1, class _U2>
    00093         pair(_U1&& __x, _U2&& __y)
    00094     : first(std::forward<_U1>(__x)),
    00095       second(std::forward<_U2>(__y)) { }
    00096
    00097       pair(pair&& __p)
    00098       : first(std::move(__p.first)),
    00099     second(std::move(__p.second)) { }
    00100 #endif
    00101
    00102       /** There is also a templated copy ctor for the @c pair class itself.  */
    00103       template<class _U1, class _U2>
    00104         pair(const pair<_U1, _U2>& __p)
    00105     : first(__p.first),
    00106       second(__p.second) { }
    00107
    00108 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    00109       template<class _U1, class _U2>
    00110         pair(pair<_U1, _U2>&& __p)
    00111     : first(std::move(__p.first)),
    00112       second(std::move(__p.second)) { }
    00113
    00114       // http://gcc.gnu.org/ml/libstdc++/2007-08/msg00052.html
    00115       template<class _U1, class _Arg0, class... _Args>
    00116         pair(_U1&& __x, _Arg0&& __arg0, _Args&&... __args)
    00117     : first(std::forward<_U1>(__x)),
    00118       second(std::forward<_Arg0>(__arg0),
    00119          std::forward<_Args>(__args)...) { }
    00120
    00121       pair&
    00122       operator=(pair&& __p)
    00123       {
    00124     first = std::move(__p.first);
    00125     second = std::move(__p.second);
    00126     return *this;
    00127       }
    00128
    00129       template<class _U1, class _U2>
    00130         pair&
    00131         operator=(pair<_U1, _U2>&& __p)
    00132     {
    00133       first = std::move(__p.first);
    00134       second = std::move(__p.second);
    00135       return *this;
    00136     }
    00137
    00138       void
    00139       swap(pair&& __p)
    00140       {
    00141     using std::swap;
    00142     swap(first, __p.first);
    00143     swap(second, __p.second);
    00144       }
    00145 #endif
    00146     };
    00147
    00148   /// Two pairs of the same type are equal iff their members are equal.
    00149   template<class _T1, class _T2>
    00150     inline bool
    00151     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
    00152     { return __x.first == __y.first && __x.second == __y.second; }
    00153
    00154   /// <http://gcc.gnu.org/onlinedocs/libstdc++/20_util/howto.html#pairlt>
    00155   template<class _T1, class _T2>
    00156     inline bool
    00157     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
    00158     { return __x.first < __y.first
    00159          || (!(__y.first < __x.first) && __x.second < __y.second); }
    00160
    00161   /// Uses @c operator== to find the result.
    00162   template<class _T1, class _T2>
    00163     inline bool
    00164     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
    00165     { return !(__x == __y); }
    00166
    00167   /// Uses @c operator< to find the result.
    00168   template<class _T1, class _T2>
    00169     inline bool
    00170     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
    00171     { return __y < __x; }
    00172
    00173   /// Uses @c operator< to find the result.
    00174   template<class _T1, class _T2>
    00175     inline bool
    00176     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
    00177     { return !(__y < __x); }
    00178
    00179   /// Uses @c operator< to find the result.
    00180   template<class _T1, class _T2>
    00181     inline bool
    00182     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
    00183     { return !(__x < __y); }
    00184
    00185 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    00186   /// See std::pair::swap().
    00187   template<class _T1, class _T2>
    00188     inline void
    00189     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
    00190     { __x.swap(__y); }
    00191
    00192   template<class _T1, class _T2>
    00193     inline void
    00194     swap(pair<_T1, _T2>&& __x, pair<_T1, _T2>& __y)
    00195     { __x.swap(__y); }
    00196
    00197   template<class _T1, class _T2>
    00198     inline void
    00199     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>&& __y)
    00200     { __x.swap(__y); }
    00201 #endif
    00202
    00203   /**
    00204    *  @brief A convenience wrapper for creating a pair from two objects.
    00205    *  @param  x  The first object.
    00206    *  @param  y  The second object.
    00207    *  @return   A newly-constructed pair<> object of the appropriate type.
    00208    *
    00209    *  The standard requires that the objects be passed by reference-to-const,
    00210    *  but LWG issue #181 says they should be passed by const value.  We follow
    00211    *  the LWG by default.
    00212    */
    00213   // _GLIBCXX_RESOLVE_LIB_DEFECTS
    00214   // 181.  make_pair() unintended behavior
    00215 #ifndef __GXX_EXPERIMENTAL_CXX0X__
    00216   template<class _T1, class _T2>
    00217     inline pair<_T1, _T2>
    00218     make_pair(_T1 __x, _T2 __y)
    00219     { return pair<_T1, _T2>(__x, __y); }
    00220 #else
    00221   template<typename _Tp>
    00222     class reference_wrapper;
    00223
    00224   // Helper which adds a reference to a type when given a reference_wrapper
    00225   template<typename _Tp>
    00226     struct __strip_reference_wrapper
    00227     {
    00228       typedef _Tp __type;
    00229     };
    00230
    00231   template<typename _Tp>
    00232     struct __strip_reference_wrapper<reference_wrapper<_Tp> >
    00233     {
    00234       typedef _Tp& __type;
    00235     };
    00236
    00237   template<typename _Tp>
    00238     struct __strip_reference_wrapper<const reference_wrapper<_Tp> >
    00239     {
    00240       typedef _Tp& __type;
    00241     };
    00242
    00243   template<typename _Tp>
    00244     struct __decay_and_strip
    00245     {
    00246       typedef typename __strip_reference_wrapper<
    00247     typename decay<_Tp>::type>::__type __type;
    00248     };
    00249
    00250   // NB: DR 706.
    00251   template<class _T1, class _T2>
    00252     inline pair<typename __decay_and_strip<_T1>::__type,
    00253         typename __decay_and_strip<_T2>::__type>
    00254     make_pair(_T1&& __x, _T2&& __y)
    00255     {
    00256       return pair<typename __decay_and_strip<_T1>::__type,
    00257               typename __decay_and_strip<_T2>::__type>
    00258     (std::forward<_T1>(__x), std::forward<_T2>(__y));
    00259     }
    00260 #endif
    00261
    00262 _GLIBCXX_END_NAMESPACE
    00263
    00264 #endif /* _STL_PAIR_H */