stl_pair.h

Go to the documentation of this file.
00001 // Pair implementation -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
00018 // permissions described in the GCC Runtime Library Exception, version
00019 // 3.1, as published by the Free Software Foundation.
00020 
00021 // You should have received a copy of the GNU General Public License and
00022 // a copy of the GCC Runtime Library Exception along with this program;
00023 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00024 // <http://www.gnu.org/licenses/>.
00025 
00026 /*
00027  *
00028  * Copyright (c) 1994
00029  * Hewlett-Packard Company
00030  *
00031  * Permission to use, copy, modify, distribute and sell this software
00032  * and its documentation for any purpose is hereby granted without fee,
00033  * provided that the above copyright notice appear in all copies and
00034  * that both that copyright notice and this permission notice appear
00035  * in supporting documentation.  Hewlett-Packard Company makes no
00036  * representations about the suitability of this software for any
00037  * purpose.  It is provided "as is" without express or implied warranty.
00038  *
00039  *
00040  * Copyright (c) 1996,1997
00041  * Silicon Graphics Computer Systems, Inc.
00042  *
00043  * Permission to use, copy, modify, distribute and sell this software
00044  * and its documentation for any purpose is hereby granted without fee,
00045  * provided that the above copyright notice appear in all copies and
00046  * that both that copyright notice and this permission notice appear
00047  * in supporting documentation.  Silicon Graphics makes no
00048  * representations about the suitability of this software for any
00049  * purpose.  It is provided "as is" without express or implied warranty.
00050  */
00051 
00052 /** @file stl_pair.h
00053  *  This is an internal header file, included by other library headers.
00054  *  You should not attempt to use it directly.
00055  */
00056 
00057 #ifndef _STL_PAIR_H
00058 #define _STL_PAIR_H 1
00059 
00060 #include <bits/move.h> // for std::move / std::forward, std::decay, and
00061                        // std::swap
00062 
00063 _GLIBCXX_BEGIN_NAMESPACE(std)
00064 
00065   /// pair holds two objects of arbitrary type.
00066   template<class _T1, class _T2>
00067     struct pair
00068     {
00069       typedef _T1 first_type;    ///<  @c first_type is the first bound type
00070       typedef _T2 second_type;   ///<  @c second_type is the second bound type
00071 
00072       _T1 first;                 ///< @c first is a copy of the first object
00073       _T2 second;                ///< @c second is a copy of the second object
00074 
00075       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00076       // 265.  std::pair::pair() effects overly restrictive
00077       /** The default constructor creates @c first and @c second using their
00078        *  respective default constructors.  */
00079       pair()
00080       : first(), second() { }
00081 
00082       /** Two objects may be passed to a @c pair constructor to be copied.  */
00083       pair(const _T1& __a, const _T2& __b)
00084       : first(__a), second(__b) { }
00085 
00086 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00087       template<class _U1, class _U2>
00088         pair(_U1&& __x, _U2&& __y)
00089     : first(std::forward<_U1>(__x)),
00090       second(std::forward<_U2>(__y)) { }
00091 
00092       pair(pair&& __p)
00093       : first(std::move(__p.first)),
00094     second(std::move(__p.second)) { }
00095 #endif
00096 
00097       /** There is also a templated copy ctor for the @c pair class itself.  */
00098       template<class _U1, class _U2>
00099         pair(const pair<_U1, _U2>& __p)
00100     : first(__p.first),
00101       second(__p.second) { }
00102 
00103 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00104       template<class _U1, class _U2>
00105         pair(pair<_U1, _U2>&& __p)
00106     : first(std::move(__p.first)),
00107       second(std::move(__p.second)) { }
00108 
00109       // http://gcc.gnu.org/ml/libstdc++/2007-08/msg00052.html
00110       template<class _U1, class _Arg0, class... _Args>
00111         pair(_U1&& __x, _Arg0&& __arg0, _Args&&... __args)
00112     : first(std::forward<_U1>(__x)),
00113       second(std::forward<_Arg0>(__arg0),
00114          std::forward<_Args>(__args)...) { }
00115 
00116       pair&
00117       operator=(pair&& __p)
00118       { 
00119     first = std::move(__p.first);
00120     second = std::move(__p.second);
00121     return *this;
00122       }
00123 
00124       template<class _U1, class _U2>
00125         pair&
00126         operator=(pair<_U1, _U2>&& __p)
00127     {
00128       first = std::move(__p.first);
00129       second = std::move(__p.second);
00130       return *this;
00131     }
00132 
00133       void
00134       swap(pair&& __p)
00135       {
00136     using std::swap;
00137     swap(first, __p.first);
00138     swap(second, __p.second);   
00139       }
00140 #endif
00141     };
00142 
00143   /// Two pairs of the same type are equal iff their members are equal.
00144   template<class _T1, class _T2>
00145     inline bool
00146     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00147     { return __x.first == __y.first && __x.second == __y.second; }
00148 
00149   /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
00150   template<class _T1, class _T2>
00151     inline bool
00152     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00153     { return __x.first < __y.first
00154          || (!(__y.first < __x.first) && __x.second < __y.second); }
00155 
00156   /// Uses @c operator== to find the result.
00157   template<class _T1, class _T2>
00158     inline bool
00159     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00160     { return !(__x == __y); }
00161 
00162   /// Uses @c operator< to find the result.
00163   template<class _T1, class _T2>
00164     inline bool
00165     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00166     { return __y < __x; }
00167 
00168   /// Uses @c operator< to find the result.
00169   template<class _T1, class _T2>
00170     inline bool
00171     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00172     { return !(__y < __x); }
00173 
00174   /// Uses @c operator< to find the result.
00175   template<class _T1, class _T2>
00176     inline bool
00177     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00178     { return !(__x < __y); }
00179 
00180 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00181   /// See std::pair::swap().
00182   // Note:  no std::swap overloads in C++03 mode, this has performance
00183   //        implications, see, eg, libstdc++/38466.
00184   template<class _T1, class _T2>
00185     inline void
00186     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
00187     { __x.swap(__y); }
00188 
00189   template<class _T1, class _T2>
00190     inline void
00191     swap(pair<_T1, _T2>&& __x, pair<_T1, _T2>& __y)
00192     { __x.swap(__y); }
00193 
00194   template<class _T1, class _T2>
00195     inline void
00196     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>&& __y)
00197     { __x.swap(__y); }
00198 #endif
00199 
00200   /**
00201    *  @brief A convenience wrapper for creating a pair from two objects.
00202    *  @param  x  The first object.
00203    *  @param  y  The second object.
00204    *  @return   A newly-constructed pair<> object of the appropriate type.
00205    *
00206    *  The standard requires that the objects be passed by reference-to-const,
00207    *  but LWG issue #181 says they should be passed by const value.  We follow
00208    *  the LWG by default.
00209    */
00210   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00211   // 181.  make_pair() unintended behavior
00212 #ifndef __GXX_EXPERIMENTAL_CXX0X__
00213   template<class _T1, class _T2>
00214     inline pair<_T1, _T2>
00215     make_pair(_T1 __x, _T2 __y)
00216     { return pair<_T1, _T2>(__x, __y); }
00217 #else
00218   template<typename _Tp>
00219     class reference_wrapper;
00220 
00221   // Helper which adds a reference to a type when given a reference_wrapper
00222   template<typename _Tp>
00223     struct __strip_reference_wrapper
00224     {
00225       typedef _Tp __type;
00226     };
00227 
00228   template<typename _Tp>
00229     struct __strip_reference_wrapper<reference_wrapper<_Tp> >
00230     {
00231       typedef _Tp& __type;
00232     };
00233 
00234   template<typename _Tp>
00235     struct __strip_reference_wrapper<const reference_wrapper<_Tp> >
00236     {
00237       typedef _Tp& __type;
00238     };
00239 
00240   template<typename _Tp>
00241     struct __decay_and_strip
00242     {
00243       typedef typename __strip_reference_wrapper<
00244     typename decay<_Tp>::type>::__type __type;
00245     };
00246 
00247   // NB: DR 706.
00248   template<class _T1, class _T2>
00249     inline pair<typename __decay_and_strip<_T1>::__type,
00250         typename __decay_and_strip<_T2>::__type>
00251     make_pair(_T1&& __x, _T2&& __y)
00252     {
00253       return pair<typename __decay_and_strip<_T1>::__type,
00254               typename __decay_and_strip<_T2>::__type>
00255     (std::forward<_T1>(__x), std::forward<_T2>(__y));
00256     }
00257 #endif
00258 
00259 _GLIBCXX_END_NAMESPACE
00260 
00261 #endif /* _STL_PAIR_H */

Generated on Thu Jul 23 21:16:22 2009 for libstdc++ by  doxygen 1.5.8