stl_pair.h

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00001 // Pair implementation -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00064 #include <type_traits>
00065 #endif
00066 
00067 _GLIBCXX_BEGIN_NAMESPACE(std)
00068 
00069   /// pair holds two objects of arbitrary type.
00070   template<class _T1, class _T2>
00071     struct pair
00072     {
00073       typedef _T1 first_type;    ///<  @c first_type is the first bound type
00074       typedef _T2 second_type;   ///<  @c second_type is the second bound type
00075 
00076       _T1 first;                 ///< @c first is a copy of the first object
00077       _T2 second;                ///< @c second is a copy of the second object
00078 
00079       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00080       // 265.  std::pair::pair() effects overly restrictive
00081       /** The default constructor creates @c first and @c second using their
00082        *  respective default constructors.  */
00083       pair()
00084       : first(), second() { }
00085 
00086       /** Two objects may be passed to a @c pair constructor to be copied.  */
00087       pair(const _T1& __a, const _T2& __b)
00088       : first(__a), second(__b) { }
00089 
00090 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00091       // DR 811.
00092       template<class _U1, class = typename
00093            std::enable_if<std::is_convertible<_U1, _T1>::value>::type>
00094         pair(_U1&& __x, const _T2& __y)
00095     : first(std::forward<_U1>(__x)),
00096       second(__y) { }
00097 
00098       template<class _U2, class = typename
00099            std::enable_if<std::is_convertible<_U2, _T2>::value>::type>
00100         pair(const _T1& __x, _U2&& __y)
00101     : first(__x),
00102       second(std::forward<_U2>(__y)) { }
00103 
00104       template<class _U1, class _U2, class = typename
00105            std::enable_if<std::is_convertible<_U1, _T1>::value
00106                   && std::is_convertible<_U2, _T2>::value>::type>
00107         pair(_U1&& __x, _U2&& __y)
00108     : first(std::forward<_U1>(__x)),
00109       second(std::forward<_U2>(__y)) { }
00110 
00111       pair(pair&& __p)
00112       : first(std::move(__p.first)),
00113     second(std::move(__p.second)) { }
00114 #endif
00115 
00116       /** There is also a templated copy ctor for the @c pair class itself.  */
00117       template<class _U1, class _U2>
00118         pair(const pair<_U1, _U2>& __p)
00119     : first(__p.first),
00120       second(__p.second) { }
00121 
00122 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00123       template<class _U1, class _U2>
00124         pair(pair<_U1, _U2>&& __p)
00125     : first(std::move(__p.first)),
00126       second(std::move(__p.second)) { }
00127 
00128       pair&
00129       operator=(pair&& __p)
00130       { 
00131     first = std::move(__p.first);
00132     second = std::move(__p.second);
00133     return *this;
00134       }
00135 
00136       template<class _U1, class _U2>
00137         pair&
00138         operator=(pair<_U1, _U2>&& __p)
00139     {
00140       first = std::move(__p.first);
00141       second = std::move(__p.second);
00142       return *this;
00143     }
00144 
00145       void
00146       swap(pair& __p)
00147       {
00148     using std::swap;
00149     swap(first, __p.first);
00150     swap(second, __p.second);   
00151       }
00152 #endif
00153     };
00154 
00155   /// Two pairs of the same type are equal iff their members are equal.
00156   template<class _T1, class _T2>
00157     inline bool
00158     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00159     { return __x.first == __y.first && __x.second == __y.second; }
00160 
00161   /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
00162   template<class _T1, class _T2>
00163     inline bool
00164     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00165     { return __x.first < __y.first
00166          || (!(__y.first < __x.first) && __x.second < __y.second); }
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 !(__x == __y); }
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 __y < __x; }
00179 
00180   /// Uses @c operator< to find the result.
00181   template<class _T1, class _T2>
00182     inline bool
00183     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00184     { return !(__y < __x); }
00185 
00186   /// Uses @c operator< to find the result.
00187   template<class _T1, class _T2>
00188     inline bool
00189     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00190     { return !(__x < __y); }
00191 
00192 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00193   /// See std::pair::swap().
00194   // Note:  no std::swap overloads in C++03 mode, this has performance
00195   //        implications, see, eg, libstdc++/38466.
00196   template<class _T1, class _T2>
00197     inline void
00198     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
00199     { __x.swap(__y); }
00200 #endif
00201 
00202   /**
00203    *  @brief A convenience wrapper for creating a pair from two objects.
00204    *  @param  x  The first object.
00205    *  @param  y  The second object.
00206    *  @return   A newly-constructed pair<> object of the appropriate type.
00207    *
00208    *  The standard requires that the objects be passed by reference-to-const,
00209    *  but LWG issue #181 says they should be passed by const value.  We follow
00210    *  the LWG by default.
00211    */
00212   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00213   // 181.  make_pair() unintended behavior
00214 #ifndef __GXX_EXPERIMENTAL_CXX0X__
00215   template<class _T1, class _T2>
00216     inline pair<_T1, _T2>
00217     make_pair(_T1 __x, _T2 __y)
00218     { return pair<_T1, _T2>(__x, __y); }
00219 #else
00220   template<typename _Tp>
00221     class reference_wrapper;
00222 
00223   // Helper which adds a reference to a type when given a reference_wrapper
00224   template<typename _Tp>
00225     struct __strip_reference_wrapper
00226     {
00227       typedef _Tp __type;
00228     };
00229 
00230   template<typename _Tp>
00231     struct __strip_reference_wrapper<reference_wrapper<_Tp> >
00232     {
00233       typedef _Tp& __type;
00234     };
00235 
00236   template<typename _Tp>
00237     struct __strip_reference_wrapper<const reference_wrapper<_Tp> >
00238     {
00239       typedef _Tp& __type;
00240     };
00241 
00242   template<typename _Tp>
00243     struct __decay_and_strip
00244     {
00245       typedef typename __strip_reference_wrapper<
00246     typename decay<_Tp>::type>::__type __type;
00247     };
00248 
00249   // NB: DR 706.
00250   template<class _T1, class _T2>
00251     inline pair<typename __decay_and_strip<_T1>::__type,
00252         typename __decay_and_strip<_T2>::__type>
00253     make_pair(_T1&& __x, _T2&& __y)
00254     {
00255       return pair<typename __decay_and_strip<_T1>::__type,
00256               typename __decay_and_strip<_T2>::__type>
00257     (std::forward<_T1>(__x), std::forward<_T2>(__y));
00258     }
00259 #endif
00260 
00261 _GLIBCXX_END_NAMESPACE
00262 
00263 #endif /* _STL_PAIR_H */

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