libstdc++
stl_pair.h
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00001 // Pair implementation -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2013 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /*
00026  *
00027  * Copyright (c) 1994
00028  * Hewlett-Packard Company
00029  *
00030  * Permission to use, copy, modify, distribute and sell this software
00031  * and its documentation for any purpose is hereby granted without fee,
00032  * provided that the above copyright notice appear in all copies and
00033  * that both that copyright notice and this permission notice appear
00034  * in supporting documentation.  Hewlett-Packard Company makes no
00035  * representations about the suitability of this software for any
00036  * purpose.  It is provided "as is" without express or implied warranty.
00037  *
00038  *
00039  * Copyright (c) 1996,1997
00040  * Silicon Graphics Computer Systems, Inc.
00041  *
00042  * Permission to use, copy, modify, distribute and sell this software
00043  * and its documentation for any purpose is hereby granted without fee,
00044  * provided that the above copyright notice appear in all copies and
00045  * that both that copyright notice and this permission notice appear
00046  * in supporting documentation.  Silicon Graphics makes no
00047  * representations about the suitability of this software for any
00048  * purpose.  It is provided "as is" without express or implied warranty.
00049  */
00050 
00051 /** @file bits/stl_pair.h
00052  *  This is an internal header file, included by other library headers.
00053  *  Do not attempt to use it directly. @headername{utility}
00054  */
00055 
00056 #ifndef _STL_PAIR_H
00057 #define _STL_PAIR_H 1
00058 
00059 #include <bits/move.h> // for std::move / std::forward, and std::swap
00060 
00061 #if __cplusplus >= 201103L
00062 #include <type_traits> // for std::__decay_and_strip too
00063 #endif
00064 
00065 namespace std _GLIBCXX_VISIBILITY(default)
00066 {
00067 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00068 
00069   /**
00070    *  @addtogroup utilities
00071    *  @{
00072    */
00073 
00074 #if __cplusplus >= 201103L
00075   /// piecewise_construct_t
00076   struct piecewise_construct_t { };
00077 
00078   /// piecewise_construct
00079   constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
00080 
00081   // Forward declarations.
00082   template<typename...>
00083     class tuple;
00084 
00085   template<std::size_t...>
00086     struct _Index_tuple;
00087 #endif
00088 
00089  /**
00090    *  @brief Struct holding two objects of arbitrary type.
00091    *
00092    *  @tparam _T1  Type of first object.
00093    *  @tparam _T2  Type of second object.
00094    */
00095   template<class _T1, class _T2>
00096     struct pair
00097     {
00098       typedef _T1 first_type;    /// @c first_type is the first bound type
00099       typedef _T2 second_type;   /// @c second_type is the second bound type
00100 
00101       _T1 first;                 /// @c first is a copy of the first object
00102       _T2 second;                /// @c second is a copy of the second object
00103 
00104       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00105       // 265.  std::pair::pair() effects overly restrictive
00106       /** The default constructor creates @c first and @c second using their
00107        *  respective default constructors.  */
00108       _GLIBCXX_CONSTEXPR pair()
00109       : first(), second() { }
00110 
00111       /** Two objects may be passed to a @c pair constructor to be copied.  */
00112       _GLIBCXX_CONSTEXPR pair(const _T1& __a, const _T2& __b)
00113       : first(__a), second(__b) { }
00114 
00115       /** There is also a templated copy ctor for the @c pair class itself.  */
00116 #if __cplusplus < 201103L
00117       template<class _U1, class _U2>
00118     pair(const pair<_U1, _U2>& __p)
00119     : first(__p.first), second(__p.second) { }
00120 #else
00121       template<class _U1, class _U2, class = typename
00122            enable_if<__and_<is_convertible<const _U1&, _T1>,
00123                 is_convertible<const _U2&, _T2>>::value>::type>
00124     constexpr pair(const pair<_U1, _U2>& __p)
00125     : first(__p.first), second(__p.second) { }
00126 
00127       constexpr pair(const pair&) = default;
00128       constexpr pair(pair&&) = default;
00129 
00130       // DR 811.
00131       template<class _U1, class = typename
00132            enable_if<is_convertible<_U1, _T1>::value>::type>
00133     constexpr pair(_U1&& __x, const _T2& __y)
00134     : first(std::forward<_U1>(__x)), second(__y) { }
00135 
00136       template<class _U2, class = typename
00137            enable_if<is_convertible<_U2, _T2>::value>::type>
00138     constexpr pair(const _T1& __x, _U2&& __y)
00139     : first(__x), second(std::forward<_U2>(__y)) { }
00140 
00141       template<class _U1, class _U2, class = typename
00142            enable_if<__and_<is_convertible<_U1, _T1>,
00143                 is_convertible<_U2, _T2>>::value>::type>
00144     constexpr pair(_U1&& __x, _U2&& __y)
00145     : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
00146 
00147       template<class _U1, class _U2, class = typename
00148            enable_if<__and_<is_convertible<_U1, _T1>,
00149                 is_convertible<_U2, _T2>>::value>::type>
00150     constexpr pair(pair<_U1, _U2>&& __p)
00151     : first(std::forward<_U1>(__p.first)),
00152       second(std::forward<_U2>(__p.second)) { }
00153 
00154       template<typename... _Args1, typename... _Args2>
00155         pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
00156 
00157       pair&
00158       operator=(const pair& __p)
00159       {
00160     first = __p.first;
00161     second = __p.second;
00162     return *this;
00163       }
00164 
00165       pair&
00166       operator=(pair&& __p)
00167       noexcept(__and_<is_nothrow_move_assignable<_T1>,
00168                   is_nothrow_move_assignable<_T2>>::value)
00169       {
00170     first = std::forward<first_type>(__p.first);
00171     second = std::forward<second_type>(__p.second);
00172     return *this;
00173       }
00174 
00175       template<class _U1, class _U2>
00176     pair&
00177     operator=(const pair<_U1, _U2>& __p)
00178     {
00179       first = __p.first;
00180       second = __p.second;
00181       return *this;
00182     }
00183 
00184       template<class _U1, class _U2>
00185     pair&
00186     operator=(pair<_U1, _U2>&& __p)
00187     {
00188       first = std::forward<_U1>(__p.first);
00189       second = std::forward<_U2>(__p.second);
00190       return *this;
00191     }
00192 
00193       void
00194       swap(pair& __p)
00195       noexcept(noexcept(swap(first, __p.first))
00196            && noexcept(swap(second, __p.second)))
00197       {
00198     using std::swap;
00199     swap(first, __p.first);
00200     swap(second, __p.second);
00201       }
00202 
00203     private:
00204       template<typename... _Args1, std::size_t... _Indexes1,
00205                typename... _Args2, std::size_t... _Indexes2>
00206         pair(tuple<_Args1...>&, tuple<_Args2...>&,
00207              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
00208 #endif
00209     };
00210 
00211   /// Two pairs of the same type are equal iff their members are equal.
00212   template<class _T1, class _T2>
00213     inline _GLIBCXX_CONSTEXPR bool
00214     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00215     { return __x.first == __y.first && __x.second == __y.second; }
00216 
00217   /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
00218   template<class _T1, class _T2>
00219     inline _GLIBCXX_CONSTEXPR bool
00220     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00221     { return __x.first < __y.first
00222          || (!(__y.first < __x.first) && __x.second < __y.second); }
00223 
00224   /// Uses @c operator== to find the result.
00225   template<class _T1, class _T2>
00226     inline _GLIBCXX_CONSTEXPR bool
00227     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00228     { return !(__x == __y); }
00229 
00230   /// Uses @c operator< to find the result.
00231   template<class _T1, class _T2>
00232     inline _GLIBCXX_CONSTEXPR bool
00233     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00234     { return __y < __x; }
00235 
00236   /// Uses @c operator< to find the result.
00237   template<class _T1, class _T2>
00238     inline _GLIBCXX_CONSTEXPR bool
00239     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00240     { return !(__y < __x); }
00241 
00242   /// Uses @c operator< to find the result.
00243   template<class _T1, class _T2>
00244     inline _GLIBCXX_CONSTEXPR bool
00245     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00246     { return !(__x < __y); }
00247 
00248 #if __cplusplus >= 201103L
00249   /// See std::pair::swap().
00250   // Note:  no std::swap overloads in C++03 mode, this has performance
00251   //        implications, see, eg, libstdc++/38466.
00252   template<class _T1, class _T2>
00253     inline void
00254     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
00255     noexcept(noexcept(__x.swap(__y)))
00256     { __x.swap(__y); }
00257 #endif
00258 
00259   /**
00260    *  @brief A convenience wrapper for creating a pair from two objects.
00261    *  @param  __x  The first object.
00262    *  @param  __y  The second object.
00263    *  @return   A newly-constructed pair<> object of the appropriate type.
00264    *
00265    *  The standard requires that the objects be passed by reference-to-const,
00266    *  but LWG issue #181 says they should be passed by const value.  We follow
00267    *  the LWG by default.
00268    */
00269   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00270   // 181.  make_pair() unintended behavior
00271 #if __cplusplus >= 201103L
00272   // NB: DR 706.
00273   template<class _T1, class _T2>
00274     constexpr pair<typename __decay_and_strip<_T1>::__type,
00275                    typename __decay_and_strip<_T2>::__type>
00276     make_pair(_T1&& __x, _T2&& __y)
00277     {
00278       typedef typename __decay_and_strip<_T1>::__type __ds_type1;
00279       typedef typename __decay_and_strip<_T2>::__type __ds_type2;
00280       typedef pair<__ds_type1, __ds_type2>        __pair_type;
00281       return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
00282     }
00283 #else
00284   template<class _T1, class _T2>
00285     inline pair<_T1, _T2>
00286     make_pair(_T1 __x, _T2 __y)
00287     { return pair<_T1, _T2>(__x, __y); }
00288 #endif
00289 
00290   /// @}
00291 
00292 _GLIBCXX_END_NAMESPACE_VERSION
00293 } // namespace std
00294 
00295 #endif /* _STL_PAIR_H */