libstdc++
stl_pair.h
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00001 // Pair implementation -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2016 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 { explicit piecewise_construct_t() = default; };
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 
00088   // Concept utility functions, reused in conditionally-explicit
00089   // constructors.
00090   // See PR 70437, don't look at is_constructible or
00091   // is_convertible if the types are the same to
00092   // avoid querying those properties for incomplete types.
00093   template <bool, typename _T1, typename _T2>
00094     struct _PCC
00095     {
00096       template <typename _U1, typename _U2>
00097       static constexpr bool _ConstructiblePair()
00098       {
00099         return __and_<is_constructible<_T1, const _U1&>,
00100                       is_constructible<_T2, const _U2&>>::value;
00101       }
00102 
00103       template <typename _U1, typename _U2>
00104       static constexpr bool _ImplicitlyConvertiblePair()
00105       {
00106         return __and_<is_convertible<const _U1&, _T1>,
00107                       is_convertible<const _U2&, _T2>>::value;
00108       }
00109 
00110       template <typename _U1, typename _U2>
00111       static constexpr bool _MoveConstructiblePair()
00112       {
00113         return __and_<is_constructible<_T1, _U1&&>,
00114                       is_constructible<_T2, _U2&&>>::value;
00115       }
00116 
00117       template <typename _U1, typename _U2>
00118       static constexpr bool _ImplicitlyMoveConvertiblePair()
00119       {
00120         return __and_<is_convertible<_U1&&, _T1>,
00121                       is_convertible<_U2&&, _T2>>::value;
00122       }
00123 
00124       template <bool __implicit, typename _U1, typename _U2>
00125       static constexpr bool _CopyMovePair()
00126       {
00127         using __do_converts = __and_<is_convertible<const _U1&, _T1>,
00128                                   is_convertible<_U2&&, _T2>>;
00129         using __converts = typename conditional<__implicit,
00130                                        __do_converts,
00131                                        __not_<__do_converts>>::type;
00132         return __and_<is_constructible<_T1, const _U1&>,
00133                       is_constructible<_T2, _U2&&>,
00134                       __converts
00135                       >::value;
00136       }
00137 
00138       template <bool __implicit, typename _U1, typename _U2>
00139       static constexpr bool _MoveCopyPair()
00140       {
00141         using __do_converts = __and_<is_convertible<_U1&&, _T1>,
00142                                   is_convertible<const _U2&, _T2>>;
00143         using __converts = typename conditional<__implicit,
00144                                        __do_converts,
00145                                        __not_<__do_converts>>::type;
00146         return __and_<is_constructible<_T1, _U1&&>,
00147                       is_constructible<_T2, const _U2&&>,
00148                       __converts
00149                       >::value;
00150       }
00151   };
00152 
00153   template <typename _T1, typename _T2>
00154     struct _PCC<false, _T1, _T2>
00155     {
00156       template <typename _U1, typename _U2>
00157       static constexpr bool _ConstructiblePair()
00158       {
00159         return false;
00160       }
00161 
00162       template <typename _U1, typename _U2>
00163       static constexpr bool _ImplicitlyConvertiblePair()
00164       {
00165         return false;
00166       }
00167 
00168       template <typename _U1, typename _U2>
00169       static constexpr bool _MoveConstructiblePair()
00170       {
00171         return false;
00172       }
00173 
00174       template <typename _U1, typename _U2>
00175       static constexpr bool _ImplicitlyMoveConvertiblePair()
00176       {
00177         return false;
00178       }
00179   };
00180 
00181 #endif
00182 
00183  /**
00184    *  @brief Struct holding two objects of arbitrary type.
00185    *
00186    *  @tparam _T1  Type of first object.
00187    *  @tparam _T2  Type of second object.
00188    */
00189   template<typename _T1, typename _T2>
00190     struct pair
00191     {
00192       typedef _T1 first_type;    /// @c first_type is the first bound type
00193       typedef _T2 second_type;   /// @c second_type is the second bound type
00194 
00195       _T1 first;                 /// @c first is a copy of the first object
00196       _T2 second;                /// @c second is a copy of the second object
00197 
00198       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00199       // 265.  std::pair::pair() effects overly restrictive
00200       /** The default constructor creates @c first and @c second using their
00201        *  respective default constructors.  */
00202 #if __cplusplus >= 201103L
00203       template <typename _U1 = _T1,
00204                 typename _U2 = _T2,
00205                 typename enable_if<__and_<
00206                                      __is_implicitly_default_constructible<_U1>,
00207                                      __is_implicitly_default_constructible<_U2>>
00208                                    ::value, bool>::type = true>
00209 #endif
00210       _GLIBCXX_CONSTEXPR pair()
00211       : first(), second() { }
00212 
00213 #if __cplusplus >= 201103L
00214       template <typename _U1 = _T1,
00215                 typename _U2 = _T2,
00216                 typename enable_if<__and_<
00217                        is_default_constructible<_U1>,
00218                        is_default_constructible<_U2>,
00219                        __not_<
00220                          __and_<__is_implicitly_default_constructible<_U1>,
00221                                 __is_implicitly_default_constructible<_U2>>>>
00222                                    ::value, bool>::type = false>
00223       explicit constexpr pair()
00224       : first(), second() { }
00225 #endif
00226 
00227       /** Two objects may be passed to a @c pair constructor to be copied.  */
00228 #if __cplusplus < 201103L
00229       pair(const _T1& __a, const _T2& __b)
00230       : first(__a), second(__b) { }
00231 #else
00232       // Shortcut for constraining the templates that don't take pairs.
00233       using _PCCP = _PCC<true, _T1, _T2>;
00234 
00235       template<typename _U1 = _T1, typename _U2=_T2, typename
00236                enable_if<_PCCP::template
00237                            _ConstructiblePair<_U1, _U2>()
00238                          && _PCCP::template
00239                            _ImplicitlyConvertiblePair<_U1, _U2>(),
00240                          bool>::type=true>
00241       constexpr pair(const _T1& __a, const _T2& __b)
00242       : first(__a), second(__b) { }
00243 
00244        template<typename _U1 = _T1, typename _U2=_T2, typename
00245                 enable_if<_PCCP::template
00246                             _ConstructiblePair<_U1, _U2>()
00247                           && !_PCCP::template
00248                             _ImplicitlyConvertiblePair<_U1, _U2>(),
00249                          bool>::type=false>
00250       explicit constexpr pair(const _T1& __a, const _T2& __b)
00251       : first(__a), second(__b) { }
00252 #endif
00253 
00254       /** There is also a templated copy ctor for the @c pair class itself.  */
00255 #if __cplusplus < 201103L
00256       template<typename _U1, typename _U2>
00257         pair(const pair<_U1, _U2>& __p)
00258         : first(__p.first), second(__p.second) { }
00259 #else
00260       // Shortcut for constraining the templates that take pairs.
00261       template <typename _U1, typename _U2>
00262         using _PCCFP = _PCC<!is_same<_T1, _U1>::value
00263                             || !is_same<_T2, _U2>::value,
00264                             _T1, _T2>;
00265 
00266       template<typename _U1, typename _U2, typename
00267                enable_if<_PCCFP<_U1, _U2>::template
00268                            _ConstructiblePair<_U1, _U2>()
00269                          && _PCCFP<_U1, _U2>::template
00270                            _ImplicitlyConvertiblePair<_U1, _U2>(),
00271                           bool>::type=true>
00272         constexpr pair(const pair<_U1, _U2>& __p)
00273         : first(__p.first), second(__p.second) { }
00274 
00275       template<typename _U1, typename _U2, typename
00276                enable_if<_PCCFP<_U1, _U2>::template
00277                            _ConstructiblePair<_U1, _U2>()
00278                          && !_PCCFP<_U1, _U2>::template
00279                            _ImplicitlyConvertiblePair<_U1, _U2>(),
00280                          bool>::type=false>
00281         explicit constexpr pair(const pair<_U1, _U2>& __p)
00282         : first(__p.first), second(__p.second) { }
00283 
00284       constexpr pair(const pair&) = default;
00285       constexpr pair(pair&&) = default;
00286 
00287       // DR 811.
00288       template<typename _U1, typename
00289                enable_if<_PCCP::template
00290                            _MoveCopyPair<true, _U1, _T2>(),
00291                          bool>::type=true>
00292        constexpr pair(_U1&& __x, const _T2& __y)
00293        : first(std::forward<_U1>(__x)), second(__y) { }
00294 
00295       template<typename _U1, typename
00296                enable_if<_PCCP::template
00297                            _MoveCopyPair<false, _U1, _T2>(),
00298                          bool>::type=false>
00299        explicit constexpr pair(_U1&& __x, const _T2& __y)
00300        : first(std::forward<_U1>(__x)), second(__y) { }
00301 
00302       template<typename _U2, typename
00303                enable_if<_PCCP::template
00304                            _CopyMovePair<true, _T1, _U2>(),
00305                          bool>::type=true>
00306        constexpr pair(const _T1& __x, _U2&& __y)
00307        : first(__x), second(std::forward<_U2>(__y)) { }
00308 
00309       template<typename _U2, typename
00310                enable_if<_PCCP::template
00311                            _CopyMovePair<false, _T1, _U2>(),
00312                          bool>::type=false>
00313        explicit pair(const _T1& __x, _U2&& __y)
00314        : first(__x), second(std::forward<_U2>(__y)) { }
00315 
00316       template<typename _U1, typename _U2, typename
00317                enable_if<_PCCP::template
00318                            _MoveConstructiblePair<_U1, _U2>()
00319                           && _PCCP::template
00320                            _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
00321                          bool>::type=true>
00322         constexpr pair(_U1&& __x, _U2&& __y)
00323         : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
00324 
00325       template<typename _U1, typename _U2, typename
00326                enable_if<_PCCP::template
00327                            _MoveConstructiblePair<_U1, _U2>()
00328                           && !_PCCP::template
00329                            _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
00330                          bool>::type=false>
00331         explicit constexpr pair(_U1&& __x, _U2&& __y)
00332         : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
00333 
00334 
00335       template<typename _U1, typename _U2, typename
00336                enable_if<_PCCFP<_U1, _U2>::template
00337                            _MoveConstructiblePair<_U1, _U2>()
00338                           && _PCCFP<_U1, _U2>::template
00339                            _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
00340                          bool>::type=true>
00341         constexpr pair(pair<_U1, _U2>&& __p)
00342         : first(std::forward<_U1>(__p.first)),
00343           second(std::forward<_U2>(__p.second)) { }
00344 
00345       template<typename _U1, typename _U2, typename
00346                enable_if<_PCCFP<_U1, _U2>::template
00347                            _MoveConstructiblePair<_U1, _U2>()
00348                           && !_PCCFP<_U1, _U2>::template
00349                            _ImplicitlyMoveConvertiblePair<_U1, _U2>(),
00350                          bool>::type=false>
00351         explicit constexpr pair(pair<_U1, _U2>&& __p)
00352         : first(std::forward<_U1>(__p.first)),
00353           second(std::forward<_U2>(__p.second)) { }
00354 
00355       template<typename... _Args1, typename... _Args2>
00356         pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
00357 
00358       pair&
00359       operator=(typename conditional<
00360                 __and_<is_copy_assignable<_T1>,
00361                        is_copy_assignable<_T2>>::value,
00362                 const pair&, const __nonesuch&>::type __p)
00363       {
00364         first = __p.first;
00365         second = __p.second;
00366         return *this;
00367       }
00368 
00369       pair&
00370       operator=(typename conditional<
00371                 __not_<__and_<is_copy_assignable<_T1>,
00372                               is_copy_assignable<_T2>>>::value,
00373                 const pair&, const __nonesuch&>::type __p) = delete;
00374 
00375       pair&
00376       operator=(typename conditional<
00377                 __and_<is_move_assignable<_T1>,
00378                        is_move_assignable<_T2>>::value,
00379                 pair&&, __nonesuch&&>::type __p)
00380       noexcept(__and_<is_nothrow_move_assignable<_T1>,
00381                       is_nothrow_move_assignable<_T2>>::value)
00382       {
00383         first = std::forward<first_type>(__p.first);
00384         second = std::forward<second_type>(__p.second);
00385         return *this;
00386       }
00387 
00388       template<typename _U1, typename _U2>
00389       typename enable_if<__and_<is_assignable<_T1&, const _U1&>,
00390                                 is_assignable<_T2&, const _U2&>>::value,
00391                          pair&>::type
00392         operator=(const pair<_U1, _U2>& __p)
00393         {
00394           first = __p.first;
00395           second = __p.second;
00396           return *this;
00397         }
00398 
00399       template<typename _U1, typename _U2>
00400       typename enable_if<__and_<is_assignable<_T1&, _U1&&>,
00401                                 is_assignable<_T2&, _U2&&>>::value,
00402                          pair&>::type
00403         operator=(pair<_U1, _U2>&& __p)
00404         {
00405           first = std::forward<_U1>(__p.first);
00406           second = std::forward<_U2>(__p.second);
00407           return *this;
00408         }
00409 
00410       void
00411       swap(pair& __p)
00412       noexcept(__is_nothrow_swappable<_T1>::value
00413                && __is_nothrow_swappable<_T2>::value)
00414       {
00415         using std::swap;
00416         swap(first, __p.first);
00417         swap(second, __p.second);
00418       }
00419 
00420     private:
00421       template<typename... _Args1, std::size_t... _Indexes1,
00422                typename... _Args2, std::size_t... _Indexes2>
00423         pair(tuple<_Args1...>&, tuple<_Args2...>&,
00424              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
00425 #endif
00426     };
00427 
00428   /// Two pairs of the same type are equal iff their members are equal.
00429   template<typename _T1, typename _T2>
00430     inline _GLIBCXX_CONSTEXPR bool
00431     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00432     { return __x.first == __y.first && __x.second == __y.second; }
00433 
00434   /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
00435   template<typename _T1, typename _T2>
00436     inline _GLIBCXX_CONSTEXPR bool
00437     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00438     { return __x.first < __y.first
00439              || (!(__y.first < __x.first) && __x.second < __y.second); }
00440 
00441   /// Uses @c operator== to find the result.
00442   template<typename _T1, typename _T2>
00443     inline _GLIBCXX_CONSTEXPR bool
00444     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00445     { return !(__x == __y); }
00446 
00447   /// Uses @c operator< to find the result.
00448   template<typename _T1, typename _T2>
00449     inline _GLIBCXX_CONSTEXPR bool
00450     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00451     { return __y < __x; }
00452 
00453   /// Uses @c operator< to find the result.
00454   template<typename _T1, typename _T2>
00455     inline _GLIBCXX_CONSTEXPR bool
00456     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00457     { return !(__y < __x); }
00458 
00459   /// Uses @c operator< to find the result.
00460   template<typename _T1, typename _T2>
00461     inline _GLIBCXX_CONSTEXPR bool
00462     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
00463     { return !(__x < __y); }
00464 
00465 #if __cplusplus >= 201103L
00466   /// See std::pair::swap().
00467   // Note:  no std::swap overloads in C++03 mode, this has performance
00468   //        implications, see, eg, libstdc++/38466.
00469   template<typename _T1, typename _T2>
00470     inline void
00471     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
00472     noexcept(noexcept(__x.swap(__y)))
00473     { __x.swap(__y); }
00474 #endif
00475 
00476   /**
00477    *  @brief A convenience wrapper for creating a pair from two objects.
00478    *  @param  __x  The first object.
00479    *  @param  __y  The second object.
00480    *  @return   A newly-constructed pair<> object of the appropriate type.
00481    *
00482    *  The standard requires that the objects be passed by reference-to-const,
00483    *  but LWG issue #181 says they should be passed by const value.  We follow
00484    *  the LWG by default.
00485    */
00486   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00487   // 181.  make_pair() unintended behavior
00488 #if __cplusplus >= 201103L
00489   // NB: DR 706.
00490   template<typename _T1, typename _T2>
00491     constexpr pair<typename __decay_and_strip<_T1>::__type,
00492                    typename __decay_and_strip<_T2>::__type>
00493     make_pair(_T1&& __x, _T2&& __y)
00494     {
00495       typedef typename __decay_and_strip<_T1>::__type __ds_type1;
00496       typedef typename __decay_and_strip<_T2>::__type __ds_type2;
00497       typedef pair<__ds_type1, __ds_type2>            __pair_type;
00498       return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
00499     }
00500 #else
00501   template<typename _T1, typename _T2>
00502     inline pair<_T1, _T2>
00503     make_pair(_T1 __x, _T2 __y)
00504     { return pair<_T1, _T2>(__x, __y); }
00505 #endif
00506 
00507   /// @}
00508 
00509 _GLIBCXX_END_NAMESPACE_VERSION
00510 } // namespace std
00511 
00512 #endif /* _STL_PAIR_H */