libstdc++-v3/include/bits/stl_pair.h

   1 // Pair implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001-2016 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /*
  26  *
  27  * Copyright (c) 1994
  28  * Hewlett-Packard Company
  29  *
  30  * Permission to use, copy, modify, distribute and sell this software
  31  * and its documentation for any purpose is hereby granted without fee,
  32  * provided that the above copyright notice appear in all copies and
  33  * that both that copyright notice and this permission notice appear
  34  * in supporting documentation.  Hewlett-Packard Company makes no
  35  * representations about the suitability of this software for any
  36  * purpose.  It is provided "as is" without express or implied warranty.
  37  *
  38  *
  39  * Copyright (c) 1996,1997
  40  * Silicon Graphics Computer Systems, Inc.
  41  *
  42  * Permission to use, copy, modify, distribute and sell this software
  43  * and its documentation for any purpose is hereby granted without fee,
  44  * provided that the above copyright notice appear in all copies and
  45  * that both that copyright notice and this permission notice appear
  46  * in supporting documentation.  Silicon Graphics makes no
  47  * representations about the suitability of this software for any
  48  * purpose.  It is provided "as is" without express or implied warranty.
  49  */
  50
  51 /** @file bits/stl_pair.h
  52  *  This is an internal header file, included by other library headers.
  53  *  Do not attempt to use it directly. @headername{utility}
  54  */
  55
  56 #ifndef _STL_PAIR_H
  57 #define _STL_PAIR_H 1
  58
  59 #include <bits/move.h> // for std::move / std::forward, and std::swap
  60
  61 #if __cplusplus >= 201103L
  62 #include <type_traits> // for std::__decay_and_strip too
  63 #endif
  64
  65 namespace std _GLIBCXX_VISIBILITY(default)
  66 {
  67 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  68
  69   /**
  70    *  @addtogroup utilities
  71    *  @{
  72    */
  73
  74 #if __cplusplus >= 201103L
  75   /// piecewise_construct_t
  76   struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
  77
  78   /// piecewise_construct
  79   constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
  80
  81   // Forward declarations.
  82   template<typename...>
  83     class tuple;
  84
  85   template<std::size_t...>
  86     struct _Index_tuple;
  87
  88   // Concept utility functions, reused in conditionally-explicit
  89   // constructors.
  90   template <typename _T1, typename _T2, typename _U1, typename _U2>
  91   constexpr bool _ConstructiblePair()
  92   {
  93     return __and_<is_constructible<_T1, const _U1&>,
  94                   is_constructible<_T2, const _U2&>>::value;
  95   }
  96
  97   template <typename _T1, typename _T2, typename _U1, typename _U2>
  98   constexpr bool _ImplicitlyConvertiblePair()
  99   {
 100     return __and_<is_convertible<const _U1&, _T1>,
 101                   is_convertible<const _U2&, _T2>>::value;
 102   }
 103
 104   template <typename _T1, typename _T2, typename _U1, typename _U2>
 105   constexpr bool _MoveConstructiblePair()
 106   {
 107     return __and_<is_constructible<_T1, _U1&&>,
 108                   is_constructible<_T2, _U2&&>>::value;
 109   }
 110
 111   template <typename _T1, typename _T2, typename _U1, typename _U2>
 112   constexpr bool _ImplicitlyMoveConvertiblePair()
 113   {
 114     return __and_<is_convertible<_U1&&, _T1>,
 115                   is_convertible<_U2&&, _T2>>::value;
 116   }
 117
 118
 119 #endif
 120
 121  /**
 122    *  @brief Struct holding two objects of arbitrary type.
 123    *
 124    *  @tparam _T1  Type of first object.
 125    *  @tparam _T2  Type of second object.
 126    */
 127   template<typename _T1, typename _T2>
 128     struct pair
 129     {
 130       typedef _T1 first_type;    /// @c first_type is the first bound type
 131       typedef _T2 second_type;   /// @c second_type is the second bound type
 132
 133       _T1 first;                 /// @c first is a copy of the first object
 134       _T2 second;                /// @c second is a copy of the second object
 135
 136       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 137       // 265.  std::pair::pair() effects overly restrictive
 138       /** The default constructor creates @c first and @c second using their
 139        *  respective default constructors.  */
 140 #if __cplusplus >= 201103L
 141       template <typename _U1 = _T1,
 142                 typename _U2 = _T2,
 143                 typename enable_if<__and_<
 144                                      __is_implicitly_default_constructible<_U1>,
 145                                      __is_implicitly_default_constructible<_U2>>
 146                                    ::value, bool>::type = true>
 147 #endif
 148       _GLIBCXX_CONSTEXPR pair()
 149       : first(), second() { }
 150
 151 #if __cplusplus >= 201103L
 152       template <typename _U1 = _T1,
 153                 typename _U2 = _T2,
 154                 typename enable_if<__and_<
 155                        is_default_constructible<_U1>,
 156                        is_default_constructible<_U2>,
 157                        __not_<
 158                          __and_<__is_implicitly_default_constructible<_U1>,
 159                                 __is_implicitly_default_constructible<_U2>>>>
 160                                    ::value, bool>::type = false>
 161       explicit constexpr pair()
 162       : first(), second() { }
 163 #endif
 164
 165       /** Two objects may be passed to a @c pair constructor to be copied.  */
 166 #if __cplusplus < 201103L
 167       pair(const _T1& __a, const _T2& __b)
 168       : first(__a), second(__b) { }
 169 #else
 170       template<typename _U1 = _T1, typename _U2=_T2, typename
 171                 enable_if<_ConstructiblePair<_T1, _T2, _U1, _U2>()
 172                          && _ImplicitlyConvertiblePair<_T1, _T2, _U1, _U2>(),
 173                          bool>::type=true>
 174       constexpr pair(const _T1& __a, const _T2& __b)
 175       : first(__a), second(__b) { }
 176
 177        template<typename _U1 = _T1, typename _U2=_T2, typename
 178                enable_if<_ConstructiblePair<_T1, _T2, _U1, _U2>()
 179                          && !_ImplicitlyConvertiblePair<_T1, _T2, _U1, _U2>(),
 180                          bool>::type=false>
 181       explicit constexpr pair(const _T1& __a, const _T2& __b)
 182       : first(__a), second(__b) { }
 183 #endif
 184
 185       /** There is also a templated copy ctor for the @c pair class itself.  */
 186 #if __cplusplus < 201103L
 187       template<typename _U1, typename _U2>
 188         pair(const pair<_U1, _U2>& __p)
 189         : first(__p.first), second(__p.second) { }
 190 #else
 191       template<typename _U1, typename _U2, typename
 192                enable_if<_ConstructiblePair<_T1, _T2, _U1, _U2>()
 193                          && _ImplicitlyConvertiblePair<_T1, _T2, _U1, _U2>(),
 194                          bool>::type=true>
 195         constexpr pair(const pair<_U1, _U2>& __p)
 196         : first(__p.first), second(__p.second) { }
 197
 198       template<typename _U1, typename _U2, typename
 199                enable_if<_ConstructiblePair<_T1, _T2, _U1, _U2>()
 200                          && !_ImplicitlyConvertiblePair<_T1, _T2, _U1, _U2>(),
 201                          bool>::type=false>
 202         explicit constexpr pair(const pair<_U1, _U2>& __p)
 203         : first(__p.first), second(__p.second) { }
 204
 205       constexpr pair(const pair&) = default;
 206       constexpr pair(pair&&) = default;
 207
 208       // DR 811.
 209       template<typename _U1, typename
 210                enable_if<_ConstructiblePair<_T2, _T2, _T2, _T2>()
 211                          && _MoveConstructiblePair<_T1, _T2, _U1, _T2>()
 212                          && _ImplicitlyConvertiblePair<_T2, _T2, _T2, _T2>()
 213                          && _ImplicitlyMoveConvertiblePair<_T1, _T2,
 214                                                           _U1, _T2>(),
 215                          bool>::type=true>
 216        constexpr pair(_U1&& __x, const _T2& __y)
 217        : first(std::forward<_U1>(__x)), second(__y) { }
 218
 219       template<typename _U1, typename
 220                enable_if<_ConstructiblePair<_T2, _T2, _T2, _T2>()
 221                          && _MoveConstructiblePair<_T1, _T2, _U1, _T2>()
 222                          && (!_ImplicitlyConvertiblePair<_T2, _T2, _T2, _T2>()
 223                              || !_ImplicitlyMoveConvertiblePair<_T1, _T2,
 224                                                                 _U1, _T2>()),
 225                          bool>::type=false>
 226        explicit constexpr pair(_U1&& __x, const _T2& __y)
 227        : first(std::forward<_U1>(__x)), second(__y) { }
 228
 229       template<typename _U2, typename
 230                enable_if<_ConstructiblePair<_T1, _T1, _T1, _T1>()
 231                          && _MoveConstructiblePair<_T1, _T2, _T1, _U2>()
 232                          && _ImplicitlyConvertiblePair<_T1, _T1, _T1, _T1>()
 233                          && _ImplicitlyMoveConvertiblePair<_T1, _T2,
 234                                                            _T1, _U2>(),
 235                          bool>::type=true>
 236        constexpr pair(const _T1& __x, _U2&& __y)
 237        : first(__x), second(std::forward<_U2>(__y)) { }
 238
 239       template<typename _U2, typename
 240                enable_if<_ConstructiblePair<_T1, _T1, _T1, _T1>()
 241                          && _MoveConstructiblePair<_T1, _T2, _T1, _U2>()
 242                          && (!_ImplicitlyConvertiblePair<_T1, _T1, _T1, _T1>()
 243                              || !_ImplicitlyMoveConvertiblePair<_T1, _T2,
 244                                                                 _T1, _U2>()),
 245                          bool>::type=false>
 246        explicit pair(const _T1& __x, _U2&& __y)
 247        : first(__x), second(std::forward<_U2>(__y)) { }
 248
 249       template<typename _U1, typename _U2, typename
 250                enable_if<_MoveConstructiblePair<_T1, _T2, _U1, _U2>()
 251                          && _ImplicitlyMoveConvertiblePair<_T1, _T2,
 252                                                            _U1, _U2>(),
 253                          bool>::type=true>
 254         constexpr pair(_U1&& __x, _U2&& __y)
 255         : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
 256
 257       template<typename _U1, typename _U2, typename
 258                enable_if<_MoveConstructiblePair<_T1, _T2, _U1, _U2>()
 259                          && !_ImplicitlyMoveConvertiblePair<_T1, _T2,
 260                                                             _U1, _U2>(),
 261                          bool>::type=false>
 262         explicit constexpr pair(_U1&& __x, _U2&& __y)
 263         : first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
 264
 265
 266       template<typename _U1, typename _U2, typename
 267                enable_if<_MoveConstructiblePair<_T1, _T2, _U1, _U2>()
 268                          && _ImplicitlyMoveConvertiblePair<_T1, _T2,
 269                                                            _U1, _U2>(),
 270                          bool>::type=true>
 271         constexpr pair(pair<_U1, _U2>&& __p)
 272         : first(std::forward<_U1>(__p.first)),
 273           second(std::forward<_U2>(__p.second)) { }
 274
 275       template<typename _U1, typename _U2, typename
 276                enable_if<_MoveConstructiblePair<_T1, _T2, _U1, _U2>()
 277                          && !_ImplicitlyMoveConvertiblePair<_T1, _T2,
 278                                                            _U1, _U2>(),
 279                          bool>::type=false>
 280         explicit constexpr pair(pair<_U1, _U2>&& __p)
 281         : first(std::forward<_U1>(__p.first)),
 282           second(std::forward<_U2>(__p.second)) { }
 283
 284       template<typename... _Args1, typename... _Args2>
 285         pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
 286
 287       pair&
 288       operator=(const pair& __p)
 289       {
 290         first = __p.first;
 291         second = __p.second;
 292         return *this;
 293       }
 294
 295       pair&
 296       operator=(pair&& __p)
 297       noexcept(__and_<is_nothrow_move_assignable<_T1>,
 298                       is_nothrow_move_assignable<_T2>>::value)
 299       {
 300         first = std::forward<first_type>(__p.first);
 301         second = std::forward<second_type>(__p.second);
 302         return *this;
 303       }
 304
 305       template<typename _U1, typename _U2>
 306         pair&
 307         operator=(const pair<_U1, _U2>& __p)
 308         {
 309           first = __p.first;
 310           second = __p.second;
 311           return *this;
 312         }
 313
 314       template<typename _U1, typename _U2>
 315         pair&
 316         operator=(pair<_U1, _U2>&& __p)
 317         {
 318           first = std::forward<_U1>(__p.first);
 319           second = std::forward<_U2>(__p.second);
 320           return *this;
 321         }
 322
 323       void
 324       swap(pair& __p)
 325       noexcept(__is_nothrow_swappable<_T1>::value
 326                && __is_nothrow_swappable<_T2>::value)
 327       {
 328         using std::swap;
 329         swap(first, __p.first);
 330         swap(second, __p.second);
 331       }
 332
 333     private:
 334       template<typename... _Args1, std::size_t... _Indexes1,
 335                typename... _Args2, std::size_t... _Indexes2>
 336         pair(tuple<_Args1...>&, tuple<_Args2...>&,
 337              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
 338 #endif
 339     };
 340
 341   /// Two pairs of the same type are equal iff their members are equal.
 342   template<typename _T1, typename _T2>
 343     inline _GLIBCXX_CONSTEXPR bool
 344     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 345     { return __x.first == __y.first && __x.second == __y.second; }
 346
 347   /// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
 348   template<typename _T1, typename _T2>
 349     inline _GLIBCXX_CONSTEXPR bool
 350     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 351     { return __x.first < __y.first
 352              || (!(__y.first < __x.first) && __x.second < __y.second); }
 353
 354   /// Uses @c operator== to find the result.
 355   template<typename _T1, typename _T2>
 356     inline _GLIBCXX_CONSTEXPR bool
 357     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 358     { return !(__x == __y); }
 359
 360   /// Uses @c operator< to find the result.
 361   template<typename _T1, typename _T2>
 362     inline _GLIBCXX_CONSTEXPR bool
 363     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 364     { return __y < __x; }
 365
 366   /// Uses @c operator< to find the result.
 367   template<typename _T1, typename _T2>
 368     inline _GLIBCXX_CONSTEXPR bool
 369     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 370     { return !(__y < __x); }
 371
 372   /// Uses @c operator< to find the result.
 373   template<typename _T1, typename _T2>
 374     inline _GLIBCXX_CONSTEXPR bool
 375     operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
 376     { return !(__x < __y); }
 377
 378 #if __cplusplus >= 201103L
 379   /// See std::pair::swap().
 380   // Note:  no std::swap overloads in C++03 mode, this has performance
 381   //        implications, see, eg, libstdc++/38466.
 382   template<typename _T1, typename _T2>
 383     inline void
 384     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
 385     noexcept(noexcept(__x.swap(__y)))
 386     { __x.swap(__y); }
 387 #endif
 388
 389   /**
 390    *  @brief A convenience wrapper for creating a pair from two objects.
 391    *  @param  __x  The first object.
 392    *  @param  __y  The second object.
 393    *  @return   A newly-constructed pair<> object of the appropriate type.
 394    *
 395    *  The standard requires that the objects be passed by reference-to-const,
 396    *  but LWG issue #181 says they should be passed by const value.  We follow
 397    *  the LWG by default.
 398    */
 399   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 400   // 181.  make_pair() unintended behavior
 401 #if __cplusplus >= 201103L
 402   // NB: DR 706.
 403   template<typename _T1, typename _T2>
 404     constexpr pair<typename __decay_and_strip<_T1>::__type,
 405                    typename __decay_and_strip<_T2>::__type>
 406     make_pair(_T1&& __x, _T2&& __y)
 407     {
 408       typedef typename __decay_and_strip<_T1>::__type __ds_type1;
 409       typedef typename __decay_and_strip<_T2>::__type __ds_type2;
 410       typedef pair<__ds_type1, __ds_type2>            __pair_type;
 411       return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
 412     }
 413 #else
 414   template<typename _T1, typename _T2>
 415     inline pair<_T1, _T2>
 416     make_pair(_T1 __x, _T2 __y)
 417     { return pair<_T1, _T2>(__x, __y); }
 418 #endif
 419
 420   /// @}
 421
 422 _GLIBCXX_END_NAMESPACE_VERSION
 423 } // namespace std
 424
 425 #endif /* _STL_PAIR_H */