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

   1 // Allocator traits -*- C++ -*-
   2
   3 // Copyright (C) 2011-2016 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 /** @file bits/alloc_traits.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{memory}
  28  */
  29
  30 #ifndef _ALLOC_TRAITS_H
  31 #define _ALLOC_TRAITS_H 1
  32
  33 #if __cplusplus >= 201103L
  34
  35 #include <bits/memoryfwd.h>
  36 #include <bits/ptr_traits.h>
  37 #include <ext/numeric_traits.h>
  38
  39 #define __cpp_lib_allocator_traits_is_always_equal 201411
  40
  41 namespace std _GLIBCXX_VISIBILITY(default)
  42 {
  43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  44
  45   struct __allocator_traits_base
  46   {
  47     template<typename _Alloc, typename _Up>
  48       using __rebind = typename _Alloc::template rebind<_Up>::other;
  49
  50   protected:
  51     template<typename _Tp>
  52       using __pointer = typename _Tp::pointer;
  53     template<typename _Tp>
  54       using __c_pointer = typename _Tp::const_pointer;
  55     template<typename _Tp>
  56       using __v_pointer = typename _Tp::void_pointer;
  57     template<typename _Tp>
  58       using __cv_pointer = typename _Tp::const_void_pointer;
  59     template<typename _Tp>
  60       using __diff_type = typename _Tp::difference_type;
  61     template<typename _Tp>
  62       using __size_type = typename _Tp::size_type;
  63     template<typename _Tp>
  64       using __pocca = typename _Tp::propagate_on_container_copy_assignment;
  65     template<typename _Tp>
  66       using __pocma = typename _Tp::propagate_on_container_move_assignment;
  67     template<typename _Tp>
  68       using __pocs = typename _Tp::propagate_on_container_swap;
  69     template<typename _Tp>
  70       using __equal = typename _Tp::is_always_equal;
  71   };
  72
  73   template<typename _Alloc, typename _Up>
  74     using __alloc_rebind = __detected_or_t_<__replace_first_arg_t,
  75                                             __allocator_traits_base::__rebind,
  76                                             _Alloc, _Up>;
  77
  78   /**
  79    * @brief  Uniform interface to all allocator types.
  80    * @ingroup allocators
  81   */
  82   template<typename _Alloc>
  83     struct allocator_traits : __allocator_traits_base
  84     {
  85       /// The allocator type
  86       typedef _Alloc allocator_type;
  87       /// The allocated type
  88       typedef typename _Alloc::value_type value_type;
  89
  90       /**
  91        * @brief   The allocator's pointer type.
  92        *
  93        * @c Alloc::pointer if that type exists, otherwise @c value_type*
  94       */
  95       using pointer = __detected_or_t<value_type*, __pointer, _Alloc>;
  96
  97       /**
  98        * @brief   The allocator's const pointer type.
  99        *
 100        * @c Alloc::const_pointer if that type exists, otherwise
 101        * <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
 102       */
 103       using const_pointer
 104         = __detected_or_t<__ptr_rebind<pointer, const value_type>,
 105                           __c_pointer, _Alloc>;
 106
 107       /**
 108        * @brief   The allocator's void pointer type.
 109        *
 110        * @c Alloc::void_pointer if that type exists, otherwise
 111        * <tt> pointer_traits<pointer>::rebind<void> </tt>
 112       */
 113       using void_pointer
 114         = __detected_or_t<__ptr_rebind<pointer, void>, __v_pointer, _Alloc>;
 115
 116       /**
 117        * @brief   The allocator's const void pointer type.
 118        *
 119        * @c Alloc::const_void_pointer if that type exists, otherwise
 120        * <tt> pointer_traits<pointer>::rebind<const void> </tt>
 121       */
 122       using const_void_pointer
 123         = __detected_or_t<__ptr_rebind<pointer, const void>, __cv_pointer,
 124                           _Alloc>;
 125
 126       /**
 127        * @brief   The allocator's difference type
 128        *
 129        * @c Alloc::difference_type if that type exists, otherwise
 130        * <tt> pointer_traits<pointer>::difference_type </tt>
 131       */
 132       using difference_type
 133         = __detected_or_t<typename pointer_traits<pointer>::difference_type,
 134                           __diff_type, _Alloc>;
 135
 136       /**
 137        * @brief   The allocator's size type
 138        *
 139        * @c Alloc::size_type if that type exists, otherwise
 140        * <tt> make_unsigned<difference_type>::type </tt>
 141       */
 142       using size_type
 143         = __detected_or_t<typename make_unsigned<difference_type>::type,
 144                           __size_type, _Alloc>;
 145
 146       /**
 147        * @brief   How the allocator is propagated on copy assignment
 148        *
 149        * @c Alloc::propagate_on_container_copy_assignment if that type exists,
 150        * otherwise @c false_type
 151       */
 152       using propagate_on_container_copy_assignment
 153         = __detected_or_t<false_type, __pocca, _Alloc>;
 154
 155       /**
 156        * @brief   How the allocator is propagated on move assignment
 157        *
 158        * @c Alloc::propagate_on_container_move_assignment if that type exists,
 159        * otherwise @c false_type
 160       */
 161       using propagate_on_container_move_assignment
 162         = __detected_or_t<false_type, __pocma, _Alloc>;
 163
 164       /**
 165        * @brief   How the allocator is propagated on swap
 166        *
 167        * @c Alloc::propagate_on_container_swap if that type exists,
 168        * otherwise @c false_type
 169       */
 170       using propagate_on_container_swap
 171         = __detected_or_t<false_type, __pocs, _Alloc>;
 172
 173       /**
 174        * @brief   Whether all instances of the allocator type compare equal.
 175        *
 176        * @c Alloc::is_always_equal if that type exists,
 177        * otherwise @c is_empty<Alloc>::type
 178       */
 179       using is_always_equal
 180         = __detected_or_t<typename is_empty<_Alloc>::type, __equal, _Alloc>;
 181
 182       template<typename _Tp>
 183         using rebind_alloc = __alloc_rebind<_Alloc, _Tp>;
 184       template<typename _Tp>
 185         using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
 186
 187       static_assert(!is_same<rebind_alloc<value_type>, __undefined>::value,
 188           "allocator defines rebind or is like Alloc<T, Args>");
 189
 190     private:
 191       template<typename _Alloc2>
 192         static auto
 193         _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint, int)
 194         -> decltype(__a.allocate(__n, __hint))
 195         { return __a.allocate(__n, __hint); }
 196
 197       template<typename _Alloc2>
 198         static pointer
 199         _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer, ...)
 200         { return __a.allocate(__n); }
 201
 202       template<typename _Tp, typename... _Args>
 203         struct __construct_helper
 204         {
 205           template<typename _Alloc2,
 206             typename = decltype(std::declval<_Alloc2*>()->construct(
 207                   std::declval<_Tp*>(), std::declval<_Args>()...))>
 208             static true_type __test(int);
 209
 210           template<typename>
 211             static false_type __test(...);
 212
 213           using type = decltype(__test<_Alloc>(0));
 214         };
 215
 216       template<typename _Tp, typename... _Args>
 217         using __has_construct
 218           = typename __construct_helper<_Tp, _Args...>::type;
 219
 220       template<typename _Tp, typename... _Args>
 221         static _Require<__has_construct<_Tp, _Args...>>
 222         _S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
 223         { __a.construct(__p, std::forward<_Args>(__args)...); }
 224
 225       template<typename _Tp, typename... _Args>
 226         static
 227         _Require<__and_<__not_<__has_construct<_Tp, _Args...>>,
 228                                is_constructible<_Tp, _Args...>>>
 229         _S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
 230         { ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); }
 231
 232       template<typename _Alloc2, typename _Tp>
 233         static auto
 234         _S_destroy(_Alloc2& __a, _Tp* __p, int)
 235         -> decltype(__a.destroy(__p))
 236         { __a.destroy(__p); }
 237
 238       template<typename _Alloc2, typename _Tp>
 239         static void
 240         _S_destroy(_Alloc2&, _Tp* __p, ...)
 241         { __p->~_Tp(); }
 242
 243       template<typename _Alloc2>
 244         static auto
 245         _S_max_size(_Alloc2& __a, int)
 246         -> decltype(__a.max_size())
 247         { return __a.max_size(); }
 248
 249       template<typename _Alloc2>
 250         static size_type
 251         _S_max_size(_Alloc2&, ...)
 252         {
 253           // _GLIBCXX_RESOLVE_LIB_DEFECTS
 254           // 2466. allocator_traits::max_size() default behavior is incorrect
 255           return __gnu_cxx::__numeric_traits<size_type>::__max
 256             / sizeof(value_type);
 257         }
 258
 259       template<typename _Alloc2>
 260         static auto
 261         _S_select(_Alloc2& __a, int)
 262         -> decltype(__a.select_on_container_copy_construction())
 263         { return __a.select_on_container_copy_construction(); }
 264
 265       template<typename _Alloc2>
 266         static _Alloc2
 267         _S_select(_Alloc2& __a, ...)
 268         { return __a; }
 269
 270     public:
 271
 272       /**
 273        *  @brief  Allocate memory.
 274        *  @param  __a  An allocator.
 275        *  @param  __n  The number of objects to allocate space for.
 276        *
 277        *  Calls @c a.allocate(n)
 278       */
 279       static pointer
 280       allocate(_Alloc& __a, size_type __n)
 281       { return __a.allocate(__n); }
 282
 283       /**
 284        *  @brief  Allocate memory.
 285        *  @param  __a  An allocator.
 286        *  @param  __n  The number of objects to allocate space for.
 287        *  @param  __hint Aid to locality.
 288        *  @return Memory of suitable size and alignment for @a n objects
 289        *          of type @c value_type
 290        *
 291        *  Returns <tt> a.allocate(n, hint) </tt> if that expression is
 292        *  well-formed, otherwise returns @c a.allocate(n)
 293       */
 294       static pointer
 295       allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
 296       { return _S_allocate(__a, __n, __hint, 0); }
 297
 298       /**
 299        *  @brief  Deallocate memory.
 300        *  @param  __a  An allocator.
 301        *  @param  __p  Pointer to the memory to deallocate.
 302        *  @param  __n  The number of objects space was allocated for.
 303        *
 304        *  Calls <tt> a.deallocate(p, n) </tt>
 305       */
 306       static void
 307       deallocate(_Alloc& __a, pointer __p, size_type __n)
 308       { __a.deallocate(__p, __n); }
 309
 310       /**
 311        *  @brief  Construct an object of type @a _Tp
 312        *  @param  __a  An allocator.
 313        *  @param  __p  Pointer to memory of suitable size and alignment for Tp
 314        *  @param  __args Constructor arguments.
 315        *
 316        *  Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
 317        *  if that expression is well-formed, otherwise uses placement-new
 318        *  to construct an object of type @a _Tp at location @a __p from the
 319        *  arguments @a __args...
 320       */
 321       template<typename _Tp, typename... _Args>
 322         static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
 323         -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...))
 324         { _S_construct(__a, __p, std::forward<_Args>(__args)...); }
 325
 326       /**
 327        *  @brief  Destroy an object of type @a _Tp
 328        *  @param  __a  An allocator.
 329        *  @param  __p  Pointer to the object to destroy
 330        *
 331        *  Calls @c __a.destroy(__p) if that expression is well-formed,
 332        *  otherwise calls @c __p->~_Tp()
 333       */
 334       template<typename _Tp>
 335         static void destroy(_Alloc& __a, _Tp* __p)
 336         { _S_destroy(__a, __p, 0); }
 337
 338       /**
 339        *  @brief  The maximum supported allocation size
 340        *  @param  __a  An allocator.
 341        *  @return @c __a.max_size() or @c numeric_limits<size_type>::max()
 342        *
 343        *  Returns @c __a.max_size() if that expression is well-formed,
 344        *  otherwise returns @c numeric_limits<size_type>::max()
 345       */
 346       static size_type max_size(const _Alloc& __a) noexcept
 347       { return _S_max_size(__a, 0); }
 348
 349       /**
 350        *  @brief  Obtain an allocator to use when copying a container.
 351        *  @param  __rhs  An allocator.
 352        *  @return @c __rhs.select_on_container_copy_construction() or @a __rhs
 353        *
 354        *  Returns @c __rhs.select_on_container_copy_construction() if that
 355        *  expression is well-formed, otherwise returns @a __rhs
 356       */
 357       static _Alloc
 358       select_on_container_copy_construction(const _Alloc& __rhs)
 359       { return _S_select(__rhs, 0); }
 360     };
 361
 362   /// Partial specialization for std::allocator.
 363   template<typename _Tp>
 364     struct allocator_traits<allocator<_Tp>>
 365     {
 366       /// The allocator type
 367       using allocator_type = allocator<_Tp>;
 368       /// The allocated type
 369       using value_type = _Tp;
 370
 371       /// The allocator's pointer type.
 372       using pointer = _Tp*;
 373
 374       /// The allocator's const pointer type.
 375       using const_pointer = const _Tp*;
 376
 377       /// The allocator's void pointer type.
 378       using void_pointer = void*;
 379
 380       /// The allocator's const void pointer type.
 381       using const_void_pointer = const void*;
 382
 383       /// The allocator's difference type
 384       using difference_type = std::ptrdiff_t;
 385
 386       /// The allocator's size type
 387       using size_type = std::size_t;
 388
 389       /// How the allocator is propagated on copy assignment
 390       using propagate_on_container_copy_assignment = false_type;
 391
 392       /// How the allocator is propagated on move assignment
 393       using propagate_on_container_move_assignment = true_type;
 394
 395       /// How the allocator is propagated on swap
 396       using propagate_on_container_swap = false_type;
 397
 398       /// Whether all instances of the allocator type compare equal.
 399       using is_always_equal = true_type;
 400
 401       template<typename _Up>
 402         using rebind_alloc = allocator<_Up>;
 403
 404       template<typename _Up>
 405         using rebind_traits = allocator_traits<allocator<_Up>>;
 406
 407       /**
 408        *  @brief  Allocate memory.
 409        *  @param  __a  An allocator.
 410        *  @param  __n  The number of objects to allocate space for.
 411        *
 412        *  Calls @c a.allocate(n)
 413       */
 414       static pointer
 415       allocate(allocator_type& __a, size_type __n)
 416       { return __a.allocate(__n); }
 417
 418       /**
 419        *  @brief  Allocate memory.
 420        *  @param  __a  An allocator.
 421        *  @param  __n  The number of objects to allocate space for.
 422        *  @param  __hint Aid to locality.
 423        *  @return Memory of suitable size and alignment for @a n objects
 424        *          of type @c value_type
 425        *
 426        *  Returns <tt> a.allocate(n, hint) </tt>
 427       */
 428       static pointer
 429       allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
 430       { return __a.allocate(__n, __hint); }
 431
 432       /**
 433        *  @brief  Deallocate memory.
 434        *  @param  __a  An allocator.
 435        *  @param  __p  Pointer to the memory to deallocate.
 436        *  @param  __n  The number of objects space was allocated for.
 437        *
 438        *  Calls <tt> a.deallocate(p, n) </tt>
 439       */
 440       static void
 441       deallocate(allocator_type& __a, pointer __p, size_type __n)
 442       { __a.deallocate(__p, __n); }
 443
 444       /**
 445        *  @brief  Construct an object of type @a _Up
 446        *  @param  __a  An allocator.
 447        *  @param  __p  Pointer to memory of suitable size and alignment for Tp
 448        *  @param  __args Constructor arguments.
 449        *
 450        *  Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
 451       */
 452       template<typename _Up, typename... _Args>
 453         static void
 454         construct(allocator_type& __a, _Up* __p, _Args&&... __args)
 455         { __a.construct(__p, std::forward<_Args>(__args)...); }
 456
 457       /**
 458        *  @brief  Destroy an object of type @a _Up
 459        *  @param  __a  An allocator.
 460        *  @param  __p  Pointer to the object to destroy
 461        *
 462        *  Calls @c __a.destroy(__p).
 463       */
 464       template<typename _Up>
 465         static void
 466         destroy(allocator_type& __a, _Up* __p)
 467         { __a.destroy(__p); }
 468
 469       /**
 470        *  @brief  The maximum supported allocation size
 471        *  @param  __a  An allocator.
 472        *  @return @c __a.max_size()
 473       */
 474       static size_type
 475       max_size(const allocator_type& __a) noexcept
 476       { return __a.max_size(); }
 477
 478       /**
 479        *  @brief  Obtain an allocator to use when copying a container.
 480        *  @param  __rhs  An allocator.
 481        *  @return @c __rhs
 482       */
 483       static allocator_type
 484       select_on_container_copy_construction(const allocator_type& __rhs)
 485       { return __rhs; }
 486     };
 487
 488
 489   template<typename _Alloc>
 490     inline void
 491     __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type)
 492     { __one = __two; }
 493
 494   template<typename _Alloc>
 495     inline void
 496     __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type)
 497     { }
 498
 499   template<typename _Alloc>
 500     inline void __alloc_on_copy(_Alloc& __one, const _Alloc& __two)
 501     {
 502       typedef allocator_traits<_Alloc> __traits;
 503       typedef typename __traits::propagate_on_container_copy_assignment __pocca;
 504       __do_alloc_on_copy(__one, __two, __pocca());
 505     }
 506
 507   template<typename _Alloc>
 508     inline _Alloc __alloc_on_copy(const _Alloc& __a)
 509     {
 510       typedef allocator_traits<_Alloc> __traits;
 511       return __traits::select_on_container_copy_construction(__a);
 512     }
 513
 514   template<typename _Alloc>
 515     inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type)
 516     { __one = std::move(__two); }
 517
 518   template<typename _Alloc>
 519     inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type)
 520     { }
 521
 522   template<typename _Alloc>
 523     inline void __alloc_on_move(_Alloc& __one, _Alloc& __two)
 524     {
 525       typedef allocator_traits<_Alloc> __traits;
 526       typedef typename __traits::propagate_on_container_move_assignment __pocma;
 527       __do_alloc_on_move(__one, __two, __pocma());
 528     }
 529
 530   template<typename _Alloc>
 531     inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type)
 532     {
 533       using std::swap;
 534       swap(__one, __two);
 535     }
 536
 537   template<typename _Alloc>
 538     inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type)
 539     { }
 540
 541   template<typename _Alloc>
 542     inline void __alloc_on_swap(_Alloc& __one, _Alloc& __two)
 543     {
 544       typedef allocator_traits<_Alloc> __traits;
 545       typedef typename __traits::propagate_on_container_swap __pocs;
 546       __do_alloc_on_swap(__one, __two, __pocs());
 547     }
 548
 549   template<typename _Alloc>
 550     class __is_copy_insertable_impl
 551     {
 552       typedef allocator_traits<_Alloc> _Traits;
 553
 554       template<typename _Up, typename
 555                = decltype(_Traits::construct(std::declval<_Alloc&>(),
 556                                              std::declval<_Up*>(),
 557                                              std::declval<const _Up&>()))>
 558         static true_type
 559         _M_select(int);
 560
 561       template<typename _Up>
 562         static false_type
 563         _M_select(...);
 564
 565     public:
 566       typedef decltype(_M_select<typename _Alloc::value_type>(0)) type;
 567     };
 568
 569   // true if _Alloc::value_type is CopyInsertable into containers using _Alloc
 570   template<typename _Alloc>
 571     struct __is_copy_insertable
 572     : __is_copy_insertable_impl<_Alloc>::type
 573     { };
 574
 575   // std::allocator<_Tp> just requires CopyConstructible
 576   template<typename _Tp>
 577     struct __is_copy_insertable<allocator<_Tp>>
 578     : is_copy_constructible<_Tp>
 579     { };
 580
 581 _GLIBCXX_END_NAMESPACE_VERSION
 582 } // namespace std
 583
 584 #endif
 585 #endif