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

   1 // Allocator traits -*- C++ -*-
   2
   3 // Copyright (C) 2011-2013 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 namespace std _GLIBCXX_VISIBILITY(default)
  40 {
  41 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  42
  43   template<typename _Alloc, typename _Tp>
  44     class __alloctr_rebind_helper
  45     {
  46       template<typename _Alloc2, typename _Tp2>
  47         static constexpr bool
  48         _S_chk(typename _Alloc2::template rebind<_Tp2>::other*)
  49         { return true; }
  50
  51       template<typename, typename>
  52         static constexpr bool
  53         _S_chk(...)
  54         { return false; }
  55
  56     public:
  57       static const bool __value = _S_chk<_Alloc, _Tp>(nullptr);
  58     };
  59
  60   template<typename _Alloc, typename _Tp>
  61     const bool __alloctr_rebind_helper<_Alloc, _Tp>::__value;
  62
  63   template<typename _Alloc, typename _Tp,
  64            bool = __alloctr_rebind_helper<_Alloc, _Tp>::__value>
  65     struct __alloctr_rebind;
  66
  67   template<typename _Alloc, typename _Tp>
  68     struct __alloctr_rebind<_Alloc, _Tp, true>
  69     {
  70       typedef typename _Alloc::template rebind<_Tp>::other __type;
  71     };
  72
  73   template<template<typename, typename...> class _Alloc, typename _Tp,
  74             typename _Up, typename... _Args>
  75     struct __alloctr_rebind<_Alloc<_Up, _Args...>, _Tp, false>
  76     {
  77       typedef _Alloc<_Tp, _Args...> __type;
  78     };
  79
  80   /**
  81    * @brief  Uniform interface to all allocator types.
  82    * @ingroup allocators
  83   */
  84   template<typename _Alloc>
  85     struct allocator_traits
  86     {
  87       /// The allocator type
  88       typedef _Alloc allocator_type;
  89       /// The allocated type
  90       typedef typename _Alloc::value_type value_type;
  91
  92 #define _GLIBCXX_ALLOC_TR_NESTED_TYPE(_NTYPE, _ALT) \
  93   private: \
  94   template<typename _Tp> \
  95     static typename _Tp::_NTYPE _S_##_NTYPE##_helper(_Tp*); \
  96   static _ALT _S_##_NTYPE##_helper(...); \
  97     typedef decltype(_S_##_NTYPE##_helper((_Alloc*)0)) __##_NTYPE; \
  98   public:
  99
 100 _GLIBCXX_ALLOC_TR_NESTED_TYPE(pointer, value_type*)
 101
 102       /**
 103        * @brief   The allocator's pointer type.
 104        *
 105        * @c Alloc::pointer if that type exists, otherwise @c value_type*
 106       */
 107       typedef __pointer pointer;
 108
 109 _GLIBCXX_ALLOC_TR_NESTED_TYPE(const_pointer,
 110   typename pointer_traits<pointer>::template rebind<const value_type>)
 111
 112       /**
 113        * @brief   The allocator's const pointer type.
 114        *
 115        * @c Alloc::const_pointer if that type exists, otherwise
 116        * <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
 117       */
 118       typedef __const_pointer const_pointer;
 119
 120 _GLIBCXX_ALLOC_TR_NESTED_TYPE(void_pointer,
 121   typename pointer_traits<pointer>::template rebind<void>)
 122
 123       /**
 124        * @brief   The allocator's void pointer type.
 125        *
 126        * @c Alloc::void_pointer if that type exists, otherwise
 127        * <tt> pointer_traits<pointer>::rebind<void> </tt>
 128       */
 129       typedef __void_pointer void_pointer;
 130
 131 _GLIBCXX_ALLOC_TR_NESTED_TYPE(const_void_pointer,
 132   typename pointer_traits<pointer>::template rebind<const void>)
 133
 134       /**
 135        * @brief   The allocator's const void pointer type.
 136        *
 137        * @c Alloc::const_void_pointer if that type exists, otherwise
 138        * <tt> pointer_traits<pointer>::rebind<const void> </tt>
 139       */
 140       typedef __const_void_pointer const_void_pointer;
 141
 142 _GLIBCXX_ALLOC_TR_NESTED_TYPE(difference_type,
 143                               typename pointer_traits<pointer>::difference_type)
 144
 145       /**
 146        * @brief   The allocator's difference type
 147        *
 148        * @c Alloc::difference_type if that type exists, otherwise
 149        * <tt> pointer_traits<pointer>::difference_type </tt>
 150       */
 151       typedef __difference_type difference_type;
 152
 153 _GLIBCXX_ALLOC_TR_NESTED_TYPE(size_type,
 154                               typename make_unsigned<difference_type>::type)
 155
 156       /**
 157        * @brief   The allocator's size type
 158        *
 159        * @c Alloc::size_type if that type exists, otherwise
 160        * <tt> make_unsigned<difference_type>::type </tt>
 161       */
 162       typedef __size_type size_type;
 163
 164 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_copy_assignment,
 165                               false_type)
 166
 167       /**
 168        * @brief   How the allocator is propagated on copy assignment
 169        *
 170        * @c Alloc::propagate_on_container_copy_assignment if that type exists,
 171        * otherwise @c false_type
 172       */
 173       typedef __propagate_on_container_copy_assignment
 174         propagate_on_container_copy_assignment;
 175
 176 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_move_assignment,
 177                               false_type)
 178
 179       /**
 180        * @brief   How the allocator is propagated on move assignment
 181        *
 182        * @c Alloc::propagate_on_container_move_assignment if that type exists,
 183        * otherwise @c false_type
 184       */
 185       typedef __propagate_on_container_move_assignment
 186         propagate_on_container_move_assignment;
 187
 188 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_swap,
 189                               false_type)
 190
 191       /**
 192        * @brief   How the allocator is propagated on swap
 193        *
 194        * @c Alloc::propagate_on_container_swap if that type exists,
 195        * otherwise @c false_type
 196       */
 197       typedef __propagate_on_container_swap propagate_on_container_swap;
 198
 199 #undef _GLIBCXX_ALLOC_TR_NESTED_TYPE
 200
 201       template<typename _Tp>
 202         using rebind_alloc = typename __alloctr_rebind<_Alloc, _Tp>::__type;
 203       template<typename _Tp>
 204         using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
 205
 206     private:
 207       template<typename _Alloc2>
 208         struct __allocate_helper
 209         {
 210           template<typename _Alloc3,
 211             typename = decltype(std::declval<_Alloc3*>()->allocate(
 212                   std::declval<size_type>(),
 213                   std::declval<const_void_pointer>()))>
 214             static true_type __test(int);
 215
 216           template<typename>
 217             static false_type __test(...);
 218
 219           typedef decltype(__test<_Alloc>(0)) type;
 220           static const bool value = type::value;
 221         };
 222
 223       template<typename _Alloc2>
 224         static typename
 225         enable_if<__allocate_helper<_Alloc2>::value, pointer>::type
 226         _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint)
 227         { return __a.allocate(__n, __hint); }
 228
 229       template<typename _Alloc2>
 230         static typename
 231         enable_if<!__allocate_helper<_Alloc2>::value, pointer>::type
 232         _S_allocate(_Alloc2& __a, size_type __n, ...)
 233         { return __a.allocate(__n); }
 234
 235       template<typename _Tp, typename... _Args>
 236         struct __construct_helper
 237         {
 238           template<typename _Alloc2,
 239             typename = decltype(std::declval<_Alloc2*>()->construct(
 240                   std::declval<_Tp*>(), std::declval<_Args>()...))>
 241             static true_type __test(int);
 242
 243           template<typename>
 244             static false_type __test(...);
 245
 246           typedef decltype(__test<_Alloc>(0)) type;
 247           static const bool value = type::value;
 248         };
 249
 250       template<typename _Tp, typename... _Args>
 251         static typename
 252         enable_if<__construct_helper<_Tp, _Args...>::value, void>::type
 253         _S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
 254         { __a.construct(__p, std::forward<_Args>(__args)...); }
 255
 256       template<typename _Tp, typename... _Args>
 257         static typename
 258         enable_if<__and_<__not_<__construct_helper<_Tp, _Args...>>,
 259                          is_constructible<_Tp, _Args...>>::value, void>::type
 260         _S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
 261         { ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); }
 262
 263       template<typename _Tp>
 264         struct __destroy_helper
 265         {
 266           template<typename _Alloc2,
 267             typename = decltype(std::declval<_Alloc2*>()->destroy(
 268                   std::declval<_Tp*>()))>
 269             static true_type __test(int);
 270
 271           template<typename>
 272             static false_type __test(...);
 273
 274           typedef decltype(__test<_Alloc>(0)) type;
 275           static const bool value = type::value;
 276         };
 277
 278       template<typename _Tp>
 279         static typename enable_if<__destroy_helper<_Tp>::value, void>::type
 280         _S_destroy(_Alloc& __a, _Tp* __p)
 281         { __a.destroy(__p); }
 282
 283       template<typename _Tp>
 284         static typename enable_if<!__destroy_helper<_Tp>::value, void>::type
 285         _S_destroy(_Alloc&, _Tp* __p)
 286         { __p->~_Tp(); }
 287
 288       template<typename _Alloc2>
 289         struct __maxsize_helper
 290         {
 291           template<typename _Alloc3,
 292             typename = decltype(std::declval<_Alloc3*>()->max_size())>
 293             static true_type __test(int);
 294
 295           template<typename>
 296             static false_type __test(...);
 297
 298           typedef decltype(__test<_Alloc2>(0)) type;
 299           static const bool value = type::value;
 300         };
 301
 302       template<typename _Alloc2>
 303         static typename
 304         enable_if<__maxsize_helper<_Alloc2>::value, size_type>::type
 305         _S_max_size(_Alloc2& __a)
 306         { return __a.max_size(); }
 307
 308       template<typename _Alloc2>
 309         static typename
 310         enable_if<!__maxsize_helper<_Alloc2>::value, size_type>::type
 311         _S_max_size(_Alloc2&)
 312         { return __gnu_cxx::__numeric_traits<size_type>::__max; }
 313
 314       template<typename _Alloc2>
 315         struct __select_helper
 316         {
 317           template<typename _Alloc3, typename
 318             = decltype(std::declval<_Alloc3*>()
 319                 ->select_on_container_copy_construction())>
 320             static true_type __test(int);
 321
 322           template<typename>
 323             static false_type __test(...);
 324
 325           typedef decltype(__test<_Alloc2>(0)) type;
 326           static const bool value = type::value;
 327         };
 328       template<typename _Alloc2>
 329         static typename
 330         enable_if<__select_helper<_Alloc2>::value, _Alloc2>::type
 331         _S_select(_Alloc2& __a)
 332         { return __a.select_on_container_copy_construction(); }
 333
 334       template<typename _Alloc2>
 335         static typename
 336         enable_if<!__select_helper<_Alloc2>::value, _Alloc2>::type
 337         _S_select(_Alloc2& __a)
 338         { return __a; }
 339
 340     public:
 341
 342       /**
 343        *  @brief  Allocate memory.
 344        *  @param  __a  An allocator.
 345        *  @param  __n  The number of objects to allocate space for.
 346        *
 347        *  Calls @c a.allocate(n)
 348       */
 349       static pointer
 350       allocate(_Alloc& __a, size_type __n)
 351       { return __a.allocate(__n); }
 352
 353       /**
 354        *  @brief  Allocate memory.
 355        *  @param  __a  An allocator.
 356        *  @param  __n  The number of objects to allocate space for.
 357        *  @param  __hint Aid to locality.
 358        *  @return Memory of suitable size and alignment for @a n objects
 359        *          of type @c value_type
 360        *
 361        *  Returns <tt> a.allocate(n, hint) </tt> if that expression is
 362        *  well-formed, otherwise returns @c a.allocate(n)
 363       */
 364       static pointer
 365       allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
 366       { return _S_allocate(__a, __n, __hint); }
 367
 368       /**
 369        *  @brief  Deallocate memory.
 370        *  @param  __a  An allocator.
 371        *  @param  __p  Pointer to the memory to deallocate.
 372        *  @param  __n  The number of objects space was allocated for.
 373        *
 374        *  Calls <tt> a.deallocate(p, n) </tt>
 375       */
 376       static void deallocate(_Alloc& __a, pointer __p, size_type __n)
 377       { __a.deallocate(__p, __n); }
 378
 379       /**
 380        *  @brief  Construct an object of type @a _Tp
 381        *  @param  __a  An allocator.
 382        *  @param  __p  Pointer to memory of suitable size and alignment for Tp
 383        *  @param  __args Constructor arguments.
 384        *
 385        *  Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
 386        *  if that expression is well-formed, otherwise uses placement-new
 387        *  to construct an object of type @a _Tp at location @a __p from the
 388        *  arguments @a __args...
 389       */
 390       template<typename _Tp, typename... _Args>
 391         static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
 392         -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...))
 393         { _S_construct(__a, __p, std::forward<_Args>(__args)...); }
 394
 395       /**
 396        *  @brief  Destroy an object of type @a _Tp
 397        *  @param  __a  An allocator.
 398        *  @param  __p  Pointer to the object to destroy
 399        *
 400        *  Calls @c __a.destroy(__p) if that expression is well-formed,
 401        *  otherwise calls @c __p->~_Tp()
 402       */
 403       template <class _Tp>
 404         static void destroy(_Alloc& __a, _Tp* __p)
 405         { _S_destroy(__a, __p); }
 406
 407       /**
 408        *  @brief  The maximum supported allocation size
 409        *  @param  __a  An allocator.
 410        *  @return @c __a.max_size() or @c numeric_limits<size_type>::max()
 411        *
 412        *  Returns @c __a.max_size() if that expression is well-formed,
 413        *  otherwise returns @c numeric_limits<size_type>::max()
 414       */
 415       static size_type max_size(const _Alloc& __a) noexcept
 416       { return _S_max_size(__a); }
 417
 418       /**
 419        *  @brief  Obtain an allocator to use when copying a container.
 420        *  @param  __rhs  An allocator.
 421        *  @return @c __rhs.select_on_container_copy_construction() or @a __rhs
 422        *
 423        *  Returns @c __rhs.select_on_container_copy_construction() if that
 424        *  expression is well-formed, otherwise returns @a __rhs
 425       */
 426       static _Alloc
 427       select_on_container_copy_construction(const _Alloc& __rhs)
 428       { return _S_select(__rhs); }
 429     };
 430
 431   template<typename _Alloc>
 432   template<typename _Alloc2>
 433     const bool allocator_traits<_Alloc>::__allocate_helper<_Alloc2>::value;
 434
 435   template<typename _Alloc>
 436   template<typename _Tp, typename... _Args>
 437     const bool
 438     allocator_traits<_Alloc>::__construct_helper<_Tp, _Args...>::value;
 439
 440   template<typename _Alloc>
 441   template<typename _Tp>
 442     const bool allocator_traits<_Alloc>::__destroy_helper<_Tp>::value;
 443
 444   template<typename _Alloc>
 445   template<typename _Alloc2>
 446     const bool allocator_traits<_Alloc>::__maxsize_helper<_Alloc2>::value;
 447
 448   template<typename _Alloc>
 449   template<typename _Alloc2>
 450     const bool allocator_traits<_Alloc>::__select_helper<_Alloc2>::value;
 451
 452   template<typename _Alloc>
 453     inline void
 454     __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type)
 455     { __one = __two; }
 456
 457   template<typename _Alloc>
 458     inline void
 459     __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type)
 460     { }
 461
 462   template<typename _Alloc>
 463     inline void __alloc_on_copy(_Alloc& __one, const _Alloc& __two)
 464     {
 465       typedef allocator_traits<_Alloc> __traits;
 466       typedef typename __traits::propagate_on_container_copy_assignment __pocca;
 467       __do_alloc_on_copy(__one, __two, __pocca());
 468     }
 469
 470   template<typename _Alloc>
 471     inline _Alloc __alloc_on_copy(const _Alloc& __a)
 472     {
 473       typedef allocator_traits<_Alloc> __traits;
 474       return __traits::select_on_container_copy_construction(__a);
 475     }
 476
 477   template<typename _Alloc>
 478     inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type)
 479     { __one = std::move(__two); }
 480
 481   template<typename _Alloc>
 482     inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type)
 483     { }
 484
 485   template<typename _Alloc>
 486     inline void __alloc_on_move(_Alloc& __one, _Alloc& __two)
 487     {
 488       typedef allocator_traits<_Alloc> __traits;
 489       typedef typename __traits::propagate_on_container_move_assignment __pocma;
 490       __do_alloc_on_move(__one, __two, __pocma());
 491     }
 492
 493   template<typename _Alloc>
 494     inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type)
 495     {
 496       using std::swap;
 497       swap(__one, __two);
 498     }
 499
 500   template<typename _Alloc>
 501     inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type)
 502     { }
 503
 504   template<typename _Alloc>
 505     inline void __alloc_on_swap(_Alloc& __one, _Alloc& __two)
 506     {
 507       typedef allocator_traits<_Alloc> __traits;
 508       typedef typename __traits::propagate_on_container_swap __pocs;
 509       __do_alloc_on_swap(__one, __two, __pocs());
 510     }
 511
 512   template<typename _Alloc>
 513     class __is_copy_insertable_impl
 514     {
 515       typedef allocator_traits<_Alloc> _Traits;
 516
 517       template<typename _Up, typename
 518                = decltype(_Traits::construct(std::declval<_Alloc&>(),
 519                                              std::declval<_Up*>(),
 520                                              std::declval<const _Up&>()))>
 521         static true_type
 522         _M_select(int);
 523
 524       template<typename _Up>
 525         static false_type
 526         _M_select(...);
 527
 528     public:
 529       typedef decltype(_M_select<typename _Alloc::value_type>(0)) type;
 530     };
 531
 532   // true if _Alloc::value_type is CopyInsertable into containers using _Alloc
 533   template<typename _Alloc>
 534     struct __is_copy_insertable
 535     : __is_copy_insertable_impl<_Alloc>::type
 536     { };
 537
 538   // std::allocator<_Tp> just requires CopyConstructible
 539   template<typename _Tp>
 540     struct __is_copy_insertable<allocator<_Tp>>
 541     : is_copy_constructible<_Tp>
 542     { };
 543
 544   // Used to allow copy construction of unordered containers
 545   template<bool> struct __allow_copy_cons { };
 546
 547   // Used to delete copy constructor of unordered containers
 548   template<>
 549     struct __allow_copy_cons<false>
 550     {
 551       __allow_copy_cons() = default;
 552       __allow_copy_cons(const __allow_copy_cons&) = delete;
 553       __allow_copy_cons(__allow_copy_cons&&) = default;
 554       __allow_copy_cons& operator=(const __allow_copy_cons&) = default;
 555       __allow_copy_cons& operator=(__allow_copy_cons&&) = default;
 556     };
 557
 558   template<typename _Alloc>
 559     using __check_copy_constructible
 560       = __allow_copy_cons<__is_copy_insertable<_Alloc>::value>;
 561
 562 _GLIBCXX_END_NAMESPACE_VERSION
 563 } // namespace std
 564
 565 #endif
 566 #endif