libstdc++
alloc_traits.h
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00001 // Allocator traits -*- C++ -*-
00002 
00003 // Copyright (C) 2011-2013 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 /** @file bits/alloc_traits.h
00026  *  This is an internal header file, included by other library headers.
00027  *  Do not attempt to use it directly. @headername{memory}
00028  */
00029 
00030 #ifndef _ALLOC_TRAITS_H
00031 #define _ALLOC_TRAITS_H 1
00032 
00033 #if __cplusplus >= 201103L
00034 
00035 #include <bits/memoryfwd.h>
00036 #include <bits/ptr_traits.h>
00037 #include <ext/numeric_traits.h>
00038 
00039 namespace std _GLIBCXX_VISIBILITY(default)
00040 {
00041 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00042 
00043   template<typename _Alloc, typename _Tp>
00044     class __alloctr_rebind_helper
00045     {
00046       template<typename _Alloc2, typename _Tp2>
00047     static constexpr bool
00048         _S_chk(typename _Alloc2::template rebind<_Tp2>::other*)
00049     { return true; }
00050 
00051       template<typename, typename>
00052         static constexpr bool
00053         _S_chk(...)
00054         { return false; }
00055 
00056     public:
00057       static const bool __value = _S_chk<_Alloc, _Tp>(nullptr);
00058     };
00059 
00060   template<typename _Alloc, typename _Tp>
00061     const bool __alloctr_rebind_helper<_Alloc, _Tp>::__value;
00062 
00063   template<typename _Alloc, typename _Tp,
00064            bool = __alloctr_rebind_helper<_Alloc, _Tp>::__value>
00065     struct __alloctr_rebind;
00066 
00067   template<typename _Alloc, typename _Tp>
00068     struct __alloctr_rebind<_Alloc, _Tp, true>
00069     {
00070       typedef typename _Alloc::template rebind<_Tp>::other __type;
00071     };
00072 
00073   template<template<typename, typename...> class _Alloc, typename _Tp,
00074             typename _Up, typename... _Args>
00075     struct __alloctr_rebind<_Alloc<_Up, _Args...>, _Tp, false>
00076     {
00077       typedef _Alloc<_Tp, _Args...> __type;
00078     };
00079 
00080   /**
00081    * @brief  Uniform interface to all allocator types.
00082    * @ingroup allocators
00083   */
00084   template<typename _Alloc>
00085     struct allocator_traits
00086     {
00087       /// The allocator type
00088       typedef _Alloc allocator_type;
00089       /// The allocated type
00090       typedef typename _Alloc::value_type value_type;
00091 
00092 #define _GLIBCXX_ALLOC_TR_NESTED_TYPE(_NTYPE, _ALT) \
00093   private: \
00094   template<typename _Tp> \
00095     static typename _Tp::_NTYPE _S_##_NTYPE##_helper(_Tp*); \
00096   static _ALT _S_##_NTYPE##_helper(...); \
00097     typedef decltype(_S_##_NTYPE##_helper((_Alloc*)0)) __##_NTYPE; \
00098   public:
00099 
00100 _GLIBCXX_ALLOC_TR_NESTED_TYPE(pointer, value_type*)
00101 
00102       /**
00103        * @brief   The allocator's pointer type.
00104        *
00105        * @c Alloc::pointer if that type exists, otherwise @c value_type*
00106       */
00107       typedef __pointer pointer;
00108 
00109 _GLIBCXX_ALLOC_TR_NESTED_TYPE(const_pointer,
00110   typename pointer_traits<pointer>::template rebind<const value_type>)
00111 
00112       /**
00113        * @brief   The allocator's const pointer type.
00114        *
00115        * @c Alloc::const_pointer if that type exists, otherwise
00116        * <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
00117       */
00118       typedef __const_pointer const_pointer;
00119 
00120 _GLIBCXX_ALLOC_TR_NESTED_TYPE(void_pointer,
00121   typename pointer_traits<pointer>::template rebind<void>)
00122 
00123       /**
00124        * @brief   The allocator's void pointer type.
00125        *
00126        * @c Alloc::void_pointer if that type exists, otherwise
00127        * <tt> pointer_traits<pointer>::rebind<void> </tt>
00128       */
00129       typedef __void_pointer void_pointer;
00130 
00131 _GLIBCXX_ALLOC_TR_NESTED_TYPE(const_void_pointer,
00132   typename pointer_traits<pointer>::template rebind<const void>)
00133 
00134       /**
00135        * @brief   The allocator's const void pointer type.
00136        *
00137        * @c Alloc::const_void_pointer if that type exists, otherwise
00138        * <tt> pointer_traits<pointer>::rebind<const void> </tt>
00139       */
00140       typedef __const_void_pointer const_void_pointer;
00141 
00142 _GLIBCXX_ALLOC_TR_NESTED_TYPE(difference_type,
00143                               typename pointer_traits<pointer>::difference_type)
00144 
00145       /**
00146        * @brief   The allocator's difference type
00147        *
00148        * @c Alloc::difference_type if that type exists, otherwise
00149        * <tt> pointer_traits<pointer>::difference_type </tt>
00150       */
00151       typedef __difference_type difference_type;
00152 
00153 _GLIBCXX_ALLOC_TR_NESTED_TYPE(size_type,
00154                               typename make_unsigned<difference_type>::type)
00155 
00156       /**
00157        * @brief   The allocator's size type
00158        *
00159        * @c Alloc::size_type if that type exists, otherwise
00160        * <tt> make_unsigned<difference_type>::type </tt>
00161       */
00162       typedef __size_type size_type;
00163 
00164 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_copy_assignment,
00165                               false_type)
00166 
00167       /**
00168        * @brief   How the allocator is propagated on copy assignment
00169        *
00170        * @c Alloc::propagate_on_container_copy_assignment if that type exists,
00171        * otherwise @c false_type
00172       */
00173       typedef __propagate_on_container_copy_assignment
00174         propagate_on_container_copy_assignment;
00175 
00176 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_move_assignment,
00177                               false_type)
00178 
00179       /**
00180        * @brief   How the allocator is propagated on move assignment
00181        *
00182        * @c Alloc::propagate_on_container_move_assignment if that type exists,
00183        * otherwise @c false_type
00184       */
00185       typedef __propagate_on_container_move_assignment
00186         propagate_on_container_move_assignment;
00187 
00188 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_swap,
00189                               false_type)
00190 
00191       /**
00192        * @brief   How the allocator is propagated on swap
00193        *
00194        * @c Alloc::propagate_on_container_swap if that type exists,
00195        * otherwise @c false_type
00196       */
00197       typedef __propagate_on_container_swap propagate_on_container_swap;
00198 
00199 #undef _GLIBCXX_ALLOC_TR_NESTED_TYPE
00200 
00201       template<typename _Tp>
00202         using rebind_alloc = typename __alloctr_rebind<_Alloc, _Tp>::__type;
00203       template<typename _Tp>
00204         using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
00205 
00206     private:
00207       template<typename _Alloc2>
00208     struct __allocate_helper
00209     {
00210       template<typename _Alloc3,
00211         typename = decltype(std::declval<_Alloc3*>()->allocate(
00212           std::declval<size_type>(),
00213           std::declval<const_void_pointer>()))>
00214         static true_type __test(int);
00215 
00216       template<typename>
00217         static false_type __test(...);
00218 
00219       typedef decltype(__test<_Alloc>(0)) type;
00220       static const bool value = type::value;
00221     };
00222 
00223       template<typename _Alloc2>
00224     static typename
00225         enable_if<__allocate_helper<_Alloc2>::value, pointer>::type
00226         _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint)
00227     { return __a.allocate(__n, __hint); }
00228 
00229       template<typename _Alloc2>
00230     static typename
00231         enable_if<!__allocate_helper<_Alloc2>::value, pointer>::type
00232         _S_allocate(_Alloc2& __a, size_type __n, ...)
00233     { return __a.allocate(__n); }
00234 
00235       template<typename _Tp, typename... _Args>
00236     struct __construct_helper
00237     {
00238       template<typename _Alloc2,
00239         typename = decltype(std::declval<_Alloc2*>()->construct(
00240           std::declval<_Tp*>(), std::declval<_Args>()...))>
00241         static true_type __test(int);
00242 
00243       template<typename>
00244         static false_type __test(...);
00245 
00246       typedef decltype(__test<_Alloc>(0)) type;
00247       static const bool value = type::value;
00248     };
00249 
00250       template<typename _Tp, typename... _Args>
00251     static typename
00252         enable_if<__construct_helper<_Tp, _Args...>::value, void>::type
00253         _S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
00254     { __a.construct(__p, std::forward<_Args>(__args)...); }
00255 
00256       template<typename _Tp, typename... _Args>
00257     static typename
00258     enable_if<__and_<__not_<__construct_helper<_Tp, _Args...>>,
00259              is_constructible<_Tp, _Args...>>::value, void>::type
00260         _S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
00261     { ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); }
00262 
00263       template<typename _Tp>
00264     struct __destroy_helper
00265     {
00266       template<typename _Alloc2,
00267         typename = decltype(std::declval<_Alloc2*>()->destroy(
00268           std::declval<_Tp*>()))>
00269         static true_type __test(int);
00270 
00271       template<typename>
00272         static false_type __test(...);
00273 
00274       typedef decltype(__test<_Alloc>(0)) type;
00275       static const bool value = type::value;
00276     };
00277 
00278       template<typename _Tp>
00279     static typename enable_if<__destroy_helper<_Tp>::value, void>::type
00280         _S_destroy(_Alloc& __a, _Tp* __p)
00281     { __a.destroy(__p); }
00282 
00283       template<typename _Tp>
00284     static typename enable_if<!__destroy_helper<_Tp>::value, void>::type
00285         _S_destroy(_Alloc&, _Tp* __p)
00286     { __p->~_Tp(); }
00287 
00288       template<typename _Alloc2>
00289     struct __maxsize_helper
00290     {
00291       template<typename _Alloc3,
00292         typename = decltype(std::declval<_Alloc3*>()->max_size())>
00293         static true_type __test(int);
00294 
00295       template<typename>
00296         static false_type __test(...);
00297 
00298       typedef decltype(__test<_Alloc2>(0)) type;
00299       static const bool value = type::value;
00300     };
00301 
00302       template<typename _Alloc2>
00303     static typename
00304         enable_if<__maxsize_helper<_Alloc2>::value, size_type>::type
00305         _S_max_size(_Alloc2& __a)
00306     { return __a.max_size(); }
00307 
00308       template<typename _Alloc2>
00309     static typename
00310         enable_if<!__maxsize_helper<_Alloc2>::value, size_type>::type
00311     _S_max_size(_Alloc2&)
00312     { return __gnu_cxx::__numeric_traits<size_type>::__max; }
00313 
00314       template<typename _Alloc2>
00315     struct __select_helper
00316     {
00317       template<typename _Alloc3, typename
00318         = decltype(std::declval<_Alloc3*>()
00319         ->select_on_container_copy_construction())>
00320         static true_type __test(int);
00321 
00322       template<typename>
00323         static false_type __test(...);
00324 
00325       typedef decltype(__test<_Alloc2>(0)) type;
00326       static const bool value = type::value;
00327     };
00328       template<typename _Alloc2>
00329     static typename
00330         enable_if<__select_helper<_Alloc2>::value, _Alloc2>::type
00331         _S_select(_Alloc2& __a)
00332     { return __a.select_on_container_copy_construction(); }
00333 
00334       template<typename _Alloc2>
00335     static typename
00336         enable_if<!__select_helper<_Alloc2>::value, _Alloc2>::type
00337         _S_select(_Alloc2& __a)
00338     { return __a; }
00339 
00340     public:
00341 
00342       /**
00343        *  @brief  Allocate memory.
00344        *  @param  __a  An allocator.
00345        *  @param  __n  The number of objects to allocate space for.
00346        *
00347        *  Calls @c a.allocate(n)
00348       */
00349       static pointer
00350       allocate(_Alloc& __a, size_type __n)
00351       { return __a.allocate(__n); }
00352 
00353       /**
00354        *  @brief  Allocate memory.
00355        *  @param  __a  An allocator.
00356        *  @param  __n  The number of objects to allocate space for.
00357        *  @param  __hint Aid to locality.
00358        *  @return Memory of suitable size and alignment for @a n objects
00359        *          of type @c value_type
00360        *
00361        *  Returns <tt> a.allocate(n, hint) </tt> if that expression is
00362        *  well-formed, otherwise returns @c a.allocate(n)
00363       */
00364       static pointer
00365       allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
00366       { return _S_allocate(__a, __n, __hint); }
00367 
00368       /**
00369        *  @brief  Deallocate memory.
00370        *  @param  __a  An allocator.
00371        *  @param  __p  Pointer to the memory to deallocate.
00372        *  @param  __n  The number of objects space was allocated for.
00373        *
00374        *  Calls <tt> a.deallocate(p, n) </tt>
00375       */
00376       static void deallocate(_Alloc& __a, pointer __p, size_type __n)
00377       { __a.deallocate(__p, __n); }
00378 
00379       /**
00380        *  @brief  Construct an object of type @a _Tp
00381        *  @param  __a  An allocator.
00382        *  @param  __p  Pointer to memory of suitable size and alignment for Tp
00383        *  @param  __args Constructor arguments.
00384        *
00385        *  Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
00386        *  if that expression is well-formed, otherwise uses placement-new
00387        *  to construct an object of type @a _Tp at location @a __p from the
00388        *  arguments @a __args...
00389       */
00390       template<typename _Tp, typename... _Args>
00391     static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
00392     -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...))
00393     { _S_construct(__a, __p, std::forward<_Args>(__args)...); }
00394 
00395       /**
00396        *  @brief  Destroy an object of type @a _Tp
00397        *  @param  __a  An allocator.
00398        *  @param  __p  Pointer to the object to destroy
00399        *
00400        *  Calls @c __a.destroy(__p) if that expression is well-formed,
00401        *  otherwise calls @c __p->~_Tp()
00402       */
00403       template <class _Tp>
00404     static void destroy(_Alloc& __a, _Tp* __p)
00405     { _S_destroy(__a, __p); }
00406 
00407       /**
00408        *  @brief  The maximum supported allocation size
00409        *  @param  __a  An allocator.
00410        *  @return @c __a.max_size() or @c numeric_limits<size_type>::max()
00411        *
00412        *  Returns @c __a.max_size() if that expression is well-formed,
00413        *  otherwise returns @c numeric_limits<size_type>::max()
00414       */
00415       static size_type max_size(const _Alloc& __a)
00416       { return _S_max_size(__a); }
00417 
00418       /**
00419        *  @brief  Obtain an allocator to use when copying a container.
00420        *  @param  __rhs  An allocator.
00421        *  @return @c __rhs.select_on_container_copy_construction() or @a __rhs
00422        *
00423        *  Returns @c __rhs.select_on_container_copy_construction() if that
00424        *  expression is well-formed, otherwise returns @a __rhs
00425       */
00426       static _Alloc
00427       select_on_container_copy_construction(const _Alloc& __rhs)
00428       { return _S_select(__rhs); }
00429     };
00430 
00431   template<typename _Alloc>
00432   template<typename _Alloc2>
00433     const bool allocator_traits<_Alloc>::__allocate_helper<_Alloc2>::value;
00434 
00435   template<typename _Alloc>
00436   template<typename _Tp, typename... _Args>
00437     const bool
00438     allocator_traits<_Alloc>::__construct_helper<_Tp, _Args...>::value;
00439 
00440   template<typename _Alloc>
00441   template<typename _Tp>
00442     const bool allocator_traits<_Alloc>::__destroy_helper<_Tp>::value;
00443 
00444   template<typename _Alloc>
00445   template<typename _Alloc2>
00446     const bool allocator_traits<_Alloc>::__maxsize_helper<_Alloc2>::value;
00447 
00448   template<typename _Alloc>
00449   template<typename _Alloc2>
00450     const bool allocator_traits<_Alloc>::__select_helper<_Alloc2>::value;
00451 
00452   template<typename _Alloc>
00453     inline void
00454     __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type)
00455     { __one = __two; }
00456 
00457   template<typename _Alloc>
00458     inline void
00459     __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type)
00460     { }
00461 
00462   template<typename _Alloc>
00463     inline void __alloc_on_copy(_Alloc& __one, const _Alloc& __two)
00464     {
00465       typedef allocator_traits<_Alloc> __traits;
00466       typedef typename __traits::propagate_on_container_copy_assignment __pocca;
00467       __do_alloc_on_copy(__one, __two, __pocca());
00468     }
00469 
00470   template<typename _Alloc>
00471     inline _Alloc __alloc_on_copy(const _Alloc& __a)
00472     {
00473       typedef allocator_traits<_Alloc> __traits;
00474       return __traits::select_on_container_copy_construction(__a);
00475     }
00476 
00477   template<typename _Alloc>
00478     inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type)
00479     { __one = std::move(__two); }
00480 
00481   template<typename _Alloc>
00482     inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type)
00483     { }
00484 
00485   template<typename _Alloc>
00486     inline void __alloc_on_move(_Alloc& __one, _Alloc& __two)
00487     {
00488       typedef allocator_traits<_Alloc> __traits;
00489       typedef typename __traits::propagate_on_container_move_assignment __pocma;
00490       __do_alloc_on_move(__one, __two, __pocma());
00491     }
00492 
00493   template<typename _Alloc>
00494     inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type)
00495     {
00496       using std::swap;
00497       swap(__one, __two);
00498     }
00499 
00500   template<typename _Alloc>
00501     inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type)
00502     { }
00503 
00504   template<typename _Alloc>
00505     inline void __alloc_on_swap(_Alloc& __one, _Alloc& __two)
00506     {
00507       typedef allocator_traits<_Alloc> __traits;
00508       typedef typename __traits::propagate_on_container_swap __pocs;
00509       __do_alloc_on_swap(__one, __two, __pocs());
00510     }
00511 
00512   template<typename _Alloc>
00513     class __is_copy_insertable_impl
00514     {
00515       typedef allocator_traits<_Alloc> _Traits;
00516 
00517       template<typename _Up, typename
00518            = decltype(_Traits::construct(std::declval<_Alloc&>(),
00519                          std::declval<_Up*>(),
00520                          std::declval<const _Up&>()))>
00521     static true_type
00522     _M_select(int);
00523 
00524       template<typename _Up>
00525     static false_type
00526     _M_select(...);
00527 
00528     public:
00529       typedef decltype(_M_select<typename _Alloc::value_type>(0)) type;
00530     };
00531 
00532   // true if _Alloc::value_type is CopyInsertable into containers using _Alloc
00533   template<typename _Alloc>
00534     struct __is_copy_insertable
00535     : __is_copy_insertable_impl<_Alloc>::type
00536     { };
00537 
00538   // std::allocator<_Tp> just requires CopyConstructible
00539   template<typename _Tp>
00540     struct __is_copy_insertable<allocator<_Tp>>
00541     : is_copy_constructible<_Tp>
00542     { };
00543 
00544   // Used to allow copy construction of unordered containers
00545   template<bool> struct __allow_copy_cons { };
00546 
00547   // Used to delete copy constructor of unordered containers
00548   template<>
00549     struct __allow_copy_cons<false>
00550     {
00551       __allow_copy_cons() = default;
00552       __allow_copy_cons(const __allow_copy_cons&) = delete;
00553       __allow_copy_cons(__allow_copy_cons&&) = default;
00554       __allow_copy_cons& operator=(const __allow_copy_cons&) = default;
00555       __allow_copy_cons& operator=(__allow_copy_cons&&) = default;
00556     };
00557 
00558   template<typename _Alloc>
00559     using __check_copy_constructible
00560       = __allow_copy_cons<__is_copy_insertable<_Alloc>::value>;
00561 
00562 _GLIBCXX_END_NAMESPACE_VERSION
00563 } // namespace std
00564 
00565 #endif
00566 #endif