← Back
Editing: alloc_traits.h
// Allocator traits -*- C++ -*- // Copyright (C) 2011-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file bits/alloc_traits.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{memory} */ #ifndef _ALLOC_TRAITS_H #define _ALLOC_TRAITS_H 1 #if __cplusplus >= 201103L #include <bits/memoryfwd.h> #include <bits/ptr_traits.h> #include <ext/numeric_traits.h> #define __cpp_lib_allocator_traits_is_always_equal 201411 namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION struct __allocator_traits_base { template<typename _Tp, typename _Up, typename = void> struct __rebind : __replace_first_arg<_Tp, _Up> { }; template<typename _Tp, typename _Up> struct __rebind<_Tp, _Up, __void_t<typename _Tp::template rebind<_Up>::other>> { using type = typename _Tp::template rebind<_Up>::other; }; protected: template<typename _Tp> using __pointer = typename _Tp::pointer; template<typename _Tp> using __c_pointer = typename _Tp::const_pointer; template<typename _Tp> using __v_pointer = typename _Tp::void_pointer; template<typename _Tp> using __cv_pointer = typename _Tp::const_void_pointer; template<typename _Tp> using __pocca = typename _Tp::propagate_on_container_copy_assignment; template<typename _Tp> using __pocma = typename _Tp::propagate_on_container_move_assignment; template<typename _Tp> using __pocs = typename _Tp::propagate_on_container_swap; template<typename _Tp> using __equal = typename _Tp::is_always_equal; }; template<typename _Alloc, typename _Up> using __alloc_rebind = typename __allocator_traits_base::template __rebind<_Alloc, _Up>::type; /** * @brief Uniform interface to all allocator types. * @ingroup allocators */ template<typename _Alloc> struct allocator_traits : __allocator_traits_base { /// The allocator type typedef _Alloc allocator_type; /// The allocated type typedef typename _Alloc::value_type value_type; /** * @brief The allocator's pointer type. * * @c Alloc::pointer if that type exists, otherwise @c value_type* */ using pointer = __detected_or_t<value_type*, __pointer, _Alloc>; private: // Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp> template<template<typename> class _Func, typename _Tp, typename = void> struct _Ptr { using type = typename pointer_traits<pointer>::template rebind<_Tp>; }; template<template<typename> class _Func, typename _Tp> struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>> { using type = _Func<_Alloc>; }; // Select _A2::difference_type or pointer_traits<_Ptr>::difference_type template<typename _A2, typename _PtrT, typename = void> struct _Diff { using type = typename pointer_traits<_PtrT>::difference_type; }; template<typename _A2, typename _PtrT> struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>> { using type = typename _A2::difference_type; }; // Select _A2::size_type or make_unsigned<_DiffT>::type template<typename _A2, typename _DiffT, typename = void> struct _Size : make_unsigned<_DiffT> { }; template<typename _A2, typename _DiffT> struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>> { using type = typename _A2::size_type; }; public: /** * @brief The allocator's const pointer type. * * @c Alloc::const_pointer if that type exists, otherwise * <tt> pointer_traits<pointer>::rebind<const value_type> </tt> */ using const_pointer = typename _Ptr<__c_pointer, const value_type>::type; /** * @brief The allocator's void pointer type. * * @c Alloc::void_pointer if that type exists, otherwise * <tt> pointer_traits<pointer>::rebind<void> </tt> */ using void_pointer = typename _Ptr<__v_pointer, void>::type; /** * @brief The allocator's const void pointer type. * * @c Alloc::const_void_pointer if that type exists, otherwise * <tt> pointer_traits<pointer>::rebind<const void> </tt> */ using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type; /** * @brief The allocator's difference type * * @c Alloc::difference_type if that type exists, otherwise * <tt> pointer_traits<pointer>::difference_type </tt> */ using difference_type = typename _Diff<_Alloc, pointer>::type; /** * @brief The allocator's size type * * @c Alloc::size_type if that type exists, otherwise * <tt> make_unsigned<difference_type>::type </tt> */ using size_type = typename _Size<_Alloc, difference_type>::type; /** * @brief How the allocator is propagated on copy assignment * * @c Alloc::propagate_on_container_copy_assignment if that type exists, * otherwise @c false_type */ using propagate_on_container_copy_assignment = __detected_or_t<false_type, __pocca, _Alloc>; /** * @brief How the allocator is propagated on move assignment * * @c Alloc::propagate_on_container_move_assignment if that type exists, * otherwise @c false_type */ using propagate_on_container_move_assignment = __detected_or_t<false_type, __pocma, _Alloc>; /** * @brief How the allocator is propagated on swap * * @c Alloc::propagate_on_container_swap if that type exists, * otherwise @c false_type */ using propagate_on_container_swap = __detected_or_t<false_type, __pocs, _Alloc>; /** * @brief Whether all instances of the allocator type compare equal. * * @c Alloc::is_always_equal if that type exists, * otherwise @c is_empty<Alloc>::type */ using is_always_equal = __detected_or_t<typename is_empty<_Alloc>::type, __equal, _Alloc>; template<typename _Tp> using rebind_alloc = __alloc_rebind<_Alloc, _Tp>; template<typename _Tp> using rebind_traits = allocator_traits<rebind_alloc<_Tp>>; private: template<typename _Alloc2> static auto _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint, int) -> decltype(__a.allocate(__n, __hint)) { return __a.allocate(__n, __hint); } template<typename _Alloc2> static pointer _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer, ...) { return __a.allocate(__n); } template<typename _Tp, typename... _Args> struct __construct_helper { template<typename _Alloc2, typename = decltype(std::declval<_Alloc2*>()->construct( std::declval<_Tp*>(), std::declval<_Args>()...))> static true_type __test(int); template<typename> static false_type __test(...); using type = decltype(__test<_Alloc>(0)); }; template<typename _Tp, typename... _Args> using __has_construct = typename __construct_helper<_Tp, _Args...>::type; template<typename _Tp, typename... _Args> static _Require<__has_construct<_Tp, _Args...>> _S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args) { __a.construct(__p, std::forward<_Args>(__args)...); } template<typename _Tp, typename... _Args> static _Require<__and_<__not_<__has_construct<_Tp, _Args...>>, is_constructible<_Tp, _Args...>>> _S_construct(_Alloc&, _Tp* __p, _Args&&... __args) { ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); } template<typename _Alloc2, typename _Tp> static auto _S_destroy(_Alloc2& __a, _Tp* __p, int) -> decltype(__a.destroy(__p)) { __a.destroy(__p); } template<typename _Alloc2, typename _Tp> static void _S_destroy(_Alloc2&, _Tp* __p, ...) { __p->~_Tp(); } template<typename _Alloc2> static auto _S_max_size(_Alloc2& __a, int) -> decltype(__a.max_size()) { return __a.max_size(); } template<typename _Alloc2> static size_type _S_max_size(_Alloc2&, ...) { // _GLIBCXX_RESOLVE_LIB_DEFECTS // 2466. allocator_traits::max_size() default behavior is incorrect return __gnu_cxx::__numeric_traits<size_type>::__max / sizeof(value_type); } template<typename _Alloc2> static auto _S_select(_Alloc2& __a, int) -> decltype(__a.select_on_container_copy_construction()) { return __a.select_on_container_copy_construction(); } template<typename _Alloc2> static _Alloc2 _S_select(_Alloc2& __a, ...) { return __a; } public: /** * @brief Allocate memory. * @param __a An allocator. * @param __n The number of objects to allocate space for. * * Calls @c a.allocate(n) */ static pointer allocate(_Alloc& __a, size_type __n) { return __a.allocate(__n); } /** * @brief Allocate memory. * @param __a An allocator. * @param __n The number of objects to allocate space for. * @param __hint Aid to locality. * @return Memory of suitable size and alignment for @a n objects * of type @c value_type * * Returns <tt> a.allocate(n, hint) </tt> if that expression is * well-formed, otherwise returns @c a.allocate(n) */ static pointer allocate(_Alloc& __a, size_type __n, const_void_pointer __hint) { return _S_allocate(__a, __n, __hint, 0); } /** * @brief Deallocate memory. * @param __a An allocator. * @param __p Pointer to the memory to deallocate. * @param __n The number of objects space was allocated for. * * Calls <tt> a.deallocate(p, n) </tt> */ static void deallocate(_Alloc& __a, pointer __p, size_type __n) { __a.deallocate(__p, __n); } /** * @brief Construct an object of type @a _Tp * @param __a An allocator. * @param __p Pointer to memory of suitable size and alignment for Tp * @param __args Constructor arguments. * * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt> * if that expression is well-formed, otherwise uses placement-new * to construct an object of type @a _Tp at location @a __p from the * arguments @a __args... */ template<typename _Tp, typename... _Args> static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args) -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...)) { _S_construct(__a, __p, std::forward<_Args>(__args)...); } /** * @brief Destroy an object of type @a _Tp * @param __a An allocator. * @param __p Pointer to the object to destroy * * Calls @c __a.destroy(__p) if that expression is well-formed, * otherwise calls @c __p->~_Tp() */ template<typename _Tp> static void destroy(_Alloc& __a, _Tp* __p) { _S_destroy(__a, __p, 0); } /** * @brief The maximum supported allocation size * @param __a An allocator. * @return @c __a.max_size() or @c numeric_limits<size_type>::max() * * Returns @c __a.max_size() if that expression is well-formed, * otherwise returns @c numeric_limits<size_type>::max() */ static size_type max_size(const _Alloc& __a) noexcept { return _S_max_size(__a, 0); } /** * @brief Obtain an allocator to use when copying a container. * @param __rhs An allocator. * @return @c __rhs.select_on_container_copy_construction() or @a __rhs * * Returns @c __rhs.select_on_container_copy_construction() if that * expression is well-formed, otherwise returns @a __rhs */ static _Alloc select_on_container_copy_construction(const _Alloc& __rhs) { return _S_select(__rhs, 0); } }; /// Partial specialization for std::allocator. template<typename _Tp> struct allocator_traits<allocator<_Tp>> { /// The allocator type using allocator_type = allocator<_Tp>; /// The allocated type using value_type = _Tp; /// The allocator's pointer type. using pointer = _Tp*; /// The allocator's const pointer type. using const_pointer = const _Tp*; /// The allocator's void pointer type. using void_pointer = void*; /// The allocator's const void pointer type. using const_void_pointer = const void*; /// The allocator's difference type using difference_type = std::ptrdiff_t; /// The allocator's size type using size_type = std::size_t; /// How the allocator is propagated on copy assignment using propagate_on_container_copy_assignment = false_type; /// How the allocator is propagated on move assignment using propagate_on_container_move_assignment = true_type; /// How the allocator is propagated on swap using propagate_on_container_swap = false_type; /// Whether all instances of the allocator type compare equal. using is_always_equal = true_type; template<typename _Up> using rebind_alloc = allocator<_Up>; template<typename _Up> using rebind_traits = allocator_traits<allocator<_Up>>; /** * @brief Allocate memory. * @param __a An allocator. * @param __n The number of objects to allocate space for. * * Calls @c a.allocate(n) */ static pointer allocate(allocator_type& __a, size_type __n) { return __a.allocate(__n); } /** * @brief Allocate memory. * @param __a An allocator. * @param __n The number of objects to allocate space for. * @param __hint Aid to locality. * @return Memory of suitable size and alignment for @a n objects * of type @c value_type * * Returns <tt> a.allocate(n, hint) </tt> */ static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer __hint) { return __a.allocate(__n, __hint); } /** * @brief Deallocate memory. * @param __a An allocator. * @param __p Pointer to the memory to deallocate. * @param __n The number of objects space was allocated for. * * Calls <tt> a.deallocate(p, n) </tt> */ static void deallocate(allocator_type& __a, pointer __p, size_type __n) { __a.deallocate(__p, __n); } /** * @brief Construct an object of type @a _Up * @param __a An allocator. * @param __p Pointer to memory of suitable size and alignment for Tp * @param __args Constructor arguments. * * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt> */ template<typename _Up, typename... _Args> static void construct(allocator_type& __a, _Up* __p, _Args&&... __args) { __a.construct(__p, std::forward<_Args>(__args)...); } /** * @brief Destroy an object of type @a _Up * @param __a An allocator. * @param __p Pointer to the object to destroy * * Calls @c __a.destroy(__p). */ template<typename _Up> static void destroy(allocator_type& __a, _Up* __p) { __a.destroy(__p); } /** * @brief The maximum supported allocation size * @param __a An allocator. * @return @c __a.max_size() */ static size_type max_size(const allocator_type& __a) noexcept { return __a.max_size(); } /** * @brief Obtain an allocator to use when copying a container. * @param __rhs An allocator. * @return @c __rhs */ static allocator_type select_on_container_copy_construction(const allocator_type& __rhs) { return __rhs; } }; template<typename _Alloc> inline void __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type) { __one = __two; } template<typename _Alloc> inline void __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type) { } template<typename _Alloc> inline void __alloc_on_copy(_Alloc& __one, const _Alloc& __two) { typedef allocator_traits<_Alloc> __traits; typedef typename __traits::propagate_on_container_copy_assignment __pocca; __do_alloc_on_copy(__one, __two, __pocca()); } template<typename _Alloc> inline _Alloc __alloc_on_copy(const _Alloc& __a) { typedef allocator_traits<_Alloc> __traits; return __traits::select_on_container_copy_construction(__a); } template<typename _Alloc> inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type) { __one = std::move(__two); } template<typename _Alloc> inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type) { } template<typename _Alloc> inline void __alloc_on_move(_Alloc& __one, _Alloc& __two) { typedef allocator_traits<_Alloc> __traits; typedef typename __traits::propagate_on_container_move_assignment __pocma; __do_alloc_on_move(__one, __two, __pocma()); } template<typename _Alloc> inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type) { using std::swap; swap(__one, __two); } template<typename _Alloc> inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type) { } template<typename _Alloc> inline void __alloc_on_swap(_Alloc& __one, _Alloc& __two) { typedef allocator_traits<_Alloc> __traits; typedef typename __traits::propagate_on_container_swap __pocs; __do_alloc_on_swap(__one, __two, __pocs()); } template<typename _Alloc> class __is_copy_insertable_impl { typedef allocator_traits<_Alloc> _Traits; template<typename _Up, typename = decltype(_Traits::construct(std::declval<_Alloc&>(), std::declval<_Up*>(), std::declval<const _Up&>()))> static true_type _M_select(int); template<typename _Up> static false_type _M_select(...); public: typedef decltype(_M_select<typename _Alloc::value_type>(0)) type; }; // true if _Alloc::value_type is CopyInsertable into containers using _Alloc template<typename _Alloc> struct __is_copy_insertable : __is_copy_insertable_impl<_Alloc>::type { }; // std::allocator<_Tp> just requires CopyConstructible template<typename _Tp> struct __is_copy_insertable<allocator<_Tp>> : is_copy_constructible<_Tp> { }; // Trait to detect Allocator-like types. template<typename _Alloc, typename = void> struct __is_allocator : false_type { }; template<typename _Alloc> struct __is_allocator<_Alloc, __void_t<typename _Alloc::value_type, decltype(std::declval<_Alloc&>().allocate(size_t{}))>> : true_type { }; template<typename _Alloc> using _RequireAllocator = typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type; _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // C++11 #endif // _ALLOC_TRAITS_H
Save File
Cancel