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336 lines
9.5 KiB
336 lines
9.5 KiB
// Allocators -*- C++ -*-
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// Copyright (C) 2001-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/*
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* Copyright (c) 1996-1997
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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/** @file bits/allocator.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{memory}
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*/
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#ifndef _ALLOCATOR_H
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#define _ALLOCATOR_H 1
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#include <bits/c++allocator.h> // Define the base class to std::allocator.
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#include <bits/memoryfwd.h>
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#if __cplusplus >= 201103L
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#include <type_traits>
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#endif
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#define __cpp_lib_incomplete_container_elements 201505
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @addtogroup allocators
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* @{
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*/
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// Since C++20 the primary template should be used for allocator<void>,
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// but then it would have a non-trivial default ctor and dtor for C++20,
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// but trivial for C++98-17, which would be an ABI incompatibiliy between
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// different standard dialects. So C++20 still uses the allocator<void>
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// explicit specialization, with the historical ABI properties, but with
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// the same members that are present in the primary template.
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/// allocator<void> specialization.
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template<>
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class allocator<void>
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{
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public:
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typedef void value_type;
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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#if __cplusplus <= 201703L
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// These were removed for C++20, allocator_traits does the right thing.
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typedef void* pointer;
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typedef const void* const_pointer;
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template<typename _Tp1>
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struct rebind
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{ typedef allocator<_Tp1> other; };
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#endif
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#if __cplusplus >= 201103L
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2103. std::allocator propagate_on_container_move_assignment
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using propagate_on_container_move_assignment = true_type;
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using is_always_equal
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_GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal")
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= true_type;
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#if __cplusplus >= 202002L
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// As noted above, these members are present for C++20 to provide the
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// same API as the primary template, but still trivial as in pre-C++20.
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allocator() = default;
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~allocator() = default;
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template<typename _Up>
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constexpr
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allocator(const allocator<_Up>&) noexcept { }
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// No allocate member because it's ill-formed by LWG 3307.
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// No deallocate member because it would be undefined to call it
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// with any pointer which wasn't obtained from allocate.
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#endif // C++20
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#endif // C++11
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};
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/**
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* @brief The @a standard allocator, as per C++03 [20.4.1].
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*
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* See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
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* for further details.
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*
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* @tparam _Tp Type of allocated object.
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*/
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template<typename _Tp>
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class allocator : public __allocator_base<_Tp>
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{
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public:
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typedef _Tp value_type;
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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#if __cplusplus <= 201703L
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// These were removed for C++20.
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typedef _Tp* pointer;
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typedef const _Tp* const_pointer;
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typedef _Tp& reference;
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typedef const _Tp& const_reference;
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template<typename _Tp1>
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struct rebind
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{ typedef allocator<_Tp1> other; };
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#endif
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#if __cplusplus >= 201103L
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2103. std::allocator propagate_on_container_move_assignment
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using propagate_on_container_move_assignment = true_type;
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using is_always_equal
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_GLIBCXX20_DEPRECATED_SUGGEST("std::allocator_traits::is_always_equal")
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= true_type;
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#endif
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 3035. std::allocator's constructors should be constexpr
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_GLIBCXX20_CONSTEXPR
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allocator() _GLIBCXX_NOTHROW { }
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_GLIBCXX20_CONSTEXPR
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allocator(const allocator& __a) _GLIBCXX_NOTHROW
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: __allocator_base<_Tp>(__a) { }
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#if __cplusplus >= 201103L
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// Avoid implicit deprecation.
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allocator& operator=(const allocator&) = default;
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#endif
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template<typename _Tp1>
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_GLIBCXX20_CONSTEXPR
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allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { }
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#if __cpp_constexpr_dynamic_alloc
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constexpr
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#endif
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~allocator() _GLIBCXX_NOTHROW { }
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#if __cplusplus > 201703L
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[[nodiscard,__gnu__::__always_inline__]]
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constexpr _Tp*
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allocate(size_t __n)
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{
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
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#endif
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return __allocator_base<_Tp>::allocate(__n, 0);
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}
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[[__gnu__::__always_inline__]]
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constexpr void
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deallocate(_Tp* __p, size_t __n)
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{
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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{
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::operator delete(__p);
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return;
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}
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#endif
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__allocator_base<_Tp>::deallocate(__p, __n);
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}
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#endif // C++20
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friend _GLIBCXX20_CONSTEXPR bool
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operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW
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{ return true; }
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#if __cpp_impl_three_way_comparison < 201907L
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friend _GLIBCXX20_CONSTEXPR bool
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operator!=(const allocator&, const allocator&) _GLIBCXX_NOTHROW
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{ return false; }
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#endif
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// Inherit everything else.
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};
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template<typename _T1, typename _T2>
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inline _GLIBCXX20_CONSTEXPR bool
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operator==(const allocator<_T1>&, const allocator<_T2>&)
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_GLIBCXX_NOTHROW
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{ return true; }
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#if __cpp_impl_three_way_comparison < 201907L
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template<typename _T1, typename _T2>
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inline _GLIBCXX20_CONSTEXPR bool
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operator!=(const allocator<_T1>&, const allocator<_T2>&)
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_GLIBCXX_NOTHROW
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{ return false; }
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#endif
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// Invalid allocator<cv T> partial specializations.
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// allocator_traits::rebind_alloc can be used to form a valid allocator type.
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template<typename _Tp>
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class allocator<const _Tp>
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{
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public:
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typedef _Tp value_type;
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template<typename _Up> allocator(const allocator<_Up>&) { }
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};
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template<typename _Tp>
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class allocator<volatile _Tp>
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{
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public:
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typedef _Tp value_type;
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template<typename _Up> allocator(const allocator<_Up>&) { }
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};
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template<typename _Tp>
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class allocator<const volatile _Tp>
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{
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public:
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typedef _Tp value_type;
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template<typename _Up> allocator(const allocator<_Up>&) { }
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};
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/// @} group allocator
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// Inhibit implicit instantiations for required instantiations,
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// which are defined via explicit instantiations elsewhere.
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#if _GLIBCXX_EXTERN_TEMPLATE
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extern template class allocator<char>;
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extern template class allocator<wchar_t>;
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#endif
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// Undefine.
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#undef __allocator_base
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// To implement Option 3 of DR 431.
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template<typename _Alloc, bool = __is_empty(_Alloc)>
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struct __alloc_swap
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{ static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
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template<typename _Alloc>
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struct __alloc_swap<_Alloc, false>
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{
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static void
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_S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
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{
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// Precondition: swappable allocators.
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if (__one != __two)
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swap(__one, __two);
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}
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};
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// Optimize for stateless allocators.
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template<typename _Alloc, bool = __is_empty(_Alloc)>
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struct __alloc_neq
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{
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static bool
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_S_do_it(const _Alloc&, const _Alloc&)
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{ return false; }
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};
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template<typename _Alloc>
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struct __alloc_neq<_Alloc, false>
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{
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static bool
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_S_do_it(const _Alloc& __one, const _Alloc& __two)
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{ return __one != __two; }
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};
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#if __cplusplus >= 201103L
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template<typename _Tp, bool
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= __or_<is_copy_constructible<typename _Tp::value_type>,
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is_nothrow_move_constructible<typename _Tp::value_type>>::value>
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struct __shrink_to_fit_aux
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{ static bool _S_do_it(_Tp&) noexcept { return false; } };
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template<typename _Tp>
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struct __shrink_to_fit_aux<_Tp, true>
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{
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static bool
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_S_do_it(_Tp& __c) noexcept
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{
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#if __cpp_exceptions
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try
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{
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_Tp(__make_move_if_noexcept_iterator(__c.begin()),
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__make_move_if_noexcept_iterator(__c.end()),
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__c.get_allocator()).swap(__c);
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return true;
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}
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catch(...)
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{ return false; }
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#else
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return false;
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#endif
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}
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};
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#endif
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif
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