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1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H10#define _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H11 12#include <__config>13#include <__cstddef/size_t.h>14#include <__memory/addressof.h>15#include <__memory_resource/memory_resource.h>16 17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)18# pragma GCC system_header19#endif20 21#if _LIBCPP_STD_VER >= 1722 23_LIBCPP_BEGIN_NAMESPACE_STD24 25namespace pmr {26 27// [mem.res.monotonic.buffer]28 29class _LIBCPP_AVAILABILITY_PMR _LIBCPP_EXPORTED_FROM_ABI monotonic_buffer_resource : public memory_resource {30 static constexpr size_t __default_buffer_capacity = 1024;31 32 struct __chunk_footer {33 __chunk_footer* __next_;34 char* __start_;35 char* __cur_;36 size_t __align_;37 _LIBCPP_HIDE_FROM_ABI size_t __allocation_size() {38 return (reinterpret_cast<char*>(this) - __start_) + sizeof(*this);39 }40 };41 42 struct __initial_descriptor {43 char* __start_;44 char* __cur_;45 union {46 char* __end_;47 size_t __size_;48 };49 };50 51public:52 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource()53 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, get_default_resource()) {}54 55 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(size_t __initial_size)56 : monotonic_buffer_resource(nullptr, __initial_size, get_default_resource()) {}57 58 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size)59 : monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource()) {}60 61 _LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(memory_resource* __upstream)62 : monotonic_buffer_resource(nullptr, __default_buffer_capacity, __upstream) {}63 64 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(size_t __initial_size, memory_resource* __upstream)65 : monotonic_buffer_resource(nullptr, __initial_size, __upstream) {}66 67 _LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size, memory_resource* __upstream)68 : __res_(__upstream) {69 __initial_.__start_ = static_cast<char*>(__buffer);70 if (__buffer != nullptr) {71 __initial_.__cur_ = static_cast<char*>(__buffer) + __buffer_size;72 __initial_.__end_ = static_cast<char*>(__buffer) + __buffer_size;73 } else {74 __initial_.__cur_ = nullptr;75 __initial_.__size_ = __buffer_size;76 }77 __chunks_ = nullptr;78 }79 80 monotonic_buffer_resource(const monotonic_buffer_resource&) = delete;81 82 _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~monotonic_buffer_resource() override { release(); }83 84 monotonic_buffer_resource& operator=(const monotonic_buffer_resource&) = delete;85 86 _LIBCPP_HIDE_FROM_ABI void release() {87 if (__initial_.__start_ != nullptr)88 __initial_.__cur_ = __initial_.__end_;89 while (__chunks_ != nullptr) {90 __chunk_footer* __next = __chunks_->__next_;91 __res_->deallocate(__chunks_->__start_, __chunks_->__allocation_size(), __chunks_->__align_);92 __chunks_ = __next;93 }94 }95 96 _LIBCPP_HIDE_FROM_ABI memory_resource* upstream_resource() const { return __res_; }97 98protected:99 void* do_allocate(size_t __bytes, size_t __alignment) override; // key function100 101 _LIBCPP_HIDE_FROM_ABI_VIRTUAL void do_deallocate(void*, size_t, size_t) override {}102 103 _LIBCPP_HIDE_FROM_ABI_VIRTUAL bool do_is_equal(const memory_resource& __other) const _NOEXCEPT override {104 return this == std::addressof(__other);105 }106 107private:108 __initial_descriptor __initial_;109 __chunk_footer* __chunks_;110 memory_resource* __res_;111};112 113} // namespace pmr114 115_LIBCPP_END_NAMESPACE_STD116 117#endif // _LIBCPP_STD_VER >= 17118 119#endif // _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H120