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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H
#define _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H
#include <__config>
#include <__memory/addressof.h>
#include <__memory_resource/memory_resource.h>
#include <cstddef>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#if _LIBCPP_STD_VER > 14
_LIBCPP_BEGIN_NAMESPACE_STD
namespace pmr {
// [mem.res.monotonic.buffer]
class _LIBCPP_TYPE_VIS monotonic_buffer_resource : public memory_resource {
static const size_t __default_buffer_capacity = 1024;
static const size_t __default_buffer_alignment = 16;
struct __chunk_footer {
__chunk_footer* __next_;
char* __start_;
char* __cur_;
size_t __align_;
size_t __allocation_size() { return (reinterpret_cast<char*>(this) - __start_) + sizeof(*this); }
void* __try_allocate_from_chunk(size_t, size_t);
};
struct __initial_descriptor {
char* __start_;
char* __cur_;
union {
char* __end_;
size_t __size_;
};
void* __try_allocate_from_chunk(size_t, size_t);
};
public:
_LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource()
: monotonic_buffer_resource(nullptr, __default_buffer_capacity, get_default_resource()) {}
_LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(size_t __initial_size)
: monotonic_buffer_resource(nullptr, __initial_size, get_default_resource()) {}
_LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size)
: monotonic_buffer_resource(__buffer, __buffer_size, get_default_resource()) {}
_LIBCPP_HIDE_FROM_ABI explicit monotonic_buffer_resource(memory_resource* __upstream)
: monotonic_buffer_resource(nullptr, __default_buffer_capacity, __upstream) {}
_LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(size_t __initial_size, memory_resource* __upstream)
: monotonic_buffer_resource(nullptr, __initial_size, __upstream) {}
_LIBCPP_HIDE_FROM_ABI monotonic_buffer_resource(void* __buffer, size_t __buffer_size, memory_resource* __upstream)
: __res_(__upstream) {
__initial_.__start_ = static_cast<char*>(__buffer);
if (__buffer != nullptr) {
__initial_.__cur_ = static_cast<char*>(__buffer) + __buffer_size;
__initial_.__end_ = static_cast<char*>(__buffer) + __buffer_size;
} else {
__initial_.__cur_ = nullptr;
__initial_.__size_ = __buffer_size;
}
__chunks_ = nullptr;
}
monotonic_buffer_resource(const monotonic_buffer_resource&) = delete;
_LIBCPP_HIDE_FROM_ABI_VIRTUAL ~monotonic_buffer_resource() override { release(); }
monotonic_buffer_resource& operator=(const monotonic_buffer_resource&) = delete;
_LIBCPP_HIDE_FROM_ABI void release() {
if (__initial_.__start_ != nullptr)
__initial_.__cur_ = __initial_.__end_;
while (__chunks_ != nullptr) {
__chunk_footer* __next = __chunks_->__next_;
__res_->deallocate(__chunks_->__start_, __chunks_->__allocation_size(), __chunks_->__align_);
__chunks_ = __next;
}
}
_LIBCPP_HIDE_FROM_ABI memory_resource* upstream_resource() const { return __res_; }
protected:
void* do_allocate(size_t __bytes, size_t __alignment) override; // key function
_LIBCPP_HIDE_FROM_ABI_VIRTUAL void do_deallocate(void*, size_t, size_t) override {}
_LIBCPP_HIDE_FROM_ABI_VIRTUAL bool do_is_equal(const memory_resource& __other) const _NOEXCEPT override {
return this == std::addressof(__other);
}
private:
__initial_descriptor __initial_;
__chunk_footer* __chunks_;
memory_resource* __res_;
};
} // namespace pmr
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_STD_VER > 14
#endif // _LIBCPP___MEMORY_RESOURCE_MONOTONIC_BUFFER_RESOURCE_H
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