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