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64 lines
2.1 KiB
C++
64 lines
2.1 KiB
C++
/**
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* \file libpmr/memory_resource.h
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* \author mutouyun (orz@orzz.org)
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* \brief Implement memory allocation strategies that can be used by pmr::allocator.
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* \date 2022-11-13
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*/
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#pragma once
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#include <type_traits>
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#include <cstddef> // std::size_t, std::max_align_t
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#include "libimp/export.h"
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#include "libpmr/def.h"
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LIBPMR_NAMESPACE_BEG_
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/// \brief Helper trait for memory resource.
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template <typename T, typename = void>
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struct has_allocate : std::false_type {};
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template <typename T>
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struct has_allocate<T,
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typename std::enable_if<std::is_convertible<
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decltype(std::declval<T &>().allocate(std::declval<std::size_t>())), void *
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>::value>::type> : std::true_type {};
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template <typename T, typename = void>
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struct has_deallocate : std::false_type {};
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template <typename T>
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struct has_deallocate<T,
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decltype(std::declval<T &>().deallocate(std::declval<void *>(),
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std::declval<std::size_t>()))
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> : std::true_type {};
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template <typename T>
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using verify_memory_resource =
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std::enable_if_t<has_allocate <T>::value &&
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has_deallocate<T>::value, bool>;
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/**
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* \brief A memory resource that uses the
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* standard memory allocation and deallocation interface to allocate memory.
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*
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* \see https://en.cppreference.com/w/cpp/memory/new_delete_resource
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*/
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class LIBIMP_EXPORT new_delete_resource {
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public:
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/// \brief Returns a pointer to a new_delete_resource.
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static new_delete_resource *get() noexcept;
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/// \brief Allocates storage with a size of at least bytes bytes, aligned to the specified alignment.
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/// \remark Returns nullptr if storage of the requested size and alignment cannot be obtained.
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/// \see https://en.cppreference.com/w/cpp/memory/memory_resource/do_allocate
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void *allocate(std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
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/// \brief Deallocates the storage pointed to by p.
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/// \see https://en.cppreference.com/w/cpp/memory/memory_resource/deallocate
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void deallocate(void *p, std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
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};
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LIBPMR_NAMESPACE_END_
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