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96 lines
2.7 KiB
C++
96 lines
2.7 KiB
C++
/**
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* \file libipc/container_allocator.h
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* \author mutouyun (orz@orzz.org)
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* \brief An allocator that can be used by all standard library containers.
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*/
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#pragma once
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#include <cstddef>
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#include <utility>
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#include "libipc/imp/uninitialized.h"
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#include "libipc/mem/new.h"
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namespace ipc {
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namespace mem {
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/**
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* \brief An allocator that can be used by all standard library containers.
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*
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* \see https://en.cppreference.com/w/cpp/memory/allocator
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* https://en.cppreference.com/w/cpp/memory/polymorphic_allocator
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*/
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template <typename T>
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class container_allocator {
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template <typename U>
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friend class container_allocator;
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public:
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// type definitions
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typedef T value_type;
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typedef value_type * pointer;
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typedef const value_type *const_pointer;
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typedef value_type & reference;
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typedef const value_type &const_reference;
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typedef std::size_t size_type;
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typedef std::ptrdiff_t difference_type;
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// the other type of std_allocator
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template <typename U>
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struct rebind {
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using other = container_allocator<U>;
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};
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container_allocator() noexcept {}
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// construct by copying (do nothing)
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container_allocator (container_allocator<T> const &) noexcept {}
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container_allocator& operator=(container_allocator<T> const &) noexcept { return *this; }
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// construct from a related allocator (do nothing)
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template <typename U> container_allocator (container_allocator<U> const &) noexcept {}
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template <typename U> container_allocator &operator=(container_allocator<U> const &) noexcept { return *this; }
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container_allocator (container_allocator &&) noexcept = default;
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container_allocator& operator=(container_allocator &&) noexcept = default;
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constexpr size_type max_size() const noexcept {
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return 1;
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}
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pointer allocate(size_type count) noexcept {
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if (count == 0) return nullptr;
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if (count > this->max_size()) return nullptr;
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return mem::$new<value_type>();
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}
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void deallocate(pointer p, size_type count) noexcept {
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if (count == 0) return;
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if (count > this->max_size()) return;
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mem::$delete(p);
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}
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template <typename... P>
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static void construct(pointer p, P && ... params) {
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std::ignore = ipc::construct<T>(p, std::forward<P>(params)...);
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}
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static void destroy(pointer p) {
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std::ignore = ipc::destroy(p);
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}
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};
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template <typename T, typename U>
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constexpr bool operator==(container_allocator<T> const &, container_allocator<U> const &) noexcept {
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return true;
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}
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template <typename T, typename U>
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constexpr bool operator!=(container_allocator<T> const &, container_allocator<U> const &) noexcept {
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return false;
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}
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} // namespace mem
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} // namespace ipc
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