111 lines
3.0 KiB
C++
111 lines
3.0 KiB
C++
#ifndef FURVM_THING_ALLOCATOR_HPP
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#define FURVM_THING_ALLOCATOR_HPP
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#include "furlang/arena.hpp"
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#include <vector>
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namespace furvm {
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template <typename T>
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class thing_allocator {
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template <typename>
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friend class thing_allocator;
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using dead_things = std::vector<std::pair<T*, std::size_t>>;
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public:
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using value_type = T; /**< Value type. */
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public:
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/**
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* @brief Constructs a thing allocator.
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*
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* @param arena Base arena allocator.
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*/
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explicit thing_allocator(furlang::arena& arena) noexcept
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: m_arena(&arena), m_deadThings(std::make_shared<dead_things>()) {}
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/**
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* @brief Move constructor.
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*/
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template <typename U>
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thing_allocator(thing_allocator<U>&& other) noexcept
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: m_arena(std::move(other.m_arena)), m_deadThings(std::move(other.m_deadThings)) {}
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/**
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* @brief Move constructor.
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*/
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template <typename U>
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thing_allocator& operator=(thing_allocator<U>&& other) noexcept {
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if (this == &other) return *this;
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m_arena = std::move(other.m_arena);
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m_deadThings = std::move(other.m_deadThings);
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return *this;
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}
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/**
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* @brief Copy constructor.
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*/
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template <typename U>
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thing_allocator(const thing_allocator<U>& other) noexcept
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: m_arena(other.m_arena), m_deadThings(other.m_deadThings) {}
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/**
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* @brief Copy constructor.
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*/
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template <typename U>
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thing_allocator& operator=(const thing_allocator<U>& other) noexcept {
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if (this == &other) return *this;
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m_arena = other.m_arena;
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m_deadThings = other.m_deadThings;
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return *this;
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}
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public:
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/**
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* @brief Returns a free chunk of memory.
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*
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* @param count Count of the things that must fit inside the chunk.
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* @return The chunk.
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*/
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[[nodiscard]] T* allocate(std::size_t count = 1) {
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for (auto it = m_deadThings->begin(); it != m_deadThings->end(); ++it) {
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if (it->second != count) continue;
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m_deadThings->erase(it);
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return it->first;
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}
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return m_arena->allocate<T>(count);
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}
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/**
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* @brief Recycles the pointer.
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*/
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void deallocate(T* ptr, std::size_t count) noexcept { m_deadThings->emplace_back(ptr, count); }
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public:
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/**
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* @brief Compares two thing allocators for equality.
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*
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* @return true if the two things are equal.
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*/
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template <typename U>
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bool operator==(const thing_allocator<U>& other) const noexcept {
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return m_arena == other.m_arena && m_deadThings == other.m_deadThings;
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}
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/**
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* @brief Compares two thing allocators for inequality.
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*
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* @return true if the two things are not equal.
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*/
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template <typename U>
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bool operator!=(const thing_allocator<U>& other) const noexcept {
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return m_arena != other.m_arena || m_deadThings != other.m_deadThings;
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}
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private:
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furlang::arena* m_arena;
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std::shared_ptr<dead_things> m_deadThings;
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};
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} // namespace furvm
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#endif // FURVM_THING_ALLOCATOR_HPP
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