AllocatorStack.hpp

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#pragma once
#include "Allocator.hpp"
#include "Atomic.hpp"
namespace Foundation::Core
{
    class AllocatorStack : public Allocator
    {
    public:
        AllocatorStack() = default;
        AllocatorStack(Arena arena) { Reset(arena); }
        void Reset(Arena arena)
        {
            mMemory = arena.memory;
            mCurrent = reinterpret_cast<size_type>(arena.memory);
            mEnd = reinterpret_cast<size_type>(arena.memory) + arena.size;
        }
        void Reset() { Reset({nullptr, 0}); }
        pointer Allocate(size_type size, size_type alignment) override;
        void Deallocate(pointer ptr) override { /* nop */ }
        pointer Reallocate(pointer ptr, size_type new_size, size_t alignment) override
        {
            throw std::runtime_error("Allocator does not support reallocation");
        }
        constexpr operator bool() const noexcept { return mMemory != nullptr; }
 
        void QueryBudget(size_t& used, size_t& budget) const override
        {
            used = mCurrent - reinterpret_cast<size_type>(mMemory);
            budget = mEnd - reinterpret_cast<size_type>(mMemory);
        }
    private:
        pointer mMemory{nullptr};
        Atomic<size_type> mCurrent{};
        size_type mEnd{};
    };
} // namespace Foundation::Core