gaming-core/memory/StackAllocator.h

#ifndef STACKALLOCATOR_H
#define STACKALLOCATOR_H

#include <new>
#include <type_traits>

namespace StackAllocator {
    struct Pointer {
        int lastPointer;
        int pointer;
    };

    Pointer allocate(int bytesPerElement, int& elements);
    void free(const Pointer& p);
    int grow(const Pointer& p, int bytesPerElement, int elements);
    void* get(const Pointer& p);

    template<typename T>
    class Array final {
        int length;
        Pointer dataPointer;

    public:
        Array(int n)
            : length(n),
              dataPointer(StackAllocator::allocate(sizeof(T), length)) {
            for(int i = 0; i < length; i++) {
                new((*this) + i) T;
            }
        }

        ~Array() {
            for(int i = 0; i < length; i++) {
                (*this)[i].~T();
            }
            StackAllocator::free(dataPointer);
        }

        Array(const Array&) = delete;
        Array& operator=(const Array&) = delete;
        Array(Array&&) = delete;
        Array& operator=(Array&&) = delete;

        int getLength() const {
            return length;
        }

        int grow(int n) {
            int add = StackAllocator::grow(dataPointer, sizeof(T), n);
            for(int i = length; i < length + add; i++) {
                new((*this) + i) T();
            }
            length += add;
            return add;
        }

        T& operator[](int index) {
            return static_cast<T*>(StackAllocator::get(dataPointer))[index];
        }

        const T& operator[](int index) const {
            return static_cast<T*>(StackAllocator::get(dataPointer))[index];
        }

        operator T*() {
            return static_cast<T*>(StackAllocator::get(dataPointer));
        }
    };

    template<typename T>
    class Object final {
        int length;
        Pointer dataPointer;

    public:
        Object()
            : length(1),
              dataPointer(StackAllocator::allocate(sizeof(T), length)) {
            if(!hasError()) {
                new(StackAllocator::get(dataPointer)) T;
            }
        }

        ~Object() {
            if(!hasError()) {
                (*this)->~T();
            }
            StackAllocator::free(dataPointer);
        }

        Object(const Object&) = delete;
        Object& operator=(const Object&) = delete;
        Object(Object&&) = delete;
        Object& operator=(Object&&) = delete;

        bool hasError() {
            return length != 1;
        }

        T* operator->() {
            return static_cast<T*>(StackAllocator::get(dataPointer));
        }

        operator T&() {
            return *static_cast<T*>(StackAllocator::get(dataPointer));
        }
    };
}

#endif