core/modules/Queue.cppm

export module Core.Queue;

export import Core.New;
export import Core.ToString;

import Core.AlignedData;
import Core.Meta;
import Core.Utility;
import Core.Assert;

export namespace Core {
    template<Moveable T, size_t N>
    class Queue final {
        AlignedType<T> data[N];
        size_t writeIndex = 0;
        size_t readIndex = 0;
        size_t values = 0;

    public:
        Queue() noexcept = default;

        Queue(const Queue& other) noexcept {
            copy(other);
        }

        Queue(Queue&& other) noexcept {
            move(Core::move(other));
            other.clear();
        }

        ~Queue() noexcept {
            clear();
        }

        Queue& operator=(const Queue& other) noexcept {
            if(&other != this) {
                clear();
                copy(other);
            }
            return *this;
        }

        Queue& operator=(Queue&& other) noexcept {
            if(&other != this) {
                clear();
                move(Core::move(other));
                other.clear();
            }
            return *this;
        }

        template<typename... Args>
        T* put(Args&&... args) noexcept {
            if(getLength() >= N) {
                return nullptr;
            }
            static_assert(noexcept(new(data + writeIndex)
                                       T(Core::forward<Args>(args)...)));
            T* t = new(data + writeIndex) T(Core::forward<Args>(args)...);
            writeIndex = (writeIndex + 1) % N;
            values++;
            return t;
        }

        template<typename... Args>
        Queue& add(Args&&... args) noexcept {
            put(Core::forward<Args>(args)...);
            return *this;
        }

        T& operator[](size_t index) noexcept {
            return reinterpret_cast<T*>(data)[(index + readIndex) % N];
        }

        const T& operator[](size_t index) const noexcept {
            return reinterpret_cast<const T*>(data)[(index + readIndex) % N];
        }

        size_t getLength() const noexcept {
            return values;
        }

        bool canRemove() const noexcept {
            return getLength() > 0;
        }

        void clear() noexcept {
            for(size_t i = 0; i < getLength(); i++) {
                (*this)[i].~T();
            }
            writeIndex = 0;
            readIndex = 0;
            values = 0;
        }

        void remove() noexcept {
            assert(canRemove());
            values--;
            (*this)[0].~T();
            readIndex = (readIndex + 1) % N;
        }

        size_t toString(StringBase& b) const noexcept {
            size_t oldtotal = b.getTotal();
            b.add("[");
            size_t end = getLength();
            if(end > 0) {
                end--;
                for(size_t i = 0; i < end; i++) {
                    b.add((*this)[i]);
                    b.add(", ");
                }
                b.add((*this)[end]);
            }
            b.add("]");
            return b.getTotal() - oldtotal;
        }

    private:
        void copy(const Queue& other) noexcept {
            for(size_t i = 0; i < other.getLength(); i++) {
                add(other[i]);
            }
        }

        void move(Queue&& other) noexcept {
            for(size_t i = 0; i < other.getLength(); i++) {
                add(Core::move(other[i]));
            }
        }
    };
}