core/modules/ToString.cppm

export module Core.ToString;

import Core.Math;
import Core.Meta;
import Core.Types;

export import Core.StringFormat;

export namespace Core {
    class StringBase;

    template<typename T>
    concept ToString = requires(const T& t, StringBase& b) { t.toString(b); };

    class StringBase {
        size_t index = 0;
        size_t capacity = 0;
        char* buffer = nullptr;

    public:
        StringBase() noexcept {
        }

        StringBase(char* s, size_t n) noexcept : capacity(n), buffer(s) {
        }

        StringBase(StringBase&& other) = default;
        StringBase(const StringBase& other) = delete;
        StringBase& operator=(StringBase&& other) = default;
        StringBase& operator=(const StringBase& other) = delete;

        operator const char*() const noexcept {
            return buffer;
        }

        void clear() noexcept {
            index = 0;
            if(buffer != nullptr) {
                *buffer = '\0';
            }
        }

        size_t getCapacity() const noexcept {
            return index >= capacity ? 0 : capacity - index;
        }

        size_t getTotal() const noexcept {
            return index;
        }

        char* getCurrent() const noexcept {
            return buffer + min(index, capacity);
        }

        template<typename... Args>
        size_t addFormat(const char* format, Args&&... args) noexcept {
            size_t oldIndex = index;
            (
                [&] {
                    StringFormat f;
                    copyFormatUntil(format, f);
                    switcher(args, f);
                }(),
                ...);

            while(*format != '\0') {
                StringFormat f;
                copyFormatUntil(format, f);
            }
            return index - oldIndex;
        }

        template<typename... Args>
        size_t format(const char* format, Args&&... args) noexcept {
            clear();
            return addFormat<Args...>(format, Core::forward<Args>(args)...);
        }

        template<typename T>
        size_t add(const T& t) noexcept {
            size_t oldIndex = index;
            switcher(t);
            return index - oldIndex;
        }

        void print() const noexcept;

    private:
        void copyFormatUntil(const char*& format, StringFormat& f) noexcept;

#define TO_STRING(type)                                        \
    void toString(type t, const StringFormat& format) noexcept

        TO_STRING(signed char);
        TO_STRING(char);
        TO_STRING(short);
        TO_STRING(int);
        TO_STRING(long);
        TO_STRING(long long);
        TO_STRING(unsigned char);
        TO_STRING(unsigned short);
        TO_STRING(unsigned int);
        TO_STRING(unsigned long);
        TO_STRING(unsigned long long);
        TO_STRING(float);
        TO_STRING(double);
        TO_STRING(const char*);
        TO_STRING(const unsigned char*);
        TO_STRING(bool);

        template<typename T>
        void switcher(const T& t, const StringFormat& format = {}) noexcept {
            size_t oldIndex = index;
            if constexpr(Core::Iterable<T>) {
                switcher("[");
                auto current = t.begin();
                auto end = t.end();
                if(current != end) {
                    switcher(*current);
                    ++current;
                }
                while(current != end) {
                    switcher(", ");
                    switcher(*current);
                    ++current;
                }
                switcher("]");
            } else if constexpr(ToString<T>) {
                t.toString(*this);
            } else {
                toString(t, format);
            }
            applyPostFormat(oldIndex, index - oldIndex, format);
        }

        void addChar(char c);
        void applyPostFormat(
            size_t startIndex, size_t length,
            const StringFormat& format) noexcept;
        void insertSpace(size_t startIndex) noexcept;
    };

    template<size_t N>
    struct String : public StringBase {
        char data[N]{};

        String() noexcept : StringBase(data, N) {
        }
    };

    template<typename... Args>
    void print(const char* format, Args&&... args) noexcept {
        String<256> s;
        s.addFormat(format, Core::forward<Args>(args)...);
        s.print();
    }
}