core/modules/ToString.cppm

export module Core.ToString;

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

export import Core.StringFormat;

#define TO_STRING(type) \
    size_t toString(type t, char* s, size_t n, const StringFormat& format = {})

export namespace Core {
    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(unsigned char*);
    TO_STRING(bool);

    template<typename T>
    void addString(
        const T& t, char*& s, size_t& n, size_t& total,
        const StringFormat& format = {});

    template<Core::Iterable T>
    size_t toString(
        const T& t, char* s, size_t n, const StringFormat& format = {}) {
        (void)format;
        size_t total = 0;
        addString("[", s, n, total);
        auto current = t.begin();
        auto end = t.end();
        if(current != end) {
            addString(*current, s, n, total);
            ++current;
        }
        while(current != end) {
            addString(", ", s, n, total);
            addString(*current, s, n, total);
            ++current;
        }
        addString("]", s, n, total);
        return total;
    }

    template<typename T>
    concept ToString =
        requires(const T& t, char* s, size_t n) { t.toString(s, n); };

    template<ToString T>
    size_t toString(
        const T& t, char* s, size_t n, const StringFormat& format = {}) {
        (void)format;
        return t.toString(s, n);
    }

    template<typename T>
    void addString(
        const T& t, char*& s, size_t& n, size_t& total,
        const StringFormat& format) {
        size_t w = toString(t, s, n, format);
        total += w;
        w = Core::min(n, w);
        s += w;
        n -= w;
    }

    size_t copyFormatUntil(
        const char*& format, char*& s, size_t& n, StringFormat& f);

    template<typename T, typename... Args>
    void formatR(
        const char*& format, char*& s, size_t& n, size_t& total, const T& t,
        Args&&... args) {
        StringFormat f;
        total += copyFormatUntil(format, s, n, f);
        addString(t, s, n, total, f);
        if constexpr(sizeof...(args) > 0) {
            formatR(format, s, n, total, Core::forward<Args>(args)...);
        }
    }

    template<typename... Args>
    size_t formatBuffer(char* s, size_t n, const char* format, Args&&... args) {
        StringFormat f;
        size_t total = 0;
        if constexpr(sizeof...(args) > 0) {
            formatR(format, s, n, total, Core::forward<Args>(args)...);
        }
        return total + copyFormatUntil(format, s, n, f);
    }

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

        StringBase() {
        }

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

        template<typename... Args>
        size_t format(const char* format, Args&&... args) {
            size_t total = formatBuffer(
                buffer + index, capacity - index, format,
                Core::forward<Args>(args)...);
            index = Core::min(index + total, capacity);
            return total;
        }

        template<typename T>
        size_t add(const T& t) {
            size_t total = toString(t, buffer + index, capacity - index);
            index = Core::min(index + total, capacity);
            return total;
        }

        void print();
    };

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

        String() {
            buffer = data;
            capacity = N;
        }
    };

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