gaming-core/utils/StringBuffer.h

#ifndef STRINGBUFFER_H
#define STRINGBUFFER_H

#include <cstdarg>
#include <cstring>
#include <iostream>

#include "utils/Check.h"
#include "utils/Types.h"

// ignore buffer overflow warnings with snprintf
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-truncation"

template<int N>
class StringBuffer final {
    int length;
    Hash hash;
    static_assert(N > 0, "StringBuffer must have a positive size");
    char data[static_cast<unsigned int>(N)];

    void addToHash(char c) {
        hash = static_cast<Hash>(2120251889) * hash + static_cast<Hash>(c);
    }

    void addToHash(int from, int to) {
        for(int i = from; i < to; i++) {
            addToHash(data[i]);
        }
    }

public:
    StringBuffer() : length(0), hash(0) {
        data[0] = '\0';
    }

    template<typename T>
    StringBuffer(const T& t) : StringBuffer() {
        append(t);
    }

    bool operator==(const char* str) const {
        return strcmp(data, str) == 0;
    }

    bool operator==(const StringBuffer& other) const {
        return length == other.length && other == data;
    }

    bool operator!=(const char* str) const {
        return !((*this) == str);
    }

    bool operator!=(const StringBuffer& other) const {
        return !((*this) == other);
    }

    operator const char*() const {
        return data;
    }

    char operator[](int index) const {
        return data[index];
    }

    int getLength() const {
        return length;
    }

    StringBuffer& append(char c) {
        if(length < N - 1) {
            data[length++] = c;
            addToHash(c);
            data[length] = '\0';
        }
        return *this;
    }

    StringBuffer& append(signed char c) {
        return append(static_cast<char>(c));
    }

    StringBuffer& append(unsigned char c) {
        return append(static_cast<char>(c));
    }

    StringBuffer& append(const char* str) {
        return appendString<const char*>(str);
    }

    StringBuffer& append(const signed char* str) {
        return appendString<const char*>(str);
    }

    StringBuffer& append(const unsigned char* str) {
        return appendString<const unsigned char*>(str);
    }

    check_format(2, 3) StringBuffer& appendFormat(const char* format, ...) {
        int left = N - length;

        va_list args;
        va_start(args, format);
        int written = vsnprintf(data + length, static_cast<unsigned int>(left),
                                format, args);
        va_end(args);

        int oldLength = length;
        if(written < left) {
            length += written;
        } else {
            length = N - 1;
        }
        addToHash(oldLength, length);
        return *this;
    }

    StringBuffer& append(signed short s) {
        return appendFormat("%hd", s);
    }

    StringBuffer& append(unsigned short s) {
        return appendFormat("%hu", s);
    }

    StringBuffer& append(signed int i) {
        return appendFormat("%d", i);
    }

    StringBuffer& append(unsigned int i) {
        return appendFormat("%u", i);
    }

    StringBuffer& append(float f) {
        return appendFormat("%.2f", static_cast<double>(f));
    }

    StringBuffer& append(bool b) {
        return b ? append("true") : append("false");
    }

    template<typename T>
    StringBuffer& append(const T& t) {
        t.toString(*this);
        return *this;
    }

    template<int L>
    void toString(StringBuffer<L>& s) const {
        if(reinterpret_cast<const void*>(this) ==
           reinterpret_cast<const void*>(&s)) {
            return;
        }
        s.append(data);
    }

    StringBuffer& appendUnicode(unsigned int c) {
        if(c < (1 << 7)) {
            append(static_cast<char>(c & 0x7F));
        } else if(c < (1 << 11)) {
            append(static_cast<char>(((c >> 6) & 0x1F) | 0xC0));
            append(static_cast<char>(((c >> 0) & 0x3F) | 0x80));
        } else if(c < (1 << 16)) {
            append(static_cast<char>(((c >> 12) & 0x0F) | 0xE0));
            append(static_cast<char>(((c >> 6) & 0x3F) | 0x80));
            append(static_cast<char>(((c >> 0) & 0x3F) | 0x80));
        } else if(c < (1 << 21)) {
            append(static_cast<char>(((c >> 18) & 0x07) | 0xF0));
            append(static_cast<char>(((c >> 12) & 0x3F) | 0x80));
            append(static_cast<char>(((c >> 6) & 0x3F) | 0x80));
            append(static_cast<char>(((c >> 0) & 0x3F) | 0x80));
        }
        return *this;
    }

    StringBuffer& clear() {
        length = 0;
        hash = 0;
        data[0] = '\0';
        return *this;
    }

    Hash hashCode() const {
        return hash;
    }

    void print() const {
        std::cout << data;
    }

    void printLine() const {
        std::cout << data << '\n';
    }

private:
    template<typename T>
    StringBuffer& appendString(T str) {
        for(int i = 0; length < N - 1 && str[i] != '\0'; length++, i++) {
            data[length] = static_cast<char>(str[i]);
            addToHash(static_cast<char>(str[i]));
        }
        data[length] = '\0';
        return *this;
    }
};

template<int N>
bool operator==(const char* str, const StringBuffer<N> buffer) {
    return buffer == str;
}

template<int N>
bool operator!=(const char* str, const StringBuffer<N> buffer) {
    return buffer != str;
}

#pragma GCC diagnostic pop

#endif