utf8.cpp

#include <cctype>
#include <iostream>
#include <sstream>

std::string convertUnicodeLiteral(std::string literal) {
    // if (!util::startswith(escape, "\\u") ...
    literal = literal.substr(2);
    std::stringstream ss;
    ss << std::hex << literal/*.substr(0, 4)*/;
    unsigned int ord;
    ss >> ord;
    std::cout << "ord " << literal << " = " << ord << std::endl;
    
    std::string str;
    if (ord <= 0x7f)
        str += (char) ord;
    else if (ord <= 0x7ff) {
        str += (char) (0b11000000 | (ord >> 6));
        str += (char) (0b10000000 | (ord & 0b00111111));
    } else if (ord <= 0xffff) {
        str += (char) (0b11100000 | (ord >> 12));
        str += (char) (0b10000000 | ((ord >> 6) & 0b00111111));
        str += (char) (0b10000000 | (ord & 0b00111111));
    } else if (ord <= 0x1fffff) {
        str += (char) (0b11110000 | (ord >> 18));
        str += (char) (0b10000000 | ((ord >> 12) & 0b00111111));
        str += (char) (0b10000000 | ((ord >> 6)  & 0b00111111));
        str += (char) (0b10000000 | (ord & 0b00111111));
    } else if (ord <= 0x3ffffff) {
        str += (char) (0b11111000 | (ord >> 24));
        str += (char) (0b10000000 | ((ord >> 18) & 0b00111111));
        str += (char) (0b10000000 | ((ord >> 12) & 0b00111111));
        str += (char) (0b10000000 | ((ord >> 6)  & 0b00111111));
        str += (char) (0b10000000 | (ord & 0b00111111));
    } else if (ord <= 0x7fffffff) {
        str += (char) (0b11111100 | (ord >> 30));
        str += (char) (0b10000000 | ((ord >> 24) & 0b00111111));
        str += (char) (0b10000000 | ((ord >> 18) & 0b00111111));
        str += (char) (0b10000000 | ((ord >> 12) & 0b00111111));
        str += (char) (0b10000000 | ((ord >> 6)  & 0b00111111));
        str += (char) (0b10000000 | (ord & 0b00111111));
    }
    return str;
}

std::string replaceUnicodeEscapes(std::string str) {
    
}

void compare(std::string chr, std::string literal) {
    std::cout << "---" << std::endl;
    std::cout << "testing " << literal << " = " << chr << std::endl;
    std::cout << "chr len " << chr.size() << " " << chr << std::endl;
    std::string chr_converted = convertUnicodeLiteral(literal);
    std::cout << "literal len " << chr_converted.size() << " " << chr_converted << std::endl;
    if (chr != chr_converted) {
        std::cout << "ERROR!" << std::endl;
    }
    std::cout << "---" << std::endl;
}

int main() {
    compare("\u0024", "\\u0024");
    compare("\u00a2", "\\u00a2");
    compare("\u20ac", "\\u20ac");
    compare("\u07ff", "\\u7ff");
    compare("\uffff", "\\uffff");
    
    compare(u8"\U001fffff", "\\u1fffff");
    compare(u8"\U03ffffff", "\\u3ffffff");
    compare(u8"\U7fffffff", "\\u7fffffff");
}