Function common_unicode_cpt_to_utf8

common/unicode.cpp:94–121

}

std::string common_unicode_cpt_to_utf8(uint32_t cpt) {
    std::string result;

    if (/* 0x00 <= cpt && */ cpt <= 0x7f) {
        result.push_back(cpt);
        return result;
    }
    if (0x80 <= cpt && cpt <= 0x7ff) {
        result.push_back(0xc0 | ((cpt >> 6) & 0x1f));
        result.push_back(0x80 | (cpt & 0x3f));
        return result;
    }
    if (0x800 <= cpt && cpt <= 0xffff) {
        result.push_back(0xe0 | ((cpt >> 12) & 0x0f));
        result.push_back(0x80 | ((cpt >> 6) & 0x3f));
        result.push_back(0x80 | (cpt & 0x3f));
        return result;
    }
    if (0x10000 <= cpt && cpt <= 0x10ffff) {
        result.push_back(0xf0 | ((cpt >> 18) & 0x07));
        result.push_back(0x80 | ((cpt >> 12) & 0x3f));
        result.push_back(0x80 | ((cpt >> 6) & 0x3f));
        result.push_back(0x80 | (cpt & 0x3f));
        return result;
    }

    throw std::invalid_argument("invalid codepoint");
}