Function utf16DecodeCheck

valdi_core/src/valdi_core/cpp/Text/UTF16Utils.cpp:38–49

* Like utf8DecodeCheck, but for UTF-16. */

 * Like utf8DecodeCheck, but for UTF-16.
 */
static inline OffsetPt utf16DecodeCheck(const char16_t* str, std::u16string::size_type i) {
    if (isHighSurrogate(str[i]) && isLowSurrogate(str[i + 1])) {
        // High surrogate followed by low surrogate
        char32_t pt = (((str[i] - 0xD800) << 10) | (str[i + 1] - 0xDC00)) + 0x10000;
        return {2, pt};
    } else if (isHighSurrogate(str[i]) || isLowSurrogate(str[i])) {
        // High surrogate *not* followed by low surrogate, or unpaired low surrogate
        return kInvalidPt;
    } else {
        return {1, str[i]};
    }
}

static inline char32_t utf16Decode(const char16_t* str, std::u16string::size_type& i) {
    OffsetPt res = utf16DecodeCheck(str, i);