private char lastChar() {
        int idx = buff.length() - 1;
        return idx >= 0 ? buff.charAt(idx) : '\0';
    }
Gets the original string being parsed.

@return The original string.
exts/jphp-zend-ext/src/main/java/org/develnext/jphp/zend/ext/standard/date/DateTimeTokenizer.java