return ".*" + appendFileterPath(buf, escape(v)) + ".*";
        }
        if (s.startsWith(REGEXP_IGNORE_CASE)) {
            final String v = s.substring(REGEXP_IGNORE_CASE.length());
            final StringBuilder buf = new StringBuilder(100);
            buf.append("(?i)");
            return appendFileterPath(buf, unescape(v));
        }
        if (s.startsWith(REGEXP_CASE)) {

        assertEquals("", parser.appendFileterPath(buf, ""));
        assertEquals("", parser.appendFileterPath(buf, null));
        assertEquals("", parser.appendFileterPath(buf, "   "));

        assertEquals("^test.*", parser.appendFileterPath(new StringBuilder(), "^test"));
        assertEquals("^test$", parser.appendFileterPath(new StringBuilder(), "^test$"));