final StringBuilder buf = new StringBuilder(pattern.length());
        for (int i = 0; i < pattern.length(); ++i) {
            final char ch = pattern.charAt(i);
            if (Character.isLetterOrDigit(ch) || Character.isWhitespace(ch)) {
                buf.append(ch);
            }
        }
        if (buf.indexOf("yy") == -1) {
            final int pos = buf.indexOf("y");
            if (pos != -1) {