private void require(String delim) throws SAXException, IOException {
        int length = delim.length();
        char[] ch;

        if (length < dataBuffer.length) {
            ch = dataBuffer;
            delim.getChars(0, length, ch, 0);
        } else {
            ch = delim.toCharArray();
        }

        for (int i = 0; i < length; i++) {
                require(ch[i]);
        }
    }
Require a string to appear, or throw an exception.
<p>
<em>Precondition:</em> Entity expansion is not required.
<p>
<em>Precondition:</em> data buffer has no characters that will get sent
to the application.
src/nu/validator/gnu/xml/aelfred2/XmlParser.java