public void match(final String expression,
final Handler<Triple> handler,
final TweetContext context) throws MatcherException {
// TODO: is it very inefficient to create a new lexer and parser for each input string?
CharStream s = new ANTLRStringStream(expression);
TwipleLexer lexer = new TwipleLexer(s);
CommonTokenStream tokens = new CommonTokenStream();
tokens.setTokenSource(lexer);
TwipleParser parser = new TwipleParser(tokens);
List<List<Resource>> sequences;