class IntegerParser {

    public IntegerParser () {

	// Create a default transition that leads to a failure state.
	FailureState failureState = new FailureState();
	DefaultTransition defaultToFailureTransition =
	    new DefaultTransition(failureState);

	// Create a success state.
	SuccessState successState = new SuccessState();

	// Create a state that represents a partial integer parsing.
	State partialState = new State(defaultToFailureTransition,
				       "Intermediate");
	WhiteSpaceTransition whiteSpaceTransition =
	    new WhiteSpaceTransition(successState);
	partialState.addTransition(whiteSpaceTransition);
	DigitTransition digitTransition =
	    new DigitTransition(partialState);
	partialState.addTransition(digitTransition);

	// Create the initial state.
	_initialState = new InitialState(defaultToFailureTransition,
					 "Initial");
	DigitTransition negativeOrDigitTransition =
	    new DigitTransition(partialState);
	negativeOrDigitTransition.addSymbol('-');
	_initialState.addTransition(negativeOrDigitTransition);

    }

    public boolean parse (String s) {

	// Iterate through the symbols, each time transitioning to a
	// new state until success, failure, or the end of the string
	// is reached.
	int index = 0;
	State currentState = _initialState;
	while ((index < s.length()) &&
	       (!currentState.success()) &&
	       (!currentState.failure())) {

	    char c = s.charAt(index);
	    currentState = currentState.followTransition(c);
	    index++;

	}

	return currentState.success();

    }

    protected void testString (String s) {

	boolean result = parse(s);
	System.out.println(s + ": " + result);

    }

    public static void main (String[] args) {

	IntegerParser ip = new IntegerParser();
	ip.testString("4 ");
	ip.testString("143 ");
	ip.testString("-15\n");
	ip.testString("Foo");
	ip.testString("668\t-- The Neighbor of The Beast!");

    }

    protected InitialState _initialState;

}