package org.apidesign.test.visitor;

import static junit.framework.Assert.*;

import org.apidesign.visitor.Language.Expression;

import org.apidesign.visitor.Language.Number;

import org.apidesign.visitor.Language.Plus;

import org.apidesign.visitor.Language.Visitor;

import org.junit.Test;

public class CountNumbersTest {

    // BEGIN: visitor.count.numbers.traversal

    private static class CountNumbers extends Visitor/*version1.0*/ {

        int cnt;

        @Override

        public boolean visitUnknown(Expression exp) {

            return true;

        }

        @Override

        public void visitNumber(Number n) {

            cnt++;

        }

    }

    public static int countNumbers(Expression expression) {

        CountNumbers counter = new CountNumbers();

        expression.visit(counter);

        return counter.cnt;

    }

    // END: visitor.count.numbers.traversal

    @Test public void printOnePlusOne() {

        Number one = new Number(1);

        Expression expression = new Plus(one, one);

        assertEquals("Two 1's", 2, countNumbers(expression));

    }

    @Test public void printOnePlusTwoPlusThree() {

        Number one = new Number(1);

        Number two = new Number(2);

        Number three = new Number(3);

        Expression plus = new Plus(one, new Plus(two, three));

        assertEquals("Three", 3, countNumbers(plus));

    }

}