package org.apidesign.test.visitor;

 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 static junit.framework.Assert.*;

 import org.junit.Test;

 public class PrintTest {

     public static Number newNumber(final int value) {

         return new Number() {

             public int getValue() {

                 return value;

             }

             public void visit(Visitor v) {

                 v.dispatchNumber(this);

             }

         };

     }

     public static Plus newPlus(

         final Expression first, final Expression second

     ) {

         return new Plus() {

             public Expression getFirst() {

                 return first;

             }

             public Expression getSecond() {

                 return second;

             }

             public void visit(Visitor v) {

                 v.dispatchPlus(this);

             }

         };

     }

     // BEGIN: visitor.clientprovider.print

     public static class PrintVisitor implements Visitor.Version1_0 {

         StringBuffer sb = new StringBuffer();

         final Visitor dispatch = Visitor.create(this);

         public void visitPlus(Plus s) {

             // s.getFirst().visit(this); // does not compile, we need:

             s.getFirst().visit(dispatch);

             sb.append(" + ");

             s.getSecond().visit(dispatch);

         }

         public void visitNumber(Number n) {

             sb.append (n.getValue());

         }

         public boolean visitUnknown(Expression e) {

             sb.append("unknown");

             return true;

         }

     }

     // END: visitor.clientprovider.print

     @Test public void printOnePlusOne() {

         Number one = newNumber(1);

         Expression plus = newPlus(one, one);

         PrintVisitor print = new PrintVisitor();

         plus.visit(print.dispatch);

         assertEquals("1 + 1", print.sb.toString());

     }

     @Test public void printOnePlusTwoPlusThree() {

         Number one = newNumber(1);

         Number two = newNumber(2);

         Number three = newNumber(3);

         Expression plus = newPlus(one, newPlus(two, three));

         PrintVisitor print = new PrintVisitor();

         plus.visit(print.dispatch);

         assertEquals("1 + 2 + 3", print.sb.toString());

     }

 }