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 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);

            }

        };

    }

    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(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;

        }

    }

    @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());

    }

}