Visitor pattern with abstract class is relatively good
authorJaroslav Tulach <jtulach@netbeans.org>
Sat, 14 Jun 2008 09:58:24 +0200
changeset 1591e6c4e7145d6
parent 158 daad426b116d
child 160 1990a9775cda
Visitor pattern with abstract class is relatively good
samples/visitor/abstractclass/build.xml
samples/visitor/abstractclass/nbproject/project.xml
samples/visitor/abstractclass/src-api1.0/org/apidesign/visitor/Language.java
samples/visitor/abstractclass/src-api2.0/org/apidesign/visitor/Language.java
samples/visitor/abstractclass/src-test/org/apidesign/test/visitor/LanguageCheckTest.java
samples/visitor/abstractclass/src-test/org/apidesign/test/visitor/PrintTest.java
samples/visitor/abstractclass/src-test2.0/org/apidesign/test/visitor/InvalidLanguageCheckTest.java
samples/visitor/abstractclass/src-test2.0/org/apidesign/test/visitor/PrintOfMinusStructureTest.java
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/samples/visitor/abstractclass/build.xml	Sat Jun 14 09:58:24 2008 +0200
     1.3 @@ -0,0 +1,94 @@
     1.4 +<?xml version="1.0" encoding="UTF-8"?>
     1.5 +<project name="Build Script" default="test" basedir=".">
     1.6 +    <target name="clean">
     1.7 +        <delete dir="build"/>
     1.8 +    </target>
     1.9 +    
    1.10 +    <target name="compile" depends="build"/>
    1.11 +    <target name="build" depends="-libraries">
    1.12 +        <antcall target="-build-one">
    1.13 +            <param name="version" value="api1.0"/>
    1.14 +        </antcall>
    1.15 +        <antcall target="-build-one">
    1.16 +            <param name="version" value="api2.0"/>
    1.17 +        </antcall>
    1.18 +        
    1.19 +        <antcall target="-build-one">
    1.20 +            <param name="version" value="test"/>
    1.21 +            <param name="cp" value="build/api1.0/classes:${junit.jar}"/>
    1.22 +        </antcall>
    1.23 +
    1.24 +        <antcall target="-build-one">
    1.25 +            <param name="version" value="test"/>
    1.26 +            <param name="out" value="will-not-compile"/>
    1.27 +            <param name="cp" value="build/api2.0/classes:${junit.jar}"/>
    1.28 +        </antcall>
    1.29 +
    1.30 +        <antcall target="-build-one">
    1.31 +            <param name="version" value="test2.0"/>
    1.32 +            <param name="cp" value="build/api2.0/classes:build/test/classes:${junit.jar}"/>
    1.33 +        </antcall>
    1.34 +    </target>
    1.35 +    
    1.36 +    <target name="test" depends="build">
    1.37 +        <echo level="info" message="PrintVisitor on old API. This should succeeds."/>
    1.38 +        <antcall target="-run-one">
    1.39 +            <param name="version" value="api1.0"/>
    1.40 +        </antcall>
    1.41 +        <echo level="info" message="PrintVisitor on old API. This would not compile, but it runs as it does not deal with minus at all."/>
    1.42 +        <antcall target="-run-one">
    1.43 +            <param name="version" value="api2.0"/>
    1.44 +        </antcall>
    1.45 +        <echo level="info" message="PrintVisitor on new API. This yields runtime error."/>
    1.46 +        <antcall target="-run-one">
    1.47 +            <param name="test" value="test2.0"/>
    1.48 +            <param name="extra.cp" value="build/test/classes"/>
    1.49 +            <param name="version" value="api2.0"/>
    1.50 +        </antcall>
    1.51 +    </target>
    1.52 +    
    1.53 +    <!-- support methods -->
    1.54 +    
    1.55 +    <target name="-libraries">
    1.56 +        <ant dir="../../libs/"/>
    1.57 +        
    1.58 +        <property name="junit.jar" location="../../libs/dist/junit-4.4.jar"/>
    1.59 +    </target>
    1.60 +    
    1.61 +    <target name="-run-one">
    1.62 +        <fail message="You need to specify API version number" unless="version"/>
    1.63 +        <property name="test" value="test"/>
    1.64 +        <mkdir dir="build/${test}results${version}"/>
    1.65 +        <junit dir="build/test/classes" errorproperty="tests.failed" failureproperty="tests.failed" fork="true" showoutput="true">
    1.66 +            <batchtest todir="build/${test}results${version}">
    1.67 +                <fileset dir="build/${test}/classes">
    1.68 +                    <filename name="**/*Test.class"/>
    1.69 +                </fileset>
    1.70 +            </batchtest>
    1.71 +            <classpath>
    1.72 +                <path location="build/${version}/classes"/>
    1.73 +                <path location="build/${test}/classes"/>
    1.74 +                <path location="${junit.jar}"/>
    1.75 +                <path path="${extra.cp}"/>
    1.76 +            </classpath>
    1.77 +            <formatter type="brief" usefile="false"/>
    1.78 +            <formatter type="xml"/>
    1.79 +        </junit>
    1.80 +    </target>
    1.81 +    
    1.82 +    <target name="-build-one">
    1.83 +        <fail message="You need to specify version number" unless="version"/>
    1.84 +        
    1.85 +        <property name="cp" value=""/>
    1.86 +        <property name="out" value="${version}"/>
    1.87 +        <property name="failonerror" value="true"/>
    1.88 +        <mkdir dir="build/${out}/classes"/>
    1.89 +        <javac 
    1.90 +            srcdir="src-${version}" 
    1.91 +            destdir="build/${out}/classes" 
    1.92 +            source="1.5" target="1.5"
    1.93 +            classpath="${cp}"
    1.94 +            failonerror="${failonerror}"
    1.95 +        />
    1.96 +    </target>
    1.97 +</project>
     2.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     2.2 +++ b/samples/visitor/abstractclass/nbproject/project.xml	Sat Jun 14 09:58:24 2008 +0200
     2.3 @@ -0,0 +1,107 @@
     2.4 +<?xml version="1.0" encoding="UTF-8"?>
     2.5 +<project xmlns="http://www.netbeans.org/ns/project/1" xmlns:ns4="null">
     2.6 +    <type>org.netbeans.modules.ant.freeform</type>
     2.7 +    <configuration>
     2.8 +        <general-data xmlns="http://www.netbeans.org/ns/freeform-project/1">
     2.9 +            <name>abstractclass</name>
    2.10 +        </general-data>
    2.11 +        <general-data xmlns="http://www.netbeans.org/ns/freeform-project/2">
    2.12 +            <!-- Do not use Project Properties customizer when editing this file manually. -->
    2.13 +            <name>abstractclass</name>
    2.14 +            <properties/>
    2.15 +            <folders>
    2.16 +                <source-folder>
    2.17 +                    <label>src-api1.0</label>
    2.18 +                    <type>java</type>
    2.19 +                    <location>src-api1.0</location>
    2.20 +                    <encoding>UTF-8</encoding>
    2.21 +                </source-folder>
    2.22 +                <source-folder>
    2.23 +                    <label>src-api2.0</label>
    2.24 +                    <type>java</type>
    2.25 +                    <location>src-api2.0</location>
    2.26 +                    <encoding>UTF-8</encoding>
    2.27 +                </source-folder>
    2.28 +                <source-folder>
    2.29 +                    <label>test</label>
    2.30 +                    <type>java</type>
    2.31 +                    <location>src-test</location>
    2.32 +                    <encoding>UTF-8</encoding>
    2.33 +                </source-folder>
    2.34 +                <source-folder>
    2.35 +                    <label>test-2.0</label>
    2.36 +                    <type>java</type>
    2.37 +                    <location>src-test2.0</location>
    2.38 +                    <encoding>UTF-8</encoding>
    2.39 +                </source-folder>
    2.40 +            </folders>
    2.41 +            <ide-actions>
    2.42 +                <action name="build">
    2.43 +                    <target>build</target>
    2.44 +                </action>
    2.45 +                <action name="clean">
    2.46 +                    <target>clean</target>
    2.47 +                </action>
    2.48 +                <action name="test">
    2.49 +                    <target>test</target>
    2.50 +                </action>
    2.51 +                <action name="run">
    2.52 +                    <target>test</target>
    2.53 +                </action>
    2.54 +                <action name="rebuild">
    2.55 +                    <target>clean</target>
    2.56 +                    <target>build</target>
    2.57 +                </action>
    2.58 +            </ide-actions>
    2.59 +            <view>
    2.60 +                <items>
    2.61 +                    <source-folder style="packages">
    2.62 +                        <label>API Version 1.0</label>
    2.63 +                        <location>src-api1.0</location>
    2.64 +                    </source-folder>
    2.65 +                    <source-folder style="packages">
    2.66 +                        <label>API Version 2.0</label>
    2.67 +                        <location>src-api2.0</location>
    2.68 +                    </source-folder>
    2.69 +                    <source-folder style="packages">
    2.70 +                        <label>Usage of the API</label>
    2.71 +                        <location>src-test</location>
    2.72 +                    </source-folder>
    2.73 +                    <source-folder style="packages">
    2.74 +                        <label>Usage of new structures with old visitor</label>
    2.75 +                        <location>src-test2.0</location>
    2.76 +                    </source-folder>
    2.77 +                    <source-file>
    2.78 +                        <location>build.xml</location>
    2.79 +                    </source-file>
    2.80 +                </items>
    2.81 +                <context-menu>
    2.82 +                    <ide-action name="build"/>
    2.83 +                    <ide-action name="rebuild"/>
    2.84 +                    <ide-action name="clean"/>
    2.85 +                    <ide-action name="test"/>
    2.86 +                </context-menu>
    2.87 +            </view>
    2.88 +        </general-data>
    2.89 +        <java-data xmlns="http://www.netbeans.org/ns/freeform-project-java/1">
    2.90 +            <compilation-unit>
    2.91 +                <package-root>src-api1.0</package-root>
    2.92 +                <source-level>1.5</source-level>
    2.93 +            </compilation-unit>
    2.94 +            <compilation-unit>
    2.95 +                <package-root>src-api2.0</package-root>
    2.96 +                <source-level>1.5</source-level>
    2.97 +            </compilation-unit>
    2.98 +            <compilation-unit>
    2.99 +                <package-root>src-test</package-root>
   2.100 +                <classpath mode="compile">src-api1.0:../../libs/dist/junit-4.4.jar</classpath>
   2.101 +                <source-level>1.5</source-level>
   2.102 +            </compilation-unit>
   2.103 +            <compilation-unit>
   2.104 +                <package-root>src-test2.0</package-root>
   2.105 +                <classpath mode="compile">src-api2.0:src-test:../../libs/dist/junit-4.4.jar</classpath>
   2.106 +                <source-level>1.5</source-level>
   2.107 +            </compilation-unit>
   2.108 +        </java-data>
   2.109 +    </configuration>
   2.110 +</project>
     3.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     3.2 +++ b/samples/visitor/abstractclass/src-api1.0/org/apidesign/visitor/Language.java	Sat Jun 14 09:58:24 2008 +0200
     3.3 @@ -0,0 +1,34 @@
     3.4 +package org.apidesign.visitor;
     3.5 +
     3.6 +public final class Language {
     3.7 +    private Language() { }
     3.8 +    
     3.9 +    public static abstract class Expression {
    3.10 +        public abstract void visit(Visitor v);
    3.11 +    }
    3.12 +    public static final class Plus extends Expression {
    3.13 +        private final Expression first;
    3.14 +        private final Expression second;
    3.15 +        
    3.16 +        public Plus(Expression first, Expression second) {
    3.17 +            this.first = first;
    3.18 +            this.second = second;
    3.19 +        }
    3.20 +        public Expression getFirst() { return first; }
    3.21 +        public Expression getSecond() { return second; }
    3.22 +        @Override
    3.23 +        public void visit(Visitor v) { v.visitPlus(this); }
    3.24 +    }
    3.25 +    public static final class Number extends Expression {
    3.26 +        private final int value;
    3.27 +        public Number(int value) { this.value = value; }
    3.28 +        public int getValue() { return value; }
    3.29 +        @Override
    3.30 +        public void visit(Visitor v) { v.visitNumber(this); }
    3.31 +    }
    3.32 +
    3.33 +    public static abstract class Visitor {
    3.34 +        public abstract void visitPlus(Plus s);
    3.35 +        public abstract void visitNumber(Number n);
    3.36 +    }
    3.37 +}
     4.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     4.2 +++ b/samples/visitor/abstractclass/src-api2.0/org/apidesign/visitor/Language.java	Sat Jun 14 09:58:24 2008 +0200
     4.3 @@ -0,0 +1,56 @@
     4.4 +package org.apidesign.visitor;
     4.5 +
     4.6 +public final class Language {
     4.7 +    private Language() { }
     4.8 +    
     4.9 +    public static abstract class Expression {
    4.10 +        public abstract void visit(Visitor v);
    4.11 +    }
    4.12 +    public static final class Plus extends Expression {
    4.13 +        private final Expression first;
    4.14 +        private final Expression second;
    4.15 +        
    4.16 +        public Plus(Expression first, Expression second) {
    4.17 +            this.first = first;
    4.18 +            this.second = second;
    4.19 +        }
    4.20 +        public Expression getFirst() { return first; }
    4.21 +        public Expression getSecond() { return second; }
    4.22 +        @Override
    4.23 +        public void visit(Visitor v) { v.visitPlus(this); }
    4.24 +    }
    4.25 +    public static final class Number extends Expression {
    4.26 +        private final int value;
    4.27 +        public Number(int value) { this.value = value; }
    4.28 +        public int getValue() { return value; }
    4.29 +        @Override
    4.30 +        public void visit(Visitor v) { v.visitNumber(this); }
    4.31 +    }
    4.32 +    // BEGIN: visitor.abstractclass.v2
    4.33 +    /** @since 2.0 */
    4.34 +    public static final class Minus extends Expression {
    4.35 +        private final Expression first;
    4.36 +        private final Expression second;
    4.37 +        
    4.38 +        public Minus(Expression first, Expression second) {
    4.39 +            this.first = first;
    4.40 +            this.second = second;
    4.41 +        }
    4.42 +        public Expression getFirst() { return first; }
    4.43 +        public Expression getSecond() { return second; }
    4.44 +        public void visit(Visitor v) { 
    4.45 +            v.visitMinus(this);
    4.46 +        }
    4.47 +    }
    4.48 +
    4.49 +    public static abstract class Visitor {
    4.50 +        public abstract void visitPlus(Plus s);
    4.51 +        public abstract void visitNumber(Number n);
    4.52 +        public void visitMinus(Minus s) {
    4.53 +            throw new IllegalStateException(
    4.54 +                "Old visitor used on new exceptions"
    4.55 +            );
    4.56 +        }
    4.57 +    }
    4.58 +    // END: visitor.abstractclass.v2
    4.59 +}
     5.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     5.2 +++ b/samples/visitor/abstractclass/src-test/org/apidesign/test/visitor/LanguageCheckTest.java	Sat Jun 14 09:58:24 2008 +0200
     5.3 @@ -0,0 +1,48 @@
     5.4 +package org.apidesign.test.visitor;
     5.5 +
     5.6 +import static junit.framework.Assert.*;
     5.7 +import org.apidesign.visitor.Language.Expression;
     5.8 +import org.apidesign.visitor.Language.Number;
     5.9 +import org.apidesign.visitor.Language.Plus;
    5.10 +import org.apidesign.visitor.Language.Visitor;
    5.11 +import org.junit.Test;
    5.12 +
    5.13 +public class LanguageCheckTest {
    5.14 +
    5.15 +    // BEGIN: visitor.language.check.exception
    5.16 +    private static class Valid1_0Language extends Visitor/*version1.0*/ {
    5.17 +        public void visitPlus(Plus s) {
    5.18 +            s.getFirst().visit(this);
    5.19 +            s.getSecond().visit(this);
    5.20 +        }
    5.21 +        public void visitNumber(Number n) { 
    5.22 +        }
    5.23 +    }
    5.24 +
    5.25 +    public static boolean isValid1_0Language(Expression expression) {
    5.26 +        Valid1_0Language valid = new Valid1_0Language();
    5.27 +        try {
    5.28 +            expression.visit(valid);
    5.29 +            return true; // yes, no unknown elements
    5.30 +        } catch (IllegalStateException ex) {
    5.31 +            return false; // no, probably from visitMinus of Visitor/*2.0*/
    5.32 +        }
    5.33 +    }
    5.34 +    // END: visitor.language.check.exception
    5.35 +    
    5.36 +    @Test public void printOnePlusOne() {
    5.37 +        Number one = new Number(1);
    5.38 +        Expression expression = new Plus(one, one);
    5.39 +
    5.40 +        assertTrue("Valid language", isValid1_0Language(expression));
    5.41 +    }
    5.42 +
    5.43 +    @Test public void printOnePlusTwoPlusThree() {
    5.44 +        Number one = new Number(1);
    5.45 +        Number two = new Number(2);
    5.46 +        Number three = new Number(3);
    5.47 +        Expression plus = new Plus(one, new Plus(two, three));
    5.48 +        
    5.49 +        assertTrue("Valid language", isValid1_0Language(plus));
    5.50 +    }
    5.51 +}
     6.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     6.2 +++ b/samples/visitor/abstractclass/src-test/org/apidesign/test/visitor/PrintTest.java	Sat Jun 14 09:58:24 2008 +0200
     6.3 @@ -0,0 +1,46 @@
     6.4 +package org.apidesign.test.visitor;
     6.5 +
     6.6 +import static junit.framework.Assert.*;
     6.7 +import org.apidesign.visitor.Language.Expression;
     6.8 +import org.apidesign.visitor.Language.Number;
     6.9 +import org.apidesign.visitor.Language.Plus;
    6.10 +import org.apidesign.visitor.Language.Visitor;
    6.11 +import org.junit.Test;
    6.12 +
    6.13 +public class PrintTest {
    6.14 +    public static class PrintVisitor extends Visitor {
    6.15 +        StringBuffer sb = new StringBuffer();
    6.16 +        
    6.17 +        public void visitPlus(Plus s) {
    6.18 +            s.getFirst().visit(this);
    6.19 +            sb.append(" + ");
    6.20 +            s.getSecond().visit(this);
    6.21 +        }
    6.22 +
    6.23 +        public void visitNumber(Number n) {
    6.24 +            sb.append (n.getValue());
    6.25 +        }
    6.26 +    }
    6.27 +    
    6.28 +    @Test public void printOnePlusOne() {
    6.29 +        Number one = new Number(1);
    6.30 +        Expression plus = new Plus(one, one);
    6.31 +        
    6.32 +        PrintVisitor print = new PrintVisitor();
    6.33 +        plus.visit(print);
    6.34 +        
    6.35 +        assertEquals("1 + 1", print.sb.toString());
    6.36 +    }
    6.37 +
    6.38 +    @Test public void printOnePlusTwoPlusThree() {
    6.39 +        Number one = new Number(1);
    6.40 +        Number two = new Number(2);
    6.41 +        Number three = new Number(3);
    6.42 +        Expression plus = new Plus(one, new Plus(two, three));
    6.43 +        
    6.44 +        PrintVisitor print = new PrintVisitor();
    6.45 +        plus.visit(print);
    6.46 +        
    6.47 +        assertEquals("1 + 2 + 3", print.sb.toString());
    6.48 +    }
    6.49 +}
     7.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     7.2 +++ b/samples/visitor/abstractclass/src-test2.0/org/apidesign/test/visitor/InvalidLanguageCheckTest.java	Sat Jun 14 09:58:24 2008 +0200
     7.3 @@ -0,0 +1,17 @@
     7.4 +package org.apidesign.test.visitor;
     7.5 +
     7.6 +import static junit.framework.Assert.*;
     7.7 +import org.apidesign.visitor.Language.Expression;
     7.8 +import org.apidesign.visitor.Language.Minus;
     7.9 +import org.apidesign.visitor.Language.Number;
    7.10 +import org.junit.Test;
    7.11 +
    7.12 +public class InvalidLanguageCheckTest {
    7.13 +    @Test public void printOneMinusTwo() {
    7.14 +        Number one = new Number(1);
    7.15 +        Number two = new Number(2);
    7.16 +        Expression minus = new Minus(one, two);
    7.17 +        
    7.18 +        assertFalse("Recognized as invalid 1.0 version of the language", LanguageCheckTest.isValid1_0Language(minus));
    7.19 +    }
    7.20 +}
     8.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     8.2 +++ b/samples/visitor/abstractclass/src-test2.0/org/apidesign/test/visitor/PrintOfMinusStructureTest.java	Sat Jun 14 09:58:24 2008 +0200
     8.3 @@ -0,0 +1,23 @@
     8.4 +package org.apidesign.test.visitor;
     8.5 +
     8.6 +import org.apidesign.test.visitor.PrintTest.PrintVisitor;
     8.7 +import static junit.framework.Assert.*;
     8.8 +import org.apidesign.visitor.Language.Expression;
     8.9 +import org.apidesign.visitor.Language.Minus;
    8.10 +import org.apidesign.visitor.Language.Number;
    8.11 +import org.apidesign.visitor.Language.Plus;
    8.12 +import org.apidesign.visitor.Language.Visitor;
    8.13 +import org.junit.Test;
    8.14 +
    8.15 +public class PrintOfMinusStructureTest {
    8.16 +    @Test public void printOneMinusTwo() {
    8.17 +        Number one = new Number(1);
    8.18 +        Number two = new Number(2);
    8.19 +        Expression minus = new Minus(one, two);
    8.20 +        
    8.21 +        PrintVisitor print = new PrintVisitor();
    8.22 +        minus.visit(print); // fails with IllegalStateException
    8.23 +        
    8.24 +        assertEquals("1 - 2", print.sb.toString());
    8.25 +    }
    8.26 +}