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Groovy example source code file (DummyClassGenerator.java)

This example Groovy source code file (DummyClassGenerator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

classgenerator, classloader, classnode, classnode, classvisitor, compileunit, compileunit, dummyclassgenerator, dummyclassgenerator, generatorcontext, groovyruntimeexception, parameter, string, string, util

The Groovy DummyClassGenerator.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.classgen;

import groovy.lang.GroovyRuntimeException;
import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.classgen.asm.BytecodeHelper;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

import java.util.Iterator;

/**
 * To generate a class that has all the fields and methods, except that fields are not initialized
 * and methods are empty. It's intended for being used as a place holder during code generation
 * of reference to the "this" class itself.
 *
 * @author <a href="mailto:james@coredevelopers.net">James Strachan
 * @author <a href="mailto:b55r@sina.com">Bing Ran
 * @version $Revision: 21223 $
 */
public class DummyClassGenerator extends ClassGenerator {

    private ClassVisitor cv;
    private MethodVisitor mv;
    private GeneratorContext context;

    // current class details
    private ClassNode classNode;
    private String internalClassName;
    private String internalBaseClassName;


    public DummyClassGenerator(
            GeneratorContext context,
            ClassVisitor classVisitor,
            ClassLoader classLoader,
            String sourceFile) {
        this.context = context;
        this.cv = classVisitor;
    }

    // GroovyClassVisitor interface
    //-------------------------------------------------------------------------
    public void visitClass(ClassNode classNode) {
        try {
            this.classNode = classNode;
            this.internalClassName = BytecodeHelper.getClassInternalName(classNode);

            //System.out.println("Generating class: " + classNode.getName());

            this.internalBaseClassName = BytecodeHelper.getClassInternalName(classNode.getSuperClass());

            cv.visit(
                    Opcodes.V1_3,
                    classNode.getModifiers(),
                    internalClassName,
                    (String) null,
                    internalBaseClassName,
                    BytecodeHelper.getClassInternalNames(classNode.getInterfaces())
            );

            classNode.visitContents(this);

            for (Iterator iter = innerClasses.iterator(); iter.hasNext();) {
                ClassNode innerClass = (ClassNode) iter.next();
                ClassNode innerClassType = innerClass;
                String innerClassInternalName = BytecodeHelper.getClassInternalName(innerClassType);
                String outerClassName = internalClassName; // default for inner classes
                MethodNode enclosingMethod = innerClass.getEnclosingMethod();
                if (enclosingMethod != null) {
                    // local inner classes do not specify the outer class name
                    outerClassName = null;
                }
                cv.visitInnerClass(
                        innerClassInternalName,
                        outerClassName,
                        innerClassType.getName(),
                        innerClass.getModifiers());
            }
            cv.visitEnd();
        }
        catch (GroovyRuntimeException e) {
            e.setModule(classNode.getModule());
            throw e;
        }
    }

    public void visitConstructor(ConstructorNode node) {

        visitParameters(node, node.getParameters());

        String methodType = BytecodeHelper.getMethodDescriptor(ClassHelper.VOID_TYPE, node.getParameters());
        mv = cv.visitMethod(node.getModifiers(), "<init>", methodType, null, null);
        mv.visitTypeInsn(NEW, "java/lang/RuntimeException");
        mv.visitInsn(DUP);
        mv.visitLdcInsn("not intended for execution");
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/RuntimeException", "<init>", "(Ljava/lang/String;)V");
        mv.visitInsn(ATHROW);
        mv.visitMaxs(0, 0);
    }

    public void visitMethod(MethodNode node) {

        visitParameters(node, node.getParameters());

        String methodType = BytecodeHelper.getMethodDescriptor(node.getReturnType(), node.getParameters());
        mv = cv.visitMethod(node.getModifiers(), node.getName(), methodType, null, null);

        mv.visitTypeInsn(NEW, "java/lang/RuntimeException");
        mv.visitInsn(DUP);
        mv.visitLdcInsn("not intended for execution");
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/RuntimeException", "<init>", "(Ljava/lang/String;)V");
        mv.visitInsn(ATHROW);

        mv.visitMaxs(0, 0);
    }

    public void visitField(FieldNode fieldNode) {

        cv.visitField(
                fieldNode.getModifiers(),
                fieldNode.getName(),
                BytecodeHelper.getTypeDescription(fieldNode.getType()),
                null, //fieldValue,  //br  all the sudden that one cannot init the field here. init is done in static initializer and instance initializer.
                null);
    }

    /**
     * Creates a getter, setter and field
     */
    public void visitProperty(PropertyNode statement) {
    }

    protected CompileUnit getCompileUnit() {
        CompileUnit answer = classNode.getCompileUnit();
        if (answer == null) {
            answer = context.getCompileUnit();
        }
        return answer;
    }

    protected void visitParameters(ASTNode node, Parameter[] parameters) {
        for (int i = 0, size = parameters.length; i < size; i++) {
            visitParameter(node, parameters[i]);
        }
    }

    protected void visitParameter(ASTNode node, Parameter parameter) {
    }


    public void visitAnnotations(AnnotatedNode node) {
    }
}

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