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Groovy example source code file (

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

Java - Groovy tags/keywords

annotatednode, annotatednode, annotationnode, binaryexpression, blockstatement, blockstatement, classnode, classnode, fieldnode, my_type_name, parameter, parameter, string, util, variableexpression

The Groovy source code

 * Copyright 2008-2010 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.
package org.codehaus.groovy.transform;

import groovy.transform.IndexedProperty;
import org.codehaus.groovy.GroovyBugError;
import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.AnnotatedNode;
import org.codehaus.groovy.ast.AnnotationNode;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.FieldNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.ast.expr.BinaryExpression;
import org.codehaus.groovy.ast.expr.VariableExpression;
import org.codehaus.groovy.ast.stmt.BlockStatement;
import org.codehaus.groovy.ast.stmt.ExpressionStatement;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.control.messages.SyntaxErrorMessage;
import org.codehaus.groovy.runtime.MetaClassHelper;
import org.codehaus.groovy.syntax.SyntaxException;
import org.codehaus.groovy.syntax.Token;
import org.objectweb.asm.Opcodes;

import java.util.Arrays;
import java.util.List;

 * Handles generation of code for the {@code @}IndexedProperty annotation.
 * @author Paul King
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class IndexedPropertyASTTransformation implements ASTTransformation, Opcodes {

    private static final Class MY_CLASS = IndexedProperty.class;
    private static final ClassNode MY_TYPE = ClassHelper.make(MY_CLASS);
    private static final String MY_TYPE_NAME = "@" + MY_TYPE.getNameWithoutPackage();
    private static final ClassNode LIST_TYPE = ClassHelper.makeWithoutCaching(List.class, false);
    private static final Token ASSIGN = Token.newSymbol("=", -1, -1);
    private static final Token INDEX = Token.newSymbol("[", -1, -1);

    public void visit(ASTNode[] nodes, SourceUnit source) {
        if (nodes.length != 2 || !(nodes[0] instanceof AnnotationNode) || !(nodes[1] instanceof AnnotatedNode)) {
            throw new GroovyBugError("Internal error: expecting [AnnotationNode, AnnotatedNode] but got: " + Arrays.asList(nodes));

        AnnotatedNode parent = (AnnotatedNode) nodes[1];
        AnnotationNode node = (AnnotationNode) nodes[0];
        if (!MY_TYPE.equals(node.getClassNode())) return;

        if (parent instanceof FieldNode) {
            FieldNode fNode = (FieldNode) parent;
            ClassNode cNode = fNode.getDeclaringClass();
            if (cNode.getProperty(fNode.getName()) == null) {
                addError("Error during " + MY_TYPE_NAME + " processing. Field '" + fNode.getName() +
                        "' doesn't appear to be a property; incorrect visibility?", fNode, source);
            ClassNode fType = fNode.getType();
            if (fType.isArray()) {
            } else if (fType.isDerivedFrom(LIST_TYPE)) {
            } else {
                addError("Error during " + MY_TYPE_NAME + " processing. Non-Indexable property '" + fNode.getName() +
                        "' found. Type must be array or list but found " + fType.getName(), fNode, source);

    private void addListGetter(FieldNode fNode) {
        addGetter(fNode, getComponentTypeForList(fNode.getType()));

    private void addListSetter(FieldNode fNode) {
        addSetter(fNode, getComponentTypeForList(fNode.getType()));

    private void addArrayGetter(FieldNode fNode) {
        addGetter(fNode, fNode.getType().getComponentType());

    private void addArraySetter(FieldNode fNode) {
        addSetter(fNode, fNode.getType().getComponentType());

    private void addGetter(FieldNode fNode, ClassNode componentType) {
        ClassNode cNode = fNode.getDeclaringClass();
        BlockStatement body = new BlockStatement();
        Parameter[] params = new Parameter[1];
        params[0] = new Parameter(ClassHelper.int_TYPE, "index");
        body.addStatement(new ExpressionStatement(
                new BinaryExpression(
                        new VariableExpression(fNode.getName()),
                        new VariableExpression(params[0]))
        cNode.addMethod(makeName(fNode, "get"), getModifiers(fNode), componentType, params, null, body);

    private void addSetter(FieldNode fNode, ClassNode componentType) {
        ClassNode cNode = fNode.getDeclaringClass();
        BlockStatement body = new BlockStatement();
        Parameter[] params = new Parameter[2];
        params[0] = new Parameter(ClassHelper.int_TYPE, "index");
        params[1] = new Parameter(componentType, "value");
        body.addStatement(new ExpressionStatement(
                new BinaryExpression(
                        new BinaryExpression(
                                new VariableExpression(fNode.getName()),
                                new VariableExpression(params[0])),
                        new VariableExpression(params[1])
        cNode.addMethod(makeName(fNode, "set"), getModifiers(fNode), ClassHelper.VOID_TYPE, params, null, body);

    private ClassNode getComponentTypeForList(ClassNode fType) {
        if (fType.isUsingGenerics() && fType.getGenericsTypes().length == 1) {
            return fType.getGenericsTypes()[0].getType();
        } else {
            return ClassHelper.OBJECT_TYPE;

    private int getModifiers(FieldNode fNode) {
        int mods = ACC_PUBLIC;
        if (fNode.isStatic()) mods |= ACC_STATIC;
        return mods;

    private String makeName(FieldNode fNode, String prefix) {
        return prefix + MetaClassHelper.capitalize(fNode.getName());

    private void addError(String msg, ASTNode expr, SourceUnit source) {
        int line = expr.getLineNumber();
        int col = expr.getColumnNumber();
                new SyntaxErrorMessage(new SyntaxException(msg + '\n', line, col), source)


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