src/main/java/groovy/transform/IndexedProperty.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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 groovy.transform;

import org.codehaus.groovy.transform.GroovyASTTransformationClass;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Field annotation used with properties to provide an indexed getter and setter for the property.
 * Groovy provides nice GPath syntax support for accessing indexed properties but Java tools
 * or frameworks may expect the JavaBean style setters and getters.
 * <p>
 * <em>Example usage:</em> suppose you have a class with the following properties:
 * <pre>
 * {@code @IndexedProperty} FieldType[] someField
 * {@code @IndexedProperty} List<FieldType> otherField
 * {@code @IndexedProperty} List furtherField
 * </pre>
 * will add the following methods to the class containing the properties:
 * <pre>
 * FieldType getSomeField(int index) {
 *     someField[index]
 * }
 * FieldType getOtherField(int index) {
 *     otherField[index]
 * }
 * Object getFurtherField(int index) {
 *     furtherField[index]
 * }
 * void setSomeField(int index, FieldType val) {
 *     someField[index] = val
 * }
 * void setOtherField(int index, FieldType val) {
 *     otherField[index] = val
 * }
 * void setFurtherField(int index, Object val) {
 *     furtherField[index] = val
 * }
 * </pre>
 * Normal Groovy visibility rules for properties apply
 * (i.e. no <code>public</code>, <code>private</code> or <code>package</code>
 * visibility can be specified) or you will receive a compile-time error message.
 * The normal Groovy property getters and setters will also be created.
 * <p>
 * <p>More examples:</p>
 * <pre class="groovyTestCase">
 * import groovy.transform.IndexedProperty
 *
 * class Group {
 *     String name
 *     List members = []
 * }
 *
 * class IndexedGroup {
 *     String name
 *     &#64;IndexedProperty List members = []
 * }
 *
 * def group = new Group(name: 'Groovy')
 * group.members[0] = 'mrhaki'
 * group.members[1] = 'Hubert'
 * assert 2 == group.members.size()
 * assert ['mrhaki', 'Hubert'] == group.members
 *
 * try {
 *     group.setMembers(0, 'hubert') // Not index property
 * } catch (MissingMethodException e) {
 *     assert e
 * }
 *
 * def indexedGroup = new IndexedGroup(name: 'Grails')
 * indexedGroup.members[0] = 'mrhaki'
 * indexedGroup.setMembers 1, 'Hubert'
 * assert 2 == indexedGroup.members.size()
 * assert 'mrhaki' == indexedGroup.getMembers(0)
 * assert 'Hubert' == indexedGroup.members[1]
 * </pre>
 *
 * @since 1.7.3
 */
@java.lang.annotation.Documented
@Retention(RetentionPolicy.SOURCE)
@Target({ElementType.FIELD})
@GroovyASTTransformationClass("org.codehaus.groovy.transform.IndexedPropertyASTTransformation")
public @interface IndexedProperty {
}