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Groovy example source code file (ListenerListASTTransformation.groovy)

This example Groovy source code file (ListenerListASTTransformation.groovy) 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

acc_public, binaryexpression, binaryexpression, blockstatement, blockstatement, booleanexpression, classnode, classnode, emptystatement, expressionstatement, methodnode, parameter, variableexpression, variableexpression

The Groovy ListenerListASTTransformation.groovy source code

/*
 * Copyright 2003-2011 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 groovy.beans

import org.codehaus.groovy.control.CompilePhase
import org.codehaus.groovy.control.SourceUnit
import org.codehaus.groovy.control.messages.SyntaxErrorMessage
import org.codehaus.groovy.syntax.SyntaxException
import org.codehaus.groovy.syntax.Token
import org.codehaus.groovy.syntax.Types
import org.codehaus.groovy.transform.ASTTransformation
import org.codehaus.groovy.transform.GroovyASTTransformation
import org.objectweb.asm.Opcodes
import org.codehaus.groovy.ast.*
import org.codehaus.groovy.ast.expr.*
import org.codehaus.groovy.ast.stmt.*

/**
 * Handles generation of code for the {@code @ListenerList} annotation.
 * <p/>
 * Generally, it adds the needed add<Listener>, remove<Listener> and
 * get<Listener>s methods to support the Java Beans API.
 * <p/>
 * Additionally it adds corresponding fire<Event> methods.
 * <p/>
 *
 * @author Alexander Klein
 * @author Hamlet D'Arcy
 */
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
class ListenerListASTTransformation implements ASTTransformation, Opcodes {
    private static final Class MY_CLASS = groovy.beans.ListenerList.class
    private static final ClassNode COLLECTION_TYPE = ClassHelper.make(Collection)

    public void visit(ASTNode[] nodes, SourceUnit source) {
        if (!(nodes[0] instanceof AnnotationNode) || !(nodes[1] instanceof AnnotatedNode)) {
            throw new RuntimeException("Internal error: wrong types: ${node.class} / ${parent.class}")
        }
        AnnotationNode node = nodes[0]
        FieldNode field = nodes[1]
        ClassNode declaringClass = nodes[1].declaringClass
        ClassNode parentClass = field.type

        boolean isCollection = parentClass.isDerivedFrom(COLLECTION_TYPE) || parentClass.implementsInterface(COLLECTION_TYPE)

        if (!isCollection) {
            addError(node, source, '@' + MY_CLASS.name + ' can only annotate collection properties.')
            return
        }

        def types = field.type.genericsTypes
        if (!types) {
            addError(node, source, '@' + MY_CLASS.name + ' fields must have a generic type.')
            return
        }

        if (types[0].wildcard) {
            addError(node, source, '@' + MY_CLASS.name + ' fields with generic wildcards not yet supported.')
            return
        }

        def listener = types[0].type

        if (!field.initialValueExpression) {
            field.initialValueExpression = new ListExpression()
        }

        def name = node.getMember('name')?.value ?: listener.nameWithoutPackage

        def fireList = listener.methods.findAll { MethodNode m ->
            m.isPublic() && !m.isSynthetic() && !m.isStatic()
        }

        def synchronize = node.getMember('synchronize')?.value ?: false
        addAddListener(source, node, declaringClass, field, listener, name, synchronize)
        addRemoveListener(source, node, declaringClass, field, listener, name, synchronize)
        addGetListeners(source, node, declaringClass, field, listener, name, synchronize)

        fireList.each { MethodNode method ->
            addFireMethods(source, node, declaringClass, field, types, synchronize, method)
        }
    }

    private static def addError(AnnotationNode node, SourceUnit source, String message) {
        source.errorCollector.addError(
                new SyntaxErrorMessage(new SyntaxException(
                        message,
                        node.lineNumber,
                        node.columnNumber),
                        source))
    }

    /**
     * Adds the add<Listener> method like:
     * <p/>
     * <pre>
     * synchronized void add${name.capitalize}(${listener.name} listener) {
     *     if (listener == null)
     *         return
     *     if (${field.name} == null)
     *        ${field.name} = []
     *     ${field.name}.add(listener)
     * }
     * </pre>
     */
    void addAddListener(SourceUnit source, AnnotationNode node, ClassNode declaringClass, FieldNode field, ClassNode listener, String name, synchronize) {

        def methodModifiers = synchronize ? ACC_PUBLIC | ACC_SYNCHRONIZED : ACC_PUBLIC
        def methodReturnType = ClassHelper.make(Void.TYPE)
        def methodName = "add${name.capitalize()}"
        def cn = ClassHelper.makeWithoutCaching(listener.name)
        cn.redirect = listener
        def methodParameter = [new Parameter(cn,'listener')] as Parameter[]

        if (declaringClass.hasMethod(methodName, methodParameter)) {
            addError node, source, "Conflict using @${MY_CLASS.name}. Class $declaringClass.name already has method $methodName"
            return
        }

        BlockStatement block = new BlockStatement()
        block.addStatements([
                new IfStatement(
                        new BooleanExpression(
                                new BinaryExpression(
                                        new VariableExpression('listener'),
                                        Token.newSymbol(Types.COMPARE_EQUAL, 0, 0),
                                        ConstantExpression.NULL
                                )
                        ),
                        new ReturnStatement(ConstantExpression.NULL),
                        new EmptyStatement()
                ),
                new IfStatement(
                        new BooleanExpression(
                                new BinaryExpression(
                                        new VariableExpression(field.name),
                                        Token.newSymbol(Types.COMPARE_EQUAL, 0, 0),
                                        ConstantExpression.NULL
                                )
                        ),
                        new ExpressionStatement(
                                new BinaryExpression(
                                        new VariableExpression(field.name),
                                        Token.newSymbol(Types.EQUAL, 0, 0),
                                        new ListExpression()
                                )
                        ),
                        new EmptyStatement()
                ),
                new ExpressionStatement(
                        new MethodCallExpression(new VariableExpression(field.name), new ConstantExpression('add'), new ArgumentListExpression(new VariableExpression('listener')))
                )
        ])
        declaringClass.addMethod(new MethodNode(methodName, methodModifiers, methodReturnType, methodParameter, [] as ClassNode[], block))
    }

    /**
     * Adds the remove<Listener> method like:
     * <p/>
     * <pre>
     * synchronized void remove${name.capitalize}(${listener.name} listener) {
     *     if (listener == null)
     *         return
     *     if (${field.name} == null)
     *         ${field.name} = []
     *     ${field.name}.remove(listener)
     * }
     * </pre>
     */
    void addRemoveListener(SourceUnit source, AnnotationNode node, ClassNode declaringClass, FieldNode field, ClassNode listener, String name, synchronize) {
        def methodModifiers = synchronize ? ACC_PUBLIC | ACC_SYNCHRONIZED : ACC_PUBLIC
        def methodReturnType = ClassHelper.make(Void.TYPE)
        def methodName = "remove${name.capitalize()}"
        def cn = ClassHelper.makeWithoutCaching(listener.name)
        cn.redirect = listener
        def methodParameter = [new Parameter(cn,'listener')] as Parameter[]

        if (declaringClass.hasMethod(methodName, methodParameter)) {
            addError node, source, "Conflict using @${MY_CLASS.name}. Class $declaringClass.name already has method $methodName"
            return
        }

        BlockStatement block = new BlockStatement()
        block.addStatements([
                new IfStatement(
                        new BooleanExpression(
                                new BinaryExpression(
                                        new VariableExpression('listener'),
                                        Token.newSymbol(Types.COMPARE_EQUAL, 0, 0),
                                        ConstantExpression.NULL
                                )
                        ),
                        new ReturnStatement(ConstantExpression.NULL),
                        new EmptyStatement()
                ),
                new IfStatement(
                        new BooleanExpression(
                                new BinaryExpression(
                                        new VariableExpression(field.name),
                                        Token.newSymbol(Types.COMPARE_EQUAL, 0, 0),
                                        ConstantExpression.NULL
                                )
                        ),
                        new ExpressionStatement(
                                new BinaryExpression(
                                        new VariableExpression(field.name),
                                        Token.newSymbol(Types.EQUAL, 0, 0),
                                        new ListExpression()
                                )
                        ),
                        new EmptyStatement()
                ),
                new ExpressionStatement(
                        new MethodCallExpression(new VariableExpression(field.name), new ConstantExpression('remove'), new ArgumentListExpression(new VariableExpression("listener")))
                )
        ])
        declaringClass.addMethod(new MethodNode(methodName, methodModifiers, methodReturnType, methodParameter, [] as ClassNode[], block))
    }

    /**
     * Adds the get<Listener>s method like:
     * <p/>
     * <pre>
     * synchronized ${name.capitalize}[] get${name.capitalize}s() {
     *     def __result = []
     *     if (${field.name} != null)
     *         __result.addAll(${field.name})
     *     return __result as ${name.capitalize}[]
     * }
     * </pre>
     */
    void addGetListeners(SourceUnit source, AnnotationNode node, ClassNode declaringClass, FieldNode field, ClassNode listener, String name, synchronize) {
        def methodModifiers = synchronize ? ACC_PUBLIC | ACC_SYNCHRONIZED : ACC_PUBLIC
        def methodReturnType = listener.makeArray()
        def methodName = "get${name.capitalize()}s"
        def methodParameter = [] as Parameter[]

        if (declaringClass.hasMethod(methodName, methodParameter)) {
            addError node, source, "Conflict using @${MY_CLASS.name}. Class $declaringClass.name already has method $methodName"
            return
        }

        BlockStatement block = new BlockStatement()
        block.addStatements([
                new ExpressionStatement(
                        new DeclarationExpression(
                                new VariableExpression("__result", ClassHelper.DYNAMIC_TYPE),
                                Token.newSymbol(Types.EQUALS, 0, 0),
                                new ListExpression()
                        )),
                new IfStatement(
                        new BooleanExpression(
                                new BinaryExpression(
                                        new VariableExpression(field.name),
                                        Token.newSymbol(Types.COMPARE_NOT_EQUAL, 0, 0),
                                        ConstantExpression.NULL
                                )
                        ),
                        new ExpressionStatement(
                                new MethodCallExpression(new VariableExpression('__result'), new ConstantExpression('addAll'), new ArgumentListExpression(new VariableExpression(field.name)))
                        ),
                        new EmptyStatement()
                ),
                new ReturnStatement(
                        new CastExpression(
                                methodReturnType,
                                new VariableExpression('__result')
                        )
                )
        ])
        declaringClass.addMethod(new MethodNode(methodName, methodModifiers, methodReturnType, methodParameter, [] as ClassNode[], block))
    }

    /**
     * Adds the fire<Event> methods like:
     * <p/>
     * <pre>
     * void fire${fireMethod.capitalize()}(${parameterList.join(', ')}) {
     *     if (${field.name} != null) {
     *         def __list = new ArrayList(${field.name})
     *         __list.each { listener ->
     *             listener.$eventMethod(${evt})
     *         }
     *     }
     * }
     * </pre>
     */
    void addFireMethods(SourceUnit source, AnnotationNode node, ClassNode declaringClass, FieldNode field, GenericsType[] types, boolean synchronize, MethodNode method) {

        def methodReturnType = ClassHelper.make(Void.TYPE)
        def methodName = "fire${method.name.capitalize()}"
        def methodModifiers = synchronize ? ACC_PUBLIC | ACC_SYNCHRONIZED : ACC_PUBLIC

        if (declaringClass.hasMethod(methodName, method.parameters)) {
            addError node, source, "Conflict using @${MY_CLASS.name}. Class $declaringClass.name already has method $methodName"
            return
        }

        def args = new ArgumentListExpression(method.parameters)

        BlockStatement block = new BlockStatement()
        def listenerListType = ClassHelper.make(ArrayList)
        listenerListType.setGenericsTypes(types)
        block.addStatements([
                new IfStatement(
                        new BooleanExpression(
                                new BinaryExpression(
                                        new VariableExpression(field.name),
                                        Token.newSymbol(Types.COMPARE_NOT_EQUAL, 0, 0),
                                        ConstantExpression.NULL
                                )
                        ),
                        new BlockStatement([
                                new ExpressionStatement(
                                        new DeclarationExpression(
                                                new VariableExpression('__list', listenerListType),
                                                Token.newSymbol(Types.EQUALS, 0, 0),
                                                new ConstructorCallExpression(listenerListType, new ArgumentListExpression(
                                                        new VariableExpression(field.name)
                                                ))
                                        )
                                ),
                                new ForStatement(
                                        new Parameter(ClassHelper.DYNAMIC_TYPE, 'listener'),
                                        new VariableExpression('__list'),
                                        new BlockStatement([
                                                new ExpressionStatement(
                                                        new MethodCallExpression(
                                                                new VariableExpression('listener'),
                                                                method.name,
                                                                args
                                                        )
                                                )
                                        ], new VariableScope())
                                )
                        ], new VariableScope()),
                        new EmptyStatement()
                )
        ])

        def params = method.parameters.collect {
            def paramType = ClassHelper.getWrapper(it.type)
            def cn = ClassHelper.makeWithoutCaching(paramType.name)
            cn.setRedirect(paramType)
            new Parameter(cn, it.name)
        }
        declaringClass.addMethod(methodName, methodModifiers, methodReturnType, params as Parameter[], [] as ClassNode[], block)
    }
}

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