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Groovy: A powerful, dynamic language for the JVM
/*
* 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.util;
import groovy.lang.Closure;
import groovy.lang.GroovyObjectSupport;
import groovy.lang.GroovyRuntimeException;
import groovy.lang.MissingMethodException;
import org.codehaus.groovy.runtime.InvokerHelper;
import java.util.List;
import java.util.Map;
/**
* An abstract base class for creating arbitrary nested trees of objects
* or events
*
* @author James Strachan
*/
public abstract class BuilderSupport extends GroovyObjectSupport {
private Object current;
private Closure nameMappingClosure;
private final BuilderSupport proxyBuilder;
public BuilderSupport() {
this.proxyBuilder = this;
}
public BuilderSupport(BuilderSupport proxyBuilder) {
this(null, proxyBuilder);
}
public BuilderSupport(Closure nameMappingClosure, BuilderSupport proxyBuilder) {
this.nameMappingClosure = nameMappingClosure;
this.proxyBuilder = proxyBuilder;
}
/**
* Convenience method when no arguments are required
*
* @param methodName the name of the method to invoke
* @return the result of the call
*/
public Object invokeMethod(String methodName) {
return invokeMethod(methodName, null);
}
public Object invokeMethod(String methodName, Object args) {
Object name = getName(methodName);
return doInvokeMethod(methodName, name, args);
}
protected Object doInvokeMethod(String methodName, Object name, Object args) {
Object node = null;
Closure closure = null;
List list = InvokerHelper.asList(args);
//System.out.println("Called invokeMethod with name: " + name + " arguments: " + list);
switch (list.size()) {
case 0:
node = proxyBuilder.createNode(name);
break;
case 1: {
Object object = list.get(0);
if (object instanceof Map) {
node = proxyBuilder.createNode(name, (Map) object);
} else if (object instanceof Closure) {
closure = (Closure) object;
node = proxyBuilder.createNode(name);
} else {
node = proxyBuilder.createNode(name, object);
}
}
break;
case 2: {
Object object1 = list.get(0);
Object object2 = list.get(1);
if (object1 instanceof Map) {
if (object2 instanceof Closure) {
closure = (Closure) object2;
node = proxyBuilder.createNode(name, (Map) object1);
} else {
node = proxyBuilder.createNode(name, (Map) object1, object2);
}
} else {
if (object2 instanceof Closure) {
closure = (Closure) object2;
node = proxyBuilder.createNode(name, object1);
} else if (object2 instanceof Map) {
node = proxyBuilder.createNode(name, (Map) object2, object1);
} else {
throw new MissingMethodException(name.toString(), getClass(), list.toArray(), false);
}
}
}
break;
case 3: {
Object arg0 = list.get(0);
Object arg1 = list.get(1);
Object arg2 = list.get(2);
if (arg0 instanceof Map && arg2 instanceof Closure) {
closure = (Closure) arg2;
node = proxyBuilder.createNode(name, (Map) arg0, arg1);
} else if (arg1 instanceof Map && arg2 instanceof Closure) {
closure = (Closure) arg2;
node = proxyBuilder.createNode(name, (Map) arg1, arg0);
} else {
throw new MissingMethodException(name.toString(), getClass(), list.toArray(), false);
}
}
break;
default: {
throw new MissingMethodException(name.toString(), getClass(), list.toArray(), false);
}
}
if (current != null) {
proxyBuilder.setParent(current, node);
}
if (closure != null) {
// push new node on stack
Object oldCurrent = getCurrent();
setCurrent(node);
// let's register the builder as the delegate
setClosureDelegate(closure, node);
try {
closure.call();
} catch (Exception e) {
throw new GroovyRuntimeException(e);
}
setCurrent(oldCurrent);
}
proxyBuilder.nodeCompleted(current, node);
return proxyBuilder.postNodeCompletion(current, node);
}
/**
* A strategy method to allow derived builders to use
* builder-trees and switch in different kinds of builders.
* This method should call the setDelegate() method on the closure
* which by default passes in this but if node is-a builder
* we could pass that in instead (or do something wacky too)
*
* @param closure the closure on which to call setDelegate()
* @param node the node value that we've just created, which could be
* a builder
*/
protected void setClosureDelegate(Closure closure, Object node) {
closure.setDelegate(this);
}
protected abstract void setParent(Object parent, Object child);
protected abstract Object createNode(Object name);
protected abstract Object createNode(Object name, Object value);
protected abstract Object createNode(Object name, Map attributes);
protected abstract Object createNode(Object name, Map attributes, Object value);
/**
* A hook to allow names to be converted into some other object
* such as a QName in XML or ObjectName in JMX.
*
* @param methodName the name of the desired method
* @return the object representing the name
*/
protected Object getName(String methodName) {
if (nameMappingClosure != null) {
return nameMappingClosure.call(methodName);
}
return methodName;
}
/**
* A hook to allow nodes to be processed once they have had all of their
* children applied.
*
* @param node the current node being processed
* @param parent the parent of the node being processed
*/
protected void nodeCompleted(Object parent, Object node) {
}
/**
* A hook to allow nodes to be processed once they have had all of their
* children applied and allows the actual node object that represents
* the Markup element to be changed
*
* @param node the current node being processed
* @param parent the parent of the node being processed
* @return the node, possibly new, that represents the markup element
*/
protected Object postNodeCompletion(Object parent, Object node) {
return node;
}
protected Object getCurrent() {
return current;
}
protected void setCurrent(Object current) {
this.current = current;
}
}