/**
* 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 org.waveprotocol.wave.client.editor.extract;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Node;
import com.google.gwt.dom.client.Text;
import org.waveprotocol.wave.client.common.util.DomHelper;
import org.waveprotocol.wave.client.common.util.SignalEvent;
import org.waveprotocol.wave.client.editor.EditorStaticDeps;
import org.waveprotocol.wave.client.editor.impl.NodeManager;
import java.util.ArrayList;
import java.util.List;
/**
* Utility for recording unwanted destructive dom mutation events
* into a stack, and reverting the changes.
*
* TODO(danilatos): GWTTestCase this. Quite browser specific though... hard.
*
* @author danilatos@google.com (Daniel Danilatos)
*/
public class DomMutationReverter {
public interface RevertListener {
void scheduleRevert();
}
interface Undoable {
void undo();
void cleanup();
}
private static class RemovalEntry implements Undoable {
Node removedNode;
Element oldParent;
Node oldNodeAfter;
boolean removeAfter;
public RemovalEntry(Node removedNode, Element oldParent, Node oldNodeAfter,
boolean removeAfter) {
if (oldParent == null) {
throw new IllegalArgumentException("Old parent cannot be null");
}
this.removeAfter = removeAfter;
this.removedNode = removedNode;
this.oldParent = oldParent;
this.oldNodeAfter = oldNodeAfter;
}
@Override
public void undo() {
oldParent.insertBefore(removedNode, oldNodeAfter);
}
@Override
public void cleanup() {
if (removeAfter) {
EditorStaticDeps.logger.trace().log("REVERT CLEANUP: " + (DomHelper.isTextNode(removedNode)
? removedNode.<Text>cast().getData() : removedNode.<Element>cast().getTagName()));
removedNode.removeFromParent();
}
}
}
private final RevertListener listener;
private final List<Undoable> entries = new ArrayList<Undoable>();
public DomMutationReverter(RevertListener listener) {
this.listener = listener;
}
/**
* Deals with a dom mutation event, deciding if it is damaging or not.
*
* WARNING: This method should NOT be called for mutation events that are a
* result of programmatic changes - only for changes that the browser did by
* itself and we need to investigate. Doing otherwise will result in
* programmatic changes being reverted!
*
* @param event a dom mutation event
*/
public void handleMutationEvent(SignalEvent event) {
// TODO(user): Do we care about other types of events?
if (event.getType().equals("DOMNodeRemoved")) {
Node target = event.getTarget();
boolean ignorableWhenEmpty = DomHelper.isTextNode(target)
|| !NodeManager.hasBackReference(target.<Element>cast());
if (ignorableWhenEmpty && entries.isEmpty()) {
// If it's a text node, or a non-backreferenced element,
// and we don't already have entries, then we just ignore it as regular typing. Ok.
} else {
EditorStaticDeps.logger.trace().log("REVERT REMOVAL: " + (DomHelper.isTextNode(target)
? target.<Text>cast().getData() : target.<Element>cast().getTagName()));
addEntry(new RemovalEntry(target, target.getParentElement(), target.getNextSibling(),
ignorableWhenEmpty));
}
}
}
private void addEntry(Undoable entry) {
entries.add(entry);
listener.scheduleRevert();
}
public void flush() {
if (entries.size() > 0) {
EditorStaticDeps.logger.trace().log("DomMutation Flush of " + entries.size() + " mutations.");
}
for (int i = entries.size() - 1; i >= 0; i--) {
entries.get(i).undo();
}
for (int i = 0; i < entries.size(); i++) {
entries.get(i).cleanup();
}
clear();
}
public void clear() {
entries.clear();
}
public boolean hasPendingReverts() {
return !entries.isEmpty();
}
}