org.apache.jackrabbit.oak.plugins.tree.impl.ChildOrderDiff Maven / Gradle / Ivy
/*
* 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.apache.jackrabbit.oak.plugins.tree.impl;
import java.util.Iterator;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.apache.jackrabbit.oak.api.PropertyState;
import org.apache.jackrabbit.oak.api.Type;
import static com.google.common.collect.Sets.newLinkedHashSet;
/**
* Helper class to handle modifications to the hidden
* {@link org.apache.jackrabbit.oak.plugins.tree.impl.TreeConstants#OAK_CHILD_ORDER} property.
*/
public final class ChildOrderDiff {
private ChildOrderDiff() {}
/**
* Tests if there was any user-supplied reordering involved with the
* modification of the {@link org.apache.jackrabbit.oak.plugins.tree.impl.TreeConstants#OAK_CHILD_ORDER}
* property.
*
* @param before
* @param after
* @return the name of the first reordered child if any user-supplied node
* reorder happened; {@code null} otherwise.
*/
@CheckForNull
public static String firstReordered(PropertyState before, PropertyState after) {
Set afterNames = newLinkedHashSet(after.getValue(Type.NAMES));
Set beforeNames = newLinkedHashSet(before.getValue(Type.NAMES));
Iterator a = afterNames.iterator();
Iterator b = beforeNames.iterator();
while (a.hasNext() && b.hasNext()) {
String aName = a.next();
String bName = b.next();
while (!aName.equals(bName)) {
if (!beforeNames.contains(aName)) {
if (a.hasNext()) {
aName = a.next();
} else {
return null;
}
} else if (!afterNames.contains(bName)) {
if (b.hasNext()) {
bName = b.next();
} else {
return null;
}
} else {
return aName;
}
}
}
return null;
}
}