org.apache.jackrabbit.oak.plugins.observation.EventHandler Maven / Gradle / Ivy
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* 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.observation;
import javax.annotation.CheckForNull;
import org.apache.jackrabbit.oak.api.PropertyState;
import org.apache.jackrabbit.oak.spi.state.NodeState;
/**
* Handler of content change events. Used to decouple processing of changes
* from the content diff logic that detects them.
*
* As the content diff recurses down the content tree, it will call the
* {@link #getChildHandler(String, NodeState, NodeState)} method to
* specialize the handler instance for each node under which changes are
* detected. The other handler methods always apply to the properties
* and direct children of the node for which that handler instance is
* specialized. The handler is expected to keep track of contextual
* information like the path or identifier of the current node based on
* the sequence of those specialization calls.
*
* The events belonging to this instance should be delivered
* before events to other instance deeper down the tree are delivered.
*
* All names and paths passed to handler methods use unmapped Oak names.
*/
public interface EventHandler {
/**
* Called before the given before and after states are compared.
* The implementation can use this method to initialize any internal
* state needed for processing the results of the comparison.
*
* @param before before state, non-existent if this node was added
* @param after after state, non-existent if this node was removed
*/
void enter(NodeState before, NodeState after);
/**
* Called after the given before and after states are compared.
* The implementation can use this method to post-process information
* collected during the content diff.
*
* @param before before state, non-existent if this node was added
* @param after after state, non-existent if this node was removed
*/
void leave(NodeState before, NodeState after);
/**
* Returns a handler of events within the given child node, or
* {@code null} if changes within that child are not to be processed.
*
* @param name name of the child node
* @param before before state of the child node, possibly non-existent
* @param after after state of the child node, possibly non-existent
* @return handler of events within the child node, or {@code null}
*/
@CheckForNull
EventHandler getChildHandler(
String name, NodeState before, NodeState after);
/**
* Notification for an added property
* @param after added property
*/
void propertyAdded(PropertyState after);
/**
* Notification for a changed property
* @param before property before the change
* @param after property after the change
*/
void propertyChanged(PropertyState before, PropertyState after);
/**
* Notification for a deleted property
* @param before deleted property
*/
void propertyDeleted(PropertyState before);
/**
* Notification for an added node
* @param name name of the node
* @param after added node
*/
void nodeAdded(String name, NodeState after);
/**
* Notification for a deleted node
* @param name name of the deleted node
* @param before deleted node
*/
void nodeDeleted(String name, NodeState before);
/**
* Notification for a moved node
* @param sourcePath source of the moved node
* @param name name of the moved node
* @param moved moved node
*/
void nodeMoved(String sourcePath, String name, NodeState moved);
/**
* Notification for a reordered node
* @param destName name of the {@code orderBefore()} destination node
* @param name name of the moved node
* @param reordered moved node
*/
void nodeReordered(String destName, String name, NodeState reordered);
}