/*
* Copyright 2010 JBoss Inc
*
* 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 org.drools.core.reteoo.compiled;
import org.drools.core.base.ClassFieldReader;
import org.drools.core.util.Iterator;
import org.drools.core.util.ObjectHashMap;
import org.drools.core.reteoo.*;
import org.drools.core.rule.constraint.MvelConstraint;
import org.drools.core.spi.AlphaNodeFieldConstraint;
/**
* This class is used for reading an {@link ObjectTypeNode} using callbacks.
* <p/>
* The user defines a number of callback methods in a {@link NetworkHandler} that will be called when events occur
* during parsing. The events include :
* <li>ObjectTypeNode</li>
* <li>Non-hashed and hashed AlphaNodes</li>
* <li>BetaNodes</li>
* <li>LeftInputAdapterNodes</li>
* <p/>
* Events are fired when each of these network features are encountered, and again when the end of them is encountered.
* OTN parsing is unidirectional; previously parsed data cannot be re-read without starting the parsing operation again.
*/
public class ObjectTypeNodeParser {
/**
* OTN we are parsing/traversing
*/
private final ObjectTypeNode objectTypeNode;
/**
* Creates a new parser for the specified ObjectTypeNode
*
* @param objectTypeNode otn to parse
*/
public ObjectTypeNodeParser(ObjectTypeNode objectTypeNode) {
this.objectTypeNode = objectTypeNode;
}
/**
* Parse the {@link #objectTypeNode}.
* <p/>
* <p>The application can use this method to instruct the OTN parser to begin parsing an {@link ObjectTypeNode}.</p>
* <p/>
* Once a parse is complete, an application may reuse the same Parser object, possibly with a different
* {@link NetworkHandler}.</p>
*
* @param handler handler that will receieve the events generated by this parser
* @see NetworkHandler
*/
public void accept(NetworkHandler handler) {
ObjectSinkPropagator propagator = objectTypeNode.getSinkPropagator();
handler.startObjectTypeNode(objectTypeNode);
traversePropagator(propagator, handler);
handler.endObjectTypeNode(objectTypeNode);
}
private void traversePropagator(ObjectSinkPropagator propagator, NetworkHandler handler) {
if (propagator instanceof SingleObjectSinkAdapter) {
// we know there is only a single child sink for this propagator
ObjectSink sink = propagator.getSinks()[0];
traverseSink(sink, handler);
} else if (propagator instanceof CompositeObjectSinkAdapter) {
CompositeObjectSinkAdapter composite = (CompositeObjectSinkAdapter) propagator;
traverseSinkLisk(composite.getHashableSinks(), handler);
traverseSinkLisk(composite.getOthers(), handler);
traverseHashedAlphaNodes(composite.getHashedSinkMap(), handler);
}
}
private void traversePropagator(LeftTupleSinkPropagator propagator, NetworkHandler handler) {
if (propagator instanceof SingleLeftTupleSinkAdapter) {
// we know there is only a single child sink for this propagator
LeftTupleSink sink = propagator.getSinks()[0];
traverseSink(sink, handler);
} else if (propagator instanceof CompositeLeftTupleSinkAdapter) {
CompositeLeftTupleSinkAdapter composite = (CompositeLeftTupleSinkAdapter) propagator;
LeftTupleSink[] sinks = composite.getSinks();
traverseSinkLisk(sinks, handler);
}
}
private void traverseSinkLisk(ObjectSinkNodeList sinks, NetworkHandler handler) {
if (sinks != null) {
for (ObjectSinkNode sink = sinks.getFirst(); sink != null; sink = sink.getNextObjectSinkNode()) {
traverseSink(sink, handler);
}
}
}
private void traverseSinkLisk(LeftTupleSink[] sinks, NetworkHandler handler) {
if (sinks != null) {
for (int sinkIndex = 0; sinkIndex < sinks.length; ++sinkIndex) {
traverseSink(sinks[sinkIndex], handler);
}
}
}
private void traverseHashedAlphaNodes(ObjectHashMap hashedAlphaNodes, NetworkHandler handler) {
if (hashedAlphaNodes != null && hashedAlphaNodes.size() > 0) {
AlphaNode firstAlpha = getFirstAlphaNode(hashedAlphaNodes);
ClassFieldReader hashedFieldReader = getClassFieldReaderForHashedAlpha(firstAlpha);
// start the hashed alphas
handler.startHashedAlphaNodes(hashedFieldReader);
Iterator iter = hashedAlphaNodes.iterator();
for (ObjectHashMap.ObjectEntry entry = (ObjectHashMap.ObjectEntry) iter.next(); entry != null; entry = (ObjectHashMap.ObjectEntry) iter.next()) {
CompositeObjectSinkAdapter.HashKey hashKey = (CompositeObjectSinkAdapter.HashKey) entry.getKey();
AlphaNode alphaNode = (AlphaNode) entry.getValue();
handler.startHashedAlphaNode(alphaNode, hashKey.getObjectValue());
// traverse the propagator for each alpha
traversePropagator(alphaNode.getSinkPropagator(), handler);
handler.endHashedAlphaNode(alphaNode, hashKey.getObjectValue());
}
// end of the hashed alphas
handler.endHashedAlphaNodes(hashedFieldReader);
}
}
private void traverseSink(ObjectSink sink, NetworkHandler handler) {
if (sink.getType() == NodeTypeEnums.AlphaNode) {
AlphaNode alphaNode = (AlphaNode) sink;
handler.startNonHashedAlphaNode(alphaNode);
traversePropagator(alphaNode.getSinkPropagator(), handler);
handler.endNonHashedAlphaNode(alphaNode);
} else if (NodeTypeEnums.isBetaNode( sink ) ) {
BetaNode betaNode = (BetaNode) sink;
handler.startBetaNode(betaNode);
// todo traverse beta
handler.endBetaNode(betaNode);
} else if (sink.getType() == NodeTypeEnums.LeftInputAdapterNode) {
LeftInputAdapterNode leftInputAdapterNode = (LeftInputAdapterNode) sink;
handler.startLeftInputAdapterNode(leftInputAdapterNode);
// todo traverse lia
handler.endLeftInputAdapterNode(leftInputAdapterNode);
}
}
private void traverseSink(LeftTupleSink sink, NetworkHandler handler) {
// todo traverse sink's propagator
}
/**
* Returns the first {@link org.kie.reteoo.AlphaNode} from the specified {@link ObjectHashMap}.
*
* @param hashedAlphaNodes map of hashed AlphaNodes
* @return first alpha from the specified map
* @throws IllegalArgumentException thrown if the map doesn't contain any alpha nodes
*/
private AlphaNode getFirstAlphaNode(final ObjectHashMap hashedAlphaNodes) throws IllegalArgumentException {
AlphaNode firstAlphaNode;
final Iterator iter = hashedAlphaNodes.iterator();
final ObjectHashMap.ObjectEntry entry = (ObjectHashMap.ObjectEntry) iter.next();
if (entry != null) {
firstAlphaNode = (AlphaNode) entry.getValue();
} else {
throw new IllegalArgumentException("ObjectHashMap does not contain any hashed AlphaNodes!");
}
return firstAlphaNode;
}
/**
* Returns the {@link ClassFieldReader} for the hashed AlphaNode. The AlphaNode's constraint has to be a
* MvelConstraint. This is the only type of hashed alpha currently supported.
*
* @param alphaNode hashed alpha to get reader for
* @return ClassFieldReader
* @throws IllegalArgumentException thrown if the AlphaNode's {@link org.kie.spi.AlphaNodeFieldConstraint} is not a
* {@link MvelConstraint}.
*/
private ClassFieldReader getClassFieldReaderForHashedAlpha(final AlphaNode alphaNode) throws IllegalArgumentException {
final AlphaNodeFieldConstraint fieldConstraint = alphaNode.getConstraint();
if (!(fieldConstraint instanceof MvelConstraint)) {
throw new IllegalArgumentException("Only support MvelConstraint hashed AlphaNodes, not " + fieldConstraint.getClass());
}
// we need to get the first alpha in the map to get the attribute name that be use for the prefix of the
// generated variable name
return (ClassFieldReader) ((MvelConstraint)fieldConstraint).getFieldExtractor();
}
}