/*
* ModeShape (http://www.modeshape.org)
*
* 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.modeshape.jcr.query.optimize;
import java.util.LinkedList;
import org.modeshape.common.annotation.Immutable;
import org.modeshape.jcr.query.QueryContext;
import org.modeshape.jcr.query.plan.PlanNode;
import org.modeshape.jcr.query.plan.PlanNode.Property;
import org.modeshape.jcr.query.plan.PlanNode.Traversal;
import org.modeshape.jcr.query.plan.PlanNode.Type;
/**
* An {@link OptimizerRule optimizer rule} that moves up higher in the plan any {@link Property#VARIABLE_NAME variable name}
* property to the node immediately under a {@link Type#DEPENDENT_QUERY dependent query} node.
*/
@Immutable
public class RaiseVariableName implements OptimizerRule {
public static final RaiseVariableName INSTANCE = new RaiseVariableName();
@Override
public PlanNode execute( QueryContext context,
PlanNode plan,
LinkedList<OptimizerRule> ruleStack ) {
for (PlanNode depQuery : plan.findAllAtOrBelow(Traversal.PRE_ORDER, Type.DEPENDENT_QUERY)) {
// Check the left ...
PlanNode left = depQuery.getFirstChild();
raiseVariableName(left);
// Check the right ...
PlanNode right = depQuery.getLastChild();
raiseVariableName(right);
}
return plan;
}
protected void raiseVariableName( PlanNode node ) {
if (node.getType() != Type.DEPENDENT_QUERY) {
String variableName = removeVariableName(node);
if (variableName != null) {
node.setProperty(Property.VARIABLE_NAME, variableName);
}
}
}
protected String removeVariableName( PlanNode node ) {
if (node == null) return null;
String variableName = node.getProperty(Property.VARIABLE_NAME, String.class);
if (variableName != null) {
node.removeProperty(Property.VARIABLE_NAME);
return variableName;
}
// Look for it in the left side ...
return removeVariableName(node.getFirstChild());
}
@Override
public String toString() {
return getClass().getSimpleName();
}
}