/**
* 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.reteoo.builder;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.drools.RuntimeDroolsException;
import org.drools.common.BetaConstraints;
import org.drools.common.TupleStartEqualsConstraint;
import org.drools.reteoo.ExistsNode;
import org.drools.reteoo.JoinNode;
import org.drools.reteoo.LeftInputAdapterNode;
import org.drools.reteoo.LeftTupleSource;
import org.drools.reteoo.NotNode;
import org.drools.reteoo.ObjectSource;
import org.drools.reteoo.RightInputAdapterNode;
import org.drools.rule.Behavior;
import org.drools.rule.GroupElement;
import org.drools.rule.RuleConditionElement;
import org.drools.rule.GroupElement.Type;
/**
* @author etirelli
*
*/
public class GroupElementBuilder
implements
ReteooComponentBuilder {
private final Map<Type, ReteooComponentBuilder> geBuilders = new HashMap<Type, ReteooComponentBuilder>();
public GroupElementBuilder() {
this.geBuilders.put( GroupElement.AND,
new AndBuilder() );
this.geBuilders.put( GroupElement.OR,
new OrBuilder() );
this.geBuilders.put( GroupElement.NOT,
new NotBuilder() );
this.geBuilders.put( GroupElement.EXISTS,
new ExistsBuilder() );
}
/**
* @inheritDoc
*/
public void build(final BuildContext context,
final BuildUtils utils,
final RuleConditionElement rce) {
final GroupElement ge = (GroupElement) rce;
final ReteooComponentBuilder builder = this.geBuilders.get( ge.getType() );
context.push( ge );
context.pushRuleComponent( ge );
builder.build( context,
utils,
rce );
context.pop();
context.popRuleComponent();
}
/**
* @inheritDoc
*/
public boolean requiresLeftActivation(final BuildUtils utils,
final RuleConditionElement rce) {
final GroupElement ge = (GroupElement) rce;
final ReteooComponentBuilder builder = this.geBuilders.get( ge.getType() );
return builder.requiresLeftActivation( utils,
rce );
}
private static Behavior[] createBehaviorArray(final BuildContext context) {
Behavior[] behaviors = Behavior.EMPTY_BEHAVIOR_LIST;
if( ! context.getBehaviors().isEmpty() ) {
behaviors = (Behavior[]) context.getBehaviors().toArray( new Behavior[ context.getBehaviors().size() ]);
}
context.setBehaviors( Collections.EMPTY_LIST );
return behaviors;
}
private static class AndBuilder
implements
ReteooComponentBuilder {
/**
* @inheritDoc
*
* And group elements just iterate over their children
* selecting and calling the build procedure for each one
*
*/
public void build(final BuildContext context,
final BuildUtils utils,
final RuleConditionElement rce) {
final GroupElement ge = (GroupElement) rce;
// iterate over each child and build it
for ( final Iterator it = ge.getChildren().iterator(); it.hasNext(); ) {
final RuleConditionElement child = (RuleConditionElement) it.next();
final ReteooComponentBuilder builder = utils.getBuilderFor( child );
builder.build( context,
utils,
child );
// if a previous object source was bound, but no tuple source
if ( context.getObjectSource() != null && context.getTupleSource() == null ) {
// adapt it to a Tuple source
context.setTupleSource( (LeftTupleSource) utils.attachNode( context,
new LeftInputAdapterNode( context.getNextId(),
context.getObjectSource(),
context ) ) );
context.setObjectSource( null );
}
// if there was a previous tuple source, then a join node is needed
if ( context.getObjectSource() != null && context.getTupleSource() != null ) {
// so, create the tuple source and clean up the constraints and object source
final BetaConstraints betaConstraints = utils.createBetaNodeConstraint( context,
context.getBetaconstraints(),
false );
Behavior[] behaviors = createBehaviorArray( context );
context.setTupleSource( (LeftTupleSource) utils.attachNode( context,
new JoinNode( context.getNextId(),
context.getTupleSource(),
context.getObjectSource(),
betaConstraints,
behaviors,
context ) ) );
context.setBetaconstraints( null );
context.setObjectSource( null );
}
}
}
public boolean requiresLeftActivation(final BuildUtils utils,
final RuleConditionElement rce) {
final GroupElement and = (GroupElement) rce;
// need to check this because in the case of an empty rule, the root AND
// will have no child
if ( and.getChildren().isEmpty() ) {
return true;
}
final RuleConditionElement child = (RuleConditionElement) and.getChildren().get( 0 );
final ReteooComponentBuilder builder = utils.getBuilderFor( child );
return builder.requiresLeftActivation( utils,
child );
}
}
private static class OrBuilder
implements
ReteooComponentBuilder {
/**
* @inheritDoc
*/
public void build(final BuildContext context,
final BuildUtils utils,
final RuleConditionElement rce) {
throw new RuntimeDroolsException( "BUG: Can't build a rete network with an inner OR group element" );
}
public boolean requiresLeftActivation(final BuildUtils utils,
final RuleConditionElement rce) {
throw new RuntimeDroolsException( "BUG: Can't build a rete network with an inner OR group element" );
}
}
private static class NotBuilder
implements
ReteooComponentBuilder {
/**
* @inheritDoc
*
* Not must verify what is the class of its child:
*
* If it is a pattern, a simple NotNode is added to the rulebase
* If it is a group element, than a subnetwork must be created
*/
public void build(final BuildContext context,
final BuildUtils utils,
final RuleConditionElement rce) {
final GroupElement not = (GroupElement) rce;
// NOT must save some context info to restore it later
final int currentPatternIndex = context.getCurrentPatternOffset();
final LeftTupleSource tupleSource = context.getTupleSource();
// get child
final RuleConditionElement child = (RuleConditionElement) not.getChildren().get( 0 );
// get builder for child
final ReteooComponentBuilder builder = utils.getBuilderFor( child );
// builds the child
builder.build( context,
utils,
child );
// if it is a subnetwork
if ( context.getObjectSource() == null && context.getTupleSource() != null ) {
// attach right input adapter node to convert tuple source into an object source
context.setObjectSource( (ObjectSource) utils.attachNode( context,
new RightInputAdapterNode( context.getNextId(),
context.getTupleSource(),
context ) ) );
// restore tuple source from before the start of the sub network
context.setTupleSource( tupleSource );
// create a tuple start equals constraint and set it in the context
final TupleStartEqualsConstraint constraint = TupleStartEqualsConstraint.getInstance();
final List<TupleStartEqualsConstraint> predicates = new ArrayList<TupleStartEqualsConstraint>();
predicates.add( constraint );
context.setBetaconstraints( predicates );
}
final BetaConstraints betaConstraints = utils.createBetaNodeConstraint( context,
context.getBetaconstraints(),
false );
Behavior[] behaviors = createBehaviorArray( context );
// then attach the NOT node. It will work both as a simple not node
// or as subnetwork join node as the context was set appropriatelly
// in each case
NotNode node = null;
node = new NotNode( context.getNextId(),
context.getTupleSource(),
context.getObjectSource(),
betaConstraints,
behaviors,
context );
context.setTupleSource( (LeftTupleSource) utils.attachNode( context,
node ) );
context.setBetaconstraints( null );
context.setObjectSource( null );
// restore pattern index
context.setCurrentPatternOffset( currentPatternIndex );
}
public boolean requiresLeftActivation(final BuildUtils utils,
final RuleConditionElement rce) {
return true;
}
}
private static class ExistsBuilder
implements
ReteooComponentBuilder {
/**
* @inheritDoc
*
* Exists must verify what is the class of its child:
*
* If it is a pattern, a simple ExistsNode is added to the rulebase
* If it is a group element, than a subnetwork must be created
*/
public void build(final BuildContext context,
final BuildUtils utils,
final RuleConditionElement rce) {
final GroupElement exists = (GroupElement) rce;
// EXISTS must save some context info to restore it later
final int currentPatternIndex = context.getCurrentPatternOffset();
final LeftTupleSource tupleSource = context.getTupleSource();
// get child
final RuleConditionElement child = (RuleConditionElement) exists.getChildren().get( 0 );
// get builder for child
final ReteooComponentBuilder builder = utils.getBuilderFor( child );
// builds the child
builder.build( context,
utils,
child );
// if it is a subnetwork
if ( context.getObjectSource() == null && context.getTupleSource() != null ) {
// attach right input adapter node to convert tuple source into an object source
context.setObjectSource( (ObjectSource) utils.attachNode( context,
new RightInputAdapterNode( context.getNextId(),
context.getTupleSource(),
context ) ) );
// restore tuple source from before the start of the sub network
context.setTupleSource( tupleSource );
// create a tuple start equals constraint and set it in the context
final TupleStartEqualsConstraint constraint = TupleStartEqualsConstraint.getInstance();
final List<TupleStartEqualsConstraint> predicates = new ArrayList<TupleStartEqualsConstraint>();
predicates.add( constraint );
context.setBetaconstraints( predicates );
}
final BetaConstraints betaConstraints = utils.createBetaNodeConstraint( context,
context.getBetaconstraints(),
false );
Behavior[] behaviors = createBehaviorArray( context );
// then attach the EXISTS node. It will work both as a simple exists node
// or as subnetwork join node as the context was set appropriatelly
// in each case
context.setTupleSource( (LeftTupleSource) utils.attachNode( context,
new ExistsNode( context.getNextId(),
context.getTupleSource(),
context.getObjectSource(),
betaConstraints,
behaviors,
context ) ) );
context.setBetaconstraints( null );
context.setObjectSource( null );
// restore pattern index
context.setCurrentPatternOffset( currentPatternIndex );
}
/**
* @inheritDoc
*/
public boolean requiresLeftActivation(final BuildUtils utils,
final RuleConditionElement rce) {
return true;
}
}
}