Package org.drools.reteoo.builder

Source Code of org.drools.reteoo.builder.AccumulateBuilder

/*
* 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.List;

import org.drools.common.BetaConstraints;
import org.drools.common.TupleStartEqualsConstraint;
import org.drools.reteoo.AccumulateNode;
import org.drools.reteoo.LeftTupleSource;
import org.drools.reteoo.ObjectSource;
import org.drools.reteoo.QueryRiaFixerNode;
import org.drools.reteoo.RightInputAdapterNode;
import org.drools.rule.Accumulate;
import org.drools.rule.GroupElement;
import org.drools.rule.RuleConditionElement;
import org.drools.spi.AlphaNodeFieldConstraint;

public class AccumulateBuilder
    implements
    ReteooComponentBuilder {

    /**
     * @inheritDoc
     */
    public void build(final BuildContext context,
                      final BuildUtils utils,
                      final RuleConditionElement rce) {
        final Accumulate accumulate = (Accumulate) rce;
        boolean existSubNetwort = false;
        context.pushRuleComponent( accumulate );

        final List resultBetaConstraints = context.getBetaconstraints();
        final List resultAlphaConstraints = context.getAlphaConstraints();

        RuleConditionElement source = accumulate.getSource();
        if( source instanceof GroupElement ) {
            GroupElement ge = (GroupElement) source;
            if( ge.isAnd() && ge.getChildren().size() == 1 ) {
                source = (RuleConditionElement) ge.getChildren().get( 0 );
            }
        }

        // get builder for the pattern
        final ReteooComponentBuilder builder = utils.getBuilderFor( source );

        // save tuple source and current pattern offset for later if needed
        LeftTupleSource tupleSource = context.getTupleSource();
        final int currentPatternIndex = context.getCurrentPatternOffset();
       
        // builds the source pattern
        builder.build( context,
                       utils,
                       source );                
       
        // if object source is null, then we need to adapt tuple source into a subnetwork
        if ( context.getObjectSource() == 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(),
                                                                                                 tupleSource,
                                                                                                 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 betaConstraints = new ArrayList();
            betaConstraints.add( constraint );
            context.setBetaconstraints( betaConstraints );
            existSubNetwort = true;
        }
       
        if ( !context.isTupleMemoryEnabled() && existSubNetwort ) {
            // If there is a RIANode, so need to handle. This only happens with queries, so need to worry about sharing
            context.setTupleSource( (LeftTupleSource) utils.attachNode( context, new QueryRiaFixerNode( context.getNextId(), context.getTupleSource(), context ) ) );  
        }         
       
        final BetaConstraints resultsBinder = utils.createBetaNodeConstraint( context,
                                                                              resultBetaConstraints,
                                                                              true );
        final BetaConstraints sourceBinder = utils.createBetaNodeConstraint( context,
                                                                             context.getBetaconstraints(),
                                                                             false );
       
        context.setTupleSource( (LeftTupleSource) utils.attachNode( context,
                                                                    new AccumulateNode( context.getNextId(),
                                                                                        context.getTupleSource(),
                                                                                        context.getObjectSource(),
                                                                                        (AlphaNodeFieldConstraint[]) resultAlphaConstraints.toArray( new AlphaNodeFieldConstraint[resultAlphaConstraints.size()] ),
                                                                                        sourceBinder,
                                                                                        resultsBinder,
                                                                                        accumulate,
                                                                                        existSubNetwort,
                                                                                        context ) ) );
       
        // source pattern was bound, so nulling context
        context.setObjectSource( null );
        context.setCurrentPatternOffset( currentPatternIndex );
        context.popRuleComponent();
    }

    /**
     * @inheritDoc
     */
    public boolean requiresLeftActivation(final BuildUtils utils,
                                          final RuleConditionElement rce) {
        return true;
    }

}
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