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Complex event processing and event series analysis component

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/*
 ***************************************************************************************
 *  Copyright (C) 2006 EsperTech, Inc. All rights reserved.                            *
 *  http://www.espertech.com/esper                                                     *
 *  http://www.espertech.com                                                           *
 *  ---------------------------------------------------------------------------------- *
 *  The software in this package is published under the terms of the GPL license       *
 *  a copy of which has been included with this distribution in the license.txt file.  *
 ***************************************************************************************
 */
package com.espertech.esper.epl.expression.visitor;

import com.espertech.esper.epl.enummethod.dot.ExprLambdaGoesNode;
import com.espertech.esper.epl.expression.baseagg.ExprAggregateNode;
import com.espertech.esper.epl.expression.core.*;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class ExprNodeIdentifierAndStreamRefVisitor implements ExprNodeVisitor {
    private final boolean isVisitAggregateNodes;
    private List refs;

    public ExprNodeIdentifierAndStreamRefVisitor(boolean isVisitAggregateNodes) {
        this.isVisitAggregateNodes = isVisitAggregateNodes;
    }

    public boolean isVisit(ExprNode exprNode) {
        if (exprNode instanceof ExprLambdaGoesNode) {
            return false;
        }
        if (isVisitAggregateNodes) {
            return true;
        }
        return !(exprNode instanceof ExprAggregateNode);
    }

    public List getRefs() {
        if (refs == null) {
            return Collections.emptyList();
        }
        return refs;
    }

    public void visit(ExprNode exprNode) {
        if (exprNode instanceof ExprIdentNode) {
            ExprIdentNode identNode = (ExprIdentNode) exprNode;

            int streamId = identNode.getStreamId();
            String propertyName = identNode.getResolvedPropertyName();
            checkAllocatedRefs();
            refs.add(new ExprNodePropOrStreamPropDesc(streamId, propertyName));
        } else if (exprNode instanceof ExprStreamRefNode) {
            ExprStreamRefNode streamRefNode = (ExprStreamRefNode) exprNode;
            Integer stream = streamRefNode.getStreamReferencedIfAny();
            checkAllocatedRefs();
            if (stream != null) {
                refs.add(new ExprNodePropOrStreamExprDesc(stream, streamRefNode));
            }
        }
    }

    public void reset() {
        if (refs != null) {
            refs.clear();
        }
    }

    private void checkAllocatedRefs() {
        if (refs == null) {
            refs = new ArrayList(4);
        }
    }
}