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Complex event processing and event series analysis component
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/**************************************************************************************
 * Copyright (C) 2006-2015 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.ops;

import com.espertech.esper.client.EventBean;
import com.espertech.esper.epl.expression.core.*;
import com.espertech.esper.metrics.instrumentation.InstrumentationHelper;
import com.espertech.esper.util.JavaClassHelper;

import java.io.StringWriter;

/**
 * Represents an OR expression in a filter expression tree.
 */
public class ExprOrNode extends ExprNodeBase implements ExprEvaluator
{
    private transient ExprEvaluator[] evaluators;
    private static final long serialVersionUID = -1079540621551505814L;

    public ExprEvaluator getExprEvaluator()
    {
        return this;
    }

    public ExprNode validate(ExprValidationContext validationContext) throws ExprValidationException
    {
        evaluators = ExprNodeUtility.getEvaluators(this.getChildNodes());

        // Sub-nodes must be returning boolean
        for (ExprEvaluator child : evaluators)
        {
            Class childType = child.getType();
            if (!JavaClassHelper.isBoolean(childType))
            {
                throw new ExprValidationException("Incorrect use of OR clause, sub-expressions do not return boolean");
            }
        }

        if (this.getChildNodes().length <= 1)
        {
            throw new ExprValidationException("The OR operator requires at least 2 child expressions");
        }
        return null;
    }

    public Class getType()
    {
        return Boolean.class;
    }

    public boolean isConstantResult()
    {
        return false;
    }

    public Object evaluate(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext)
    {
        if (InstrumentationHelper.ENABLED) { InstrumentationHelper.get().qExprOr(this);}
        Boolean result = false;
        // At least one child must evaluate to true
        for (ExprEvaluator child : evaluators)
        {
            Boolean evaluated = (Boolean) child.evaluate(eventsPerStream, isNewData, exprEvaluatorContext);
            if (evaluated == null)
            {
                result = null;
            }
            else {
                if (evaluated)
                {
                    if (InstrumentationHelper.ENABLED) { InstrumentationHelper.get().aExprOr(true);}
                    return true;
                }
            }
        }
        if (InstrumentationHelper.ENABLED) { InstrumentationHelper.get().aExprOr(result);}
        return result;
    }

    public void toPrecedenceFreeEPL(StringWriter writer) {
        String appendStr = "";
        for (ExprNode child : this.getChildNodes())
        {
            writer.append(appendStr);
            child.toEPL(writer, getPrecedence());
            appendStr = " or ";
        }
    }

    public ExprPrecedenceEnum getPrecedence() {
        return ExprPrecedenceEnum.OR;
    }

    public boolean equalsNode(ExprNode node)
    {
        if (!(node instanceof ExprOrNode))
        {
            return false;
        }

        return true;
    }
}