FirstEverProjectionExpression.java

/**************************************************************************************
 * Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 * http://esper.codehaus.org                                                          *
 * 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.client.soda;

import java.io.StringWriter;

/**
 * Represents the "firstever" aggregation function.
 */
public class FirstEverProjectionExpression extends ExpressionBase
{
    private static final long serialVersionUID = 4793677355945144559L;

    private boolean distinct;

    /**
     * Ctor.
     */
    public FirstEverProjectionExpression() {
    }

    /**

     * Ctor.
     * @param isDistinct true for distinct
     */
    public FirstEverProjectionExpression(boolean isDistinct)
    {
        this.distinct = isDistinct;
    }

    /**
     * Ctor.
     * @param expression to aggregate
     * @param isDistinct true for distinct
     */
    public FirstEverProjectionExpression(Expression expression, boolean isDistinct)
    {
        this.distinct = isDistinct;
        this.getChildren().add(expression);
    }

    public ExpressionPrecedenceEnum getPrecedence()
    {
        return ExpressionPrecedenceEnum.UNARY;
    }

    public void toPrecedenceFreeEPL(StringWriter writer)
    {
        writer.write("firstever");
        writer.write('(');
        if (distinct)
        {
            writer.write("distinct ");
        }
        String delimiter = "";
        for (Expression param : this.getChildren()) {
            writer.write(delimiter);
            delimiter = ", ";
            param.toEPL(writer, ExpressionPrecedenceEnum.MINIMUM);
        }
        writer.write(")");
    }

    /**
     * Returns true for distinct.
     * @return boolean indicating distinct or not
     */
    public boolean isDistinct()
    {
        return distinct;
    }

    /**
     * Returns true for distinct.
     * @return boolean indicating distinct or not
     */
    public boolean getDistinct()
    {
        return distinct;
    }

    /**
     * Set to true for distinct.
     * @param distinct indicating distinct or not
     */
    public void setDistinct(boolean distinct)
    {
        this.distinct = distinct;
    }
}