com.espertech.esper.client.soda.ArithmaticExpression Maven / Gradle / Ivy

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Complex event processing and event series analysis component
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/**************************************************************************************
 * 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;

/**
 * Arithmatic expression for addition, subtraction, multiplication, division and modulo.
 */
public class ArithmaticExpression extends ExpressionBase
{
    private static final long serialVersionUID = 2237615280620839719L;
    
    private String operator;

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

    /**
     * Ctor.
     * @param operator can be any of '-', '+', '*', '/' or '%' (modulo).
     */
    public ArithmaticExpression(String operator)
    {
        this.operator = operator;
    }

    /**
     * Ctor.
     * @param left the left hand side
     * @param operator can be any of '-', '+', '*', '/' or '%' (modulo).
     * @param right the right hand side 
     */
    public ArithmaticExpression(Expression left, String operator, Expression right)
    {
        this.operator = operator;
        addChild(left);
        addChild(right);
    }

    /**
     * Returns the arithmatic operator.
     * @return operator
     */
    public String getOperator()
    {
        return operator;
    }

    /**
     * Set operator
     * @param operator new value
     */
    public void setOperator(String operator) {
        this.operator = operator;
    }

    /**
     * Add a constant to include in the computation.
     * @param object constant to add
     * @return expression
     */
    public ArithmaticExpression add(Object object)
    {
        this.getChildren().add(new ConstantExpression(object));
        return this;
    }

    /**
     * Add an expression to include in the computation. 
     * @param expression to add
     * @return expression
     */
    public ArithmaticExpression add(Expression expression)
    {
        this.getChildren().add(expression);
        return this;
    }

    /**
     * Add a property to include in the computation.
     * @param propertyName is the name of the property
     * @return expression
     */
    public ArithmaticExpression add(String propertyName)
    {
        this.getChildren().add(new PropertyValueExpression(propertyName));
        return this;
    }

    public ExpressionPrecedenceEnum getPrecedence() {
        if (operator.equals("*") || operator.equals("/") || operator.equals("%")) {
            return ExpressionPrecedenceEnum.MULTIPLY;
        }
        else {
            return ExpressionPrecedenceEnum.ADDITIVE;
        }
    }

    public void toPrecedenceFreeEPL(StringWriter writer) {
        String delimiter = "";
        for (Expression child : this.getChildren())
        {
            writer.write(delimiter);
            child.toEPL(writer, getPrecedence());
            delimiter = " " + operator + " ";
        }
    }
}