ConcatExpression.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;

/**
 * Concatenation expression that concatenates the result of child expressions to the expression.
 */
public class ConcatExpression extends ExpressionBase
{
    private static final long serialVersionUID = 0L;

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

    /**
     * Add a constant to include in the computation.
     * @param object constant to add
     * @return expression
     */
    public ConcatExpression 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 ConcatExpression 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 ConcatExpression add(String propertyName)
    {
        this.getChildren().add(new PropertyValueExpression(propertyName));
        return this;
    }

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

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