[Ant-contrib-developers] CVS: ant-contrib/src/net/sf/antcontrib/logic IfTask.java,NONE,1.1

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Update of /cvsroot/ant-contrib/ant-contrib/src/net/sf/antcontrib/logic
In directory usw-pr-cvs1:/tmp/cvs-serv26275/src/net/sf/antcontrib/logic

Added Files:
	IfTask.java 
Log Message:
<if> task

--- NEW FILE: IfTask.java ---
/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Ant", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact ap...@ap....
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package net.sf.antcontrib.logic;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.taskdefs.Sequential;
import org.apache.tools.ant.taskdefs.condition.Condition;
import org.apache.tools.ant.taskdefs.condition.ConditionBase;

/**
 * Perform some tasks based on whether a given condition holds true or
 * not.
 *
 * This task is heavily based on the Condition framework that can
 * be found in Ant 1.4 and later, therefore it cannot be used in
 * conjunction with versions of Ant prior to 1.4.
 *
 * This task doesn't have any attributes, the condition to test is
 * specified by a nested element - see the documentation of your
 * <code>&lt;condition&gt;</code> task (see 
 * <a href="http://jakarta.apache.org/ant/manual/CoreTasks/condition.html">the
 * online documentation</a> for example) for a complete list of nested
 * elements.
 *
 * Just like the <code>&lt;condition&gt;</code> task, only a single
 * condition can be specified - you combine them using
 * <code>&lt;and&gt;</code> or <code>&lt;or&gt;</code> conditions.
 *
 * In addition to the condition, you can specify two different
 * child elements, <code>&lt;then&gt;</code> and
 * <code>&lt;else&gt;</code>. Both are optional and both must not be
 * used more than once inside the same task. Both elements are
 * containers for Ant tasks, just like Ant's
 * <code>&lt;parallel&gt;</code> and <code>&lt;sequential&gt;</code>
 * tasks - in fact they are implemented using the same class as Ant's
 * <code>&lt;sequential&gt;</code> task.
 *
 * Use the following task to define the <code>&lt;if&gt;</code>
 * task before you use it the first time:
 *
 * <pre><code>
 * &lt;taskdef name="if" classname="net.sf.antcontrib.logic.IfTask" /&gt;
 * </code></pre>
 * 
 * <h3>Crude Example</h3>
 *
 * <pre><code>
 * &lt;if&gt;
 * &lt;equals arg1=&quot;${foo}&quot; arg2=&quot;bar&quot; /&gt;
 * &lt;then&gt;
 * &lt;echo message=&quot;The value of property foo is bar&quot; /&gt;
 * &lt;/then&gt;
 * &lt;else&gt;
 * &lt;echo message=&quot;The value of property foo is not bar&quot; /&gt;
 * &lt;/else&gt;
 * &lt;/if&gt;
 * </code></pre>
 *
 * @author <a href="mailto:ste...@ep...">Stefan Bodewig</a>
 */
public class IfTask extends ConditionBase {

    private Sequential thenTasks = null;
    private Sequential elseTasks = null;

    /**
     * A nested &lt;then&gt; element - a container of tasks that will
     * be run if the condition holds true.
     *
     * <p>Not required.</p>
     */
    public void addThen(Sequential t) {
        if (thenTasks != null) {
            throw new BuildException("You must not nest more than one <then> into <if>");
        }
        thenTasks = t;
    }

    /**
     * A nested &lt;else&gt; element - a container of tasks that will
     * be run if the condition doesn't hold true.
     *
     * <p>Not required.</p>
     */
    public void addElse(Sequential e) {
        if (elseTasks != null) {
            throw new BuildException("You must not nest more than one <else> into <if>");
        }
        elseTasks = e;
    }

    public void execute() throws BuildException {
        if (countConditions() > 1) {
            throw new BuildException("You must not nest more than one condition into <if>");
        }
        if (countConditions() < 1) {
            throw new BuildException("You must nest a condition into <if>");
        }
        Condition c = (Condition) getConditions().nextElement();
        if (c.eval()) {
            if (thenTasks != null) {
                thenTasks.perform();
            }
        } else {
            if (elseTasks != null) {
                elseTasks.perform();
            }
        }
    }
}