antliscence/src/main/org/apache/tools/ant/taskdefs/ConditionTask.java

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001-2003 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 "Ant" and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
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 * 5. Products derived from this software may not be called "Apache"
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 *
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 * 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 org.apache.tools.ant.taskdefs;

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

/**
 * Task to set a property conditionally using &lt;uptodate&gt;, &lt;available&gt;,
 * and many other supported conditions.
 *
 * <p>This task supports boolean logic as well as pluggable conditions
 * to decide, whether a property should be set.</p>
 *
 * <p>This task does not extend Task to take advantage of
 * ConditionBase.</p>
 *
 * @author Stefan Bodewig
 * @version $Revision$
 *
 * @since Ant 1.4
 *
 * @ant.task category="control"
 */
public class ConditionTask extends ConditionBase {

    private String property = null;
    private String value = "true";

    /**
     * The name of the property to set. Required.
     * @param p the name of the property
     * @since Ant 1.4
     */
    public void setProperty(String p) {
        property = p;
    }

    /**
     * The value for the property to set, if condition evaluates to true.
     * Defaults to "true".
     * @param v the value of the property
     * @since Ant 1.4
     */
    public void setValue(String v) {
        value = v;
    }

    /**
     * See whether our nested condition holds and set the property.
     *
     * @since Ant 1.4
     * @exception BuildException if an error occurs
     */
    public void execute() throws BuildException {
        if (countConditions() > 1) {
            throw new BuildException("You must not nest more than one "
                + "condition into <condition>");
        }
        if (countConditions() < 1) {
            throw new BuildException("You must nest a condition into "
                + "<condition>");
        }
        if (property == null) {
            throw new BuildException("The property attribute is required.");
        }

        Condition c = (Condition) getConditions().nextElement();
        if (c.eval()) {
            log("Condition true; setting " + property + " to " + value,
                Project.MSG_DEBUG);
            getProject().setNewProperty(property, value);
        } else {
            log("Condition false; not setting " + property,
                Project.MSG_DEBUG);
        }
    }
}