/*
* Copyright (c) 2001-2004 Ant-Contrib project. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.moxie.ant;
import java.util.Vector;
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;
import org.moxie.MoxieException;
/**
* Perform some tasks based on whether a given condition holds true or
* not.
*
* <p>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.</p>
*
* <p>This task doesn't have any attributes, the condition to test is
* specified by a nested element - see the documentation of your
* <code><condition></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.</p>
*
* <p>Just like the <code><condition></code> task, only a single
* condition can be specified - you combine them using
* <code><and></code> or <code><or></code> conditions.</p>
*
* <p>In addition to the condition, you can specify three different
* child elements, <code><elseif></code>, <code><then></code> and
* <code><else></code>. All three subelements are optional.
*
* Both <code><then></code> and <code><else></code> must not be
* used more than once inside the if task. Both are
* containers for Ant tasks, just like Ant's
* <code><parallel></code> and <code><sequential></code>
* tasks - in fact they are implemented using the same class as Ant's
* <code><sequential></code> task.</p>
*
* The <code><elseif></code> behaves exactly like an <code><if></code>
* except that it cannot contain the <code><else></code> element
* inside of it. You may specify as may of these as you like, and the
* order they are specified is the order they are evaluated in. If the
* condition on the <code><if></code> is false, then the first
* <code><elseif></code> who's conditional evaluates to true
* will be executed. The <code><else></code> will be executed
* only if the <code><if></code> and all <code><elseif></code>
* conditions are false.
*
* <p>Use the following task to define the <code><if></code>
* task before you use it the first time:</p>
*
* <pre><code>
* <taskdef name="if" classname="net.sf.antcontrib.logic.IfTask" />
* </code></pre>
*
* <h3>Crude Example</h3>
*
* <pre><code>
* <if>
* <equals arg1="${foo}" arg2="bar" />
* <then>
* <echo message="The value of property foo is bar" />
* </then>
* <else>
* <echo message="The value of property foo is not bar" />
* </else>
* </if>
* </code>
*
* <code>
* <if>
* <equals arg1="${foo}" arg2="bar" />
* <then>
* <echo message="The value of property foo is 'bar'" />
* </then>
*
* <elseif>
* <equals arg1="${foo}" arg2="foo" />
* <then>
* <echo message="The value of property foo is 'foo'" />
* </then>
* </elseif>
*
* <else>
* <echo message="The value of property foo is not 'foo' or 'bar'" />
* </else>
* </if>
* </code></pre>
*
* @author <a href="mailto:stefan.bodewig@freenet.de">Stefan Bodewig</a>
*/
public class MxIf extends ConditionBase {
public static final class ElseIf
extends ConditionBase
{
private Sequential thenTasks = null;
public void addThen(Sequential t)
{
if (thenTasks != null)
{
throw new MoxieException("You must not nest more than one <then> into <elseif>");
}
thenTasks = t;
}
public boolean eval()
throws MoxieException
{
if (countConditions() > 1) {
throw new MoxieException("You must not nest more than one condition into <elseif>");
}
if (countConditions() < 1) {
throw new MoxieException("You must nest a condition into <elseif>");
}
Condition c = (Condition) getConditions().nextElement();
return c.eval();
}
public void execute()
throws BuildException
{
if (thenTasks != null)
{
thenTasks.execute();
}
}
}
private Sequential thenTasks = null;
private Vector elseIfTasks = new Vector();
private Sequential elseTasks = null;
public MxIf() {
super();
setTaskName("mx:if");
}
/***
* A nested Else if task
*/
public void addElseIf(ElseIf ei)
{
elseIfTasks.addElement(ei);
}
/**
* A nested <then> 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 MoxieException("You must not nest more than one <then> into <if>");
}
thenTasks = t;
}
/**
* A nested <else> 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 MoxieException("You must not nest more than one <else> into <if>");
}
elseTasks = e;
}
public void execute() throws BuildException {
if (countConditions() > 1) {
throw new MoxieException("You must not nest more than one condition into <if>");
}
if (countConditions() < 1) {
throw new MoxieException("You must nest a condition into <if>");
}
Condition c = (Condition) getConditions().nextElement();
if (c.eval()) {
if (thenTasks != null) {
thenTasks.execute();
}
}
else
{
boolean done = false;
int sz = elseIfTasks.size();
for (int i=0;i<sz && ! done;i++)
{
ElseIf ei = (ElseIf)(elseIfTasks.elementAt(i));
if (ei.eval())
{
done = true;
ei.execute();
}
}
if (!done && elseTasks != null)
{
elseTasks.execute();
}
}
}
}