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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.tools.ant;
import java.util.ArrayList;
import java.util.List;
/**
* <p>Helper class for the check of the configuration of a given task.
* This class provides methods for making assumptions about the task configuration.
* After collecting all violations with <tt>assert*</tt> and <tt>fail</tt>
* methods the <tt>checkErrors</tt> will throw a BuildException with all collected
* messages or does nothing if there wasn't any error.</p>
*
* <p>Example:</p>
*
* <pre>
* public class MyTask extends Task {
* ...
* public void execute() {
* TaskConfigurationChecker checker = TaskConfigurationChecker(this);
* checker.assertConfig(
* srcdir != null,
* "Attribute 'srcdir' must be set.
* );
* checker.assertConfig(
* srcdir.exists(),
* "Srcdir (" + srcdir + ") must exist."
* );
* if (someComplexCondition()) {
* fail("Complex condition failed.");
* }
* checker.checkErrors();
* }
* }
* </pre>
*
* @see <a href="http://martinfowler.com/eaaDev/Notification.html">Notification Pattern</a>
*/
public class TaskConfigurationChecker {
/** List of all collected error messages. */
private List<String> errors = new ArrayList<String>();
/** Task for which the configuration should be checked. */
private final Task task;
/**
* Constructor.
* @param task which task should be checked
*/
public TaskConfigurationChecker(Task task) {
this.task = task;
}
/**
* Asserts that a condition is true.
* @param condition which condition to check
* @param errormessage errormessage to throw if a condition failed
*/
public void assertConfig(boolean condition, String errormessage) {
if (!condition) {
errors.add(errormessage);
}
}
/**
* Registers an error.
* @param errormessage the message for the registered error
*/
public void fail(String errormessage) {
errors.add(errormessage);
}
/**
* Checks if there are any collected errors and throws a BuildException
* with all messages if there was one or more.
* @throws BuildException if one or more errors were registered
*/
public void checkErrors() throws BuildException {
if (!errors.isEmpty()) {
StringBuffer sb = new StringBuffer();
sb.append("Configurationerror on <");
sb.append(task.getTaskName());
sb.append(">:");
sb.append(System.getProperty("line.separator"));
for (String msg : errors) {
sb.append("- ");
sb.append(msg);
sb.append(System.getProperty("line.separator"));
}
throw new BuildException(sb.toString(), task.getLocation());
}
}
}
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