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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.util.regexp;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.MagicNames;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.util.ClasspathUtils;
/**
* Simple Factory Class that produces an implementation of RegexpMatcher based on the system
* property <code>ant.regexp.regexpimpl</code> and the classes available.
*
* <p>
* In a more general framework this class would be abstract and have a static newInstance method.
* </p>
*
*/
public class RegexpMatcherFactory {
/** Constructor for RegexpMatcherFactory. */
public RegexpMatcherFactory() {
}
/***
* Create a new regular expression instance.
* @return the matcher
* @throws BuildException on error
*/
public RegexpMatcher newRegexpMatcher() throws BuildException {
return newRegexpMatcher(null);
}
/***
* Create a new regular expression instance.
*
* @param p Project whose ant.regexp.regexpimpl property will be used.
* @return the matcher
* @throws BuildException on error
*/
public RegexpMatcher newRegexpMatcher(Project p) throws BuildException {
String systemDefault = null;
if (p == null) {
systemDefault = System.getProperty(MagicNames.REGEXP_IMPL);
} else {
systemDefault = p.getProperty(MagicNames.REGEXP_IMPL);
}
if (systemDefault != null) {
return createInstance(systemDefault);
// TODO should we silently catch possible exceptions and try to
// load a different implementation?
}
return new Jdk14RegexpMatcher();
}
/**
* Create an instance of a matcher from a classname.
*
* @param className a <code>String</code> value
* @return a <code>RegexpMatcher</code> value
* @exception BuildException if an error occurs
*/
protected RegexpMatcher createInstance(String className) throws BuildException {
return (RegexpMatcher) ClasspathUtils.newInstance(className, RegexpMatcherFactory.class
.getClassLoader(), RegexpMatcher.class);
}
/**
* Test if a particular class is available to be used.
*
* @param className a <code>String</code> value
* @exception BuildException if an error occurs
*/
protected void testAvailability(String className) throws BuildException {
try {
Class.forName(className);
} catch (Throwable t) {
throw new BuildException(t);
}
}
/**
* Checks if a RegExp-Matcher is available.
* @param project The project to check for (may be <code>null</code>)
* @return <code>true</code> if available otherwise <code>false</code>
*/
public static boolean regexpMatcherPresent(Project project) {
try {
// The factory throws a BuildException if no usable matcher
// cannot be instantiated. We dont need the matcher itself here.
new RegexpMatcherFactory().newRegexpMatcher(project);
return true;
} catch (Throwable ex) {
return false;
}
}
}
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