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/*
* Copyright 2000-2004 The Apache Software Foundation
*
* 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.apache.tools.ant.util.regexp;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
/**
* Simple Factory Class that produces an implementation of
* RegexpMatcher based on the system property
* <code>ant.regexp.matcherimpl</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 {
public RegexpMatcherFactory() {
}
/***
* Create a new regular expression instance.
*/
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.
*/
public RegexpMatcher newRegexpMatcher(Project p)
throws BuildException {
String systemDefault = null;
if (p == null) {
systemDefault = System.getProperty("ant.regexp.regexpimpl");
} else {
systemDefault = p.getProperty("ant.regexp.regexpimpl");
}
if (systemDefault != null) {
return createInstance(systemDefault);
// XXX should we silently catch possible exceptions and try to
// load a different implementation?
}
try {
testAvailability("java.util.regex.Matcher");
return createInstance("org.apache.tools.ant.util.regexp.Jdk14RegexpMatcher");
} catch (BuildException be) {
// ignore
}
try {
testAvailability("org.apache.oro.text.regex.Pattern");
return createInstance("org.apache.tools.ant.util.regexp.JakartaOroMatcher");
} catch (BuildException be) {
// ignore
}
try {
testAvailability("org.apache.regexp.RE");
return createInstance("org.apache.tools.ant.util.regexp.JakartaRegexpMatcher");
} catch (BuildException be) {
// ignore
}
throw new BuildException("No supported regular expression matcher found");
}
protected RegexpMatcher createInstance(String className)
throws BuildException {
try {
Class implClass = Class.forName(className);
return (RegexpMatcher) implClass.newInstance();
} catch (Throwable t) {
throw new BuildException(t);
}
}
protected void testAvailability(String className) throws BuildException {
try {
Class.forName(className);
} catch (Throwable t) {
throw new BuildException(t);
}
}
}
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