/*
* Terrier - Terabyte Retriever
* Webpage: http://terrier.org
* Contact: terrier{a.}dcs.gla.ac.uk
* University of Glasgow - School of Computing Science
* http://www.gla.ac.uk/
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is QueryExpansionModelFactory.java.
*
* The Original Code is Copyright (C) 2004-2011 the University of Glasgow.
* All Rights Reserved.
*
* Contributor(s):
* Rodrgyo Santos <rodrygo{a.}dcs.gla.ac.uk> (original author)
*
*/
package org.terrier.matching.models.queryexpansion;
import java.lang.reflect.InvocationTargetException;
import java.util.Hashtable;
import org.apache.log4j.Logger;
/**
* A factory method for handling the initialisation of expansion models.
*
* @author Rodrygo Santos
*/
public class QueryExpansionModelFactory {
/** The default namespace for expansion models. */
public static final String NAMESPACE = "org.terrier.matching.models.queryexpansion.";
/** A cache for instantiated weighting models. */
private static Hashtable<String, QueryExpansionModel> cache = new Hashtable<String, QueryExpansionModel>();
/**
* Returns the requested weighting model.
* @param name The name of the weighting model to instantiate.
*/
public static QueryExpansionModel newInstance(String name) {
Logger logger = Logger.getLogger(QueryExpansionModelFactory.class);
QueryExpansionModel model = null;
if (name.indexOf(".") < 0) {
name = NAMESPACE + name;
}
else if (name.startsWith("uk.ac.gla.terrier")) {
name = name.replaceAll("uk.ac.gla.terrier", "org.terrier");
}
//check for already instantiated model
if (cache.containsKey(name)) {
model = cache.get(name);
}
else {
try {
if (name.indexOf("(") > 0) {
String params = name.substring(name.indexOf("(")+1, name.indexOf(")"));
String[] parameters = params.split("\\s*,\\s*");
model = (QueryExpansionModel) Class.forName(name.substring(0,name.indexOf("(")))
.getConstructor(new Class[]{String[].class})
.newInstance(new Object[]{parameters});
}
else{
model = (QueryExpansionModel) Class.forName(name).newInstance();
}
} catch(InvocationTargetException e) {
logger.error("Recursive problem with weighting model named: "+name, e);
} catch(Exception e) {
logger.error("Problem with weighting model named: " + name, e);
}
cache.put(name, model);
}
return model;
}
}