/*****************************************************************
* 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.cayenne.ejbql;
/**
* Creates {@link EJBQLParser} based on the system settings.
*
* @since 3.0
*/
public class EJBQLParserFactory {
// this is the parser generated by JJTree/JavaCC
private static String DEFAULT_PARSER_CLASS = "org.apache.cayenne.ejbql.parser.EJBQL$EJBQLDefaultParser";
private static Class parserClass;
private static Class getParserClass() throws ClassNotFoundException {
if (parserClass == null) {
// for now support only the default parser. If needed it should be
// easy to plug external parsers via a System property...
parserClass = Class.forName(DEFAULT_PARSER_CLASS, true, Thread
.currentThread()
.getContextClassLoader());
}
return parserClass;
}
public static EJBQLParser getParser() throws EJBQLException {
try {
return (EJBQLParser) getParserClass().newInstance();
}
catch (Exception e) {
throw new EJBQLException("Error creating EJBQL parser", e);
}
}
}