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Java > Open Source Codes > org > apache > cayenne > ejbql > EJBQLParserFactory


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19 package org.apache.cayenne.ejbql;
20
21 /**
22  * Creates {@link EJBQLParser} based on the system settings.
23  *
24  * @since 3.0
25  * @author Andrus Adamchik
26  */
27 public class EJBQLParserFactory {
28
29     // this is the parser generated by JJTree/JavaCC
30 private static String JavaDoc DEFAULT_PARSER_CLASS = "org.apache.cayenne.ejbql.parser.EJBQL$EJBQLDefaultParser";
31
32     private static Class JavaDoc parserClass;
33
34     private static Class JavaDoc getParserClass() throws ClassNotFoundException JavaDoc {
35         if (parserClass == null) {
36             // for now support only the default parser. If needed it should be
37 // easy to plug external parsers via a System property...
38 parserClass = Class.forName(DEFAULT_PARSER_CLASS, true, Thread
39                     .currentThread()
40                     .getContextClassLoader());
41         }
42
43         return parserClass;
44     }
45
46     public static EJBQLParser getParser() throws EJBQLException {
47         try {
48             return (EJBQLParser) getParserClass().newInstance();
49         }
50         catch (Exception JavaDoc e) {
51             throw new EJBQLException("Error creating EJBQL parser", e);
52         }
53     }
54 }
55
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