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1   /*
2    * Copyright 2006 Outsource Cafe, Inc.
3    *
4    * Licensed under the Apache License, Version 2.0 (the 'License')
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *    http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an 'AS IS' BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.javagen.agile.db.visitor;
17  
18  import org.javagen.agile.db.model.Table;
19  
20  /***
21   * Identify and flag pure link or association tables - that is tables
22   * whose only function is to link one table to another. 
23   *
24   * @author Richard Easterling
25   */
26  public class LinkTableFinderVisitor extends DefaultDatabaseVisitor {
27  
28      private static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(LinkTableFinderVisitor.class);
29  
30      public LinkTableFinderVisitor() {
31          this.setItinerary(new String[] {Table.DEFAULT_MODEL_TYPE});
32      }
33  		
34  	/***
35  	 * Identify and flag link tables.   Link tables are determined here as having
36  	 *  exactly two foreign key columns.
37  	 */
38  	public void visit(Table table) {
39  		if ( ! Boolean.TRUE.equals(table.isLinkTable()) 
40  				&& table.getFkColumns()!=null && table.getFkColumns().size()==2
41  				&& table.getColumns()!=null && table.getColumns().size()==2
42                  && table.getColumns().get(0).isKey()
43                  && table.getColumns().get(1).isKey()
44             )
45  		{
46  			table.setLinkTable(true);
47              if (log.isInfoEnabled())
48                  log.info("Removing "+table.getName()+" link table from mapping");
49  		}
50  	}
51  }