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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software 
12   * distributed under the License is distributed on an "AS IS" BASIS, 
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
14   * See the License for the specific language governing permissions and 
15   * limitations under the License.
16   */
17  
18  package org.apache.jdo.impl.model.jdo.caching;
19  
20  import org.apache.jdo.impl.model.jdo.JDOCollectionImplDynamic;
21  import org.apache.jdo.model.jdo.JDORelationship;
22  import org.apache.jdo.model.java.JavaType;
23  
24  /***
25   * An instance of this class represents the JDO relationship metadata 
26   * of a collection relationship field. This caching implementation
27   * caches any calulated value to avoid re-calculating it if it is
28   * requested again. 
29   *
30   * @author Michael Bouschen
31   * @since 1.1
32   * @version 2.0
33   */
34  public class JDOCollectionImplCaching extends JDOCollectionImplDynamic {
35  
36      /*** 
37       * Get the mappedBy relationship. If there is no mappedBy relationship
38       * set, the method checks the mappedBy name as specified in the declaring
39       * field and resolves the relationship. The method returns
40       * <code>null</code> if there is no mappedBy relationship set and there
41       * is no mappedBy name specified on the declaring field.
42       * @return the mappedBy relationship if available; <code>null</code>
43       * otherwise.
44       */
45      public JDORelationship getMappedBy() {
46          if (mappedBy == null) {
47              mappedBy = super.getMappedBy();
48          }
49          return mappedBy;
50      }
51  
52      /***
53       * Get the inverse JDORelationship in the case of a two-way relationship.
54       * @return the inverse relationship
55       */
56      public JDORelationship getInverseRelationship() {
57          if (inverse == null) {
58              inverse = super.getInverseRelationship();
59          }
60          return inverse;
61      }
62  
63      /***
64       * Determines whether the values of the elements should be stored if 
65       * possible as part of the instance instead of as their own instances 
66       * in the datastore.
67       * @return <code>true</code> if the elements should be stored as part of 
68       * the instance; <code>false</code> otherwise
69       */
70      public boolean isEmbeddedElement() {
71          if (embeddedElement == null) {
72              embeddedElement = 
73                  super.isEmbeddedElement() ? Boolean.TRUE : Boolean.FALSE;
74          }
75          return (embeddedElement == null) ? false : 
76              embeddedElement.booleanValue();
77      }
78      
79      /*** 
80       * Get the type representation of the collection elements. 
81       * @return the element type
82       */
83      public JavaType getElementType()
84      {
85          if (elementType == null) {
86              elementType = super.getElementType();
87          }
88          return elementType;
89      }
90  
91  }