GraphMap


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19  
20  package org.apache.cayenne.graph;
21  
22  import java.util.Collection  ;
23  import java.util.Collections  ;
24  import java.util.HashMap  ;
25  import java.util.Map  ;
26  
27  /**
28   * A base implementation of GraphManager that stores graph nodes keyed by their ids.
29   * <h3>Tracking Object Changes</h3>
30   * <p>
31   * Registered objects may choose to notify GraphMap of their changes by using callback
32   * methods defined in GraphChangeHandler interface. GraphMap itself implements as noops,
33   * leaving it up to subclasses to handle object updates.
34   * </p>
35   * 
36   * @since 1.2
37   * @author Andrus Adamchik
38   */
39  public class GraphMap implements GraphManager {
40  
41      protected Map   nodes;
42  
43      /**
44       * Creates a new GraphMap.
45       */
46      public GraphMap() {
47          this.nodes = new HashMap  ();
48      }
49  
50      // *** GraphMap methods
51  
52      /**
53       * Returns an immutable collection of registered nodes.
54       */
55      public Collection   registeredNodes() {
56          return Collections.unmodifiableCollection(nodes.values());
57      }
58  
59      public synchronized Object   getNode(Object   nodeId) {
60          return nodes.get(nodeId);
61      }
62  
63      public synchronized void registerNode(Object   nodeId, Object   nodeObject) {
64          nodes.put(nodeId, nodeObject);
65      }
66  
67      public synchronized Object   unregisterNode(Object   nodeId) {
68          return nodes.remove(nodeId);
69      }
70  
71      // *** methods for tracking local changes declared in GraphChangeHandler interface
72      
73      public void arcCreated(Object   nodeId, Object   targetNodeId, Object   arcId) {
74          // noop
75      }
76  
77      public void arcDeleted(Object   nodeId, Object   targetNodeId, Object   arcId) {
78          // noop
79      }
80  
81      public void nodeCreated(Object   nodeId) {
82          // noop
83      }
84  
85      public void nodeRemoved(Object   nodeId) {
86          // noop
87      }
88  
89      public void nodeIdChanged(Object   nodeId, Object   newId) {
90          // noop
91      }
92  
93      public void nodePropertyChanged(
94              Object   nodeId,
95              String   property,
96              Object   oldValue,
97              Object   newValue) {
98          // noop
99      }
100 }
101
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