[power-architect] r3831 committed - Fixed an NPE when making/adding a column that does not have a snapshot...

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Revision: 3831
Author: thomasobrie...@gmail.com
Date: Tue Aug  3 13:38:41 2010
Log: Fixed an NPE when making/adding a column that does not have a snapshot  
already created. The root cause was the listener was being added before the  
snapshot being listened to was created and could not be found.

Also added documentation and the starting point of cleaning up snapshots.
http://code.google.com/p/power-architect/source/detail?r=3831

Modified:
  
/trunk/src/main/java/ca/sqlpower/architect/SPObjectSnapshotHierarchyListener.java

=======================================
---  
/trunk/src/main/java/ca/sqlpower/architect/SPObjectSnapshotHierarchyListener.java	 
Tue Aug  3 08:39:01 2010
+++  
/trunk/src/main/java/ca/sqlpower/architect/SPObjectSnapshotHierarchyListener.java	 
Tue Aug  3 13:38:41 2010
@@ -59,8 +59,8 @@
                        SQLColumn sqlColumn = (SQLColumn) e.getChild();
             if (sqlColumn.getUserDefinedSQLType() != null) {
                 sqlColumn.getUserDefinedSQLType().addSPListener(this);
-                addUpdateListener(sqlColumn.getUserDefinedSQLType());
                 createSPObjectSnapshot(sqlColumn.getUserDefinedSQLType(),  
sqlColumn.getUserDefinedSQLType().getUpstreamType());
+                addUpdateListener(sqlColumn.getUserDefinedSQLType());
             }
                }
        }
@@ -71,9 +71,11 @@
                        e.getChild().removeSPListener(this);
                        for (SQLColumn col : 
e.getChild().getChildren(SQLColumn.class)) {
                                
col.getUserDefinedSQLType().removeSPListener(this);
+                               cleanupSnapshot();
                        }
                } else if (e.getChild() instanceof SQLColumn) {
 			((SQLColumn)  
e.getChild()).getUserDefinedSQLType().removeSPListener(this);
+                       cleanupSnapshot();
                }
        }

@@ -86,12 +88,35 @@
 		        createSPObjectSnapshot((UserDefinedSQLType) e.getSource(),  
(UserDefinedSQLType) e.getNewValue());
                    }

-                   //XXX Need to remove the old listener
+                   cleanupSnapshot();
+
                        UserDefinedSQLType columnProxyType = 
(UserDefinedSQLType) e.getSource();
                        addUpdateListener(columnProxyType);
                }
        }

+    /**
+     * This method will remove the snapshot and the listener on the  
system's
+     * type if the snapshot is no longer in use.
+     */
+       private void cleanupSnapshot() {
+	    //find if the snapshot is being referenced by any of the columns in  
the workspace.
+           //if it is not referenced remove it from the project
+           //find its upstream type and remove its listener.
+           //XXX Need to remove the old listener
+       }
+
+    /**
+     * Adds a listener to the correct system type based on the given type.  
The
+     * listener on the system type will be used to update the snapshot in  
this
+     * project when the system type changes.
+     *
+     * @param columnProxyType
+     *            This type is a type that is a direct child of a column.  
The
+     *            type will have its upstreamType property pointing at a
+     *            snapshot in the workspace that we can find to locate its
+     *            actual system type.
+     */
     private void addUpdateListener(UserDefinedSQLType columnProxyType) {
         UserDefinedSQLType upstreamSnapshotType =  
columnProxyType.getUpstreamType();