path: root/projects/net.wotonomy.ui.swing/src/main/java/net/wotonomy/ui/swing/DisplayGroupNode.java

/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2001 Intersect Software Corporation

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see http://www.gnu.org
*/

package net.wotonomy.ui.swing;

import java.awt.Component;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Vector;

import javax.swing.tree.TreePath;

import net.wotonomy.control.EODataSource;
import net.wotonomy.control.EODelayedObserver;
import net.wotonomy.control.EOEditingContext;
import net.wotonomy.control.EOObjectStore;
import net.wotonomy.control.EOObserverCenter;
import net.wotonomy.control.EOQualifier;
import net.wotonomy.control.PropertyDataSource;
import net.wotonomy.foundation.NSArray;
import net.wotonomy.foundation.NSDictionary;
import net.wotonomy.foundation.NSMutableDictionary;
import net.wotonomy.foundation.NSNotification;
import net.wotonomy.foundation.internal.ValueConverter;
import net.wotonomy.foundation.internal.WotonomyException;
import net.wotonomy.ui.EODisplayGroup;
import net.wotonomy.ui.swing.TreeModelAssociation.DelegatingTreeDataSource;

/**
 * DisplayGroupNodes are used as nodes in the TreeModelAssociation's
 * implementation of TreeModel, and is tightly coupled with TreeModelAssociation
 * and MasterDetailAssociation. <br>
 * <br>
 *
 * Even though it is no longer package access, don't rely on this class because
 * we want to have the option of completely replacing this approach in the
 * future.
 *
 * @author michael@mpowers.net
 * @author $Author: cgruber $
 * @version $Revision: 904 $
 */
abstract public class DisplayGroupNode extends EODisplayGroup {
	protected TreeModelAssociation parentAssociation;
	protected EODelayedObserver targetObserver;
	protected NSMutableDictionary childNodes;
	protected EODisplayGroup parentGroup;
	protected Object target;
	protected boolean isFetched;
	protected boolean isFetchNeeded;
	protected boolean useParentOrderings;
	protected boolean useParentQualifier;

	/**
	 * Constructor for all nodes. Root node must have a null target.
	 */
	public DisplayGroupNode(TreeModelAssociation aParentAssociation, EODisplayGroup aParentGroup, Object aTarget) {
//new net.wotonomy.ui.swing.util.StackTraceInspector( ""+aTarget );
//System.out.println( "DisplayGroupNode.new: " + aTarget );            
		parentAssociation = aParentAssociation;
		target = null;
		targetObserver = null;
		parentGroup = aParentGroup;
		childNodes = new NSMutableDictionary();
		isFetched = false;
		isFetchNeeded = false;
		useParentOrderings = true;
		useParentQualifier = true;

		EODataSource parentSource = null;
		if (parentGroup != null) {
			parentSource = parentGroup.dataSource();
		} else if (parentAssociation.titlesDisplayGroup != null) {
			parentSource = parentAssociation.titlesDisplayGroup.dataSource();
		}

		// create child datasource
		if (aTarget != null) // not root node
		{
			if (parentAssociation.childrenKey != null) {
				if (parentSource == null) {
					throw new WotonomyException("Need a data source when children aspect is bound.");
				}

				NSArray displayedObjects = parentGroup.displayedObjects();
				EODataSource childSource = parentSource.dataSourceQualifiedByKey(parentAssociation.childrenKey);
				childSource.qualifyWithRelationshipKey(parentAssociation.childrenKey, aTarget);

				// create new display group using child data source
				this.setDataSource(childSource);

				// establish observer for target object
				setTarget(aTarget);
			} else // only titles is bound
			{
				// establish observer for target object
				setTarget(aTarget);

				setDataSource(new PropertyDataSource() {
					public NSArray fetchObjects() {
						return new NSArray();
					}
				});
			}
		} else // else root node
		{
			// root node uses PropertyDataSource by default
			if (parentSource == null) {
				setDataSource(new PropertyDataSource() {
					public NSArray fetchObjects() {
						if (parentGroup != null) {
							return parentGroup.displayedObjects();
						}
						return null;
					}
				});
			} else {
				// root node uses parent source directly
				setDataSource(parentSource);
			}
		}
	}

	/**
	 * Overridden to unregister as an editor of the editing context, since we don't
	 * directly present a user interface.
	 */
	public void setDataSource(EODataSource aDataSource) {
		super.setDataSource(aDataSource);
		if ((aDataSource != null) && (aDataSource.editingContext() != null)) {
			aDataSource.editingContext().removeEditor(this);
		}
	}

	/**
	 * Returns whether the node should call fetch().
	 */
	protected boolean isFetched() {
		if (isFetchNeeded()) {
			setFetchNeeded(false);
			fetch();
		}
		return isFetched;
	}

	/**
	 * Sets whether the node should call fetch().
	 */
	protected void setFetched(boolean fetched) {
//System.out.println( "DisplayGroupNode.setFetched: " + fetched + " : " + this + " : " + target );
//net.wotonomy.ui.swing.util.StackTraceInspector.printShortStackTrace();
		isFetched = fetched;
	}

	/**
	 * Returns whether the node is in need of a refetch.
	 */
	protected boolean isFetchNeeded() {
		return isFetchNeeded;
	}

	/**
	 * Returns whether the node should call fetch().
	 */
	protected void setFetchNeeded(boolean fetchNeeded) {
//System.out.println( "DisplayGroupNode.setFetchNeeded: " + fetchNeeded + " : " + this + " : " + target );
//net.wotonomy.ui.swing.util.StackTraceInspector.printShortStackTrace();
		isFetchNeeded = fetchNeeded;
	}

	/**
	 * Subclasses should override this method to fire an appropriate insertion
	 * event.
	 */
	protected void fireNodesInserted(Object[] path, int[] indexes, Object[] objects) {
//System.out.println( "fireNodesInserted: " + this );            
		parentAssociation.fireTreeNodesInserted(this, path, indexes, objects);
	}

	/**
	 * Subclasses should override this method to fire an appropriate change event.
	 */
	protected void fireNodesChanged(Object[] path, int[] indexes, Object[] objects) {
//System.out.println( "fireNodesChanged: " + this );            
		parentAssociation.fireTreeNodesChanged(this, path, indexes, objects);
	}

	/**
	 * Subclasses should override this method to fire an appropriate deletion event.
	 */
	protected void fireNodesRemoved(Object[] path, int[] indexes, Object[] objects) {
//System.out.println( "fireNodesRemoved: " + this );            
		parentAssociation.fireTreeNodesRemoved(this, path, indexes, objects);
	}

	/**
	 * Subclasses should override this method to fire an appropriate event.
	 */
	protected void fireStructureChanged(Object[] path, int[] indexes, Object[] objects) {
		parentAssociation.fireTreeStructureChanged(this, path, indexes, objects);
	}

	/**
	 * Overridden to broadcast a tree event after super executes.
	 */
	public void insertObjectAtIndex(Object anObject, int anIndex) {
		int count = getChildCount(); // gets old count
		if (target == null) {
			// if root node, forward to parent:
			// circumventing delegating data source, if any
			EODataSource dataSource = parentGroup.dataSource();
			if (dataSource instanceof DelegatingTreeDataSource) {
				parentGroup.setDataSource(((DelegatingTreeDataSource) dataSource).delegateDataSource);
			}
			parentGroup.insertObjectAtIndex(anObject, anIndex);
			if (dataSource instanceof DelegatingTreeDataSource) {
				parentGroup.setDataSource(dataSource);
			}
			return; // prevent event from firing (?)
		} else // not root node
		{
			super.insertObjectAtIndex(anObject, anIndex);
		}
	}

	/**
	 * Overridden to broadcast a tree event after super executes.
	 */
	public boolean deleteObjectAtIndex(int anIndex) {
		boolean result;
		Object node = getChildNodeAt(anIndex);
		if (target == null) {
			// if root node, forward to parent:
			result = parentGroup.deleteObjectAtIndex(anIndex);
		} else // not root node
		{
			result = super.deleteObjectAtIndex(anIndex);
		}

		return result;
	}

	/**
	 * Returns the child node that corresponds to the specified index, creating it
	 * if necessary. The index must be within bounds or an exception is thrown.
	 */
	public DisplayGroupNode getChildNodeAt(int anIndex) {
		boolean wasFetched = isFetched();
		if (!wasFetched)
			fetch();
		Object o = displayedObjects.objectAtIndex(anIndex);
		DisplayGroupNode result = getChildNodeForObject(o);
		if (result == null) {
			result = createChildNodeForObject(o);
		}
		return result;
	}

	/**
	 * Returns a child node that corresponds to the specified object, returning null
	 * if not found.
	 */
	protected DisplayGroupNode getChildNodeForObject(Object anObject) {
		return (DisplayGroupNode) childNodes.objectForKey(new ReferenceKey(anObject));
	}

	/**
	 * Creates a child node that corresponds to the specified object.
	 */
	private DisplayGroupNode createChildNodeForObject(Object anObject) {
		DisplayGroupNode result = parentAssociation.createNode(this, anObject);
		childNodes.setObjectForKey(result, new ReferenceKey(anObject));
		return result;
	}

	/**
	 * Returns a tree path of all DisplayGroupNodes leading to this node, including
	 * the root node (but excluding the titles display group).
	 */
	public TreePath treePath() {
		List path = new LinkedList();
		EODisplayGroup node = this;
		while (node instanceof DisplayGroupNode) {
			// insert at head of list
			path.add(0, node);
			node = ((DisplayGroupNode) node).parentGroup;
		}
		return new TreePath(path.toArray());
	}

	/**
	 * Overridden to return the parent group's sort ordering if useParentOrderings
	 * is true. useParentOrderings is true by default.
	 */
	public NSArray sortOrderings() {
		if ((useParentOrderings) && (parentGroup != null)) {
			return parentGroup.sortOrderings();
		}
		return super.sortOrderings();
	}

	/**
	 * Overridden to set useParentOrderings to false, or true if aList is null.
	 */
	public void setSortOrderings(List aList) {
		if (aList == null) {
			useParentOrderings = true;
		} else {
			useParentOrderings = false;
			super.setSortOrderings(aList);
		}
	}

	/**
	 * Overridden to return the parent group's qualifier if useParentQualifier is
	 * true. useParentQualifier is true by default.
	 */
	public EOQualifier qualifier() {
		if ((useParentQualifier) && (parentGroup != null)) {
			return parentGroup.qualifier();
		}
		return super.qualifier();
	}

	/**
	 * Overridden to set useParentQualifier to false, or true if aList is null.
	 */
	public void setQualifier(EOQualifier aQualifier) {
		if (aQualifier == null) {
			useParentQualifier = true;
		} else {
			useParentQualifier = false;
			super.setQualifier(aQualifier);
		}
	}

	/**
	 * Overridden to set isFetched to true.
	 */
	public boolean fetch() {
//System.out.println( "DisplayGroupNode.fetch: " + this + " : " );
//if ( getClass().getName().indexOf( "Activity" ) != -1 )
//{
//    new net.wotonomy.ui.swing.util.StackTraceInspector( this.toString() );
//}
		// set flag
		setFetched(true);

		// skip root node
		if (target == null)
			return true;

		// requalify
		dataSource().qualifyWithRelationshipKey(parentAssociation.childrenKey, target);

		// call to super
		return super.fetch();

//boolean result = super.fetch();
//System.out.println( displayedObjects() );
//return result;
	}

	/**
	 * Returns the object at the appropriate index in the parent display group.
	 */
	public Object object() {
		// if root node
		if (target == null) {
			return parentAssociation.rootLabel();
		}
		return target;
	}

	/**
	 * Returns the string value of the title property on the object in the parent
	 * display group corresponding to this index. The tree renderer asks JTrees to
	 * call this method to retrieve a value for display.
	 */
	public String toString() {
		Object result = getUserObject();
		if (result == null)
			result = "[null]";
		return result.toString();
	}

	// parts of interface TreeNode

	public int getChildCount() {
		if (!isFetched())
			fetch();
//if ( toString().indexOf("154.16406")!=-1){           
//System.out.println( "getChildCount: " + displayedObjects.count() + " : " + this );            
//new RuntimeException().printStackTrace();
//net.wotonomy.ui.swing.util.StackTraceInspector.printShortStackTrace();
//}
		return displayedObjects.count();
	}

	public int getIndex(DisplayGroupNode node) {
		if (!isFetched())
			fetch();
		return displayedObjects.indexOfObject(((DisplayGroupNode) node).target);
	}

	public boolean getAllowsChildren() {
		return true;
	}

	public boolean isLeaf() {
		// if not root node and isLeaf aspect is bound
		if ((target != null) && (parentGroup != null) && (parentAssociation.leafKey != null)) {
			Object value;
			if (parentAssociation.leafDisplayGroup != null) {
				value = parentGroup.valueForObject(target, parentAssociation.leafKey);
			} else {
				value = parentAssociation.leafKey;
			}

			// getBoolean returns true for zero, among other things
			Object result = ValueConverter.getBoolean(value);
			if (result != null) {
				return ((Boolean) result).booleanValue();
			}
		}

		// otherwise, we have to fetch and return count
		return (getChildCount() == 0);
	}

	public Enumeration children() {
		int count = getChildCount();
		Vector v = new Vector();
		for (int i = 0; i < count; i++) {
			v.add(getChildNodeAt(i));
		}
		return v.elements();
	}

	// parts of interface MutableTreeNode

	public void insert(DisplayGroupNode aChild, int anIndex) {
		insertObjectAtIndex(((DisplayGroupNode) aChild).object(), anIndex);
	}

	public void remove(int index) {
		deleteObjectAtIndex(index);
	}

	/**
	 * Removes the node at the index corresponding to the index of the object.
	 */
	public void remove(DisplayGroupNode node) {
		remove(getIndex(node));
	}

	/**
	 * Removes our object from the parent display group.
	 */
	public void removeFromParent() {
		int index = parentGroup.displayedObjects().indexOfIdenticalObject(target);
		if (index != NSArray.NotFound) {
			parentGroup.deleteObjectAtIndex(index);
		} else {
			throw new WotonomyException("Object not found in parent group: " + target);
		}
	}

	/**
	 * Removes our object from the parent display group and adds it to the end of
	 * the specified node's children.
	 */
	public void setParent(DisplayGroupNode newParent) {
		removeFromParent();
		newParent.insertObjectAtIndex(object(), newParent.displayedObjects.size());
	}

	/**
	 * Returns the value of the displayed property in the parent display group at
	 * the index that corresponds to the index of this node.
	 */
	public Object getUserObject() {
		return valueForKey(parentAssociation.titlesKey);
	}

	/**
	 * Sets the value of the displayed property in the parent display group at the
	 * index that corresponds to the index of this node.
	 */
	public void setUserObject(Object aValue) {
		setValueForKey(aValue, parentAssociation.titlesKey);
	}

	/**
	 * Returns a value from the object in the parent display group at the index that
	 * corresponds to the index of this node. For the root node, if the titles key
	 * is specified, the root label is returned, otherwise null is returned.
	 */
	public Object valueForKey(String aKey) {
		// if root node
		if (target == null) {
			// compare by ref is okay for strings
			if (aKey == parentAssociation.titlesKey) {
				return parentAssociation.rootLabel();
			}
			return null;
		}
		return parentGroup.valueForObject(target, aKey);
	}

	/**
	 * Sets a value on the object in the parent display group at the index that
	 * corresponds to the index of this node. For the root node, this method only
	 * works if aKey is the titlesAspect's key, otherwise does nothing.
	 */
	public void setValueForKey(Object aValue, String aKey) {
		// if root node, return.
		if (target == null) {
			// compare by ref is okay for strings
			if (aKey == parentAssociation.titlesKey) {
				parentAssociation.setRootLabel(aValue);

				// how to handle root node? tree event docs don't say.
				fireNodesChanged(treePath().getPath(), new int[] { 0 }, new Object[] { this });
			}
			return;
		}

		parentGroup.setValueForObject(aValue, target, aKey);
	}

	/**
	 * Perform any clean up in this method. The node will not be reused after this
	 * method is called. This implementation removes itself from the parent's set of
	 * child nodes, sets target and datasource to null, and then calls
	 * disposeChildNodes().
	 */
	protected void dispose() { // System.out.println( "dispose: " + this.getClass().getName() + " : " + this );
		if (parentGroup != null) {
			((DisplayGroupNode) parentGroup).childNodes.remove(new ReferenceKey(target));
		}
		setTarget((Object) null);
		setDataSource(null);
		disposeChildNodes();
	}

	/**
	 * Calls dispose() on all child nodes.
	 */
	protected void disposeChildNodes() {
		Iterator i = new LinkedList(childNodes.values()).iterator();
		while (i.hasNext()) {
			((DisplayGroupNode) i.next()).dispose();
		}
	}

	/**
	 * Called after the target object posts a change notification. This
	 * implementation re-fetches which triggers updateDisplayedObjects to broadcast
	 * any tree events. This method marks the parent object as changed if: (1) this
	 * object is not registered in the editing context of the titles display group's
	 * data source (if any), AND (2) the children key is not in the list of
	 * attributes of the parent object's EOClassDescription.
	 */
	public void targetChanged() {
		// if not root node
		if (target != null) {
			// if we're not root and not fetched, stop here.
			// FIXME: with this, some nodes have old values when moved.
			// FIXME: without this, nodes are unnecessarily fetched.
			// FIXME: might have parent modify isFetched of certain child nodes.
			if (isFetched()) {
				fetch();
			} else // not fetched - just update the display
			{
				updateDisplayedObjects();
			}
			/*
			 * //disabling this for performance reasons: //might reenable later or find an
			 * alternate approach // check to see if we need to mark the parent object as
			 * changed EOEditingContext context = dataSource().editingContext(); if ( (
			 * context == null ) || ( context.globalIDForObject( target ) == null ) ) {
			 * DisplayGroupNode parentNode = (DisplayGroupNode) parentGroup; if (
			 * parentNode.target != null ) { // only notify if childrenKey is an attribute
			 * of parentDesc // (and therefore not a toOne or toMany relationship)
			 * EOClassDescription parentDesc = EOClassDescription.classDescriptionForClass(
			 * parentNode.target.getClass() ); if ( parentDesc.attributeKeys().contains(
			 * parentAssociation.childrenKey ) ) { // only notify if no context is already
			 * observing the object // and we are an attribute key
			 * EOObserverCenter.notifyObserversObjectWillChange( parentNode.target ); } } }
			 */
		} else // root node
		{
			setObjectArray(parentAssociation.titlesDisplayGroup.displayedObjects());
		}

		// finally, broadcast change event for this node
		// even though we're not sure if the displayed value changed.
		fireNodeChanged();
	}

	/**
	 * Fires a change event for this node.
	 */
	public void fireNodeChanged() {
		// if not root node
		if (target != null) {
			int index = ((DisplayGroupNode) parentGroup).getIndex(this);
			if ((index != -1) && (treePath().getParentPath() != null)) {
				fireNodesChanged(treePath().getParentPath().getPath(), new int[] { index }, new Object[] { this });
			}
		}
	}

	Object[] previouslyDisplayedObjects = new Object[0];

	/**
	 * Overridden to call to super, fire any tree events, and then call
	 * updateDisplayedObjects on all fetched child nodes. This method compares this
	 * node's displayed objects against the list of child nodes, synchronizes them,
	 * and then broadcasts only the necessary events to bring the view component up
	 * to date.
	 */
	public void updateDisplayedObjects() {
//System.out.println( "updateDisplayedObjects: " + " : " + this );
//net.wotonomy.ui.swing.util.StackTraceInspector.printShortStackTrace();
//new RuntimeException().printStackTrace();
		super.updateDisplayedObjects();

		// diff lists
		boolean proceed = true;
		Object[] oldObjects = previouslyDisplayedObjects;
		Object[] newObjects = displayedObjects.toArray();
		if (oldObjects.length == newObjects.length) {
			proceed = false;
			for (int i = 0; i < newObjects.length; i++) {
				if (oldObjects[i] != newObjects[i]) {
					proceed = true;
					break;
				}
			}
		}

		// this should be set before firing the change events
		// in case some clients end up calling this again.
		previouslyDisplayedObjects = newObjects;

		DisplayGroupNode node;
		Iterator i = childNodes.values().iterator();
		while (i.hasNext()) {
			node = (DisplayGroupNode) i.next();
			if (!node.isFetchNeeded()) {
				node.updateDisplayedObjects();
			}
		}

		if (proceed) {
//System.out.println( "DisplayGroupNode.firingEventsForChanges: " );                
//new RuntimeException().printStackTrace();
			fireEventsForChanges(oldObjects, newObjects);
		}

	}

	/**
	 * Called by processRecentChanges to analyze the differences between the lists
	 * and broadcast the appropriate events.
	 */
	protected void fireEventsForChanges(Object[] oldObjects, Object[] newObjects) {
		// structure changed causes havoc while
		// establishing connection in some cases
		// if ( oldObjects.length == 0 || newObjects.length == 0 )
		// {
		// fireStructureChanged( treePath().getPath(), null, null );
		// return;
		// }

		int insertCount = 0;
		int deleteCount = 0;
		Object[] inserts = new Object[newObjects.length];
		Object[] deletes = new Object[oldObjects.length];

		int i;
		int n = -1, o = -1; // last match
		int n1 = 0, o1 = 0; // current match test
		int n2 = 0, o2 = 0; // scan ahead

		while (o1 < oldObjects.length && n1 < newObjects.length) {
			if (newObjects[n1] == oldObjects[o1]) {
				// mark as match and continue
				o = o1;
				n = n1;
			} else {
				// scan ahead for the next match, if any
				o2 = o1;
				n2 = n1;

				while (o2 < oldObjects.length || n2 < newObjects.length) {
					if (o2 < oldObjects.length && newObjects[n1] == oldObjects[o2]) {
						// run o1 to o2: mark as deletes
						for (i = o1; i < o2; i++) { // System.out.println( "delete : " + i );
							deletes[i] = oldObjects[i];
							deleteCount++;
						}
						o1 = o2; // reset test
						o = o1; // set match
						n = n1; // set match
						break;
					}
					if (n2 < newObjects.length && newObjects[n2] == oldObjects[o1]) {
						// run n1 to n2: mark as inserts
						for (i = n1; i < n2; i++) { // System.out.println( "insert : " + i );
							inserts[i] = newObjects[i];
							insertCount++;
						}
						n1 = n2; // reset test
						n = n1; // set match
						o = o1; // set match
						break;
					}
					o2++;
					n2++;
				}
			}
			if (n != n1) {
				inserts[n1] = newObjects[n1];
				insertCount++;
				deletes[o1] = oldObjects[o1];
				deleteCount++;
				// increment even though no match:
				// the new object was marked as inserted and
				// the old object was marked as deleted.
				n = n1;
				o = o1;
			}
			o1++;
			n1++;
		}

		// run o to end of oldObjects: mark as deletes
		for (i = o + 1; i < oldObjects.length; i++) { // System.out.println( "delete : " + i );
			deletes[i] = oldObjects[i];
			deleteCount++;
		}

		// run n to end of newObjects: mark as inserts
		for (i = n + 1; i < newObjects.length; i++) { // System.out.println( "insert : " + i );
			inserts[i] = newObjects[i];
			insertCount++;
		}

//System.out.println( "done   : " 
//+ o + " : " + o1 + " : " + o2 + " :: " + n + " : " + n1 + " : " + n2 );
//System.out.println( new NSArray( newObjects ) );
//System.out.println( new NSArray( inserts ) );
//System.out.println( new NSArray( deletes ) );
//System.out.println( new NSArray( oldObjects ) );

		int c;
		Object[] nodes;
		int[] indices;

		// broadcast delete event
		c = 0;
		nodes = new Object[deleteCount];
		indices = new int[deleteCount];
		for (i = 0; i < deletes.length; i++) {
			if (deletes[i] != null) {
				indices[c] = i;
				nodes[c] = getChildNodeForObject(deletes[i]);
				c++;
			}
		}
		if (c > 0) {
//                fireNodeChanged(); // force the jtree to get the correct child count
			fireNodesRemoved(treePath().getPath(), indices, nodes);
		}
		deletes = nodes; // retain for dispose check

		// broadcast insert event
		c = 0;
		nodes = new Object[insertCount];
		indices = new int[insertCount];
		for (i = 0; i < inserts.length; i++) {
			if (inserts[i] != null) {
				indices[c] = i;
				nodes[c] = getChildNodeForObject(inserts[i]);
				if (nodes[c] == null) {
					nodes[c] = createChildNodeForObject(newObjects[i]);
				}
				c++;
			}
		}
		if (c > 0) {
			fireNodesInserted(treePath().getPath(), indices, nodes);
		}

		// dispose any delete nodes not on insert list
		int j;
		boolean found;
		for (i = 0; i < deletes.length; i++) {
			for (j = 0; j < nodes.length; j++) {
				if (deletes[i] == nodes[j])
					break;
			}

			// did not break early, so not found, so dispose
			if (j == nodes.length) {
				((DisplayGroupNode) deletes[i]).dispose();
			}
		}
	}

	/**
	 * Sets the target object and creates an registers a target observer. If target
	 * was not previously null, the existing observer is unregistered. Protected
	 * access so subclasses and TreeModelAssociation can update our target.
	 */
	public void setTarget(Object aTarget) {
		if (target != null) {
			EOObserverCenter.removeObserver(targetObserver, target);
			targetObserver.discardPendingNotification();
		}

		if (aTarget != null) {
			target = aTarget;
			targetObserver = new TargetObserver(this);
			EOObserverCenter.addObserver(targetObserver, target);
		}
	}

	/**
	 * Returns the parent display group, or null if parent is root.
	 */
	public DisplayGroupNode getParentGroup() {
		if (parentGroup instanceof DisplayGroupNode) {
			return (DisplayGroupNode) parentGroup;
		}
		// presumably the root node
		return null;
	}

	/**
	 * Gets all descendants of the this node.
	 */
	public List getDescendants() {
		return getDescendants(this, true);
	}

	/**
	 * Gets only the descendants of the this node whose children has been loaded -
	 * no fetching will occur. Useful for load-on-demand trees.
	 */
	public List getLoadedDescendants() {
		return getDescendants(this, false);
	}

	// breadth first traversal implementation

	/**
	 * Returns a list of all descendants of the specified node. Unfetched nodes are
	 * traversed only if forceLoad is true. This implementation is a breadth-first
	 * traversal of the nodes starting at the specified node.
	 */
	static private List getDescendants(DisplayGroupNode aNode, boolean forceLoad) {
		if (!forceLoad && !aNode.isFetched)
			return NSArray.EmptyArray;

		LinkedList result = new LinkedList();
		LinkedList queue = new LinkedList();

		queue.add(aNode);
		while (!queue.isEmpty()) {
			checkNode((DisplayGroupNode) queue.removeFirst(), queue, result, forceLoad);
		}

		return result;
	}

	/**
	 * Adds each fetched child node of the specified node to the result set
	 * (optionally forcing the child node to load) and adding child node to the end
	 * of the queue.
	 */
	static private void checkNode(DisplayGroupNode aNode, LinkedList aQueue, LinkedList aResult, boolean forceLoad) {
		DisplayGroupNode child;
		int count = aNode.getChildCount();

		for (int i = 0; i < count; i++) {
			child = aNode.getChildNodeAt(i);

			// add to queue if node has fetched children
			if ((!child.isFetched) && (forceLoad)) {
				child.fetch();
			}
			if (child.isFetched) {
				aQueue.addLast(child);
			}

			aResult.add(child);
		}
	}

	/**
	 * Overridden to not fetch on InvalidateAllObjectsInStoreNotification unless
	 * we've already been fetched, preserving the load-on-demand functionality.
	 */
	public void objectsInvalidatedInEditingContext(NSNotification aNotification) {
		if (EOObjectStore.InvalidatedAllObjectsInStoreNotification.equals(aNotification.name())) {
//System.out.println( "DisplayGroupNode.objectsInvalidatedInEditingContext: " + aNotification.name() );        
			if (parentAssociation.isVisible(this) && targetObserver != null) {
				targetObserver.objectWillChange(target); // force ui to update
				fireNodeChanged();
			} else // make sure we fetch children when we do become visible
				setFetchNeeded(true);
			return;
		} else if ((EOEditingContext.ObjectsChangedInEditingContextNotification.equals(aNotification.name()))
				|| (EOEditingContext.EditingContextDidSaveChangesNotification.equals(aNotification.name()))) {
			int index;
			Enumeration e;
			boolean didChange = false;
			NSDictionary userInfo = aNotification.userInfo();

			// if our target object was deleted
			NSArray deletes = (NSArray) userInfo.objectForKey(EOObjectStore.DeletedKey);
			if (deletes.indexOfIdenticalObject(target) != NSArray.NotFound) {
//System.out.println( "DisplayGroupNode.objectsInvalidatedInEditingContext: delete: " + this + " : " + aNotification.name() );        
				if (parentAssociation.isVisible(this) && targetObserver != null) {
					targetObserver.objectWillChange(target); // force ui to update
					fireNodeChanged();
				} else // make sure we fetch children when we do become visible
					setFetchNeeded(true);
				return;
			}

			// if our target object was invalidated
			NSArray invalidates = (NSArray) userInfo.objectForKey(EOObjectStore.InvalidatedKey);
			if (invalidates != null && invalidates.indexOfIdenticalObject(target) != NSArray.NotFound) {
//System.out.println( "DisplayGroupNode.objectsInvalidatedInEditingContext: invalidate: " + this + " : " + aNotification.name() );        
				if (parentAssociation.isVisible(this) && targetObserver != null) {
					targetObserver.objectWillChange(target); // force ui to update
					fireNodeChanged();
				} else // make sure we fetch children when we do become visible
					setFetchNeeded(true);
				return;
			}

			// if our target object was updated, set fetchNeeded plus fire changed event
			NSArray updates = (NSArray) userInfo.objectForKey(EOObjectStore.UpdatedKey);
			if (updates.indexOfIdenticalObject(target) != NSArray.NotFound) {
				if (parentAssociation.isVisible(this) && targetObserver != null) {
					targetObserver.objectWillChange(target); // force ui to update
					fireNodeChanged();
					if (object() instanceof Component)
						((Component) object()).repaint();
				} else // make sure we fetch children when we do become visible
					setFetchNeeded(true);
				return;
			}
		}

		super.objectsInvalidatedInEditingContext(aNotification);

	}

	// inner classes

	/**
	 * Private class used to force a hashmap to perform key comparisons by
	 * reference.
	 */
	private class ReferenceKey {
		private int hashCode;
		private Object referent;

		public ReferenceKey(Object anObject) {
			referent = anObject;
			hashCode = anObject.hashCode();
		}

		/**
		 * Returns the actual key's hash code.
		 */
		public int hashCode() {
			return hashCode;
		}

		/**
		 * Compares by reference.
		 */
		public boolean equals(Object anObject) {
			if (anObject instanceof ReferenceKey) {
				return ((ReferenceKey) anObject).referent == referent;
			}
			return false;
		}
	}

	/**
	 * A private class to observe the target object of this node.
	 */
	private class TargetObserver extends EODelayedObserver {
		Reference ref;

		/**
		 * Pass in the display group node that will be updated when the target changes.
		 */
		public TargetObserver(DisplayGroupNode aDisplayGroup) {
			ref = new WeakReference(aDisplayGroup);
		}

		/**
		 * Repopulate our display group, and calculate the deltas so we can broadcast
		 * appropriate events.
		 */
		public void subjectChanged() {
			DisplayGroupNode node = (DisplayGroupNode) ref.get();
			if (node == null)
				return; // node is null if gc'd.
			// FIXME: should un-register self from observer center??

			node.targetChanged();
		}
	}

}
/*
 * $Log$ Revision 1.2 2006/02/18 23:19:05 cgruber Update imports and maven
 * dependencies.
 *
 * Revision 1.1 2006/02/16 13:22:22 cgruber Check in all sources in
 * eclipse-friendly maven-enabled packages.
 *
 * Revision 1.64 2003/08/06 23:07:52 chochos general code cleanup (mostly,
 * removing unused imports)
 *
 * Revision 1.63 2003/06/06 14:20:07 mpowers getLoadedDescendants was forcing a
 * fetch of the node it was called on.
 *
 * Revision 1.62 2003/06/03 14:48:33 mpowers Clean-up of notification handling
 * for updates/invalidation/etc. Now fetching immediately on notification if the
 * node is visible. This averts the infamous IndexOutOfBoundsException that
 * occurs if fetching happens during repaint, because the BasicTreeUI is caching
 * the number of child nodes before painting begins.
 *
 * Revision 1.61 2003/01/18 23:33:29 mpowers Fixing the build.
 *
 * Revision 1.60 2002/05/31 15:03:10 mpowers Fixes for the previous fix. Fat
 * props to yjcheung.
 *
 * Revision 1.59 2002/05/28 15:31:36 mpowers Fix for updateDisplayedObjects for
 * a subtle case where a node appears in the position that another node was
 * moved from.
 *
 * Revision 1.58 2002/05/24 14:42:02 mpowers Prevent repeat events from firing
 * if firing events loops back.
 *
 * Revision 1.57 2002/04/23 19:12:28 mpowers Reimplemented fireEventsForChanges.
 * Fitter and happier.
 *
 * Revision 1.56 2002/04/19 21:18:45 mpowers Removed tree event coalescing,
 * which was causing way too many problems. The fireChangeEvent algorithm is way
 * faster than before, so we should still be better off than before. At least
 * now, we don't have to track whether the view component has encountered a
 * particular node.
 *
 * Revision 1.55 2002/04/19 20:53:22 mpowers Now firing event fewer events in
 * fireEventsForChanges.
 *
 * Revision 1.54 2002/04/15 21:52:50 mpowers Tightening up TreeModelAssociation
 * and DisplayGroupNode. Now only firing root structure changed once. Now
 * disposing of root's children. Better event coalescing.
 *
 * Revision 1.53 2002/04/12 20:35:20 mpowers Now correctly setting parent
 * display group and data source on creation.
 *
 * Revision 1.52 2002/04/10 21:20:04 mpowers Better handling for tree nodes when
 * working with editing contexts. Better handling for invalidation. No longer
 * broadcasting events when nodes have not been "registered" in the tree.
 *
 * Revision 1.51 2002/04/03 20:13:36 mpowers Now differentiating between node
 * instantiation caused by model expansion (user initiated) and by modifications
 * to the model. Dispose now disposes all children.
 *
 * Revision 1.50 2002/03/23 16:20:27 mpowers Optimized processRecentChanges,
 * minimized tree events.
 *
 * Revision 1.49 2002/03/11 03:15:06 mpowers Optimized processRecentChanges,
 * minimize event firing, coalescing changes. Still need a better diff algorithm
 * to avoid removing nodes.
 *
 * Revision 1.48 2002/03/10 00:59:39 mpowers Interim version: coalesces calls to
 * process recent changes. Still does not handle rearranged nodes.
 *
 * Revision 1.47 2002/03/09 17:33:45 mpowers Nodes now track their child nodes
 * by reference, not index.
 *
 * Revision 1.46 2002/03/08 23:19:07 mpowers Added getParentGroup to
 * DisplayGroupNode.
 *
 * Revision 1.45 2002/03/06 13:04:16 mpowers Implemented cascading qualifiers in
 * tree nodes.
 *
 * Revision 1.44 2002/02/27 23:19:17 mpowers Refactoring of TreeAssociation to
 * create TreeModelAssociation parent.
 *
 * Revision 1.42 2002/02/19 22:28:46 mpowers DisplayGroupNodes immediately
 * unregister themselves as editors.
 *
 * Revision 1.41 2002/02/13 16:27:38 mpowers Exposing setTarget.
 *
 * Revision 1.40 2001/11/02 20:55:46 mpowers Now using fixed index to send node
 * removed events. This preserves the expanded state of the nodes in the
 * corresponding jtree.
 *
 * Revision 1.39 2001/09/21 21:09:25 mpowers Exposed more fields as protected.
 *
 * Revision 1.38 2001/09/19 15:36:08 mpowers Refined behavior for isFetched
 * after notification handling.
 *
 * Revision 1.37 2001/09/13 14:51:18 mpowers DisplayGroupNodes now dispose
 * themselves and mark their parent for update when they receive notification
 * that their target has been deleted.
 *
 * Revision 1.36 2001/09/10 14:10:24 mpowers Fix for notification handling.
 *
 * Revision 1.35 2001/07/30 16:17:01 mpowers Minor code cleanup.
 *
 * Revision 1.34 2001/07/18 22:13:39 mpowers getLoadedDescendants now works as
 * advertised. Now correctly handling invalidateAllObjects notification.
 *
 * Revision 1.33 2001/07/18 13:03:32 mpowers TreeNodes now refetch only on
 * demand. Previously, once a node had been fetched, it was always refetched
 * after an invalidate, even if the node was not being displayed.
 *
 * Revision 1.32 2001/06/18 14:10:28 mpowers Cleaned up event firing: no longer
 * firing insert or remove events twice.
 *
 * Revision 1.31 2001/06/09 16:15:39 mpowers Revised the targetChanged scheme
 * because oldObjects and newObjects were identical after the target object is
 * invalidated.
 *
 * Revision 1.30 2001/05/21 22:17:19 mpowers Fix for tree out-of-synch problems
 * when nodes are inserted.
 *
 * Revision 1.29 2001/05/18 21:07:46 mpowers Playing with refresh options.
 *
 * Revision 1.28 2001/05/14 15:25:43 mpowers DisplayGroupNodes now only respond
 * to InvalidateAllObjectsInStore if they are already fetched.
 *
 * Revision 1.27 2001/05/08 19:55:58 mpowers Fix for node children not
 * refreshing after sibling was inserted.
 *
 * Revision 1.26 2001/05/08 18:47:34 mpowers Minor fixes for d3.
 *
 * Revision 1.25 2001/05/06 22:22:55 mpowers Debugging.
 *
 * Revision 1.24 2001/05/04 14:42:58 mpowers Now getting stored values in
 * KeyValueCoding. MasterDetail now marks dirty based on whether it's an
 * attribute or relation. Implemented editing context marker.
 *
 * Revision 1.23 2001/05/02 18:00:43 mpowers Removed debug code.
 *
 * Revision 1.22 2001/05/02 17:31:20 mpowers DisplayGroupNode now does a better
 * job determining when to mark its parent dirty.
 *
 * Revision 1.21 2001/05/01 00:52:32 mpowers Implemented breadth-first traversal
 * of tree for node.
 *
 * Revision 1.20 2001/04/26 01:15:19 mpowers Major clean-up of DisplayGroupNode:
 * fitter, happier, more productive.
 *
 * Revision 1.19 2001/04/22 23:13:35 mpowers Minor bug.
 *
 * Revision 1.18 2001/04/22 23:05:33 mpowers Totally revised DisplayGroupNode so
 * each object gets its own node (so the nodes are no longer fixed by index).
 *
 * Revision 1.17 2001/04/21 23:05:12 mpowers A fairly major revisiting. I've
 * decided to scrap the pass-thru approach where every node simply represents an
 * index and not an object. The next update will have each node correspond to a
 * specific object.
 *
 * Revision 1.16 2001/04/13 16:37:37 mpowers Handling bounds checking.
 *
 * Revision 1.15 2001/04/03 20:36:01 mpowers Fixed
 * refaulting/reverting/invalidating to be self-consistent.
 *
 * Revision 1.14 2001/03/27 17:45:51 mpowers More index bounds checking.
 *
 * Revision 1.13 2001/03/22 21:25:42 mpowers Fixed some nasty issues with
 * jtree's internal state and array bounds.
 *
 * Revision 1.12 2001/03/19 22:18:58 mpowers Root node now mirrors contents of
 * titles display group.
 *
 * Revision 1.11 2001/03/19 21:38:36 mpowers Improved redisplay after edit.
 * Editing nodes off root now works.
 *
 * Revision 1.10 2001/03/09 22:08:38 mpowers Removed unused line.
 *
 * Revision 1.9 2001/03/07 16:41:04 mpowers Now checking size of parent
 * displayed objects array so that we don't get array out of bounds execeptions
 * from isLeaf() or object() when those messages are called after the
 * TreeAssociation fires a nodesDeleted event. I believe that JTree is
 * mistakenly rendering those nodes one last time before erasing them.
 *
 * Revision 1.8 2001/03/06 23:21:27 mpowers Now only notifying parent if the
 * object is not registered in the editing context, if any.
 *
 * Revision 1.7 2001/02/20 16:38:55 mpowers MasterDetailAssociations now observe
 * their controlled display group's objects for changes to that the parent
 * object will be marked as updated. Before, only inserts and deletes to an
 * object's items are registered. Also, moved ObservableArray to package access.
 *
 * Revision 1.6 2001/02/17 16:52:05 mpowers Changes in imports to support
 * building with jdk1.1 collections.
 *
 * Revision 1.5 2001/01/31 17:59:52 mpowers Fixed isLeaf aspect of
 * TreeAssociation.
 *
 * Revision 1.4 2001/01/25 02:16:25 mpowers TreeAssociation now returns
 * DisplayGroupNode.getUserObject.
 *
 * Revision 1.3 2001/01/24 18:14:40 mpowers Fixed problem with leaving children
 * aspect unspecified.
 *
 * Revision 1.2 2001/01/24 16:35:37 mpowers Improved documentation on
 * TreeAssociation. SortOrderings are now inherited from parent nodes. Updates
 * after sorting are still lost on TreeController.
 *
 * Revision 1.1 2001/01/24 14:17:12 mpowers Major revision to TreeAssociation.
 * Can now add and remove nodes. DisplayGroupNode is now it's own class.
 *
 *
 */