Attachment 35282 Details for Bug 129061 – Adds INavigatorDnDService.bindDragAssistant()

[patch] Adds INavigatorDnDService.bindDragAssistant()

org.eclipse.ui.navigator_DND_126658.txt (text/plain), 65.20 KB, created by Michael D. Elder

on 2006-02-23 23:46:18 EST

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Filename:

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Creator: Michael D. Elder

Created: 2006-02-23 23:46:18 EST

Size: 65.20 KB

patch

obsolete

>### Eclipse Workspace Patch 1.0
>#P org.eclipse.ui.navigator
>Index: src/org/eclipse/ui/navigator/CommonDragAdapter.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDragAdapter.java,v
>retrieving revision 1.1
>diff -u -r1.1 CommonDragAdapter.java
>--- src/org/eclipse/ui/navigator/CommonDragAdapter.java	9 Feb 2006 21:32:09 -0000	1.1
>+++ src/org/eclipse/ui/navigator/CommonDragAdapter.java	22 Feb 2006 04:32:48 -0000
>@@ -10,6 +10,9 @@
> *******************************************************************************/
> package org.eclipse.ui.navigator;
> 
>+import java.util.LinkedHashSet;
>+import java.util.Set;
>+
> import org.eclipse.jface.util.LocalSelectionTransfer;
> import org.eclipse.jface.viewers.ISelection;
> import org.eclipse.jface.viewers.ISelectionProvider;
>@@ -50,6 +53,8 @@
> */
> public final class CommonDragAdapter extends DragSourceAdapter {
> 
>+	private static final boolean DEBUG = false;
>+
> 	private final INavigatorContentService contentService;
> 
> 	private final ISelectionProvider provider;
>@@ -70,30 +75,67 @@
> 		provider = aProvider;
> 	}
> 
>+	/**
>+	 * 
>+	 * @return An array of supported Drag Transfer types. The list contains [
>+	 * {@link LocalSelectionTransfer#getTransfer()},
>+	 * {@link PluginTransfer#getInstance()}] in addition to any
>+	 * supported types contributed by the
>+	 * {@link CommonDragAdapterAssistant assistants}.
>+	 * @see CommonDragAdapterAssistant
>+	 * @see LocalSelectionTransfer
>+	 * @see PluginTransfer
>+	 */
>+	public Transfer[] getSupportDragTransfers() {
>+		CommonDragAdapterAssistant[] assistants = contentService
>+				.getDnDService().getCommonDragAssistants();
>+
>+		Set supportedTypes = new LinkedHashSet();
>+		supportedTypes.add(PluginTransfer.getInstance());
>+		supportedTypes.add(LocalSelectionTransfer.getTransfer());
>+		Transfer[] transferTypes = null;
>+		for (int i = 0; i < assistants.length; i++) {
>+			transferTypes = assistants[i].getSupportedTransferTypes();
>+			for (int j = 0; j < transferTypes.length; j++) {
>+				if (transferTypes[j] != null)
>+					supportedTypes.add(transferTypes[j]);
>+			}
>+		}
>+		
>+		Transfer[] transfers = (Transfer[]) supportedTypes
>+				.toArray(new Transfer[supportedTypes.size()]);
>+		return transfers;
>+	}
>+
> 	/*
> 	 * (non-Javadoc)
> 	 * 
> 	 * @see org.eclipse.swt.dnd.DragSourceAdapter#dragStart(org.eclipse.swt.dnd.DragSourceEvent)
> 	 */
> 	public void dragStart(DragSourceEvent event) {
>+		if (DEBUG)
>+			System.out.println("CommonDragAdapter.dragStart (begin): " + event); //$NON-NLS-1$
> 		try {
> 			// Workaround for 1GEUS9V
> 			DragSource dragSource = (DragSource) event.widget;
> 			Control control = dragSource.getControl();
>-			if (control != control.getDisplay().getFocusControl()) {
>-				event.doit = false;
>-				return;
>-			}
>-			ISelection selection = provider.getSelection();
>-			if (selection.isEmpty()) {
>+			if (control == control.getDisplay().getFocusControl()) {
>+				ISelection selection = provider.getSelection();
>+				if (!selection.isEmpty()) {
>+					LocalSelectionTransfer.getTransfer()
>+							.setSelection(selection);
>+					event.doit = true;
>+				} else
>+					event.doit = false;
>+			} else
> 				event.doit = false;
>-				return;
>-			}
>-			LocalSelectionTransfer.getTransfer().setSelection(selection);
>-			event.doit = true;
> 		} catch (RuntimeException e) {
> 			NavigatorPlugin.logError(0, e.getMessage(), e);
> 		}
>+
>+		if (DEBUG)
>+			System.out
>+					.println("CommonDragAdapter.dragStart (end): doit=" + event.doit); //$NON-NLS-1$
> 	}
> 
> 	/*
>@@ -105,13 +147,29 @@
> 
> 		ISelection selection = LocalSelectionTransfer.getTransfer()
> 				.getSelection();
>+
>+		if (DEBUG)
>+			System.out
>+					.println("CommonDragAdapter.dragSetData (begin): event" + event + " selection=" + selection); //$NON-NLS-1$ //$NON-NLS-2$
>+
> 		if (LocalSelectionTransfer.getTransfer()
>-				.isSupportedType(event.dataType))
>+				.isSupportedType(event.dataType)) {
> 			event.data = selection;
>-		else if (PluginTransfer.getInstance().isSupportedType(event.dataType))
>+
>+			if (DEBUG)
>+				System.out
>+						.println("CommonDragAdapter.dragSetData set LocalSelectionTransfer"); //$NON-NLS-1$
>+		} else if (PluginTransfer.getInstance().isSupportedType(event.dataType)) {
> 			event.data = NavigatorPluginDropAction
> 					.createTransferData(contentService);
>-		else if (selection instanceof IStructuredSelection) {
>+			if (DEBUG)
>+				System.out
>+						.println("CommonDragAdapter.dragSetData set PluginTransfer"); //$NON-NLS-1$
>+		} else if (selection instanceof IStructuredSelection) {
>+			if (DEBUG)
>+				System.out
>+						.println("CommonDragAdapter.dragSetData looking for assistants"); //$NON-NLS-1$
>+
> 			INavigatorDnDService dndService = contentService.getDnDService();
> 			CommonDragAdapterAssistant[] assistants = dndService
> 					.getCommonDragAssistants();
>@@ -123,6 +181,9 @@
> 					if (supportedTransferTypes[j]
> 							.isSupportedType(event.dataType))
> 						try {
>+							if (DEBUG)
>+								System.out
>+										.println("CommonDragAdapter.dragSetData set assistant transfer type"); //$NON-NLS-1$
> 							assistants[i].setDragData(event,
> 									(IStructuredSelection) selection);
> 						} catch (RuntimeException re) {
>@@ -132,7 +193,11 @@
> 				}
> 			}
> 
>-		}
>+		} else
>+			event.doit = false;
>+
>+		if (DEBUG)
>+			System.out.println("CommonDragAdapter.dragSetData (end): " + event); //$NON-NLS-1$
> 	}
> 
> 	/*
>@@ -141,9 +206,16 @@
> 	 * @see org.eclipse.swt.dnd.DragSourceAdapter#dragFinished(org.eclipse.swt.dnd.DragSourceEvent)
> 	 */
> 	public void dragFinished(DragSourceEvent event) {
>+
>+		if (DEBUG)
>+			System.out.println("CommonDragAdapter.dragFinished()."); //$NON-NLS-1$
>+
> 		LocalSelectionTransfer.getTransfer().setSelection(null);
>-		if (event.doit == false)
>-			return;
>+
>+		// TODO Handle clean up if drop target was outside of workbench
>+		// if (event.doit != false) {
>+		//			
>+		// }
> 	}
> 
> }
>Index: src/org/eclipse/ui/navigator/INavigatorDnDService.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/INavigatorDnDService.java,v
>retrieving revision 1.1
>diff -u -r1.1 INavigatorDnDService.java
>--- src/org/eclipse/ui/navigator/INavigatorDnDService.java	9 Feb 2006 21:32:09 -0000	1.1
>+++ src/org/eclipse/ui/navigator/INavigatorDnDService.java	22 Feb 2006 04:32:51 -0000
>@@ -11,6 +11,9 @@
> 
> package org.eclipse.ui.navigator;
> 
>+import org.eclipse.jface.viewers.IStructuredSelection;
>+import org.eclipse.swt.dnd.TransferData;
>+
> 
> /**
> * 
>@@ -66,24 +69,48 @@
> 	 * content extensions that are visible and active for the
> 	 * associated {@link INavigatorContentService}. The array is sorted by
> 	 * priority, with overrides taken into account.
>-	 * 
>+	 * 
> 	 * 
>-	 * That is, if an extension X overrides extension Y (see
>-	 * org.eclipse.ui.navigator.navigatorContent/override), then X will
>-	 * occur before Y in the array. If X and Y override Z, but X has higher
>-	 * priority than Y, then X will occur before Y, and Y will occur before Z.
>+	 * The array should be processed from the first element to the last, asking
>+	 * each extension to
>+	 * {@link CommonDropAdapterAssistant#validateDrop(Object, int, org.eclipse.swt.dnd.TransferData)}.
>+	 * The first to successfully validate the drop operation will have the
>+	 * opportunity to
>+	 * {@link CommonDropAdapterAssistant#handleDrop(CommonDropAdapter, org.eclipse.swt.dnd.DropTargetEvent, Object) handle the drop}
> 	 * 
>+	 * 
>+	 * @param aDropTarget
>+	 * The target element in the viewer of the drop operation.
>+	 * @param theTransferType 
>+	 * 			 The transfer type of the current drop operation.
>+	 * @return An array of {@link CommonDropAdapterAssistant}s that are defined
>+	 * by the set of
>+	 * org.eclipse.ui.navigator.navigatorContent/navigatorContent
>+	 * extensions that provide a possibleChildren expression
>+	 * that matches the given drop target.
>+	 */
>+	CommonDropAdapterAssistant[] findCommonDropAdapterAssistants(
>+			Object aDropTarget, TransferData theTransferType);
>+	
>+	/**
>+	 * 
>+	 * This method returns an array of {@link CommonDropAdapterAssistant} from
>+	 * content extensions that are visible and active for the
>+	 * associated {@link INavigatorContentService}. 
>+	 * 
> 	 * 
> 	 * The array should be processed from the first element to the last, asking
> 	 * each extension to
> 	 * {@link CommonDropAdapterAssistant#validateDrop(Object, int, org.eclipse.swt.dnd.TransferData)}.
> 	 * The first to successfully validate the drop operation will have the
> 	 * opportunity to
>-	 * {@link CommonDropAdapterAssistant#handleDrop(org.eclipse.swt.dnd.DropTargetEvent, Object)}.
>+	 * {@link CommonDropAdapterAssistant#handleDrop(CommonDropAdapter, org.eclipse.swt.dnd.DropTargetEvent, Object) handle the drop}
> 	 * 
> 	 * 
> 	 * @param aDropTarget
>-	 * The target element in the viewer of the drop operation
>+	 * The target element in the viewer of the drop operation.
>+	 * @param theDragSelection 
>+	 * 			 The drag selection of the current drop operation.
> 	 * @return An array of {@link CommonDropAdapterAssistant}s that are defined
> 	 * by the set of
> 	 * org.eclipse.ui.navigator.navigatorContent/navigatorContent
>@@ -91,5 +118,5 @@
> 	 * that matches the given drop target.
> 	 */
> 	CommonDropAdapterAssistant[] findCommonDropAdapterAssistants(
>-			Object aDropTarget);
>+			Object aDropTarget, IStructuredSelection theDragSelection);
> }
>Index: src/org/eclipse/ui/navigator/INavigatorContentDescriptor.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/INavigatorContentDescriptor.java,v
>retrieving revision 1.5
>diff -u -r1.5 INavigatorContentDescriptor.java
>--- src/org/eclipse/ui/navigator/INavigatorContentDescriptor.java	6 Feb 2006 22:24:45 -0000	1.5
>+++ src/org/eclipse/ui/navigator/INavigatorContentDescriptor.java	22 Feb 2006 04:32:51 -0000
>@@ -12,6 +12,7 @@
> 
> import java.util.Set;
> 
>+import org.eclipse.jface.viewers.IStructuredSelection;
> import org.eclipse.ui.internal.navigator.extensions.OverridePolicy;
> 
> 
>@@ -100,6 +101,14 @@
> 	boolean isPossibleChild(Object anElement);
> 	
> 	/**
>+	 * A convenience method to check all elements in a selection. 
>+	 * 
>+	 * @param aSelection A non-null selection
>+	 * @return True if and only if every element in the selection is a possible child.
>+	 */
>+	boolean arePossibleChildren(IStructuredSelection aSelection);
>+	
>+	/**
> 	 * @return Returns the suppressedExtensionId or null if none specified.
> 	 */
> 	String getSuppressedExtensionId();
>Index: src/org/eclipse/ui/navigator/CommonDropAdapterAssistant.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDropAdapterAssistant.java,v
>retrieving revision 1.1
>diff -u -r1.1 CommonDropAdapterAssistant.java
>--- src/org/eclipse/ui/navigator/CommonDropAdapterAssistant.java	9 Feb 2006 21:32:09 -0000	1.1
>+++ src/org/eclipse/ui/navigator/CommonDropAdapterAssistant.java	22 Feb 2006 04:32:49 -0000
>@@ -10,9 +10,14 @@
> *******************************************************************************/
> package org.eclipse.ui.navigator;
> 
>+import org.eclipse.core.runtime.IStatus;
>+import org.eclipse.core.runtime.Status;
> import org.eclipse.jface.util.LocalSelectionTransfer;
>+import org.eclipse.jface.viewers.IStructuredSelection;
> import org.eclipse.swt.dnd.DropTargetEvent;
> import org.eclipse.swt.dnd.TransferData;
>+import org.eclipse.swt.widgets.Shell;
>+import org.eclipse.ui.internal.navigator.NavigatorContentService;
> import org.eclipse.ui.part.PluginTransfer;
> 
> /**
>@@ -29,11 +34,11 @@
> * Whenever a match is found, the assistant will be given an opportunity to
> * first {@link #validateDrop(Object, int, TransferData) }, and then if the
> * assistant returns true, the assist must
>- * {@link #handleDrop(DropTargetEvent, Object) }. If multiple assistants match
>- * the drop target, then the potential assistants are ordered based on priority
>- * and their override relationships and given an opportunity to validate the
>- * drop operation in turn. The first one to validate will have the opportunty to
>- * carry out the drop.
>+ * {@link #handleDrop(CommonDropAdapter, DropTargetEvent, Object) }. If
>+ * multiple assistants match the drop target, then the potential assistants are
>+ * ordered based on priority and their override relationships and given an
>+ * opportunity to validate the drop operation in turn. The first one to validate
>+ * will have the opportunty to carry out the drop.
> * 
> * 
> * That is, if a content extension X overrides content extension Y (see
>@@ -42,6 +47,28 @@
> * than Y, then X will have an opportunity before Y, and Y will have an
> * opportunity before Z.
> * 
>+ * 
>+ * 
>+ * Clients may handle DND operations that begin and end in the current viewer by
>+ * overriding the following methods:
>+ * <ul>
>+ * <li>{@link #validateDrop(Object, int, TransferData)}: Indicate whether this
>+ * assistant can handle a drop onto the current viewer.</li>
>+ * <li>{@link #handleDrop(CommonDropAdapter, DropTargetEvent, Object)}: Handle
>+ * the drop operation onto the current viewer.</li>
>+ * </ul>
>+ * 
>+ * 
>+ * If a user originates a drag operation to another viewer that cannot handle
>+ * one of the available drag transfer types, drop assistants may handle the drop
>+ * operation for the target viewer. Clients must override :
>+ * <ul>
>+ * <li>{@link #validatePluginTransferDrop(IStructuredSelection, Object)}:
>+ * Indicate whether this assistant can handle the drop onto another viewer.
>+ * <li>{@link #handlePluginTransferDrop(IStructuredSelection, Object)}: Handle
>+ * the drop operation onto the other viewer.</li>
>+ * </ul>
>+ * 
> * 
> * EXPERIMENTAL. This class or interface has been added as
> * part of a work in progress. There is a guarantee neither that this API will
>@@ -53,7 +80,8 @@
> * 
> * 
> * @see INavigatorDnDService
>- * @see INavigatorDnDService#findCommonDropAdapterAssistants(Object)
>+ * @see INavigatorDnDService#findCommonDropAdapterAssistants(Object,
>+ * TransferData)
> * @since 3.2
> * 
> */
>@@ -76,7 +104,7 @@
> 	}
> 
> 	/**
>-	 * Override to perform any one-time intialization.
>+	 * Override to perform any one-time initialization.
> 	 */
> 	protected void doInit() {
> 
>@@ -88,7 +116,7 @@
> 	 * 
> 	 * Subclasses must implement this method to define which drops make sense.
> 	 * If clients return true, then they will be allowed to handle the drop in
>-	 * {@link #handleDrop(DropTargetEvent, Object) }.
>+	 * {@link #handleDrop(CommonDropAdapter, DropTargetEvent, Object) }.
> 	 * 
> 	 * 
> 	 * @param target
>@@ -98,41 +126,81 @@
> 	 * the current drag operation (copy, move, etc.)
> 	 * @param transferType
> 	 * the current transfer type
>-	 * @return <code>true</code> if the drop is valid, and <code>false</code>
>-	 * otherwise
>+	 * @return A status indicating whether the drop is valid.
> 	 */
>-	public abstract boolean validateDrop(Object target, int operation,
>+	public abstract IStatus validateDrop(Object target, int operation,
> 			TransferData transferType);
> 
> 	/**
>-	 * Carry out the DND operation
>+	 * Carry out the DND operation.
> 	 * 
>+	 * @param aDropAdapter
>+	 * The Drop Adapter contains information that has already been
>+	 * parsed from the drop event.
> 	 * @param aDropTargetEvent
> 	 * The drop target event.
> 	 * @param aTarget
> 	 * The object being dragged onto
>-	 * @return True if the operation completed.
>+	 * @return A status indicating whether the drop completed OK.
> 	 */
>-	public abstract boolean handleDrop(DropTargetEvent aDropTargetEvent,
>-			Object aTarget);
>+	public abstract IStatus handleDrop(CommonDropAdapter aDropAdapter,
>+			DropTargetEvent aDropTargetEvent, Object aTarget);
>+
>+	/**
>+	 * Clients may extend the supported transfer types beyond the default
>+	 * {@link LocalSelectionTransfer#getTransfer()} and
>+	 * {@link PluginTransfer#getInstance()} transfer types. When a transfer type
>+	 * other than one of these is encountered, the DND Service will query the
>+	 * visible and active descriptors that are enabled
>+	 * for the drop target of the current operation.
>+	 * 
>+	 * @param aTransferType
>+	 * The transfer data from the drop operation
>+	 * @return True if the given TransferData can be understood by this
>+	 * assistant.
>+	 */
>+	public boolean isSupportedType(TransferData aTransferType) {
>+		return LocalSelectionTransfer.getTransfer().isSupportedType(
>+				aTransferType);
>+	}
> 
> 	/**
>-	 * When a drop opportunity presents itself, the available TransferData types
>-	 * will be supplied in the event. The DropAdapter must select one of these
>-	 * TransferData types for the DragAdapter to provide. By default the Common
>-	 * Navigator supports {@link LocalSelectionTransfer} and
>-	 * {@link PluginTransfer}. Clients are required to indicate if they support
>-	 * other TransferData types using this method.
> 	 * 
>+	 * Return true if the client can handle the drop onto the target viewer of
>+	 * the drop operation.
> 	 * 
>-	 * If none of the given TransferData types are supported, return null.
>+	 * The default behavior of this method is to return Status.CANCEL_STATUS.
> 	 * 
> 	 * 
>-	 * @param theAvailableTransferData
>-	 * @return The supported TransferData from the set.
>-	 */
>-	public abstract TransferData findSupportedTransferData(
>-			TransferData[] theAvailableTransferData);
>+	 * @param aDragSelection
>+	 * The selection dragged from the viewer.
>+	 * @param aDropTarget
>+	 * The target of the drop operation.
>+	 * 
>+	 * @return OK if the plugin transfer can be handled by this assistant.
>+	 */
>+	public IStatus validatePluginTransferDrop(
>+			IStructuredSelection aDragSelection, Object aDropTarget) {
>+		return Status.CANCEL_STATUS;
>+	}
>+
>+	/**
>+	 * Handle the drop operation for the target viewer.
>+	 * 
>+	 * The default behavior of this method is to return Status.CANCEL_STATUS.
>+	 * 
>+	 * 
>+	 * @param aDragSelection
>+	 * The selection dragged from the viewer.
>+	 * @param aDropTarget
>+	 * The target of the drop operation.
>+	 * 
>+	 * @return OK if the drop operation succeeded.
>+	 */
>+	public IStatus handlePluginTransferDrop(
>+			IStructuredSelection aDragSelection, Object aDropTarget) {
>+		return Status.CANCEL_STATUS;
>+	}
> 
> 	/**
> 	 * 
>@@ -142,4 +210,13 @@
> 		return contentService;
> 	}
> 
>+	/**
>+	 * 
>+	 * @return A shell for the viewer currently used by the
>+	 * {@link INavigatorContentService}.
>+	 */
>+	protected final Shell getShell() {
>+		return ((NavigatorContentService) contentService).getShell();
>+	}
>+
> }
>Index: src/org/eclipse/ui/navigator/CommonDragAdapterAssistant.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDragAdapterAssistant.java,v
>retrieving revision 1.1
>diff -u -r1.1 CommonDragAdapterAssistant.java
>--- src/org/eclipse/ui/navigator/CommonDragAdapterAssistant.java	9 Feb 2006 21:32:09 -0000	1.1
>+++ src/org/eclipse/ui/navigator/CommonDragAdapterAssistant.java	22 Feb 2006 04:32:48 -0000
>@@ -17,6 +17,9 @@
> import org.eclipse.swt.dnd.Transfer;
> import org.eclipse.swt.dnd.TransferData;
> import org.eclipse.swt.widgets.Event;
>+import org.eclipse.swt.widgets.Shell;
>+import org.eclipse.ui.PlatformUI;
>+import org.eclipse.ui.internal.navigator.NavigatorContentService;
> import org.eclipse.ui.part.PluginTransfer;
> 
> /**
>@@ -31,7 +34,7 @@
> * 
> * 
> * @see INavigatorDnDService
>- * @see CommonDragAdapter 
>+ * @see CommonDragAdapter
> * @see CommonDropAdapter
> * @see CommonDropAdapterAssistant
> * @see CommonViewer#initDragAndDrop()
>@@ -47,6 +50,8 @@
> */
> public abstract class CommonDragAdapterAssistant {
> 
>+	private INavigatorContentService contentService;
>+
> 	/**
> 	 * Extra TransferTypes allow the Navigator to generate different kinds of
> 	 * payloads for DND clients. By default, the {@link CommonDragAdapter}
>@@ -81,4 +86,33 @@
> 	public abstract void setDragData(DragSourceEvent anEvent,
> 			IStructuredSelection aSelection);
> 
>+	/**
>+	 * Accept and remember the content service this assistant is associated
>+	 * with.
>+	 * 
>+	 * @param aContentService
>+	 */
>+	public final void setContentService(INavigatorContentService aContentService) {
>+		contentService = aContentService;
>+	}
>+
>+	/**
>+	 * 
>+	 * @return The associated content service.
>+	 */
>+	public INavigatorContentService getContentService() {
>+		return contentService;
>+	}
>+
>+	/**
>+	 * 
>+	 * @return The shell for the viewer this assistant is associated with or the
>+	 * shell of the active workbench window.
>+	 */
>+	public final Shell getShell() {
>+		if (contentService != null)
>+			((NavigatorContentService) contentService).getShell();
>+		return PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell();
>+	}
>+
> }
>Index: src/org/eclipse/ui/navigator/CommonDropAdapter.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDropAdapter.java,v
>retrieving revision 1.1
>diff -u -r1.1 CommonDropAdapter.java
>--- src/org/eclipse/ui/navigator/CommonDropAdapter.java	9 Feb 2006 21:32:10 -0000	1.1
>+++ src/org/eclipse/ui/navigator/CommonDropAdapter.java	22 Feb 2006 04:32:49 -0000
>@@ -10,12 +10,18 @@
> *******************************************************************************/
> package org.eclipse.ui.navigator;
> 
>+import org.eclipse.core.runtime.IStatus;
> import org.eclipse.jface.util.LocalSelectionTransfer;
> import org.eclipse.jface.viewers.StructuredViewer;
> import org.eclipse.swt.dnd.DND;
> import org.eclipse.swt.dnd.DropTargetEvent;
> import org.eclipse.swt.dnd.FileTransfer;
>+import org.eclipse.swt.dnd.Transfer;
> import org.eclipse.swt.dnd.TransferData;
>+import org.eclipse.swt.graphics.Rectangle;
>+import org.eclipse.swt.widgets.Item;
>+import org.eclipse.ui.internal.navigator.NavigatorPlugin;
>+import org.eclipse.ui.internal.navigator.dnd.NavigatorDnDService;
> import org.eclipse.ui.internal.navigator.dnd.NavigatorPluginDropAction;
> import org.eclipse.ui.part.PluginDropAdapter;
> import org.eclipse.ui.part.PluginTransfer;
>@@ -46,10 +52,16 @@
> */
> public final class CommonDropAdapter extends PluginDropAdapter {
> 
>-	// private final StructuredViewer viewer;
>+	private static final Transfer[] SUPPORTED_DROP_TRANSFERS = new Transfer[] {
>+			LocalSelectionTransfer.getTransfer(), FileTransfer.getInstance(),
>+			PluginTransfer.getInstance() };
>+
>+	private static final boolean DEBUG = false;
> 
> 	private final INavigatorContentService contentService;
> 
>+	private final NavigatorDnDService dndService;
>+
> 	/**
> 	 * Create a DropAdapter that handles a drop based on the given content
> 	 * service and selection provider.
>@@ -62,8 +74,22 @@
> 	public CommonDropAdapter(INavigatorContentService aContentService,
> 			StructuredViewer aStructuredViewer) {
> 		super(aStructuredViewer);
>-		// viewer = aStructuredViewer;
> 		contentService = aContentService;
>+		dndService = (NavigatorDnDService) contentService.getDnDService();
>+	}
>+
>+	/**
>+	 * 
>+	 * @return An array of Transfers allowed by the CommonDropAdapter. Includes
>+	 * {@link LocalSelectionTransfer#getTransfer()},
>+	 * {@link FileTransfer#getInstance()},
>+	 * {@link PluginTransfer#getInstance()}.
>+	 * @see LocalSelectionTransfer
>+	 * @see FileTransfer
>+	 * @see PluginTransfer
>+	 */
>+	public Transfer[] getSupportedDropTransfers() {
>+		return SUPPORTED_DROP_TRANSFERS;
> 	}
> 
> 	/*
>@@ -74,22 +100,28 @@
> 	public void dragEnter(DropTargetEvent event) {
> 		super.dragEnter(event);
> 
>-		for (int i = 0; i < event.dataTypes.length; i++) {
>+		for (int i = 0; i < event.dataTypes.length; i++)
> 			if (LocalSelectionTransfer.getTransfer().isSupportedType(
> 					event.dataTypes[i])) {
> 				event.currentDataType = event.dataTypes[i];
> 				return;
>-			} else if (FileTransfer.getInstance().isSupportedType(
>-					event.dataTypes[i])) {
>+			}
>+
>+		for (int i = 0; i < event.dataTypes.length; i++)
>+			if (FileTransfer.getInstance().isSupportedType(event.dataTypes[i])) {
> 				event.currentDataType = event.dataTypes[i];
> 				event.detail = DND.DROP_COPY;
> 				return;
>-			} else if (PluginTransfer.getInstance().isSupportedType(
>-					event.dataTypes[i])) {
>+			}
>+
>+		for (int i = 0; i < event.dataTypes.length; i++)
>+
>+			if (PluginTransfer.getInstance()
>+					.isSupportedType(event.dataTypes[i])) {
> 				event.currentDataType = event.dataTypes[i];
> 				return;
> 			}
>-		}
>+
> 		event.detail = DND.DROP_NONE;
> 
> 	}
>@@ -116,8 +148,27 @@
> 	public void drop(DropTargetEvent event) {
> 		if (PluginTransfer.getInstance().isSupportedType(event.currentDataType))
> 			super.drop(event);
>+		else {
> 
>-		// TODO Use the CommonDropAssistants to validate the drop.
>+			CommonDropAdapterAssistant[] assistants = dndService
>+					.findCommonDropAdapterAssistants(getCurrentTarget(),
>+							getCurrentTransfer());
>+
>+			IStatus valid = null;
>+			for (int i = 0; i < assistants.length; i++) {
>+				try {
>+					valid = assistants[i].validateDrop(getCurrentTarget(),
>+							getCurrentOperation(), getCurrentTransfer());
>+					if (valid != null && valid.isOK()) {
>+						assistants[i].handleDrop(this, event,
>+								getCurrentTarget());
>+						return;
>+					}
>+				} catch (Throwable t) {
>+					NavigatorPlugin.logError(0, t.getMessage(), t);
>+				}
>+			}
>+		}
> 	}
> 
> 	/*
>@@ -126,20 +177,97 @@
> 	 * @see org.eclipse.jface.viewers.ViewerDropAdapter#validateDrop(java.lang.Object,
> 	 * int, org.eclipse.swt.dnd.TransferData)
> 	 */
>-	public boolean validateDrop(Object target, int operation,
>-			TransferData transferType) {
>-		/*
>-		 * should be called first sense the currentTransfer field is set in the
>-		 * parent in this method
>-		 */
>-		if (super.validateDrop(target, operation, transferType)) {
>-			return true;
>-		}
>+	public boolean validateDrop(Object aDropTarget, int theDropOperation,
>+			TransferData theTransferData) {
>+
>+		if (DEBUG)
>+			System.out.println("CommonDropAdapter.validateDrop (begin)"); //$NON-NLS-1$
>+
> 		boolean result = false;
> 
>-		// TODO Use the CommonDropAssistants to validate the drop.
>+		IStatus valid = null;
>+
>+		if (super.validateDrop(aDropTarget, theDropOperation, theTransferData))
>+			result = true;
>+		else if (FileTransfer.getInstance().isSupportedType(theTransferData))
>+			// only allow copying when dragging from outside Eclipse
>+			// result = theDropOperation != DND.DROP_COPY;
>+			result = true;
>+		else {
>+			CommonDropAdapterAssistant[] assistants = dndService
>+					.findCommonDropAdapterAssistants(aDropTarget,
>+							theTransferData);
>+
>+			for (int i = 0; i < assistants.length; i++) {
>+				try {
>+					valid = assistants[i].validateDrop(aDropTarget,
>+							theDropOperation, theTransferData);
>+				} catch (Throwable t) {
>+					NavigatorPlugin.logError(0, t.getMessage(), t);
>+				}
>+				if (valid != null && valid.isOK()) {
>+					result = true;
>+					break;
>+				}
>+			}
>+		}
>+
>+		if (DEBUG)
>+			System.out
>+					.println("CommonDropAdapter.validateDrop (returning " + (valid != null ? valid.getSeverity() + ": " + valid.getMessage() : "" + result) + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
> 
> 		return result;
>+
>+	}
>+
>+	/*
>+	 * The visibility of the following methods is raised for downstream clients
>+	 * (assistants).
>+	 */
>+
>+	/*
>+	 * (non-Javadoc)
>+	 * 
>+	 * @see org.eclipse.jface.viewers.ViewerDropAdapter#getBounds(org.eclipse.swt.widgets.Item)
>+	 */
>+	public Rectangle getBounds(Item item) {
>+		return super.getBounds(item);
>+	}
>+
>+	/*
>+	 * (non-Javadoc)
>+	 * 
>+	 * @see org.eclipse.jface.viewers.ViewerDropAdapter#getCurrentLocation()
>+	 */
>+	public int getCurrentLocation() {
>+		return super.getCurrentLocation();
>+	}
>+
>+	/*
>+	 * (non-Javadoc)
>+	 * 
>+	 * @see org.eclipse.jface.viewers.ViewerDropAdapter#getCurrentOperation()
>+	 */
>+	public int getCurrentOperation() {
>+		return super.getCurrentOperation();
>+	}
>+
>+	/*
>+	 * (non-Javadoc)
>+	 * 
>+	 * @see org.eclipse.jface.viewers.ViewerDropAdapter#getCurrentTarget()
>+	 */
>+	public Object getCurrentTarget() {
>+		return super.getCurrentTarget();
>+	}
>+
>+	/*
>+	 * (non-Javadoc)
>+	 * 
>+	 * @see org.eclipse.ui.part.PluginDropAdapter#getCurrentTransfer()
>+	 */
>+	public TransferData getCurrentTransfer() {
>+		return super.getCurrentTransfer();
> 	}
> 
> }
>Index: src/org/eclipse/ui/navigator/CommonViewer.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonViewer.java,v
>retrieving revision 1.11
>diff -u -r1.11 CommonViewer.java
>--- src/org/eclipse/ui/navigator/CommonViewer.java	9 Feb 2006 21:32:09 -0000	1.11
>+++ src/org/eclipse/ui/navigator/CommonViewer.java	22 Feb 2006 04:32:51 -0000
>@@ -21,6 +21,7 @@
> import org.eclipse.jface.viewers.TreeViewer;
> import org.eclipse.jface.viewers.ViewerSorter;
> import org.eclipse.swt.SWT;
>+import org.eclipse.swt.dnd.DND;
> import org.eclipse.swt.events.DisposeEvent;
> import org.eclipse.swt.widgets.Composite;
> import org.eclipse.swt.widgets.Item;
>@@ -304,9 +305,7 @@
> 	 * By default, the following Transfer types are supported:
> 	 * <ul>
> 	 * <li>LocalSelectionTransfer.getInstance(),
>-	 * <li>PluginTransfer.getInstance(),
>-	 * <li>FileTransfer.getInstance(), and
>-	 * <li>ResourceTransfer.getInstance()
>+	 * <li>PluginTransfer.getInstance()
> 	 * </ul>
> 	 * 
> 	 * 
>@@ -314,35 +313,19 @@
> 	 * @see CommonDropAdapter
> 	 */
> 	protected void initDragAndDrop() {
>-		
>-		// TODO initDragAndDrop is in progress.
>-		
>-//		/* Handle Drag and Drop */
>-//		int operations = DND.DROP_COPY | DND.DROP_MOVE;
>-//
>-//		CommonDragAdapterAssistant[] assistants = contentService
>-//				.getDnDService().getCommonDragAssistants();
>-//
>-//		Set supportedTypes = new HashSet();
>-//		supportedTypes.add(PluginTransfer.getInstance());
>-//		supportedTypes.add(LocalSelectionTransfer.getInstance());
>-//		Transfer[] transferTypes = null;
>-//		for (int i = 0; i < assistants.length; i++) {
>-//			transferTypes = assistants[i].getSupportedTransferTypes();
>-//			for (int j = 0; j < transferTypes.length; j++) {
>-//				if (transferTypes[j] != null)
>-//					supportedTypes.add(transferTypes[j]);
>-//			}
>-//		}
>-//
>-//		Transfer[] transfers = (Transfer[]) supportedTypes
>-//				.toArray(new Transfer[supportedTypes.size()]);
>-//
>-//		addDragSupport(operations, transfers, new CommonDragAdapter(
>-//				contentService, this));
>-//		// TODO Should the Transfers be the same here?
>-//		addDropSupport(operations, transfers, new CommonDropAdapter(
>-//				contentService, this));
>+
>+		/* Handle Drag and Drop */
>+		int operations = DND.DROP_COPY | DND.DROP_MOVE;
>+
>+		CommonDragAdapter dragAdapter = new CommonDragAdapter(contentService,
>+				this);
>+		addDragSupport(operations, dragAdapter.getSupportDragTransfers(),
>+				dragAdapter);
>+
>+		CommonDropAdapter dropAdapter = new CommonDropAdapter(contentService,
>+				this);
>+		addDropSupport(operations, dropAdapter.getSupportedDropTransfers(),
>+				dropAdapter);
> 
> 	}
> 
>Index: schema/navigatorContent.exsd
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/schema/navigatorContent.exsd,v
>retrieving revision 1.22
>diff -u -r1.22 navigatorContent.exsd
>--- schema/navigatorContent.exsd	9 Feb 2006 21:32:11 -0000	1.22
>+++ schema/navigatorContent.exsd	22 Feb 2006 04:32:41 -0000
>@@ -86,7 +86,7 @@
> <element ref="actionProvider" minOccurs="0" maxOccurs="unbounded"/>
> <element ref="commonSorter" minOccurs="0" maxOccurs="unbounded"/>
> <element ref="override" minOccurs="0" maxOccurs="1"/>
>- <element ref="commonDropAdapter" minOccurs="0" maxOccurs="1"/>
>+ <element ref="commonDropAdapter" minOccurs="0" maxOccurs="unbounded"/>
> </sequence>
> <attribute name="id" type="string" use="required">
> <annotation>
>@@ -518,10 +518,19 @@
> <element name="commonDropAdapter">
> <annotation>
> <documentation>
>- Provides a subclass of &lt;code&gt;org.eclipse.ui.navigator.CommonDropAdapterAssistant&lt;/code&gt; which can provide programatic validation for a drop operation, request additional transfer types, and handle the drop.
>+ Provides a subclass of &lt;code&gt;org.eclipse.ui.navigator.CommonDropAdapterAssistant&lt;/code&gt; which can provide programatic validation for a drop operation, request additional transfer types, and handle the drop operation. 
>+&lt;br&gt;&lt;br&gt;
>+A &lt;b&gt;commonDropAdapter&lt;/b&gt; will be invoked whenever elements that are dragged match the &lt;b&gt;possibleChildren&lt;/b&gt; expression of the containing &lt;b&gt;navigatorContent&lt;/b&gt; extension &lt;i&gt;and&lt;/i&gt; the drop target of the operation is described by the &lt;b&gt;possibleDropTargets&lt;/b&gt; expression of the &lt;b&gt;commonDropAdapter&lt;/b&gt; element.
>+&lt;br&gt;&lt;br&gt;
>+An extension may have multiple drop adapters with mutually exclusive &lt;b&gt;possibleDropTargets&lt;/b&gt; expressions. The first drop adapter found that matches the given drop target and returns an OK status for &lt;code&gt;CommonDropAdapterAssistant.validateDrop(...)&lt;/code&gt; will be given an opportunity to handle the drop. 
>+&lt;br&gt;&lt;br&gt;
>+ 
> </documentation>
> </annotation>
> <complexType>
>+ <sequence>
>+ <element ref="possibleDropTargets"/>
>+ </sequence>
> <attribute name="id" type="string" use="required">
> <annotation>
> <documentation>
>@@ -542,6 +551,30 @@
> </complexType>
> </element>
> 
>+ <element name="possibleDropTargets">
>+ <annotation>
>+ <documentation>
>+ Describe the possible drop targets that a particular &lt;b&gt;commonDropAdapter&lt;/b&gt; can handle.
>+ </documentation>
>+ </annotation>
>+ <complexType>
>+ <sequence minOccurs="0" maxOccurs="unbounded">
>+ <element ref="not"/>
>+ <element ref="and"/>
>+ <element ref="or"/>
>+ <element ref="instanceof"/>
>+ <element ref="test"/>
>+ <element ref="systemTest"/>
>+ <element ref="equals"/>
>+ <element ref="count"/>
>+ <element ref="with"/>
>+ <element ref="resolve"/>
>+ <element ref="adapt"/>
>+ <element ref="iterate"/>
>+ </sequence>
>+ </complexType>
>+ </element>
>+
> <annotation>
> <appInfo>
> <meta.section type="since"/>
>Index: src/org/eclipse/ui/internal/navigator/dnd/NavigatorDnDService.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/dnd/NavigatorDnDService.java,v
>retrieving revision 1.1
>diff -u -r1.1 NavigatorDnDService.java
>--- src/org/eclipse/ui/internal/navigator/dnd/NavigatorDnDService.java	9 Feb 2006 21:32:08 -0000	1.1
>+++ src/org/eclipse/ui/internal/navigator/dnd/NavigatorDnDService.java	22 Feb 2006 04:32:45 -0000
>@@ -11,9 +11,15 @@
> 
> package org.eclipse.ui.internal.navigator.dnd;
> 
>+import java.util.HashMap;
> import java.util.Iterator;
>+import java.util.LinkedHashSet;
>+import java.util.Map;
> import java.util.Set;
> 
>+import org.eclipse.jface.util.LocalSelectionTransfer;
>+import org.eclipse.jface.viewers.IStructuredSelection;
>+import org.eclipse.swt.dnd.TransferData;
> import org.eclipse.ui.internal.navigator.NavigatorContentService;
> import org.eclipse.ui.internal.navigator.extensions.CommonDragAssistantDescriptor;
> import org.eclipse.ui.internal.navigator.extensions.NavigatorViewerDescriptor;
>@@ -28,18 +34,27 @@
> * {@link CommonDropAdapterAssistant} for the associated
> * {@link INavigatorContentService}.
> * 
>+ * 
>+ * Clients may not extend, instantiate or directly reference this class.
>+ * 
>+ * 
> * @since 3.2
> * 
> */
> public class NavigatorDnDService implements INavigatorDnDService {
> 
>+	private static final CommonDropAdapterAssistant[] NO_ASSISTANTS = new CommonDropAdapterAssistant[0];
>+
> 	private NavigatorContentService contentService;
> 
> 	private CommonDragAdapterAssistant[] dragAssistants;
> 
>+	private final Map dropAssistants = new HashMap();
>+
> 	/**
> 	 * 
>-	 * @param aContentService The associated content service
>+	 * @param aContentService
>+	 * The associated content service
> 	 */
> 	public NavigatorDnDService(NavigatorContentService aContentService) {
> 		contentService = aContentService;
>@@ -62,12 +77,81 @@
> 		return dragAssistants;
> 	}
> 
>-	/* (non-Javadoc)
>-	 * @see org.eclipse.ui.navigator.INavigatorDnDService#findCommonDropAdapterAssistants(java.lang.Object)
>-	 */
>-	public CommonDropAdapterAssistant[] findCommonDropAdapterAssistants(Object aDropTarget) {
>-		// TODO Implement the search routine
>-		return null;
>+	public CommonDropAdapterAssistant[] findCommonDropAdapterAssistants(
>+			Object aDropTarget, TransferData aTransferType) {
>+ 
>+		// TODO Make sure descriptors are sorted by priority 
>+		CommonDropAdapterDescriptor[] descriptors = CommonDropDescriptorManager
>+				.getInstance().findCommonDropAdapterAssistants(aDropTarget,
>+						contentService);
>+
>+		if (descriptors.length == 0)
>+			return NO_ASSISTANTS;
>+
>+		if (LocalSelectionTransfer.getTransfer().isSupportedType(aTransferType) 
>+						&& LocalSelectionTransfer.getTransfer().getSelection() instanceof IStructuredSelection) 
>+			return getAssistantsBySelection(descriptors, (IStructuredSelection) LocalSelectionTransfer.getTransfer().getSelection()); 
>+		return getAssistantsByTransferData(descriptors, aTransferType);
>+	}
>+	
>+
>+	public CommonDropAdapterAssistant[] findCommonDropAdapterAssistants(
>+			Object aDropTarget, IStructuredSelection theDragSelection) {
>+ 
>+		// TODO Make sure descriptors are sorted by priority 
>+		CommonDropAdapterDescriptor[] descriptors = CommonDropDescriptorManager
>+				.getInstance().findCommonDropAdapterAssistants(aDropTarget,
>+						contentService);
>+
>+		if (descriptors.length == 0)
>+			return NO_ASSISTANTS;
>+
>+		return getAssistantsBySelection(descriptors, theDragSelection); 
>+	}
>+
>+	private CommonDropAdapterAssistant[] getAssistantsByTransferData(
>+			CommonDropAdapterDescriptor[] descriptors,
>+			TransferData aTransferType) {
>+
>+		Set assistants = new LinkedHashSet();
>+		for (int i = 0; i < descriptors.length; i++) {
>+			CommonDropAdapterAssistant asst = getAssistant(descriptors[i]);
>+			if (asst.isSupportedType(aTransferType))
>+				assistants.add(asst);
>+		}
>+		return (CommonDropAdapterAssistant[]) assistants
>+				.toArray(new CommonDropAdapterAssistant[assistants.size()]);
>+
>+	}
>+
>+	private CommonDropAdapterAssistant[] getAssistantsBySelection(
>+			CommonDropAdapterDescriptor[] descriptors, IStructuredSelection aSelection) {
>+
>+		Set assistants = new LinkedHashSet(); 
>+			
>+		for (int i = 0; i < descriptors.length; i++) 
>+			if(descriptors[i].areDragElementsSupported(aSelection))
>+				assistants.add(getAssistant(descriptors[i])); 
>+
>+		return (CommonDropAdapterAssistant[]) assistants
>+				.toArray(new CommonDropAdapterAssistant[assistants.size()]);
>+	}
>+
>+	private CommonDropAdapterAssistant getAssistant(
>+			CommonDropAdapterDescriptor descriptor) {
>+		CommonDropAdapterAssistant asst = (CommonDropAdapterAssistant) dropAssistants
>+				.get(descriptor);
>+		if (asst != null)
>+			return asst;
>+		synchronized (dropAssistants) {
>+			asst = (CommonDropAdapterAssistant) dropAssistants.get(descriptor);
>+			if (asst == null) {
>+				dropAssistants.put(descriptor, (asst = descriptor
>+						.createDropAssistant()));
>+				asst.init(contentService);
>+			}
>+		}
>+		return asst;
> 	}
> 
> }
>Index: src/org/eclipse/ui/internal/navigator/dnd/NavigatorPluginDropAction.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/dnd/NavigatorPluginDropAction.java,v
>retrieving revision 1.1
>diff -u -r1.1 NavigatorPluginDropAction.java
>--- src/org/eclipse/ui/internal/navigator/dnd/NavigatorPluginDropAction.java	9 Feb 2006 21:32:08 -0000	1.1
>+++ src/org/eclipse/ui/internal/navigator/dnd/NavigatorPluginDropAction.java	22 Feb 2006 04:32:45 -0000
>@@ -10,28 +10,29 @@
> *******************************************************************************/
> package org.eclipse.ui.internal.navigator.dnd;
> 
>+import org.eclipse.core.runtime.IStatus;
>+import org.eclipse.jface.util.LocalSelectionTransfer;
>+import org.eclipse.jface.viewers.IStructuredSelection;
>+import org.eclipse.ui.navigator.CommonDropAdapterAssistant;
> import org.eclipse.ui.navigator.INavigatorContentService;
> import org.eclipse.ui.part.IDropActionDelegate;
> import org.eclipse.ui.part.PluginTransferData;
> 
> /**
> * 
>- * 
>- * EXPERIMENTAL. This class or interface has been added as
>- * part of a work in progress. There is a guarantee neither that this API will
>- * work nor that it will remain the same. Please do not use this API without
>- * consulting with the Platform/UI team.
>- * 
> * 
> * @since 3.2
> * 
> */
> public class NavigatorPluginDropAction implements IDropActionDelegate {
> 
>+	private static final boolean DEBUG = false;
>+
> 	private static final String CN_PLUGIN_ACTION_ID = "org.eclipse.ui.navigator.PluginDropAction"; //$NON-NLS-1$
> 
> 	/**
>-	 * 
>+	 * A default no-args constructor is required by the
>+	 * org.eclipse.ui.dropAdapters extension point
> 	 */
> 	public NavigatorPluginDropAction() {
> 		super();
>@@ -45,7 +46,39 @@
> 	 */
> 	public boolean run(Object sourceData, Object target) {
> 
>-		// TODO Handle the callback for drop targets that cannot handle the drop
>+		if (DEBUG)
>+			System.out.println("NavigatorPluginDropAction.run (begin)"); //$NON-NLS-1$
>+
>+		String sourceViewerId = new String((byte[]) sourceData);
>+
>+		IStructuredSelection selection = (IStructuredSelection) LocalSelectionTransfer
>+				.getTransfer().getSelection();
>+
>+		INavigatorContentService contentService = NavigatorContentServiceTransfer
>+				.getInstance().findService(sourceViewerId);
>+
>+		if (contentService == null)
>+			return false;
>+		try {
>+			CommonDropAdapterAssistant[] assistants = contentService
>+					.getDnDService().findCommonDropAdapterAssistants(target,
>+							selection); 
>+
>+			IStatus valid = null;
>+			for (int i = 0; i < assistants.length; i++) {
>+				valid = assistants[i].validatePluginTransferDrop(selection, target);
>+				if (valid != null && valid.isOK()) {
>+					valid = assistants[i].handlePluginTransferDrop(selection, target);
>+					return valid != null && valid.isOK();
>+				}
>+			}
>+		} finally {
>+			NavigatorContentServiceTransfer.getInstance()
>+					.unregisterContentService(contentService);
>+		}
>+
>+		if (DEBUG)
>+			System.out.println("NavigatorPluginDropAction.run (exit)"); //$NON-NLS-1$
> 
> 		return false;
> 	}
>@@ -59,6 +92,8 @@
> 	 */
> 	public static PluginTransferData createTransferData(
> 			INavigatorContentService aContentService) {
>+		NavigatorContentServiceTransfer.getInstance().registerContentService(
>+				aContentService);
> 		return new PluginTransferData(CN_PLUGIN_ACTION_ID, aContentService
> 				.getViewerId().getBytes());
> 	}
>Index: src/org/eclipse/ui/internal/navigator/dnd/CommonDropAdapterDescriptor.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/dnd/CommonDropAdapterDescriptor.java,v
>retrieving revision 1.1
>diff -u -r1.1 CommonDropAdapterDescriptor.java
>--- src/org/eclipse/ui/internal/navigator/dnd/CommonDropAdapterDescriptor.java	9 Feb 2006 21:32:08 -0000	1.1
>+++ src/org/eclipse/ui/internal/navigator/dnd/CommonDropAdapterDescriptor.java	22 Feb 2006 04:32:44 -0000
>@@ -16,10 +16,12 @@
> import org.eclipse.core.expressions.Expression;
> import org.eclipse.core.runtime.CoreException;
> import org.eclipse.core.runtime.IConfigurationElement;
>+import org.eclipse.jface.viewers.IStructuredSelection;
> import org.eclipse.ui.internal.navigator.CustomAndExpression;
> import org.eclipse.ui.internal.navigator.NavigatorPlugin;
> import org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtPtConstants;
> import org.eclipse.ui.navigator.CommonDropAdapterAssistant;
>+import org.eclipse.ui.navigator.INavigatorContentDescriptor;
> 
> /**
> * @since 3.2
>@@ -28,29 +30,24 @@
> public final class CommonDropAdapterDescriptor implements
> 		INavigatorContentExtPtConstants {
> 
>-	private IConfigurationElement element;
>+	private final IConfigurationElement element;
> 
>-	private Expression dragExpr;
>+	private final INavigatorContentDescriptor contentDescriptor;
> 
> 	private Expression dropExpr;
> 
> 	/* package */CommonDropAdapterDescriptor(
>-			IConfigurationElement aConfigElement) {
>+			IConfigurationElement aConfigElement,
>+			INavigatorContentDescriptor aContentDescriptor) {
> 		element = aConfigElement;
>+		contentDescriptor = aContentDescriptor;
> 		init();
> 	}
> 
> 	private void init() {
>-
>-		IConfigurationElement[] children = element
>-				.getChildren(TAG_DRAG_EXPRESSION);
>-		if (children.length == 1)
>-			dragExpr = new CustomAndExpression(children[0]);
>-
>-		children = element.getChildren(TAG_DROP_EXPRESSION);
>+		IConfigurationElement[] children = element.getChildren(TAG_POSSIBLE_DROP_TARGETS);
> 		if (children.length == 1)
> 			dropExpr = new CustomAndExpression(children[0]);
>-
> 	}
> 
> 	/**
>@@ -60,15 +57,21 @@
> 	 * @return True if the element matches the drag expression from the
> 	 * extension.
> 	 */
>-	public boolean isDragElementSupported(Object anElement) {
>-		if (dragExpr != null)
>-			try {
>-				return dragExpr
>-						.evaluate(new EvaluationContext(null, anElement)) == EvaluationResult.TRUE;
>-			} catch (CoreException e) {
>-				NavigatorPlugin.logError(0, e.getMessage(), e);
>-			}
>-		return false;
>+	public boolean isDragElementSupported(Object anElement) { 
>+		return contentDescriptor.isPossibleChild(anElement); 
>+	}
>+
>+	/**
>+	 * 
>+	 * @param aSelection
>+	 * The set of elements being dragged.
>+	 * @return True if the element matches the drag expression from the
>+	 * extension.
>+	 */
>+	public boolean areDragElementsSupported(IStructuredSelection aSelection) {
>+		if (aSelection.isEmpty())
>+			return false;
>+		return contentDescriptor.arePossibleChildren(aSelection);
> 	}
> 
> 	/**
>@@ -79,7 +82,7 @@
> 	 * extension.
> 	 */
> 	public boolean isDropElementSupported(Object anElement) {
>-		if (dropExpr != null)
>+		if (dropExpr != null && anElement != null)
> 			try {
> 				return dropExpr
> 						.evaluate(new EvaluationContext(null, anElement)) == EvaluationResult.TRUE;
>@@ -105,7 +108,14 @@
> 			NavigatorPlugin.logError(0, re.getMessage(), re);
> 		}
> 		return SkeletonCommonDropAssistant.INSTANCE;
>+	}
> 
>+	/**
>+	 * 
>+	 * @return The content descriptor that contains this drop descriptor.
>+	 */
>+	public INavigatorContentDescriptor getContentDescriptor() {
>+		return contentDescriptor;
> 	}
> 
> }
>Index: src/org/eclipse/ui/internal/navigator/dnd/CommonDropDescriptorManager.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/dnd/CommonDropDescriptorManager.java,v
>retrieving revision 1.1
>diff -u -r1.1 CommonDropDescriptorManager.java
>--- src/org/eclipse/ui/internal/navigator/dnd/CommonDropDescriptorManager.java	9 Feb 2006 21:32:08 -0000	1.1
>+++ src/org/eclipse/ui/internal/navigator/dnd/CommonDropDescriptorManager.java	22 Feb 2006 04:32:44 -0000
>@@ -11,13 +11,20 @@
> 
> package org.eclipse.ui.internal.navigator.dnd;
> 
>-import java.util.HashMap;
>+import java.util.ArrayList;
>+import java.util.Iterator;
>+import java.util.LinkedHashSet;
>+import java.util.List;
> import java.util.Map;
>+import java.util.Set;
>+import java.util.TreeMap;
> 
> import org.eclipse.core.runtime.IConfigurationElement;
>+import org.eclipse.ui.internal.navigator.extensions.ExtensionPriorityComparator;
> import org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtPtConstants;
> import org.eclipse.ui.internal.navigator.extensions.NavigatorContentRegistryReader;
> import org.eclipse.ui.navigator.INavigatorContentDescriptor;
>+import org.eclipse.ui.navigator.INavigatorContentService;
> 
> /**
> * @since 3.2
>@@ -27,37 +34,89 @@
> 
> 	private static final CommonDropDescriptorManager INSTANCE = new CommonDropDescriptorManager();
> 
>+	private static final CommonDropAdapterDescriptor[] NO_DESCRIPTORS = new CommonDropAdapterDescriptor[0];
>+
> 	/**
> 	 * A map of (INavigatorContentDescriptor,
> 	 * CommonDropAdapterDescriptor)-pairs.
> 	 */
>-	private final Map dropDescriptors = new HashMap();
>+	private final Map dropDescriptors = new TreeMap(ExtensionPriorityComparator.INSTANCE);
> 
> 	/**
> 	 * 
> 	 * @return An initialized singleton instance of the
> 	 * CommonDropDescriptorManager.
> 	 */
>-	public CommonDropDescriptorManager getInstance() {
>+	public static CommonDropDescriptorManager getInstance() {
> 		return INSTANCE;
> 	}
> 
> 	private CommonDropDescriptorManager() {
> 		new CommonDropAdapterRegistry().readRegistry();
> 	}
>-	
>-	// TODO Add fetch Drop Adapters by match method.
>+
>+	/**
>+	 * 
>+	 * @param aDropTarget
>+	 * The drop target of the operation
>+	 * @param aContentService
>+	 * The associated content service to filter results by.
>+	 * @return An array of drop descriptors that can handle the given drop
>+	 * target and are visible and active for the given
>+	 * service and enabled for the given drop target..
>+	 */
>+	public CommonDropAdapterDescriptor[] findCommonDropAdapterAssistants(Object aDropTarget, INavigatorContentService aContentService) {
>+
>+		Set foundDescriptors = new LinkedHashSet();
>+		for (Iterator iter = dropDescriptors.keySet().iterator(); iter
>+				.hasNext();) {
>+			INavigatorContentDescriptor contentDescriptor = (INavigatorContentDescriptor) iter
>+					.next();
>+			if (aContentService.isVisible(contentDescriptor.getId())
>+					&& aContentService.isActive(contentDescriptor.getId())) {
>+				List dropDescriptors = getDropDescriptors(contentDescriptor);
>+				for (Iterator iterator = dropDescriptors.iterator(); iterator
>+						.hasNext();) {
>+					CommonDropAdapterDescriptor dropDescriptor = (CommonDropAdapterDescriptor) iterator
>+							.next();
>+					if (dropDescriptor.isDropElementSupported(aDropTarget))
>+						foundDescriptors.add(dropDescriptor);
>+				}
>+			}
>+		}
>+
>+		if (foundDescriptors.isEmpty())
>+			return NO_DESCRIPTORS;
>+		return (CommonDropAdapterDescriptor[]) foundDescriptors
>+				.toArray(new CommonDropAdapterDescriptor[foundDescriptors
>+						.size()]);
>+	}
>+
>+	private List getDropDescriptors(
>+			INavigatorContentDescriptor aContentDescriptor) {
>+		List descriptors = (List) dropDescriptors.get(aContentDescriptor);
>+		if (descriptors != null)
>+			return descriptors;
>+		synchronized (dropDescriptors) {
>+			descriptors = (List) dropDescriptors.get(aContentDescriptor);
>+			if (descriptors == null)
>+				dropDescriptors.put(aContentDescriptor,
>+						(descriptors = new ArrayList()));
>+
>+		}
>+		return descriptors;
>+	}
> 
> 	/**
> 	 * @param aContentDescriptor
>-	 * A non-null content descriptor. 
>+	 * A non-null content descriptor.
> 	 * @param aDropDescriptor
> 	 * A non-null drop descriptor.
> 	 */
> 	private void addCommonDropAdapter(
> 			INavigatorContentDescriptor aContentDescriptor,
>-			CommonDropAdapterDescriptor aDropDescriptor) {
>-		dropDescriptors.put(aContentDescriptor, aDropDescriptor);
>+			CommonDropAdapterDescriptor aDropDescriptor) { 
>+		getDropDescriptors(aContentDescriptor).add(aDropDescriptor);
> 	}
> 
> 	private class CommonDropAdapterRegistry extends
>@@ -82,13 +141,13 @@
> 							.getContentDescriptor(id);
> 					if (contentDescriptor != null) {
> 
>-						IConfigurationElement[] commonDropAdapter = element
>+						IConfigurationElement[] commonDropAdapters = element
> 								.getChildren(TAG_COMMON_DROP_ADAPTER);
> 
>-						if (commonDropAdapter.length == 1) {
>+						for (int i = 0; i < commonDropAdapters.length; i++) {
> 							addCommonDropAdapter(contentDescriptor,
>-									new CommonDropAdapterDescriptor(element));
>-						}
>+									new CommonDropAdapterDescriptor(commonDropAdapters[i], contentDescriptor));
>+						} 
> 					}
> 				}
> 
>Index: src/org/eclipse/ui/internal/navigator/dnd/SkeletonCommonDropAssistant.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/dnd/SkeletonCommonDropAssistant.java,v
>retrieving revision 1.1
>diff -u -r1.1 SkeletonCommonDropAssistant.java
>--- src/org/eclipse/ui/internal/navigator/dnd/SkeletonCommonDropAssistant.java	9 Feb 2006 21:32:08 -0000	1.1
>+++ src/org/eclipse/ui/internal/navigator/dnd/SkeletonCommonDropAssistant.java	22 Feb 2006 04:32:45 -0000
>@@ -11,8 +11,11 @@
> 
> package org.eclipse.ui.internal.navigator.dnd;
> 
>+import org.eclipse.core.runtime.IStatus;
>+import org.eclipse.core.runtime.Status;
> import org.eclipse.swt.dnd.DropTargetEvent;
> import org.eclipse.swt.dnd.TransferData;
>+import org.eclipse.ui.navigator.CommonDropAdapter;
> import org.eclipse.ui.navigator.CommonDropAdapterAssistant;
> 
> /**
>@@ -34,11 +37,12 @@
> 	/*
> 	 * (non-Javadoc)
> 	 * 
>-	 * @see org.eclipse.ui.navigator.CommonDropAdapterAssistant#handleDrop(org.eclipse.swt.dnd.DropTargetEvent,
>-	 * java.lang.Object)
>+	 * @see org.eclipse.ui.navigator.CommonDropAdapterAssistant#handleDrop(org.eclipse.ui.navigator.CommonDropAdapter,
>+	 * org.eclipse.swt.dnd.DropTargetEvent, java.lang.Object)
> 	 */
>-	public boolean handleDrop(DropTargetEvent aDropTargetEvent, Object aTarget) { 
>-		return false;
>+	public IStatus handleDrop(CommonDropAdapter aDropAdapter,
>+			DropTargetEvent aDropTargetEvent, Object aTarget) {
>+		return Status.CANCEL_STATUS;
> 	}
> 
> 	/*
>@@ -47,21 +51,21 @@
> 	 * @see org.eclipse.ui.navigator.CommonDropAdapterAssistant#validateDrop(java.lang.Object,
> 	 * int, org.eclipse.swt.dnd.TransferData)
> 	 */
>-	public boolean validateDrop(Object target, int operation,
>+	public IStatus validateDrop(Object target, int operation,
> 			TransferData transferType) {
>-
>-		return false;
>+		return Status.CANCEL_STATUS;
> 	}
> 
>-	/*
>-	 * (non-Javadoc)
>-	 * 
>-	 * @see org.eclipse.ui.navigator.CommonDropAdapterAssistant#findSupportedTransferData(org.eclipse.swt.dnd.TransferData[])
>-	 */
>-	public TransferData findSupportedTransferData(
>-			TransferData[] theAvailableTransferData) {
>-
>-		return null;
>-	}
>+	// /*
>+	// * (non-Javadoc)
>+	// *
>+	// * @see
>+	// org.eclipse.ui.navigator.CommonDropAdapterAssistant#findSupportedTransferData(org.eclipse.swt.dnd.TransferData[])
>+	// */
>+	// public TransferData findSupportedTransferData(
>+	// TransferData[] theAvailableTransferData) {
>+	//
>+	// return null;
>+	// }
> 
> }
>Index: src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptor.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptor.java,v
>retrieving revision 1.3
>diff -u -r1.3 NavigatorContentDescriptor.java
>--- src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptor.java	9 Feb 2006 21:32:09 -0000	1.3
>+++ src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptor.java	22 Feb 2006 04:32:46 -0000
>@@ -11,6 +11,7 @@
> package org.eclipse.ui.internal.navigator.extensions;
> 
> import java.util.HashSet;
>+import java.util.Iterator;
> import java.util.Set;
> 
> import org.eclipse.core.expressions.ElementHandler;
>@@ -22,6 +23,7 @@
> import org.eclipse.core.runtime.IConfigurationElement;
> import org.eclipse.core.runtime.IStatus;
> import org.eclipse.jface.viewers.ILabelProvider;
>+import org.eclipse.jface.viewers.IStructuredSelection;
> import org.eclipse.jface.viewers.ITreeContentProvider;
> import org.eclipse.osgi.util.NLS;
> import org.eclipse.ui.IPluginContribution;
>@@ -347,6 +349,8 @@
> 		if ((enablement == null && possibleChildren == null)
> 				|| anElement == null)
> 			return false;
>+		else if(anElement instanceof IStructuredSelection)
>+			return arePossibleChildren((IStructuredSelection) anElement);
> 
> 		try {
> 			if (possibleChildren != null)
>@@ -360,6 +364,23 @@
> 		}
> 		return false;
> 	}
>+	
>+	/**
>+	 * A convenience method to check all elements in a selection. 
>+	 * 
>+	 * @param aSelection A non-null selection
>+	 * @return True if and only if every element in the selection is a possible child.
>+	 */
>+	public boolean arePossibleChildren(IStructuredSelection aSelection) {
>+		if(aSelection.isEmpty())
>+			return false;
>+		for (Iterator iter = aSelection.iterator(); iter.hasNext();) {
>+			Object element = iter.next();
>+			if(!isPossibleChild(element))
>+				return false;			
>+		}
>+		return true;
>+	}
> 
> 	/**
> 	 * 
>Index: src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentExtension.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentExtension.java,v
>retrieving revision 1.3
>diff -u -r1.3 NavigatorContentExtension.java
>--- src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentExtension.java	9 Feb 2006 22:38:02 -0000	1.3
>+++ src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentExtension.java	22 Feb 2006 04:32:47 -0000
>@@ -120,10 +120,9 @@
> 		return provider;
> 	}
> 
>-	/*
>-	 * (non-Javadoc)
>+	/**
> 	 * 
>-	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtension#getContentProvider()
>+	 * @return The internal content provider that is wrapped by this extension.
> 	 */
> 	public ITreeContentProvider internalGetContentProvider() {
> 		if (contentProvider != null || contentProviderInitializationFailed)
>Index: src/org/eclipse/ui/internal/navigator/extensions/INavigatorContentExtPtConstants.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/INavigatorContentExtPtConstants.java,v
>retrieving revision 1.2
>diff -u -r1.2 INavigatorContentExtPtConstants.java
>--- src/org/eclipse/ui/internal/navigator/extensions/INavigatorContentExtPtConstants.java	9 Feb 2006 21:32:09 -0000	1.2
>+++ src/org/eclipse/ui/internal/navigator/extensions/INavigatorContentExtPtConstants.java	22 Feb 2006 04:32:45 -0000
>@@ -34,13 +34,10 @@
> 	String TAG_COMMON_SORTER = "commonSorter"; //$NON-NLS-1$
> 	
> 	/** */
>-	String TAG_COMMON_DROP_ADAPTER = "commonDropAdapter"; //$NON-NLS-1$	
>+	String TAG_COMMON_DROP_ADAPTER = "commonDropAdapter"; //$NON-NLS-1$	 
> 	
> 	/** */
>-	String TAG_DRAG_EXPRESSION = "dragExpression"; //$NON-NLS-1$	 
>-	
>-	/** */
>-	String TAG_DROP_EXPRESSION = "dropExpression"; //$NON-NLS-1$	 
>+	String TAG_POSSIBLE_DROP_TARGETS = "possibleDropTargets"; //$NON-NLS-1$	 
> 	
> 	/** */
> 	String TAG_OVERRIDE = "override"; //$NON-NLS-1$	
>Index: plugin.xml
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/plugin.xml,v
>retrieving revision 1.9
>diff -u -r1.9 plugin.xml
>--- plugin.xml	9 Feb 2006 21:32:08 -0000	1.9
>+++ plugin.xml	22 Feb 2006 04:32:37 -0000
>@@ -11,7 +11,7 @@
> point="org.eclipse.ui.dropActions">
> <action
> class="org.eclipse.ui.internal.navigator.dnd.NavigatorPluginDropAction"
>- id="org.eclipse.ui.navigator.internal.dnd.PluginDropAction">
>+ id="org.eclipse.ui.navigator.PluginDropAction">
> </action>
> </extension>
> 
>Index: src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
>===================================================================
>RCS file: /home/eclipse/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java,v
>retrieving revision 1.4
>diff -u -r1.4 NavigatorContentService.java
>--- src/org/eclipse/ui/internal/navigator/NavigatorContentService.java	9 Feb 2006 22:38:02 -0000	1.4
>+++ src/org/eclipse/ui/internal/navigator/NavigatorContentService.java	22 Feb 2006 04:32:43 -0000
>@@ -30,6 +30,7 @@
> import org.eclipse.jface.viewers.ITreeContentProvider;
> import org.eclipse.jface.viewers.StructuredViewer;
> import org.eclipse.jface.viewers.Viewer;
>+import org.eclipse.swt.widgets.Shell;
> import org.eclipse.ui.IMemento;
> import org.eclipse.ui.internal.navigator.dnd.NavigatorDnDService;
> import org.eclipse.ui.internal.navigator.extensions.ExtensionPriorityComparator;
>@@ -914,9 +915,15 @@
> 			navigatorDnDService = new NavigatorDnDService(this);
> 		return navigatorDnDService;
> 	}
>-
>-	protected boolean isRootExtension(String anExtensionId) {
>-		return assistant.isRootExtension(anExtensionId);
>+	
>+	/**
>+	 * Non-API method to return a shell.
>+	 * @return A shell associated with the current viewer (if any) or null.
>+	 */
>+	public Shell getShell() {
>+		if(structuredViewerManager != null && structuredViewerManager.getViewer() != null)
>+			return structuredViewerManager.getViewer().getControl().getShell();
>+		return null;
> 	}
> 
> 	/*
>@@ -935,8 +942,12 @@
> 	 */
> 	public String toString() {
> 		return "ContentService[" + viewerDescriptor.getViewerId() + "]"; //$NON-NLS-1$//$NON-NLS-2$
>+	} 
>+	
>+	protected boolean isRootExtension(String anExtensionId) {
>+		return assistant.isRootExtension(anExtensionId);
> 	}
>-
>+	
> 	private void notifyListeners(NavigatorContentExtension aDescriptorInstance) {
> 
> 		if (listeners.size() == 0)
>Index: src/org/eclipse/ui/internal/navigator/dnd/NavigatorContentServiceTransfer.java
>===================================================================
>RCS file: src/org/eclipse/ui/internal/navigator/dnd/NavigatorContentServiceTransfer.java
>diff -N src/org/eclipse/ui/internal/navigator/dnd/NavigatorContentServiceTransfer.java
>--- /dev/null	1 Jan 1970 00:00:00 -0000
>+++ src/org/eclipse/ui/internal/navigator/dnd/NavigatorContentServiceTransfer.java	1 Jan 1970 00:00:00 -0000
>@@ -0,0 +1,93 @@
>+/*******************************************************************************
>+ * Copyright (c) 2006 IBM Corporation and others.
>+ * All rights reserved. This program and the accompanying materials
>+ * are made available under the terms of the Eclipse Public License v1.0
>+ * which accompanies this distribution, and is available at
>+ * http://www.eclipse.org/legal/epl-v10.html
>+ *
>+ * Contributors:
>+ * IBM Corporation - initial API and implementation
>+ ******************************************************************************/
>+
>+package org.eclipse.ui.internal.navigator.dnd;
>+
>+import java.lang.ref.WeakReference;
>+import java.util.HashSet;
>+import java.util.Iterator;
>+import java.util.Set;
>+
>+import org.eclipse.ui.navigator.INavigatorContentService;
>+
>+/**
>+ * Caches instances of {@link INavigatorContentService} to facilitate the
>+ * handling of drop operations in other viewers.
>+ * 
>+ * @since 3.2
>+ * 
>+ */
>+public class NavigatorContentServiceTransfer {
>+	
>+	private static final NavigatorContentServiceTransfer instance = new NavigatorContentServiceTransfer(); 
>+	
>+	/**
>+	 * 
>+	 * @return The singleton instance of the transfer service.
>+	 */
>+	public static NavigatorContentServiceTransfer getInstance() {
>+		return instance;
>+	}
>+
>+	private final Set registeredContentServices = new HashSet();
>+	
>+	/**
>+	 * 
>+	 * @param aContentService The Content Service to register.
>+	 */
>+	public synchronized void registerContentService(INavigatorContentService aContentService) { 
>+		if(findService(aContentService.getViewerId()) == null)
>+			registeredContentServices.add(new WeakReference(aContentService));
>+	}
>+	
>+	/**
>+	 * 
>+	 * @param aContentService The Content Service to unregister.
>+	 */
>+	public synchronized void unregisterContentService(INavigatorContentService aContentService) { 
>+ 
>+		for (Iterator iter = registeredContentServices.iterator(); iter.hasNext();) {
>+			WeakReference ref = (WeakReference) iter.next();
>+			if(ref.get() == null) 
>+				iter.remove();
>+			else { 
>+				if(ref.get() == aContentService) {
>+					iter.remove(); 
>+					return;
>+				}
>+			}
>+		} 
>+	}
>+	
>+	/**
>+	 * 
>+	 * @param aViewerId A viewer id that should have previously been registered with the service.
>+	 * @return The registered content service for the given viewer id.
>+	 */
>+	public synchronized INavigatorContentService findService(String aViewerId) {
>+		if(aViewerId == null || aViewerId.length() == 0)
>+			return null;
>+		INavigatorContentService contentService;
>+		for (Iterator iter = registeredContentServices.iterator(); iter.hasNext();) {
>+			WeakReference ref = (WeakReference) iter.next();
>+			if(ref.get() == null) 
>+				iter.remove();
>+			else {
>+				contentService = (INavigatorContentService)ref.get();
>+				if(aViewerId.equals(contentService.getViewerId())) 
>+					return contentService; 
>+			}
>+		}
>+		return null;
>+	} 
>+	
>+
>+}

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Attachments on bug 129061: 35282 | 35316