Bug 159944 Asynchronous viewer should allow model to set selection after selected object is removed

3 files changed, 50 insertions, 1 deletions

diff --git a/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/InternalTreeModelViewer.java b/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/InternalTreeModelViewer.java
index 380ed3487..15c903fbb 100644
--- a/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/InternalTreeModelViewer.java
+++ b/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/InternalTreeModelViewer.java
@@ -32,6 +32,7 @@ import org.eclipse.jface.viewers.IContentProvider;
 import org.eclipse.jface.viewers.ILazyTreePathContentProvider;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.jface.viewers.IStructuredSelection;
+import org.eclipse.jface.viewers.StructuredSelection;
 import org.eclipse.jface.viewers.TreePath;
 import org.eclipse.jface.viewers.TreeViewer;
 import org.eclipse.swt.SWT;
@@ -320,7 +321,30 @@ public class InternalTreeModelViewer extends TreeViewer {
 		super.hookControl(control);
 	}
 
-
+    /* (non-Javadoc)
+     * @see org.eclipse.jface.viewers.StructuredViewer#handleInvalidSelection
+     * 
+     * Override the default handler for invalid selection to allow model 
+     * selection policy to select the new selection.
+     */
+	protected void handleInvalidSelection(ISelection selection, ISelection newSelection) {
+	    IModelSelectionPolicy selectionPolicy = getSelectionPolicy(selection);
+	    if (selectionPolicy != null) {
+	    	ISelection temp = newSelection;
+            newSelection = selectionPolicy.replaceInvalidSelection(selection, newSelection);
+            if (temp != newSelection) {
+            	if (newSelection == null) {
+            		newSelection = new StructuredSelection();
+            	}
+            	// call super.setSelection(...) to avoid asking the selection policy
+            	// if the selection should be overridden
+            	super.setSelection(newSelection, false);
+            	return;
+            }
+	    }
+	    super.handleInvalidSelection(selection, newSelection);
+	}
+        
 
 	/* (non-Javadoc)
 	 * @see org.eclipse.jface.viewers.ContentViewer#handleDispose(org.eclipse.swt.events.DisposeEvent)
diff --git a/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/provisional/IModelSelectionPolicy.java b/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/provisional/IModelSelectionPolicy.java
index 951342465..53dd10ec2 100644
--- a/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/provisional/IModelSelectionPolicy.java
+++ b/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/provisional/IModelSelectionPolicy.java
@@ -65,4 +65,23 @@ public interface IModelSelectionPolicy {
 	 */
 	public boolean isSticky(ISelection selection, IPresentationContext context);
 	
+	/**
+	 * Replaces an invalid selection.
+	 * <p>
+	 * This method is called if a model change picked up by a viewer
+	 * results in an invalid selection. For instance if an element contained in
+	 * the selection has been removed from the viewer, the selection policy associated
+	 * with the invalid selection is free to specify a new selection. The default
+	 * selection policy returns the <code>newSelection</code> as is (with missing
+	 * elements removed). Model selection policies may implement a different strategy
+	 * for picking a new selection when the old selection becomes invalid.
+	 * </p>
+	 * 
+	 * @param invalidSelection
+	 *            the selection before the viewer was updated
+	 * @param newSelection
+	 *            the selection after the update, or <code>null</code> if none
+	 * @return new selection or <code>null</code> if none
+	 */
+    public ISelection replaceInvalidSelection(ISelection invalidSelection, ISelection newSelection);
 }
diff --git a/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/update/DefaultSelectionPolicy.java b/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/update/DefaultSelectionPolicy.java
index b0fe1d1ad..8dc078a12 100644
--- a/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/update/DefaultSelectionPolicy.java
+++ b/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/update/DefaultSelectionPolicy.java
@@ -103,4 +103,10 @@ public class DefaultSelectionPolicy implements IModelSelectionPolicy {
 		return false;
 	}
 
+    /* (non-Javadoc)
+     * @see org.eclipse.debug.internal.ui.viewers.model.provisional.IModelSelectionPolicy#handleInvalidSelection(org.eclipse.jface.viewers.ISelection, org.eclipse.jface.viewers.ISelection)
+     */
+    public ISelection replaceInvalidSelection(ISelection selection, ISelection newSelection) {
+        return newSelection;
+    }
 }