Do not expand same class twice in (quick) type hierarchy

Fixes eclipse-jdt#1830

org.eclipse.jdt.ui/.settings/.api_filters

@@ -137,6 +137,14 @@
             </message_arguments>
         </filter>
     </resource>
+    <resource path="ui/org/eclipse/jdt/internal/ui/typehierarchy/HierarchyInformationControl.java" type="org.eclipse.jdt.internal.ui.typehierarchy.HierarchyInformationControl">
+        <filter id="571519004">
+            <message_arguments>
+                <message_argument value="org.eclipse.jdt.internal.ui.typehierarchy.HierarchyInformationControl.createTreeViewer(Composite, int)"/>
+                <message_argument value="TreeViewer"/>
+            </message_arguments>
+        </filter>
+    </resource>
     <resource path="ui/org/eclipse/jdt/internal/ui/viewsupport/ProblemTableViewer.java" type="org.eclipse.jdt.internal.ui.viewsupport.ProblemTableViewer">
         <filter id="571473929">
             <message_arguments>

org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/HierarchyInformationControl.java

@@ -14,6 +14,8 @@
 package org.eclipse.jdt.internal.ui.typehierarchy;
 
 import java.lang.reflect.InvocationTargetException;
+import java.util.HashSet;
+import java.util.Set;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.KeyAdapter;
@@ -23,6 +25,7 @@
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swt.widgets.Text;
 import org.eclipse.swt.widgets.Tree;
+import org.eclipse.swt.widgets.Widget;
 
 import org.eclipse.jface.bindings.TriggerSequence;
 import org.eclipse.jface.bindings.keys.KeySequence;
@@ -130,7 +133,32 @@ protected TreeViewer createTreeViewer(Composite parent, int style) {
 		gd.heightHint= tree.getItemHeight() * 12;
 		tree.setLayoutData(gd);
 
-		TreeViewer treeViewer= new TreeViewer(tree);
+		TreeViewer treeViewer= new TreeViewer(tree) {
+			private Set<Object> visited;
+
+			@Override
+			protected void inputChanged(Object input, Object oldInput) {
+				visited= new HashSet<>();
+				super.inputChanged(input, oldInput);
+				visited= null;
+			}
+
+			@Override
+			protected void internalExpandToLevel(Widget node, int level) {
+				if (!shouldExpand(node))
+					return;
+
+				super.internalExpandToLevel(node, level);
+			}
+
+			private boolean shouldExpand(Widget widget) {
+				if (widget == null) {
+					return false;
+				}
+				Object data= widget.getData();
+				return data == null || visited.add(data);
+			}
+		};
 		treeViewer.addFilter(new ViewerFilter() {
 			@Override
 			public boolean select(Viewer viewer, Object parentElement, Object element) {

org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/TypeHierarchyViewPart.java

@@ -1212,7 +1212,12 @@ private void updateHierarchyViewer(final boolean doExpand) {
 			fPagebook.showPage(fNoHierarchyShownLabel);
 		} else {
 			if (getCurrentViewer().containsElements() != null) {
-				Runnable runnable= () -> JavaCore.runReadOnly(() -> getCurrentViewer().updateContent(doExpand));
+				Runnable runnable= () -> JavaCore.runReadOnly(() -> {
+					TypeHierarchyViewer viewer= getCurrentViewer();
+					viewer.preUpdateContent();
+					viewer.updateContent(doExpand);
+					viewer.postUpdateContent();
+				});
 				BusyIndicator.showWhile(getDisplay(), runnable);
 				if (!isChildVisible(fViewerbook, getCurrentViewer().getControl())) {
 					setViewerVisibility(true);

org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/TypeHierarchyViewer.java

@@ -13,10 +13,14 @@
  *******************************************************************************/
 package org.eclipse.jdt.internal.ui.typehierarchy;
 
+import java.util.HashSet;
+import java.util.Set;
+
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Menu;
 import org.eclipse.swt.widgets.Tree;
+import org.eclipse.swt.widgets.Widget;
 
 import org.eclipse.core.runtime.Assert;
 
@@ -42,6 +46,8 @@ public abstract class TypeHierarchyViewer extends ProblemTreeViewer {
 
 	private HierarchyLabelProvider fLabelProvider;
 
+	private Set<Object> visited;
+
 
 	public TypeHierarchyViewer(Composite parent, IContentProvider contentProvider, TypeHierarchyLifeCycle lifeCycle) {
 		super(new Tree(parent, SWT.SINGLE));
@@ -83,15 +89,17 @@ public void initContextMenu(IMenuListener menuListener, String popupId, IWorkben
 	}
 
 	/**
-	 * Fills up the context menu with items for the hierarchy viewer
-	 * Should be called by the creator of the context menu
+	 * Fills up the context menu with items for the hierarchy viewer Should be called by the creator
+	 * of the context menu
+	 *
 	 * @param menu the menu manager
 	 */
 	public void contributeToContextMenu(IMenuManager menu) {
 	}
 
 	/**
 	 * Set the member filter
+	 *
 	 * @param memberFilter the member filters to set
 	 */
 	public void setMemberFilter(IMember[] memberFilter) {
@@ -103,6 +111,7 @@ public void setMemberFilter(IMember[] memberFilter) {
 
 	/**
 	 * Returns if method filtering is enabled.
+	 *
 	 * @return <code>true</code>if method filtering is enabled.
 	 */
 	public boolean isMethodFiltering() {
@@ -122,8 +131,9 @@ public void setWorkingSetFilter(ViewerFilter filter) {
 	}
 
 	/**
-	 * Returns true if the hierarchy contains elements. Returns one of them
-	 * With member filtering it is possible that no elements are visible
+	 * Returns true if the hierarchy contains elements. Returns one of them With member filtering it
+	 * is possible that no elements are visible
+	 *
 	 * @return one of the elements contained
 	 */
 	public Object containsElements() {
@@ -138,14 +148,15 @@ public Object containsElements() {
 	}
 
 	/**
-	 * Returns true if the hierarchy contains elements. Returns one of them
-	 * With member filtering it is possible that no elements are visible
+	 * Returns true if the hierarchy contains elements. Returns one of them With member filtering it
+	 * is possible that no elements are visible
+	 *
 	 * @return the tree root
 	 */
 	public IType getTreeRootType() {
 		TypeHierarchyContentProvider contentProvider= getHierarchyContentProvider();
 		if (contentProvider != null) {
-			Object[] elements=  contentProvider.getElements(null);
+			Object[] elements= contentProvider.getElements(null);
 			if (elements.length > 0 && elements[0] instanceof IType) {
 				return (IType) elements[0];
 			}
@@ -155,6 +166,7 @@ public IType getTreeRootType() {
 
 	/**
 	 * Returns true if the hierarchy contains element the element.
+	 *
 	 * @param element the element
 	 * @return <code>true</code> if element is shown
 	 */
@@ -164,6 +176,7 @@ public boolean isElementShown(Object element) {
 
 	/**
 	 * Updates the content of this viewer: refresh and expanding the tree in the way wanted.
+	 *
 	 * @param doExpand if set, update should expand
 	 */
 	public abstract void updateContent(boolean doExpand);
@@ -179,7 +192,37 @@ public void setContentProvider(IContentProvider cp) {
 	}
 
 	protected TypeHierarchyContentProvider getHierarchyContentProvider() {
-		return (TypeHierarchyContentProvider)getContentProvider();
+		return (TypeHierarchyContentProvider) getContentProvider();
 	}
 
+	@Override
+	protected void inputChanged(Object input, Object oldInput) {
+		preUpdateContent();
+		super.inputChanged(input, oldInput);
+		postUpdateContent();
+	}
+
+	@Override
+	protected void internalExpandToLevel(Widget node, int level) {
+		if (!shouldExpand(node))
+			return;
+
+		super.internalExpandToLevel(node, level);
+	}
+
+	private boolean shouldExpand(Widget widget) {
+		if (widget == null) {
+			return false;
+		}
+		Object data= widget.getData();
+		return data == null || visited.add(data);
+	}
+
+	void preUpdateContent() {
+		visited= new HashSet<>();
+	}
+
+	void postUpdateContent() {
+		visited= null;
+	}
 }