Overload method AbstractTreeViewer::internalConditionalExpandToLevel

Add function to determine if the widget itself must be expanded.

Author: fedejeanne

bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java

@@ -1850,12 +1850,32 @@ protected Widget internalGetWidgetToSelect(Object elementOrTreePath) {
 	 */
 	private void internalConditionalExpandToLevel(Widget widget, int level,
 			Function<Widget, Boolean> shouldChildrenExpand) {
+		internalConditionalExpandToLevel(widget, level, __ -> Boolean.TRUE, shouldChildrenExpand);
+	}
+
+	/**
+	 * Same as
+	 * {@link #internalConditionalExpandToLevel(Widget, int, Function, Function)}
+	 * but with an extra parameter to determine if the widget itself should be
+	 * expanded.
+	 *
+	 * @param shouldWidgetExpand evaluates if the widget itself needs to be
+	 *                           expanded.
+	 * @since 3.36
+	 */
+	protected void internalConditionalExpandToLevel(Widget widget, int level,
+			Function<Widget, Boolean> shouldWidgetExpand, Function<Widget, Boolean> shouldChildrenExpand) {
 		if (level == ALL_LEVELS || level > 0) {
 			Object data = widget.getData();
 			if (widget instanceof Item it && data != null && !isExpandable(it, null, data)) {
 				return;
 			}
 			createChildren(widget, false);
+
+			if (!shouldWidgetExpand.apply(widget).booleanValue()) {
+				return;
+			}
+
 			// XXX for performance widget should be expanded after expanding children:
 			if (widget instanceof Item it) {
 				setExpanded(it, true);
@@ -1866,7 +1886,7 @@ private void internalConditionalExpandToLevel(Widget widget, int level,
 					int newLevel = (level == ALL_LEVELS ? ALL_LEVELS
 							: level - 1);
 					for (Item element : children) {
-						internalConditionalExpandToLevel(element, newLevel, shouldChildrenExpand);
+						internalConditionalExpandToLevel(element, newLevel, shouldWidgetExpand, shouldChildrenExpand);
 					}
 				}
 			}