Fix for Bug 223274 [DataBinding] API to control getParent() / hasChildren() in Observable(List|Set)TreeContentProvider
diff --git a/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/TreeStructureAdvisor.java b/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/TreeStructureAdvisor.java
index 9a0d393..eb62604 100644
--- a/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/TreeStructureAdvisor.java
+++ b/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/TreeStructureAdvisor.java
@@ -13,7 +13,8 @@
/**
* Instances of this class can be used to improve accuracy and performance of an
* {@link ObservableListTreeContentProvider} or an
- * {@link ObservableSetTreeContentProvider}.
+ * {@link ObservableSetTreeContentProvider}. This class is intended to be
+ * subclassed by clients.
*
* @since 3.4
*
@@ -24,16 +25,21 @@
* Returns the parent for the given element, or <code>null</code>
* indicating that the parent can't be computed. In this case the
* tree-structured viewer can't expand a given node correctly if requested.
+ * The default implementation returns null; clients should override.
*
* @param element
* the element
* @return the parent element, or <code>null</code> if it has none or if
* the parent cannot be computed
*/
- public abstract Object getParent(Object element);
+ public Object getParent(Object element) {
+ return null;
+ }
/**
- * Returns whether the given element has children.
+ * Returns whether the given element has children, or <code>null</code> if
+ * the actual children collection should be consulted. The default
+ * implementation returns null; clients should override.
* <p>
* Intended as an optimization for when the viewer does not need the actual
* children. Clients may be able to implement this more efficiently than
@@ -42,9 +48,13 @@
*
* @param element
* the element
- * @return <code>true</code> if the given element has children, and
- * <code>false</code> if it has no children
+ * @return <code>Boolean.TRUE</code> if the given element has children,
+ * <code>Boolean.FALSE</code> if it has no children, or
+ * <code>null</code> if the children collection should be
+ * consulted.
*/
- public abstract boolean hasChildren(Object element);
+ public Boolean hasChildren(Object element) {
+ return null;
+ }
}
diff --git a/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/ObservableCollectionTreeContentProvider.java b/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/ObservableCollectionTreeContentProvider.java
index 0a417f8..df70903 100644
--- a/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/ObservableCollectionTreeContentProvider.java
+++ b/bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/viewers/ObservableCollectionTreeContentProvider.java
@@ -165,7 +165,10 @@
public boolean hasChildren(Object element) {
if (structureAdvisor != null) {
- return structureAdvisor.hasChildren(element);
+ Boolean hasChildren = structureAdvisor.hasChildren(element);
+ if (hasChildren != null) {
+ return hasChildren.booleanValue();
+ }
}
return getOrCreateNode(element).hasChildren();
}
