internal static void AddChild(TreeViewItemViewModel parent, ModelItem item, object value, bool duplicatedNodeVisible, string childNodePrefix, ModelProperty trackingProperty)
{
// If necessary, evaluate uniqueness of given item
bool isUnique = false;
if (!duplicatedNodeVisible)
{
// Note: These evaluations expect item to be an immediate child of trackingProperty.Value
// Intermediate nodes would for example undermine simple check just below
//
// Caveat 1: Aim is to greatly reduce, not to eliminate, display of nodes visible elsewhere
// Caveat 1a: Nodes reachable from other isolated nodes are included in the collection
// Caveat 1b: Nodes that are not isolated may be reachable from isolated nodes and thus
// displayed together with the isolated ones; ShowPropertyInOutlineViewAsSiblingAttribute may make this seem normal
// (If complete duplicate elimination were the aim, would likely need a "never expand"
// display mode for duplicateNodeVisible=false children)
// Caveat 2: Use of single uniqueChildren field may cause all children of a second
// duplcatedNodeVisible=false property to be ignored if (fortunately only if) neither
// property uses ShowPropertyInOutlineViewAttribute(true) -- that attribute's default
// Caveat 3-n: Please see caveats described at top of UniqueModelItemHelper
if (1 >= item.Parents.Count())
{
isUnique = true;
}
else
{
// Avoided a thorough evaluation as long as we can
if (null == parent.uniqueChildren)
{
parent.uniqueChildren = UniqueModelItemHelper.FindUniqueChildren(trackingProperty);
}
isUnique = parent.uniqueChildren.Contains(item);
}
}
// If displayable now, create the view model node
if (duplicatedNodeVisible || isUnique)
{
TreeViewItemViewModel child = TreeViewItemViewModel.CreateViewModel(parent, value);
child.NodePrefixText = childNodePrefix;
parent.AddChild(child, trackingProperty);
}
// Track for potential addition or removal of parents even if not presently visible
if (!duplicatedNodeVisible)
{
ModelItemImpl itemImpl = item as ModelItemImpl;
if (null != itemImpl)
{
ChangeNotificationTracker tracker = parent.GetTracker(trackingProperty);
tracker.AddCollection(itemImpl.InternalParents);
tracker.AddCollection(itemImpl.InternalSources);
}
}
}
// Determine if targetParent is only reachable from item via expectedParent
// Return true if the only routes from item to targetParent include expectedParent; false otherwise
// Do not search past source Properties with a ViewIgnore attribute but continue looking for targetParent
private static bool UniqueRoute(ModelItem item, ModelItem targetParent, ModelItem expectedParent)
{
bool retval = true;
if (null == item)
{
retval = false;
}
else
{
HashSet <ModelItem> visited = new HashSet <ModelItem>();
Queue <ModelItem> todo = new Queue <ModelItem>();
todo.Enqueue(item);
while (0 < todo.Count)
{
ModelItem parent = todo.Dequeue();
if (null != parent && !visited.Contains(parent))
{
visited.Add(parent);
if (parent.Equals(targetParent))
{
// Failure: Route was not unique, have reached target without passing expectedParent
retval = false;
break;
}
else if (!parent.Equals(expectedParent))
{
UniqueModelItemHelper.EnqueueParents(parent, todo);
}
}
}
}
return(retval);
}
// Return HashSet containing ModelItems found only through given property: Cannot reach property.Parent without
// hitting property from these immediate descendents of property.Value
// Set may contain some internal duplication -- all nodes, not just the root, of a linked tree will be included
//
// Caveat 1: Due to problems removing Parents (e.g. Case content sometimes holds references to FlowSwitch after
// Case removed), this method is not entirely reliable -- customers may occasionally need to reopen Designer
// Caveat 2: Due to lazy loading of Properties (and therefore the back-pointing Parents collection), may
// temporarily include non-unique ModelItems in returned set -- cleared as tree or designer views expand
//
// (Throughout, cannot use ModelItem.GetParentEnumerator because that does not check all Sources and Parents)
internal static HashSet <ModelItem> FindUniqueChildren(ModelProperty property)
{
HashSet <ModelItem> retval = new HashSet <ModelItem>();
if (null != property && null != property.Parent && null != property.Value)
{
ModelItem target = property.Parent;
ModelItem expected = property.Value;
HashSet <ModelItem> visited = new HashSet <ModelItem>();
// Check all immediate children of property.Value
ModelItemCollection collection = expected as ModelItemCollection;
if (null == collection)
{
ModelItemDictionary dictionary = expected as ModelItemDictionary;
if (null == dictionary)
{
// ModelItem
// Can't use UniqueRoute because we're starting at expected
// Can't use EnqueueParents because we need to special-case given property
// Instead confirm property.Value is not referenced anywhere else
ModelItemImpl expectedImpl = expected as ModelItemImpl;
if (null != expectedImpl)
{
bool justThisSource = true;
// expectedImpl.InternalParents does not include ModelItems that are just Sources
if (0 == expectedImpl.InternalParents.Count)
{
// expectedImpl.InternalSources would be similar but adds a wrapper we don't need here
foreach (ModelProperty source in expected.Sources)
{
if (null != source.Parent && !visited.Contains(source.Parent))
{
visited.Add(source.Parent);
if (!property.Equals(source) && !expected.Equals(source) &&
null == ExtensibilityAccessor.GetAttribute <HidePropertyInOutlineViewAttribute>(source))
{
// Found a non-ignored property from somewhere else referencing expected
justThisSource = false;
break;
}
}
}
}
else
{
// Found a Parent that's not a Source.Parent: property.Value is in some collection
justThisSource = false;
}
if (justThisSource)
{
retval.Add(expected);
}
}
}
else
{
// ModelItemDictionary
foreach (KeyValuePair <ModelItem, ModelItem> child in dictionary)
{
if (null != child.Key && !visited.Contains(child.Key))
{
visited.Add(child.Key);
if (UniqueModelItemHelper.UniqueRoute(child.Key, target, expected))
{
retval.Add(child.Key);
}
}
if (null != child.Value && !visited.Contains(child.Value))
{
visited.Add(child.Value);
if (UniqueModelItemHelper.UniqueRoute(child.Value, target, expected))
{
retval.Add(child.Value);
}
}
}
}
}
else
{
// ModelItemCollection
foreach (ModelItem child in collection)
{
if (null != child && !visited.Contains(child))
{
visited.Add(child);
if (UniqueModelItemHelper.UniqueRoute(child, target, expected))
{
retval.Add(child);
}
}
}
}
}
return(retval);
}