#6107: Implement recursion detection when setting parent layers

codereader · Oct 1, 2022 · 919d108 · 919d108
1 parent 63ba87c
commit 919d108
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diff --git a/radiantcore/layers/LayerManager.cpp b/radiantcore/layers/LayerManager.cpp
@@ -393,13 +393,41 @@ void LayerManager::setParentLayer(int childLayerId, int parentLayerId)
         throw std::invalid_argument("Cannot assign a layer as parent of itself");
     }
 
+    // Detect recursions, if any parent layer has this layer in its hierarchy, we should throw
+    if (layerIsChildOf(parentLayerId, childLayerId))
+    {
+        throw std::invalid_argument("This relationship change would result in a recursion");
+    }
+
     if (_layerParentIds.at(childLayerId) != parentLayerId)
     {
         _layerParentIds.at(childLayerId) = parentLayerId;
         _layerHierarchyChangedSignal.emit();
     }
 }
 
+bool LayerManager::layerIsChildOf(int candidateLayerId, int parentLayerId)
+{
+    // Nothing is a parent of the null layer
+    if (candidateLayerId == NO_PARENT_ID || parentLayerId == NO_PARENT_ID)
+    {
+        return false;
+    }
+
+    // Check the hierarchy of the candidate
+    for (int immediateParentId = getParentLayer(candidateLayerId); 
+         immediateParentId != NO_PARENT_ID;
+         immediateParentId = getParentLayer(immediateParentId))
+    {
+        if (immediateParentId == parentLayerId)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 sigc::signal<void> LayerManager::signal_layersChanged()
 {
 	return _layersChangedSignal;

diff --git a/radiantcore/layers/LayerManager.h b/radiantcore/layers/LayerManager.h
@@ -136,6 +136,9 @@ class LayerManager :
 
 	// Returns the lowest unused layer ID
 	int getLowestUnusedLayerID();
+
+    // Returns true if the given candidateLayerId is a child of the given parentLayer
+    bool layerIsChildOf(int candidateLayerId, int parentLayerId);
 };
 
 } // namespace scene