Add OAGSubgraphGetTreeRoot

Author: jcmosc

Sources/OpenAttributeGraphCxx/Graph/OAGSubgraph.cpp

@@ -251,3 +251,8 @@ void OAGSubgraphEndTreeElement(OAGAttribute attribute) {
         subgraph->end_tree(attribute);
     }
 }
+
+OAGTreeElement OAGSubgraphGetTreeRoot(OAGSubgraphRef cf_subgraph) {
+    // TODO
+    return nullptr;
+}

Sources/OpenAttributeGraphCxx/include/OpenAttributeGraph/OAGSubgraph.h

@@ -9,6 +9,7 @@
 #include <OpenAttributeGraph/OAGAttributeFlags.h>
 #include <OpenAttributeGraph/OAGBase.h>
 #include <OpenAttributeGraph/OAGGraph.h>
+#include <OpenAttributeGraph/OAGTreeElement.h>
 #include <OpenAttributeGraph/OAGUniqueID.h>
 #include <OpenAttributeGraph/Private/CFRuntime.h>
 
@@ -139,6 +140,10 @@ OAG_EXPORT
 OAG_REFINED_FOR_SWIFT
 void OAGSubgraphEndTreeElement(OAGAttribute attribute);
 
+OAG_EXPORT
+OAG_REFINED_FOR_SWIFT
+_Nullable OAGTreeElement OAGSubgraphGetTreeRoot(OAGSubgraphRef cf_subgraph) OAG_SWIFT_NAME(getter:OAGSubgraphRef.treeRoot(self:));
+
 OAG_EXTERN_C_END
 
 OAG_IMPLICIT_BRIDGING_DISABLED