Allow item structure to determine if subtree is attachable

src/Dodge/Data/ComposedItem.hs

@@ -5,6 +5,7 @@
 
 module Dodge.Data.ComposedItem where
 
+import Dodge.Data.DoubleTree
 import Control.Lens
 import Data.Aeson
 import Data.Aeson.TH
@@ -59,9 +60,11 @@ data ItemLink = ILink
     , _iatOrient :: Item -> ComposeLinkType -> Item -> (Point3, Quaternion Float)
     }
 
+-- this should possibly use a full item structure tree rather than a
+-- ComposedItem as arguments
 data LinkTest = LTest
-    { _tryLeftLink :: ComposedItem -> Maybe LinkUpdate
-    , _tryRightLink :: ComposedItem -> Maybe LinkUpdate
+    { _tryLeftLink :: LabelDoubleTree ItemLink ComposedItem -> Maybe LinkUpdate
+    , _tryRightLink :: LabelDoubleTree ItemLink ComposedItem -> Maybe LinkUpdate
     }
 
 data LinkUpdate = LUpdate