Work on orienting positions for attachment items

src/Dodge/Data/DoubleTree.hs

@@ -40,6 +40,34 @@ data LabelDoubleTree b a = LDT {_ldtValue :: a, _ldtLeft :: [(b,LabelDoubleTree
         ,_ldtRight :: [(b,LabelDoubleTree b a)]}
     deriving (Eq,Ord,Show,Read)
 
+-- I am not sure about the double use of records here
+data ContextLDT b a = TopLDT 
+        { _cldtValue :: a}
+    | LeftwardLDT
+        { _cldtUp :: ContextLDT b a  
+        , _cldtCloseLeft :: [LabelDoubleTree b a] 
+        , _cldtLink :: b
+        , _cldtValue :: a
+        , _cldtCloseRight :: [LabelDoubleTree b a]
+        , _cldtFarRight :: [LabelDoubleTree b a]
+        }
+    | RightwardLDT 
+        { _cldtUp :: ContextLDT b a  
+        , _cldtFarLeft :: [LabelDoubleTree b a]
+        , _cldtCloseLeft :: [LabelDoubleTree b a] 
+        , _cldtLink :: b
+        , _cldtValue :: a
+        , _cldtCloseRight :: [LabelDoubleTree b a]
+        }
+
+-- this is not quite right, it duplicates the value when the context is at the
+-- top
+data LocationLDT b a = LocLDT
+    { _locLdtContext :: ContextLDT b a
+    , _locLdtLeft :: [LabelDoubleTree b a]
+    , _locLdtRight :: [LabelDoubleTree b a]
+    }
+
 instance Functor DoubleTree where
     fmap f (DT x l r) = DT (f x) (fmap (fmap f) l) (fmap (fmap f) r)