import TreeSearch from lass

1 files changed, 19 insertions, 0 deletions

diff --git a/TreeSearch.hs b/TreeSearch.hs
new file mode 100644
index 0000000..938b076
--- /dev/null
+++ b/TreeSearch.hs
@@ -0,0 +1,19 @@
+module TreeSearch where
+
+import Data.Tree.Zipper
+import Data.Maybe
+
+-- findTree :: PosType t => (a -> Bool) -> TreePos t a -> Maybe (TreePos t a)
+findTree :: (a -> Bool) -> TreePos Full a -> Maybe (TreePos Full a)
+findTree p loc = if p (label loc)
+    then Just loc
+    else depthFirst loc >>= findTree p
+        
+depthFirst :: TreePos Full a -> Maybe (TreePos Full a)
+depthFirst loc = case firstChild loc of
+    Just x -> Just x
+    Nothing -> case next loc of
+        Just x -> Just x
+        Nothing -> case parent loc of
+            Just x -> next x
+            Nothing -> Nothing