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module TreeSearch where
import Data.Tree.Zipper
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 -> parentWithNext loc
where
parentWithNext x =
case parent x of
Nothing -> Nothing
Just x' -> case next x' of
Just x'' -> Just x''
Nothing -> parentWithNext x'
findNext :: TreePos Full a -> Maybe (TreePos Full a)
findNext = depthFirst
findPrev :: TreePos Full a -> Maybe (TreePos Full a)
findPrev loc =
case prev loc of
Just x -> trans_lastChild x
Nothing -> case parent loc of
Just x -> Just x
Nothing -> Nothing
where
trans_lastChild x =
case lastChild x of
Nothing -> Just x
Just x' -> trans_lastChild x'
findParent :: (a -> Bool) -> TreePos Full a -> Maybe (TreePos Full a)
findParent p loc =
if p (label loc)
then Just loc
else parent loc >>= findParent p
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