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{-# LANGUAGE LambdaCase #-}
-- | Simple directed graphs, for dependency checking
module Dirgraph where
import CheckMap (MapResult (mapresultDepends))
import Data.Map.Strict (Map, mapMaybeWithKey, mapWithKey)
import qualified Data.Map.Strict as M
import Data.Set (Set, (\\))
import qualified Data.Set as S
import Paths (normalise)
import Types (Dep (LocalMap))
import Witherable (mapMaybe)
-- | a simple directed graph
type Graph a = Map a (Set a)
nodes :: Graph a -> Set a
nodes = M.keysSet
-- | simple directed graph of exits
resultToGraph :: Map FilePath MapResult -> Graph FilePath
resultToGraph = fmap (S.fromList . mapMaybe onlyLocalMaps . mapresultDepends)
where onlyLocalMaps = \case
LocalMap path -> Just (normalise "" path)
_ -> Nothing
-- | invert edges of a directed graph
invertGraph :: (Eq a, Ord a) => Graph a -> Graph a
invertGraph graph = mapWithKey collectFroms graph
where collectFroms to _ = S.fromList . M.elems . mapMaybeWithKey (select to) $ graph
select to from elems = if to `elem` elems then Just from else Nothing
-- | all nodes reachable from some entrypoint
reachableFrom :: Ord a => a -> Graph a -> Set a
reachableFrom entrypoint graph = recursive mempty (S.singleton entrypoint)
where recursive seen current
| null current = seen
| otherwise = recursive (S.union seen current) (next \\ seen)
where next = S.unions
. S.fromList -- for some reason set is not filterable?
. mapMaybe (`M.lookup` graph)
. S.toList
$ current
unreachableFrom :: Ord a => a -> Graph a -> Set a
unreachableFrom entrypoint graph =
nodes graph \\ reachableFrom entrypoint graph
|
