Unboxed vector for position mapping

Author: wz1000

ghcide/src/Development/IDE/Core/PositionMapping.hs

@@ -27,10 +27,9 @@ import qualified Data.Text as T
 import Language.Haskell.LSP.Types
 import Data.List
 import Data.Algorithm.Diff
-import Data.Maybe
 import Data.Bifunctor
 import Control.DeepSeq
-import qualified Data.Vector as V
+import qualified Data.Vector.Unboxed as V
 
 -- | Either an exact position, or the range of text that was substituted
 data PositionResult a
@@ -184,29 +183,31 @@ deltaFromDiff (T.lines -> old) (T.lines -> new) =
     (V.fromList -> !old2new, V.fromList -> !new2old) = go diff 0 0
 
     -- Compute previous and next lines that mapped successfully
-    !o2nPrevs = V.prescanl' fromMaybe        (-1) old2new
-    !o2nNexts = V.prescanr' (flip fromMaybe) lnew old2new
+    !o2nPrevs = V.prescanl' f        (-1) old2new
+    !o2nNexts = V.prescanr' (flip f) lnew old2new
 
-    !n2oPrevs = V.prescanl' fromMaybe        (-1) new2old
-    !n2oNexts = V.prescanr' (flip fromMaybe) lold new2old
+    !n2oPrevs = V.prescanl' f        (-1) new2old
+    !n2oNexts = V.prescanr' (flip f) lold new2old
 
-    lookupPos :: Int -> V.Vector Int -> V.Vector Int -> V.Vector (Maybe Int) -> Position -> PositionResult Position
+    f :: Int -> Int -> Int
+    f !a !b = if b == -1 then a else b
+
+    lookupPos :: Int -> V.Vector Int -> V.Vector Int -> V.Vector Int -> Position -> PositionResult Position
     lookupPos end prevs nexts xs (Position line col)
       | line < 0            = PositionRange (Position 0   0) (Position 0   0)
       | line >= V.length xs = PositionRange (Position end 0) (Position end 0)
       | otherwise           = case V.unsafeIndex xs line of
-          Just line' -> PositionExact (Position line' col)
-          Nothing ->
+          -1 ->
             -- look for the previous and next lines that mapped successfully
-            let !prev = 1 + (prevs V.! line)
-                !next = nexts V.! line
+            let !prev = 1 + (V.unsafeIndex prevs line)
+                !next = V.unsafeIndex nexts line
               in PositionRange (Position prev 0) (Position next 0)
+          line' -> PositionExact (Position line' col)
 
     -- Construct a mapping between lines in the diff
-    go :: [Diff T.Text] -> Int -> Int -> ([Maybe Int], [Maybe Int])
+    -- -1 for unsucessful mapping
+    go :: [Diff T.Text] -> Int -> Int -> ([Int], [Int])
     go [] _ _ = ([],[])
-    go (Both _ _ : xs) !lold !lnew = bimap  (Just lnew :) (Just lold :) $ go xs (lold+1) (lnew+1)
-    go (First _  : xs) !lold !lnew = first  (Nothing   :)               $ go xs (lold+1) lnew
-    go (Second _ : xs) !lold !lnew = second               (Nothing   :) $ go xs lold     (lnew+1)
-
-
+    go (Both _ _ : xs) !lold !lnew = bimap  (lnew :) (lold :) $ go xs (lold+1) (lnew+1)
+    go (First _  : xs) !lold !lnew = first  (-1   :)          $ go xs (lold+1) lnew
+    go (Second _ : xs) !lold !lnew = second          (-1   :) $ go xs lold     (lnew+1)

ghcide/src/Development/IDE/Core/Service.hs

@@ -32,8 +32,6 @@ import qualified Language.Haskell.LSP.Types.Capabilities as LSP
 
 import           Development.IDE.Core.Shake
 import Control.Monad
-import HieDb.Types
-
 
 
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