{-# LANGUAGE PatternGuards, ScopedTypeVariables #-}
{-# LANGUAGE FlexibleContexts #-}
module Hint.Duplicate(duplicateHint) where
import Hint.Type (CrossHint, ModuleEx(..), Idea(..),rawIdeaN',Severity(Suggestion,Warning),showSrcLoc,ghcSrcLocToHSE)
import Data.Data
import Data.Generics.Uniplate.Operations
import Data.Default
import Data.Maybe
import Data.Tuple.Extra
import Data.List hiding (find)
import qualified Data.Map as Map
import SrcLoc
import HsSyn
import Outputable
import Bag
import GHC.Util
duplicateHint :: CrossHint
duplicateHint ms =
dupes [ (m, d, y)
| (m, d, x) <- ds
, HsDo _ _ (LL _ y) :: HsExpr GhcPs <- universeBi x
] ++
dupes [ (m, d, y)
| (m, d, x) <- ds
, HsValBinds _ (ValBinds _ b _ ) :: HsLocalBinds GhcPs <- universeBi x
, let y = bagToList b
]
where
ds = [(modName m, fromMaybe "" (declName d), unLoc d)
| ModuleEx _ _ m _ <- map snd ms
, d <- hsmodDecls (unLoc m)]
dupes :: (Outputable e, Data e) => [(String, String, [Located e])] -> [Idea]
dupes ys =
[(rawIdeaN'
(if length xs >= 5 then Hint.Type.Warning else Suggestion)
"Reduce duplication" p1
(unlines $ map unsafePrettyPrint xs)
(Just $ "Combine with " ++
showSrcLoc (ghcSrcLocToHSE (srcSpanStart p2))) []
){ideaModule = [m1, m2], ideaDecl = [d1, d2]}
| ((m1, d1, SrcSpanD p1), (m2, d2, SrcSpanD p2), xs) <- duplicateOrdered 3 $ map f ys]
where
f (m, d, xs) =
[((m, d, SrcSpanD (getLoc x)), wrap (stripLocs' x)) | x <- xs]
data Dupe pos val = Dupe pos (Map.Map val (Dupe pos val))
find :: Ord val => [val] -> Dupe pos val -> (pos, Int)
find (v:vs) (Dupe p mp) | Just d <- Map.lookup v mp = second (+1) $ find vs d
find _ (Dupe p mp) = (p, 0)
add :: Ord val => pos -> [val] -> Dupe pos val -> Dupe pos val
add pos [] d = d
add pos (v:vs) (Dupe p mp) = Dupe p $ Map.insertWith f v (add pos vs $ Dupe pos Map.empty) mp
where f new = add pos vs
duplicateOrdered :: forall pos val.
(Ord pos, Default pos, Ord val) => Int -> [[(pos,val)]] -> [(pos,pos,[val])]
duplicateOrdered threshold xs = concat $ concat $ snd $ mapAccumL f (Dupe def Map.empty) xs
where
f :: Dupe pos val -> [(pos, val)] -> (Dupe pos val, [[(pos, pos, [val])]])
f d xs = second overlaps $ mapAccumL (g pos) d $ takeWhile ((>= threshold) . length) $ tails xs
where pos = Map.fromList $ zip (map fst xs) [0..]
g :: Map.Map pos Int -> Dupe pos val -> [(pos, val)] -> (Dupe pos val, [(pos, pos, [val])])
g pos d xs = (d2, res)
where
res = [(p,pme,take mx vs) | i >= threshold
,let mx = maybe i (\x -> min i $ (pos Map.! pme) - x) $ Map.lookup p pos
,mx >= threshold]
vs = map snd xs
(p,i) = find vs d
pme = fst $ head xs
d2 = add pme vs d
overlaps (x@((_,_,n):_):xs) = x : overlaps (drop (length n - 1) xs)
overlaps (x:xs) = x : overlaps xs
overlaps [] = []