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|
--------------------------------------------------------------------------------
module Language.Haskell.Stylish.Step.SimpleAlign
( Config (..)
, defaultConfig
, step
) where
--------------------------------------------------------------------------------
import Data.Data (Data)
import Data.List (foldl')
import Data.Maybe (maybeToList)
import qualified Language.Haskell.Exts as H
--------------------------------------------------------------------------------
import Language.Haskell.Stylish.Align
import Language.Haskell.Stylish.Editor
import Language.Haskell.Stylish.Step
import Language.Haskell.Stylish.Util
--------------------------------------------------------------------------------
data Config = Config
{ cCases :: !Bool
, cTopLevelPatterns :: !Bool
, cRecords :: !Bool
} deriving (Show)
--------------------------------------------------------------------------------
defaultConfig :: Config
defaultConfig = Config
{ cCases = True
, cTopLevelPatterns = True
, cRecords = True
}
--------------------------------------------------------------------------------
cases :: Data l => H.Module l -> [[H.Alt l]]
cases modu = [alts | H.Case _ _ alts <- everything modu]
--------------------------------------------------------------------------------
-- | For this to work well, we require a way to merge annotations. This merge
-- operation should follow the semigroup laws.
altToAlignable :: (l -> l -> l) -> H.Alt l -> Maybe (Alignable l)
altToAlignable _ (H.Alt _ _ _ (Just _)) = Nothing
altToAlignable _ (H.Alt ann pat rhs@(H.UnGuardedRhs _ _) Nothing) = Just $
Alignable
{ aContainer = ann
, aLeft = H.ann pat
, aRight = H.ann rhs
, aRightLead = length "-> "
}
altToAlignable
merge
(H.Alt ann pat (H.GuardedRhss _ [H.GuardedRhs _ guards rhs]) Nothing) =
-- We currently only support the case where an alternative has a single
-- guarded RHS. If there are more, we would need to return multiple
-- `Alignable`s from this function, which would be a significant change.
Just $ Alignable
{ aContainer = ann
, aLeft = foldl' merge (H.ann pat) (map H.ann guards)
, aRight = H.ann rhs
, aRightLead = length "-> "
}
altToAlignable _ _ = Nothing
--------------------------------------------------------------------------------
tlpats :: Data l => H.Module l -> [[H.Match l]]
tlpats modu = [matches | H.FunBind _ matches <- everything modu]
--------------------------------------------------------------------------------
matchToAlignable :: H.Match l -> Maybe (Alignable l)
matchToAlignable (H.InfixMatch _ _ _ _ _ _) = Nothing
matchToAlignable (H.Match _ _ [] _ _) = Nothing
matchToAlignable (H.Match _ _ _ _ (Just _)) = Nothing
matchToAlignable (H.Match ann name pats rhs Nothing) = Just $ Alignable
{ aContainer = ann
, aLeft = last (H.ann name : map H.ann pats)
, aRight = H.ann rhs
, aRightLead = length "= "
}
--------------------------------------------------------------------------------
records :: H.Module l -> [[H.FieldDecl l]]
records modu =
[ fields
| H.Module _ _ _ _ decls <- [modu]
, H.DataDecl _ _ _ _ cons _ <- decls
, H.QualConDecl _ _ _ (H.RecDecl _ _ fields) <- cons
]
--------------------------------------------------------------------------------
fieldDeclToAlignable :: H.FieldDecl a -> Maybe (Alignable a)
fieldDeclToAlignable (H.FieldDecl ann names ty) = Just $ Alignable
{ aContainer = ann
, aLeft = H.ann (last names)
, aRight = H.ann ty
, aRightLead = length ":: "
}
--------------------------------------------------------------------------------
step :: Maybe Int -> Config -> Step
step maxColumns config = makeStep "Cases" $ \ls (module', _) ->
let module'' = fmap H.srcInfoSpan module'
changes search toAlign =
[ change_
| case_ <- search module''
, aligns <- maybeToList (mapM toAlign case_)
, change_ <- align maxColumns aligns
]
configured = concat $
[ changes cases (altToAlignable H.mergeSrcSpan)
| cCases config
] ++
[changes tlpats matchToAlignable | cTopLevelPatterns config] ++
[changes records fieldDeclToAlignable | cRecords config]
in applyChanges configured ls
|
