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--------------------------------------------------------------------------------
module Language.Haskell.Stylish.Step.Records
( step
) where
--------------------------------------------------------------------------------
import Data.Char (isSpace)
import Data.List (nub)
import qualified Language.Haskell.Exts.Annotated as H
--------------------------------------------------------------------------------
import Language.Haskell.Stylish.Editor
import Language.Haskell.Stylish.Step
import Language.Haskell.Stylish.Util
--------------------------------------------------------------------------------
records :: H.Module l -> [[Alignable l]]
records modu =
[ map fieldDeclToAlignable fields
| H.Module _ _ _ _ decls <- [modu]
, H.DataDecl _ _ _ _ cons _ <- decls
, H.QualConDecl _ _ _ (H.RecDecl _ _ fields) <- cons
]
--------------------------------------------------------------------------------
data Alignable a = Alignable
{ aContainer :: !a
, aLeft :: !a
, aRight :: !a
-- | This is the minimal number of columns we need for the leading part not
-- included in our right string. For example, for datatype alignment, this
-- leading part is the string ":: " so we use 3.
, aRightLead :: !Int
} deriving (Show)
--------------------------------------------------------------------------------
fieldDeclToAlignable :: H.FieldDecl a -> Alignable a
fieldDeclToAlignable (H.FieldDecl ann names ty) = Alignable
{ aContainer = ann
, aLeft = H.ann (last names)
, aRight = H.ann ty
, aRightLead = length ":: "
}
--------------------------------------------------------------------------------
-- | Align the type of a field
align :: Int -> [Alignable H.SrcSpan] -> [Change String]
align maxColumns alignment
-- Do not make any change if we would go past the maximum number of columns.
| longestLeft + longestRight > maxColumns = info []
| otherwise = info $ map align' alignment
where
info =
id
-- trace ("Alignable: " ++ show alignment) .
-- trace ("longestLeft: " ++ show longestLeft) .
-- trace ("longestRight: " ++ show longestRight)
-- The longest thing in the left column.
longestLeft = maximum $ map (H.srcSpanEndColumn . aLeft) alignment
-- The longest thing in the right column.
longestRight = maximum
[ H.srcSpanEndColumn (aRight a) - H.srcSpanStartColumn (aRight a)
+ aRightLead a
| a <- alignment
]
align' a = changeLine (H.srcSpanStartLine $ aContainer a) $ \str ->
let column = H.srcSpanEndColumn $ aLeft a
(pre, post) = splitAt column str
in [padRight longestLeft (trimRight pre) ++ trimLeft post]
trimLeft = dropWhile isSpace
trimRight = reverse . trimLeft . reverse
--------------------------------------------------------------------------------
-- | Checks that all no field of the record appears on more than one line,
-- amonst other things
fixable :: [Alignable H.SrcSpan] -> Bool
fixable [] = False
fixable fields = all singleLine containers && nonOverlapping containers
where
containers = map aContainer fields
singleLine s = H.srcSpanStartLine s == H.srcSpanEndLine s
nonOverlapping ss = length ss == length (nub $ map H.srcSpanStartLine ss)
--------------------------------------------------------------------------------
step :: Int -> Step
step maxColumns = makeStep "Records" $ \ls (module', _) ->
let module'' = fmap H.srcInfoSpan module'
fixableRecords = filter fixable $ records module''
in applyChanges (fixableRecords >>= align maxColumns) ls
|
