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{-# LANGUAGE RecordWildCards #-}
module Language.Haskell.Stylish.Step.Data where
import Data.List (find, intercalate)
import Data.Maybe (fromMaybe, maybeToList)
import qualified Language.Haskell.Exts as H
import Language.Haskell.Exts.Comments
import Language.Haskell.Stylish.Block
import Language.Haskell.Stylish.Editor
import Language.Haskell.Stylish.Step
import Language.Haskell.Stylish.Util
import Prelude hiding (init)
data Indent
= SameLine
| Indent !Int
deriving (Show)
data Config = Config
{ cEquals :: !Indent
-- ^ Indent between type constructor and @=@ sign (measured from column 0)
, cFirstField :: !Indent
-- ^ Indent between data constructor and @{@ line (measured from column with data constructor name)
, cFieldComment :: !Int
-- ^ Indent between column with @{@ and start of field line comment (this line has @cFieldComment = 2@)
, cDeriving :: !Int
-- ^ Indent before @deriving@ lines (measured from column 0)
} deriving (Show)
datas :: H.Module l -> [H.Decl l]
datas (H.Module _ _ _ _ decls) = decls
datas _ = []
type ChangeLine = Change String
step :: Config -> Step
step cfg = makeStep "Data" (step' cfg)
step' :: Config -> Lines -> Module -> Lines
step' cfg ls (module', allComments) = applyChanges changes ls
where
datas' = datas $ fmap linesFromSrcSpan module'
changes = datas' >>= maybeToList . changeDecl allComments cfg
findCommentOnLine :: LineBlock -> [Comment] -> Maybe Comment
findCommentOnLine lb = find commentOnLine
where
commentOnLine (Comment _ (H.SrcSpan _ start _ end _) _) =
blockStart lb == start && blockEnd lb == end
findCommentBelowLine :: LineBlock -> [Comment] -> Maybe Comment
findCommentBelowLine lb = find commentOnLine
where
commentOnLine (Comment _ (H.SrcSpan _ start _ end _) _) =
blockStart lb == start - 1 && blockEnd lb == end - 1
commentsWithin :: LineBlock -> [Comment] -> [Comment]
commentsWithin lb = filter within
where
within (Comment _ (H.SrcSpan _ start _ end _) _) =
start >= blockStart lb && end <= blockEnd lb
changeDecl :: [Comment] -> Config -> H.Decl LineBlock -> Maybe ChangeLine
changeDecl _ _ (H.DataDecl _ (H.DataType _) Nothing _ [] _) = Nothing
changeDecl allComments cfg@Config{..} (H.DataDecl block (H.DataType _) Nothing dhead decls derivings)
| hasRecordFields = Just $ change block (const $ concat newLines)
| otherwise = Nothing
where
hasRecordFields = any
(\qual -> case qual of
(H.QualConDecl _ _ _ (H.RecDecl {})) -> True
_ -> False)
decls
typeConstructor = "data " <> H.prettyPrint dhead
-- In any case set @pipeIndent@ such that @|@ is aligned with @=@.
(firstLine, firstLineInit, pipeIndent) =
case cEquals of
SameLine -> (Nothing, typeConstructor <> " = ", length typeConstructor + 1)
Indent n -> (Just [[typeConstructor]], indent n "= ", n)
newLines = fromMaybe [] firstLine ++ fmap constructors zipped <> [fmap (indent cDeriving . H.prettyPrint) derivings]
zipped = zip decls ([1..] ::[Int])
constructors (decl, 1) = processConstructor allComments firstLineInit cfg decl
constructors (decl, _) = processConstructor allComments (indent pipeIndent "| ") cfg decl
changeDecl _ _ _ = Nothing
processConstructor :: [Comment] -> String -> Config -> H.QualConDecl LineBlock -> [String]
processConstructor allComments init Config{..} (H.QualConDecl _ _ _ (H.RecDecl _ dname (f:fs))) = do
fromMaybe [] firstLine <> n1 <> ns <> [indent fieldIndent "}"]
where
n1 = processName firstLinePrefix (extractField f)
ns = fs >>= processName (indent fieldIndent ", ") . extractField
-- Set @fieldIndent@ such that @,@ is aligned with @{@.
(firstLine, firstLinePrefix, fieldIndent) =
case cFirstField of
SameLine ->
( Nothing
, init <> H.prettyPrint dname <> " { "
, length init + length (H.prettyPrint dname) + 1
)
Indent n ->
( Just [init <> H.prettyPrint dname]
, indent (length init + n) "{ "
, length init + n
)
processName prefix (fnames, _type, lineComment, commentBelowLine) =
[prefix <> intercalate ", " (fmap H.prettyPrint fnames) <> " :: " <> H.prettyPrint _type <> addLineComment lineComment
] ++ addCommentBelow commentBelowLine
addLineComment (Just (Comment _ _ c)) = " --" <> c
addLineComment Nothing = ""
-- Field comment indent is measured from the column with @{@, hence adding of @fieldIndent@ here.
addCommentBelow Nothing = []
addCommentBelow (Just (Comment _ _ c)) = [indent (fieldIndent + cFieldComment) "--" <> c]
extractField (H.FieldDecl lb names _type) =
(names, _type, findCommentOnLine lb allComments, findCommentBelowLine lb allComments)
processConstructor _ init _ decl = [init <> trimLeft (H.prettyPrint decl)]
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