stylish-haskell-0.12.2.0: lib/Language/Haskell/Stylish/Step/Imports.hs
{-# LANGUAGE BlockArguments #-}
{-# LANGUAGE DoAndIfThenElse #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RecordWildCards #-}
module Language.Haskell.Stylish.Step.Imports
( Options (..)
, defaultOptions
, ImportAlign (..)
, ListAlign (..)
, LongListAlign (..)
, EmptyListAlign (..)
, ListPadding (..)
, step
, printImport
) where
--------------------------------------------------------------------------------
import Control.Monad (forM_, when, void)
import Data.Function ((&), on)
import Data.Functor (($>))
import Data.Foldable (toList)
import Data.Maybe (isJust)
import Data.List (sortBy)
import Data.List.NonEmpty (NonEmpty(..))
import qualified Data.List.NonEmpty as NonEmpty
import qualified Data.Map as Map
import qualified Data.Set as Set
--------------------------------------------------------------------------------
import BasicTypes (StringLiteral (..),
SourceText (..))
import qualified FastString as FS
import GHC.Hs.Extension (GhcPs)
import qualified GHC.Hs.Extension as GHC
import GHC.Hs.ImpExp
import Module (moduleNameString)
import RdrName (RdrName)
import SrcLoc (Located, GenLocated(..), unLoc)
--------------------------------------------------------------------------------
import Language.Haskell.Stylish.Block
import Language.Haskell.Stylish.Module
import Language.Haskell.Stylish.Ordering
import Language.Haskell.Stylish.Printer
import Language.Haskell.Stylish.Step
import Language.Haskell.Stylish.Editor
import Language.Haskell.Stylish.GHC
import Language.Haskell.Stylish.Util
--------------------------------------------------------------------------------
data Options = Options
{ importAlign :: ImportAlign
, listAlign :: ListAlign
, padModuleNames :: Bool
, longListAlign :: LongListAlign
, emptyListAlign :: EmptyListAlign
, listPadding :: ListPadding
, separateLists :: Bool
, spaceSurround :: Bool
} deriving (Eq, Show)
defaultOptions :: Options
defaultOptions = Options
{ importAlign = Global
, listAlign = AfterAlias
, padModuleNames = True
, longListAlign = Inline
, emptyListAlign = Inherit
, listPadding = LPConstant 4
, separateLists = True
, spaceSurround = False
}
data ListPadding
= LPConstant Int
| LPModuleName
deriving (Eq, Show)
data ImportAlign
= Global
| File
| Group
| None
deriving (Eq, Show)
data ListAlign
= NewLine
| WithModuleName
| WithAlias
| AfterAlias
| Repeat
deriving (Eq, Show)
data EmptyListAlign
= Inherit
| RightAfter
deriving (Eq, Show)
data LongListAlign
= Inline -- inline
| InlineWithBreak -- new_line
| InlineToMultiline -- new_line_multiline
| Multiline -- multiline
deriving (Eq, Show)
--------------------------------------------------------------------------------
step :: Maybe Int -> Options -> Step
step columns = makeStep "Imports (ghc-lib-parser)" . printImports columns
--------------------------------------------------------------------------------
printImports :: Maybe Int -> Options -> Lines -> Module -> Lines
printImports maxCols align ls m = applyChanges changes ls
where
groups = moduleImportGroups m
moduleStats = foldMap importStats . fmap unLoc $ concatMap toList groups
changes = do
group <- groups
pure $ formatGroup maxCols align m moduleStats group
formatGroup
:: Maybe Int -> Options -> Module -> ImportStats
-> NonEmpty (Located Import) -> Change String
formatGroup maxCols options m moduleStats imports =
let newLines = formatImports maxCols options m moduleStats imports in
change (importBlock imports) (const newLines)
importBlock :: NonEmpty (Located a) -> Block String
importBlock group = Block
(getStartLineUnsafe $ NonEmpty.head group)
(getEndLineUnsafe $ NonEmpty.last group)
formatImports
:: Maybe Int -- ^ Max columns.
-> Options -- ^ Options.
-> Module -- ^ Module.
-> ImportStats -- ^ Module stats.
-> NonEmpty (Located Import) -> Lines
formatImports maxCols options m moduleStats rawGroup =
runPrinter_ (PrinterConfig maxCols) [] m do
let
group
= NonEmpty.sortWith unLocated rawGroup
& mergeImports
unLocatedGroup = fmap unLocated $ toList group
align' = importAlign options
padModuleNames' = padModuleNames options
padNames = align' /= None && padModuleNames'
stats = case align' of
Global -> moduleStats {isAnyQualified = True}
File -> moduleStats
Group -> foldMap importStats unLocatedGroup
None -> mempty
forM_ group \imp -> printQualified options padNames stats imp >> newline
--------------------------------------------------------------------------------
printQualified :: Options -> Bool -> ImportStats -> Located Import -> P ()
printQualified Options{..} padNames stats (L _ decl) = do
let decl' = rawImport decl
putText "import" >> space
case (isSource decl, isAnySource stats) of
(True, _) -> putText "{-# SOURCE #-}" >> space
(_, True) -> putText " " >> space
_ -> pure ()
when (isSafe decl) (putText "safe" >> space)
case (isQualified decl, isAnyQualified stats) of
(True, _) -> putText "qualified" >> space
(_, True) -> putText " " >> space
_ -> pure ()
moduleNamePosition <- length <$> getCurrentLine
forM_ (ideclPkgQual decl') $ \pkg -> putText (stringLiteral pkg) >> space
putText (moduleName decl)
-- Only print spaces if something follows.
when padNames $
when (isJust (ideclAs decl') || isHiding decl ||
not (null $ ideclHiding decl')) $
putText $
replicate (isLongestImport stats - importModuleNameLength decl) ' '
beforeAliasPosition <- length <$> getCurrentLine
forM_ (ideclAs decl') \(L _ name) ->
space >> putText "as" >> space >> putText (moduleNameString name)
afterAliasPosition <- length <$> getCurrentLine
when (isHiding decl) (space >> putText "hiding")
let putOffset = putText $ replicate offset ' '
offset = case listPadding of
LPConstant n -> n
LPModuleName -> moduleNamePosition
case snd <$> ideclHiding decl' of
Nothing -> pure ()
Just (L _ []) -> case emptyListAlign of
RightAfter -> modifyCurrentLine trimRight >> space >> putText "()"
Inherit -> case listAlign of
NewLine ->
modifyCurrentLine trimRight >> newline >> putOffset >> putText "()"
_ -> space >> putText "()"
Just (L _ imports) -> do
let printedImports = flagEnds $ -- [P ()]
fmap ((printImport separateLists) . unLocated)
(prepareImportList imports)
-- Since we might need to output the import module name several times, we
-- need to save it to a variable:
wrapPrefix <- case listAlign of
AfterAlias -> pure $ replicate (afterAliasPosition + 1) ' '
WithAlias -> pure $ replicate (beforeAliasPosition + 1) ' '
Repeat -> fmap (++ " (") getCurrentLine
WithModuleName -> pure $ replicate (moduleNamePosition + offset) ' '
NewLine -> pure $ replicate offset ' '
let -- Helper
doSpaceSurround = when spaceSurround space
-- Try to put everything on one line.
printAsSingleLine = forM_ printedImports $ \(imp, start, end) -> do
when start $ putText "(" >> doSpaceSurround
imp
if end then doSpaceSurround >> putText ")" else comma >> space
-- Try to put everything one by one, wrapping if that fails.
printAsInlineWrapping wprefix = forM_ printedImports $
\(imp, start, end) ->
patchForRepeatHiding $ wrapping
(do
if start then putText "(" >> doSpaceSurround else space
imp
if end then doSpaceSurround >> putText ")" else comma)
(do
case listAlign of
-- In 'Repeat' mode, end lines with ')' rather than ','.
Repeat | not start -> modifyCurrentLine . withLast $
\c -> if c == ',' then ')' else c
_ | start && spaceSurround ->
-- Only necessary if spaceSurround is enabled.
modifyCurrentLine trimRight
_ -> pure ()
newline
void wprefix
case listAlign of
-- '(' already included in repeat
Repeat -> pure ()
-- Print the much needed '('
_ | start -> putText "(" >> doSpaceSurround
-- Don't bother aligning if we're not in inline mode.
_ | longListAlign /= Inline -> pure ()
-- 'Inline + AfterAlias' is really where we want to be careful
-- with spacing.
AfterAlias -> space >> doSpaceSurround
WithModuleName -> pure ()
WithAlias -> pure ()
NewLine -> pure ()
imp
if end then doSpaceSurround >> putText ")" else comma)
-- Put everything on a separate line. 'spaceSurround' can be
-- ignored.
printAsMultiLine = forM_ printedImports $ \(imp, start, end) -> do
when start $ modifyCurrentLine trimRight -- We added some spaces.
newline
putOffset
if start then putText "( " else putText ", "
imp
when end $ newline >> putOffset >> putText ")"
case longListAlign of
Multiline -> wrapping
(space >> printAsSingleLine)
printAsMultiLine
Inline | NewLine <- listAlign -> do
modifyCurrentLine trimRight
newline >> putOffset >> printAsInlineWrapping (putText wrapPrefix)
Inline -> space >> printAsInlineWrapping (putText wrapPrefix)
InlineWithBreak -> wrapping
(space >> printAsSingleLine)
(do
modifyCurrentLine trimRight
newline >> putOffset >> printAsInlineWrapping putOffset)
InlineToMultiline -> wrapping
(space >> printAsSingleLine)
(wrapping
(do
modifyCurrentLine trimRight
newline >> putOffset >> printAsSingleLine)
printAsMultiLine)
where
-- We cannot wrap/repeat 'hiding' imports since then we would get multiple
-- imports hiding different things.
patchForRepeatHiding = case listAlign of
Repeat | isHiding decl -> withColumns Nothing
_ -> id
--------------------------------------------------------------------------------
printImport :: Bool -> IE GhcPs -> P ()
printImport _ (IEVar _ name) = do
printIeWrappedName name
printImport _ (IEThingAbs _ name) = do
printIeWrappedName name
printImport separateLists (IEThingAll _ name) = do
printIeWrappedName name
when separateLists space
putText "(..)"
printImport _ (IEModuleContents _ (L _ m)) = do
putText "module"
space
putText (moduleNameString m)
printImport separateLists (IEThingWith _ name _wildcard imps _) = do
printIeWrappedName name
when separateLists space
parenthesize $
sep (comma >> space) (printIeWrappedName <$> imps)
printImport _ (IEGroup _ _ _ ) =
error "Language.Haskell.Stylish.Printer.Imports.printImportExport: unhandled case 'IEGroup'"
printImport _ (IEDoc _ _) =
error "Language.Haskell.Stylish.Printer.Imports.printImportExport: unhandled case 'IEDoc'"
printImport _ (IEDocNamed _ _) =
error "Language.Haskell.Stylish.Printer.Imports.printImportExport: unhandled case 'IEDocNamed'"
printImport _ (XIE ext) =
GHC.noExtCon ext
--------------------------------------------------------------------------------
printIeWrappedName :: LIEWrappedName RdrName -> P ()
printIeWrappedName lie = unLocated lie & \case
IEName n -> putRdrName n
IEPattern n -> putText "pattern" >> space >> putRdrName n
IEType n -> putText "type" >> space >> putRdrName n
mergeImports :: NonEmpty (Located Import) -> NonEmpty (Located Import)
mergeImports (x :| []) = x :| []
mergeImports (h :| (t : ts))
| canMergeImport (unLocated h) (unLocated t) = mergeImports (mergeModuleImport h t :| ts)
| otherwise = h :| mergeImportsTail (t : ts)
where
mergeImportsTail (x : y : ys)
| canMergeImport (unLocated x) (unLocated y) = mergeImportsTail ((mergeModuleImport x y) : ys)
| otherwise = x : mergeImportsTail (y : ys)
mergeImportsTail xs = xs
moduleName :: Import -> String
moduleName
= moduleNameString
. unLocated
. ideclName
. rawImport
--------------------------------------------------------------------------------
data ImportStats = ImportStats
{ isLongestImport :: !Int
, isAnySource :: !Bool
, isAnyQualified :: !Bool
, isAnySafe :: !Bool
}
instance Semigroup ImportStats where
l <> r = ImportStats
{ isLongestImport = isLongestImport l `max` isLongestImport r
, isAnySource = isAnySource l || isAnySource r
, isAnyQualified = isAnyQualified l || isAnyQualified r
, isAnySafe = isAnySafe l || isAnySafe r
}
instance Monoid ImportStats where
mappend = (<>)
mempty = ImportStats 0 False False False
importStats :: Import -> ImportStats
importStats i =
ImportStats (importModuleNameLength i) (isSource i) (isQualified i) (isSafe i)
-- Computes length till module name, includes package name.
-- TODO: this should reuse code with the printer
importModuleNameLength :: Import -> Int
importModuleNameLength imp =
(case ideclPkgQual (rawImport imp) of
Nothing -> 0
Just sl -> 1 + length (stringLiteral sl)) +
(length $ moduleName imp)
--------------------------------------------------------------------------------
stringLiteral :: StringLiteral -> String
stringLiteral sl = case sl_st sl of
NoSourceText -> FS.unpackFS $ sl_fs sl
SourceText s -> s
--------------------------------------------------------------------------------
isQualified :: Import -> Bool
isQualified
= (/=) NotQualified
. ideclQualified
. rawImport
isHiding :: Import -> Bool
isHiding
= maybe False fst
. ideclHiding
. rawImport
isSource :: Import -> Bool
isSource
= ideclSource
. rawImport
isSafe :: Import -> Bool
isSafe
= ideclSafe
. rawImport
--------------------------------------------------------------------------------
-- | Cleans up an import item list.
--
-- * Sorts import items.
-- * Sort inner import lists, e.g. `import Control.Monad (Monad (return, join))`
-- * Removes duplicates from import lists.
prepareImportList :: [LIE GhcPs] -> [LIE GhcPs]
prepareImportList =
sortBy compareLIE . map (fmap prepareInner) .
concatMap (toList . snd) . Map.toAscList . mergeByName
where
mergeByName :: [LIE GhcPs] -> Map.Map RdrName (NonEmpty (LIE GhcPs))
mergeByName imports0 = Map.fromListWith
-- Note that ideally every NonEmpty will just have a single entry and we
-- will be able to merge everything into that entry. Exotic imports can
-- mess this up, though. So they end up in the tail of the list.
(\(x :| xs) (y :| ys) -> case ieMerge (unLocated x) (unLocated y) of
Just z -> (x $> z) :| (xs ++ ys) -- Keep source from `x`
Nothing -> x :| (xs ++ y : ys))
[(ieName $ unLocated imp, imp :| []) | imp <- imports0]
prepareInner :: IE GhcPs -> IE GhcPs
prepareInner = \case
-- Simplify `A ()` to `A`.
IEThingWith x n NoIEWildcard [] [] -> IEThingAbs x n
IEThingWith x n w ns fs ->
IEThingWith x n w (sortBy (compareWrappedName `on` unLoc) ns) fs
ie -> ie
-- Merge two import items, assuming they have the same name.
ieMerge :: IE GhcPs -> IE GhcPs -> Maybe (IE GhcPs)
ieMerge l@(IEVar _ _) _ = Just l
ieMerge _ r@(IEVar _ _) = Just r
ieMerge (IEThingAbs _ _) r = Just r
ieMerge l (IEThingAbs _ _) = Just l
ieMerge l@(IEThingAll _ _) _ = Just l
ieMerge _ r@(IEThingAll _ _) = Just r
ieMerge (IEThingWith x0 n0 w0 ns0 []) (IEThingWith _ _ w1 ns1 [])
| w0 /= w1 = Nothing
| otherwise = Just $
-- TODO: sort the `ns0 ++ ns1`?
IEThingWith x0 n0 w0 (nubOn (unwrapName . unLoc) $ ns0 ++ ns1) []
ieMerge _ _ = Nothing
--------------------------------------------------------------------------------
nubOn :: Ord k => (a -> k) -> [a] -> [a]
nubOn f = go Set.empty
where
go _ [] = []
go acc (x : xs)
| y `Set.member` acc = go acc xs
| otherwise = x : go (Set.insert y acc) xs
where
y = f x