Language.Haskell.GHC.ExactPrint

ghc-exactprint is a library to manage manipulating Haskell source files. There are four components.

Relativising

relativiseApiAnns :: Annotate ast => Located ast -> ApiAnns -> Anns

Transform concrete annotations into relative annotations which are more useful when transforming an AST.

relativiseApiAnnsWithComments :: Annotate ast => [Comment] -> Located ast -> ApiAnns -> Anns

Exactly the same as relativiseApiAnns but with the possibilty to inject comments. This is typically used if the source has been preprocessed by e.g. CPP, and the parts stripped out of the original source are re-added as comments so they are not lost for round tripping.

type Anns = Map AnnKey Annotation

This structure holds a complete set of annotations for an AST

data Comment

A Haskell comment. The AnnKeywordId is present if it has been converted from an AnnKeywordId because the annotation must be interleaved into the stream and does not have a well-defined position

Instances

Eq Comment

Methods

(==) :: Comment -> Comment -> Bool

(/=) :: Comment -> Comment -> Bool

Data Comment

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Comment -> c Comment

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Comment

toConstr :: Comment -> Constr

dataTypeOf :: Comment -> DataType

dataCast1 :: Typeable (* -> *) t => (forall d. Data d => c (t d)) -> Maybe (c Comment)

dataCast2 :: Typeable (* -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Comment)

gmapT :: (forall b. Data b => b -> b) -> Comment -> Comment

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Comment -> r

gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Comment -> r

gmapQ :: (forall d. Data d => d -> u) -> Comment -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> Comment -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Comment -> m Comment

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Comment -> m Comment

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Comment -> m Comment

Ord Comment

Methods

compare :: Comment -> Comment -> Ordering

(<) :: Comment -> Comment -> Bool

(<=) :: Comment -> Comment -> Bool

(>) :: Comment -> Comment -> Bool

(>=) :: Comment -> Comment -> Bool

max :: Comment -> Comment -> Comment

min :: Comment -> Comment -> Comment

Show Comment

Methods

showsPrec :: Int -> Comment -> ShowS

show :: Comment -> String

showList :: [Comment] -> ShowS

Outputable Comment

Methods

ppr :: Comment -> SDoc

pprPrec :: Rational -> Comment -> SDoc

data Annotation

Constructors

Ann

Fields

• annEntryDelta :: !DeltaPos

  Offset used to get to the start of the SrcSpan, from whatever the prior output was, including all annPriorComments (field below).

• annPriorComments :: ![(Comment, DeltaPos)]

  Comments coming after the last non-comment output of the preceding element but before the SrcSpan being annotated by this Annotation. If these are changed then annEntryDelta (field above) must also change to match.

• annFollowingComments :: ![(Comment, DeltaPos)]

  Comments coming after the last output for the element subject to this Annotation. These will only be added by AST transformations, and care must be taken not to disturb layout of following elements.

• annsDP :: ![(KeywordId, DeltaPos)]

  Annotations associated with this element.

• annSortKey :: !(Maybe [SrcSpan])

  Captures the sort order of sub elements. This is needed when the sub-elements have been split (as in a HsLocalBind which holds separate binds and sigs) or for infix patterns where the order has been re-arranged. It is captured explicitly so that after the Delta phase a SrcSpan is used purely as an index into the annotations, allowing transformations of the AST including the introduction of new Located items or re-arranging existing ones.

• annCapturedSpan :: !(Maybe AnnKey)

  Occasionally we must calculate a SrcSpan for an unlocated list of elements which we must remember for the Print phase. e.g. the statements in a HsLet or HsDo. These must be managed as a group because they all need eo be vertically aligned for the Haskell layout rules, and this guarantees this property in the presence of AST edits.

Instances

Eq Annotation

Methods

(==) :: Annotation -> Annotation -> Bool

(/=) :: Annotation -> Annotation -> Bool

Show Annotation

Methods

showsPrec :: Int -> Annotation -> ShowS

show :: Annotation -> String

showList :: [Annotation] -> ShowS

Outputable Annotation

Methods

ppr :: Annotation -> SDoc

pprPrec :: Rational -> Annotation -> SDoc

Monad m => MonadState (Anns, Int) (TransformT m)

Methods

get :: TransformT m (Anns, Int)

put :: (Anns, Int) -> TransformT m ()

state :: ((Anns, Int) -> (a, (Anns, Int))) -> TransformT m a

data AnnKey

For every Located a, use the SrcSpan and constructor name of a as the key, to store the standard annotation. These are used to maintain context in the AP and EP monads

Constructors

AnnKey SrcSpan AnnConName

Instances

Eq AnnKey

Methods

(==) :: AnnKey -> AnnKey -> Bool

(/=) :: AnnKey -> AnnKey -> Bool

Ord AnnKey

Methods

compare :: AnnKey -> AnnKey -> Ordering

(<) :: AnnKey -> AnnKey -> Bool

(<=) :: AnnKey -> AnnKey -> Bool

(>) :: AnnKey -> AnnKey -> Bool

(>=) :: AnnKey -> AnnKey -> Bool

max :: AnnKey -> AnnKey -> AnnKey

min :: AnnKey -> AnnKey -> AnnKey

Show AnnKey

Methods

showsPrec :: Int -> AnnKey -> ShowS

show :: AnnKey -> String

showList :: [AnnKey] -> ShowS

Outputable AnnKey

Methods

ppr :: AnnKey -> SDoc

pprPrec :: Rational -> AnnKey -> SDoc

Monad m => MonadState (Anns, Int) (TransformT m)

Methods

get :: TransformT m (Anns, Int)

put :: (Anns, Int) -> TransformT m ()

state :: ((Anns, Int) -> (a, (Anns, Int))) -> TransformT m a

Parsing

parseModule :: FilePath -> IO (Either (SrcSpan, String) (Anns, ParsedSource))

This entry point will also work out which language extensions are required and perform CPP processing if necessary.

parseModule = parseModuleWithCpp defaultCppOptions

Note: ParsedSource is a synonym for Located (HsModule RdrName)

Transformation

module Language.Haskell.GHC.ExactPrint.Transform

Printing

exactPrint :: Annotate ast => Located ast -> Anns -> String

Print an AST with a map of potential modified Anns. The usual way to generate such a map is by using one of the parsers in Language.Haskell.GHC.ExactPrint.Parsers.