ghc-exactprint-0.3.1: ExactPrint for GHC

Safe HaskellNone
LanguageHaskell2010

Language.Haskell.GHC.ExactPrint.Transform

Contents

Description

This module is currently under heavy development, and no promises are made about API stability. Use with care.

We weclome any feedback / contributions on this, as it is the main point of the library.

Synopsis

The Transform Monad

type Transform a = RWS () [String] (Anns, Int) a Source

Monad type for updating the AST and managing the annotations at the same time. The W state is used to generate logging information if required.

runTransform :: Anns -> Transform a -> (a, (Anns, Int), [String]) Source

Run a transformation in the Transform monad, returning the updated annotations and any logging generated via logTr

Transform monad operations

logTr :: String -> Transform () Source

Log a string to the output of the Monad

getAnnsT :: Transform Anns Source

Access the Anns being modified in this transformation

putAnnsT :: Anns -> Transform () Source

Replace the Anns after any changes

modifyAnnsT :: (Anns -> Anns) -> Transform () Source

Change the stored Anns

uniqueSrcSpanT :: Transform SrcSpan Source

Once we have Anns, a SrcSpan is used purely as part of an AnnKey to index into the Anns. If we need to add new elements to the AST, they need their own SrcSpan for this.

wrapSigT :: LSig RdrName -> Transform (LHsDecl RdrName) Source

Convert a LSig into a LHsDecl, duplicating the LSig annotation for the LHsDecl. This needs to be set up so that the original annotation is restored after a pushDeclAnnT call.

wrapDeclT :: LHsBind RdrName -> Transform (LHsDecl RdrName) Source

Convert a LHsBind into a LHsDecl, duplicating the LHsBind annotation for the LHsDecl. This needs to be set up so that the original annotation is restored after a pushDeclAnnT call.

pushDeclAnnT :: LHsDecl RdrName -> Transform (LHsDecl RdrName) Source

Copy the top level annotation to a new SrcSpan and the unwrapped decl. This is required so that decl2Sig and decl2Bind will produce values that have the required annotations.

decl2BindT :: LHsDecl RdrName -> Transform [LHsBind RdrName] Source

Unwrap a LHsDecl to its underlying LHsBind, transferring the top level annotation to a new unique SrcSpan in the process.

decl2SigT :: LHsDecl RdrName -> Transform [LSig RdrName] Source

Unwrap a LHsDecl to its underlying LSig, transferring the top level annotation to a new unique SrcSpan in the process.

getEntryDPT :: Data a => Located a -> Transform DeltaPos Source

Transform monad version of getEntryDP

addSimpleAnnT :: Data a => Located a -> DeltaPos -> [(KeywordId, DeltaPos)] -> Transform () Source

Create a simple Annotation without comments, and attach it to the first parameter.

Managing lists, Transform monad

class Data t => HasDecls t where Source

Methods

hsDecls :: t -> Transform [LHsDecl RdrName] Source

Return the HsDecls that are directly enclosed in the given syntax phrase. They are always returned in the wrapped HsDecl form, even if orginating in local decls.

replaceDecls :: t -> [LHsDecl RdrName] -> Transform t Source

Replace the directly enclosed decl list by the given decl list. Runs in the Transform monad to be able to update list order annotations, and rebalance comments and other layout changes as needed.

For example, a call on replaceDecls for a wrapped FunBind having no where clause will convert

-- |This is a function
foo = x -- comment1

in to

-- |This is a function
foo = x -- comment1
  where
    nn = 2

Instances

insertAtStart :: (Data ast, HasDecls (Located ast)) => Located ast -> LHsDecl RdrName -> Transform (Located ast) Source

insertAtEnd :: (Data ast, HasDecls (Located ast)) => Located ast -> LHsDecl RdrName -> Transform (Located ast) Source

insertAfter :: (Data ast, HasDecls (Located ast)) => Located old -> Located ast -> LHsDecl RdrName -> Transform (Located ast) Source

insertBefore :: (Data ast, HasDecls (Located ast)) => Located old -> Located ast -> LHsDecl RdrName -> Transform (Located ast) Source

Low level operations used in HasDecls

balanceComments :: (Data a, Data b) => Located a -> Located b -> Transform () Source

Prior to moving an AST element, make sure any trailing comments belonging to it are attached to it, and not the following element. Of necessity this is a heuristic process, to be tuned later. Possibly a variant should be provided with a passed-in decision function.

balanceTrailingComments :: (Data a, Data b) => Located a -> Located b -> Transform [(Comment, DeltaPos)] Source

After moving an AST element, make sure any comments that may belong with the following element in fact do. Of necessity this is a heuristic process, to be tuned later. Possibly a variant should be provided with a passed-in decision function.

moveTrailingComments :: (Data a, Data b) => Located a -> Located b -> Transform () Source

Move any annFollowingComments values from the Annotation associated to the first parameter to that of the second.

Managing lists, pure functions

captureOrder :: Data a => Located a -> [Located b] -> Anns -> Anns Source

If a list has been re-ordered or had items added, capture the new order in the appropriate annSortKey attached to the Annotation for the first parameter.

captureOrderAnnKey :: AnnKey -> [Located b] -> Anns -> Anns Source

If a list has been re-ordered or had items added, capture the new order in the appropriate annSortKey item of the supplied AnnKey

Operations

isUniqueSrcSpan :: SrcSpan -> Bool Source

Test whether a given SrcSpan was generated by uniqueSrcSpanT

Managing decls

declFun :: (forall a. Data a => Located a -> b) -> LHsDecl RdrName -> b Source

Pure functions

mergeAnns :: Anns -> Anns -> Anns Source

Left bias pair union

mergeAnnList :: [Anns] -> Anns Source

Combine a list of annotations

setPrecedingLinesDecl :: LHsDecl RdrName -> Int -> Int -> Anns -> Anns Source

Unwrap a HsDecl and call setPrecedingLines on it

setPrecedingLines :: Data a => Located a -> Int -> Int -> Anns -> Anns Source

Adjust the entry annotations to provide an n line preceding gap

getEntryDP :: Data a => Anns -> Located a -> DeltaPos Source

Return the true entry DeltaPos from the annotation for a given AST element. This is the DeltaPos ignoring any comments.