Language.Haskell.GHC.ExactPrint.Parsers

This module rexposes wrapped parsers from the GHC API. Along with returning the parse result, the corresponding annotations are also returned such that it is then easy to modify the annotations and print the result.

Utility

type Parser a = DynFlags -> FilePath -> String -> ParseResult a

type ParseResult a = Either ErrorMessages a

withDynFlags :: LibDir -> (DynFlags -> a) -> IO a

Provides a safe way to consume a properly initialised set of DynFlags.

myParser fname expr = withDynFlags (\d -> parseExpr d fname expr)

data CppOptions

Constructors

CppOptions

Fields

• cppDefine :: [String]

  CPP #define macros

• cppInclude :: [FilePath]

  CPP Includes directory

• cppFile :: [FilePath]

  CPP pre-include file

defaultCppOptions :: CppOptions

type LibDir = FilePath

Module Parsers

parseModule :: LibDir -> FilePath -> IO (ParseResult 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 GhcPs)

parseModuleFromString :: LibDir -> FilePath -> String -> IO (ParseResult ParsedSource)

This entry point will work out which language extensions are required but will _not_ perform CPP processing. In contrast to parseModoule the input source is read from the provided string; the FilePath parameter solely exists to provide a name in source location annotations.

parseModuleWithOptions

Arguments

:: LibDir

GHC libdir

-> FilePath

-> IO (ParseResult ParsedSource)

parseModuleWithCpp

Arguments

:: LibDir

GHC libdir

-> CppOptions

-> FilePath

File to be parsed

-> IO (ParseResult ParsedSource)

Parse a module with specific instructions for the C pre-processor.

Basic Parsers

parseExpr :: Parser (LHsExpr GhcPs)

parseImport :: Parser (LImportDecl GhcPs)

parseType :: Parser (LHsType GhcPs)

parseDecl :: Parser (LHsDecl GhcPs)

parsePattern :: Parser (LPat GhcPs)

parseStmt :: Parser (ExprLStmt GhcPs)

parseWith :: DynFlags -> FilePath -> P w -> String -> ParseResult w

Wrapper function which returns Annotations along with the parsed element.

Internal

ghcWrapper :: LibDir -> Ghc a -> IO a

Internal function. Default runner of GHC.Ghc action in IO.

initDynFlags :: GhcMonad m => FilePath -> m DynFlags

Internal function. Initializes DynFlags value for parsing.

Passes "-hide-all-packages" to the GHC API to prevent parsing of package environment files. However this only works if there is no invocation of setSessionDynFlags before calling initDynFlags. See ghc tickets #15513, #15541.

initDynFlagsPure :: GhcMonad m => FilePath -> String -> m DynFlags

Requires GhcMonad constraint because there is no pure variant of parseDynamicFilePragma. Yet, in constrast to initDynFlags, it does not (try to) read the file at filepath, but solely depends on the module source in the input string.

Passes "-hide-all-packages" to the GHC API to prevent parsing of package environment files. However this only works if there is no invocation of setSessionDynFlags before calling initDynFlagsPure. See ghc tickets #15513, #15541.

parseModuleFromStringInternal :: Parser ParsedSource

Internal part of parseModuleFromString.

parseModuleEpAnnsWithCpp

Arguments

:: LibDir

GHC libdir

-> CppOptions

-> FilePath

File to be parsed

-> IO (Either ErrorMessages ([LEpaComment], DynFlags, ParsedSource))

Low level function which is used in the internal tests. It is advised to use parseModule or parseModuleWithCpp instead of this function.

parseModuleEpAnnsWithCppInternal :: GhcMonad m => CppOptions -> DynFlags -> FilePath -> m (Either ErrorMessages ([LEpaComment], DynFlags, ParsedSource))

Internal function. Exposed if you want to muck with DynFlags before parsing.

postParseTransform :: Either a ([LEpaComment], DynFlags, ParsedSource) -> Either a ParsedSource

Internal function. Exposed if you want to muck with DynFlags before parsing. Or after parsing.