ghc-exactprint-1.8.0.0: src/Language/Haskell/GHC/ExactPrint/Parsers.hs
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE ViewPatterns #-}
-----------------------------------------------------------------------------
-- |
-- 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.
--
----------------------------------------------------------------------------
module Language.Haskell.GHC.ExactPrint.Parsers (
-- * Utility
Parser
, ParseResult
, withDynFlags
, CppOptions(..)
, defaultCppOptions
, LibDir
-- * Module Parsers
, parseModule
, parseModuleFromString
, parseModuleWithOptions
, parseModuleWithCpp
-- * Basic Parsers
, parseExpr
, parseImport
, parseType
, parseDecl
, parsePattern
, parseStmt
, parseWith
-- * Internal
, ghcWrapper
, initDynFlags
, initDynFlagsPure
, parseModuleFromStringInternal
, parseModuleEpAnnsWithCpp
, parseModuleEpAnnsWithCppInternal
, postParseTransform
) where
import Language.Haskell.GHC.ExactPrint.Preprocess
import Data.Functor (void)
import qualified GHC hiding (parseModule)
import qualified Control.Monad.IO.Class as GHC
import qualified GHC.Data.FastString as GHC
import qualified GHC.Data.StringBuffer as GHC
import qualified GHC.Driver.Config.Parser as GHC
import qualified GHC.Driver.Errors.Types as GHC
import qualified GHC.Driver.Session as GHC
import qualified GHC.Parser as GHC
import qualified GHC.Parser.Header as GHC
import qualified GHC.Parser.Lexer as GHC
import qualified GHC.Parser.PostProcess as GHC
import qualified GHC.Types.SrcLoc as GHC
import qualified GHC.LanguageExtensions as LangExt
-- ---------------------------------------------------------------------
-- | Wrapper function which returns Annotations along with the parsed
-- element.
parseWith :: GHC.DynFlags
-> FilePath
-> GHC.P w
-> String
-> ParseResult w
parseWith dflags fileName parser s =
case runParser parser dflags fileName s of
GHC.PFailed pst
-> Left (GHC.GhcPsMessage <$> GHC.getPsErrorMessages pst)
GHC.POk _ pmod
-> Right pmod
parseWithECP :: (GHC.DisambECP w)
=> GHC.DynFlags
-> FilePath
-> GHC.P GHC.ECP
-> String
-> ParseResult (GHC.LocatedA w)
parseWithECP dflags fileName parser s =
case runParser (parser >>= \p -> GHC.runPV $ GHC.unECP p) dflags fileName s of
GHC.PFailed pst
-> Left (GHC.GhcPsMessage <$> GHC.getPsErrorMessages pst)
GHC.POk _ pmod
-> Right pmod
-- ---------------------------------------------------------------------
runParser :: GHC.P a -> GHC.DynFlags -> FilePath -> String -> GHC.ParseResult a
runParser parser flags filename str = GHC.unP parser parseState
where
location = GHC.mkRealSrcLoc (GHC.mkFastString filename) 1 1
buffer = GHC.stringToStringBuffer str
parseState = GHC.initParserState (GHC.initParserOpts flags) buffer location
-- ---------------------------------------------------------------------
-- | Provides a safe way to consume a properly initialised set of
-- 'DynFlags'.
--
-- @
-- myParser fname expr = withDynFlags (\\d -> parseExpr d fname expr)
-- @
withDynFlags :: LibDir -> (GHC.DynFlags -> a) -> IO a
withDynFlags libdir action = ghcWrapper libdir $ do
dflags <- GHC.getSessionDynFlags
void $ GHC.setSessionDynFlags dflags
return (action dflags)
-- ---------------------------------------------------------------------
parseFile :: GHC.DynFlags -> FilePath -> String -> GHC.ParseResult (GHC.Located (GHC.HsModule GHC.GhcPs))
parseFile = runParser GHC.parseModule
-- ---------------------------------------------------------------------
type LibDir = FilePath
type ParseResult a = Either GHC.ErrorMessages a
type Parser a = GHC.DynFlags -> FilePath -> String
-> ParseResult a
parseExpr :: Parser (GHC.LHsExpr GHC.GhcPs)
parseExpr df fp = parseWithECP df fp GHC.parseExpression
parseImport :: Parser (GHC.LImportDecl GHC.GhcPs)
parseImport df fp = parseWith df fp GHC.parseImport
parseType :: Parser (GHC.LHsType GHC.GhcPs)
parseType df fp = parseWith df fp GHC.parseType
-- safe, see D1007
parseDecl :: Parser (GHC.LHsDecl GHC.GhcPs)
parseDecl df fp = parseWith df fp GHC.parseDeclaration
parseStmt :: Parser (GHC.ExprLStmt GHC.GhcPs)
parseStmt df fp = parseWith df fp GHC.parseStatement
parsePattern :: Parser (GHC.LPat GHC.GhcPs)
parsePattern df fp = parseWith df fp GHC.parsePattern
-- ---------------------------------------------------------------------
--
-- | This entry point will also work out which language extensions are
-- required and perform CPP processing if necessary.
--
-- @
-- parseModule = parseModuleWithCpp defaultCppOptions
-- @
--
-- Note: 'GHC.ParsedSource' is a synonym for 'GHC.Located' ('GHC.HsModule' 'GhcPs')
parseModule :: LibDir -> FilePath -> IO (ParseResult GHC.ParsedSource)
parseModule libdir file = parseModuleWithCpp libdir defaultCppOptions file
-- | 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.
parseModuleFromString
:: LibDir -- GHC libdir
-> FilePath
-> String
-> IO (ParseResult GHC.ParsedSource)
parseModuleFromString libdir fp s = ghcWrapper libdir $ do
dflags <- initDynFlagsPure fp s
return $ parseModuleFromStringInternal dflags fp s
-- | Internal part of 'parseModuleFromString'.
parseModuleFromStringInternal :: Parser GHC.ParsedSource
parseModuleFromStringInternal dflags fileName str =
let (str1, lp) = stripLinePragmas str
res = case runParser GHC.parseModule dflags fileName str1 of
GHC.PFailed pst
-> Left (GHC.GhcPsMessage <$> GHC.getPsErrorMessages pst)
GHC.POk _ pmod
-> Right (lp, dflags, pmod)
in postParseTransform res
parseModuleWithOptions :: LibDir -- ^ GHC libdir
-> FilePath
-> IO (ParseResult GHC.ParsedSource)
parseModuleWithOptions libdir fp =
parseModuleWithCpp libdir defaultCppOptions fp
-- | Parse a module with specific instructions for the C pre-processor.
parseModuleWithCpp
:: LibDir -- ^ GHC libdir
-> CppOptions
-> FilePath -- ^ File to be parsed
-> IO (ParseResult GHC.ParsedSource)
parseModuleWithCpp libdir cpp fp = do
res <- parseModuleEpAnnsWithCpp libdir cpp fp
return $ postParseTransform res
-- ---------------------------------------------------------------------
-- | Low level function which is used in the internal tests.
-- It is advised to use 'parseModule' or 'parseModuleWithCpp' instead of
-- this function.
parseModuleEpAnnsWithCpp
:: LibDir -- ^ GHC libdir
-> CppOptions
-> FilePath -- ^ File to be parsed
-> IO
( Either
GHC.ErrorMessages
([GHC.LEpaComment], GHC.DynFlags, GHC.ParsedSource)
)
parseModuleEpAnnsWithCpp libdir cppOptions file = ghcWrapper libdir $ do
dflags <- initDynFlags file
parseModuleEpAnnsWithCppInternal cppOptions dflags file
-- | Internal function. Default runner of GHC.Ghc action in IO.
ghcWrapper :: LibDir -> GHC.Ghc a -> IO a
ghcWrapper libdir a =
GHC.defaultErrorHandler GHC.defaultFatalMessager GHC.defaultFlushOut
$ GHC.runGhc (Just libdir) a
-- | Internal function. Exposed if you want to muck with DynFlags
-- before parsing.
parseModuleEpAnnsWithCppInternal
:: GHC.GhcMonad m
=> CppOptions
-> GHC.DynFlags
-> FilePath
-> m
( Either
GHC.ErrorMessages
([GHC.LEpaComment], GHC.DynFlags, GHC.ParsedSource)
)
parseModuleEpAnnsWithCppInternal cppOptions dflags file = do
let useCpp = GHC.xopt LangExt.Cpp dflags
(fileContents, injectedComments, dflags') <-
if useCpp
then do
(contents,dflags1) <- getPreprocessedSrcDirect cppOptions file
cppComments <- getCppTokensAsComments cppOptions file
return (contents,cppComments,dflags1)
else do
txt <- GHC.liftIO $ readFileGhc file
let (contents1,lp) = stripLinePragmas txt
return (contents1,lp,dflags)
return $
case parseFile dflags' file fileContents of
GHC.PFailed pst
-> Left (GHC.GhcPsMessage <$> GHC.getPsErrorMessages pst)
GHC.POk _ pmod
-> Right $ (injectedComments, dflags', fixModuleComments pmod)
-- | Internal function. Exposed if you want to muck with DynFlags
-- before parsing. Or after parsing.
postParseTransform
:: Either a ([GHC.LEpaComment], GHC.DynFlags, GHC.ParsedSource)
-> Either a (GHC.ParsedSource)
postParseTransform parseRes = fmap mkAnns parseRes
where
mkAnns (_cs, _, m) = fixModuleComments m
fixModuleComments :: GHC.ParsedSource -> GHC.ParsedSource
fixModuleComments p = fixModuleHeaderComments $ fixModuleTrailingComments p
fixModuleTrailingComments :: GHC.ParsedSource -> GHC.ParsedSource
fixModuleTrailingComments (GHC.L l p) = GHC.L l p'
where
an' = case GHC.hsmodAnn $ GHC.hsmodExt p of
(GHC.EpAnn a an ocs) -> GHC.EpAnn a an (rebalance ocs)
unused -> unused
p' = p { GHC.hsmodExt = (GHC.hsmodExt p){ GHC.hsmodAnn = an' } }
rebalance :: GHC.EpAnnComments -> GHC.EpAnnComments
rebalance cs = cs'
where
cs' = case GHC.hsmodLayout $ GHC.hsmodExt p of
GHC.ExplicitBraces _ (GHC.L (GHC.TokenLoc (GHC.EpaSpan ss _)) _) ->
let
pc = GHC.priorComments cs
fc = GHC.getFollowingComments cs
bf (GHC.L anc _) = GHC.anchor anc > ss
(prior,f) = break bf fc
cs'' = GHC.EpaCommentsBalanced (pc <> prior) f
in cs''
_ -> cs
-- Deal with https://gitlab.haskell.org/ghc/ghc/-/issues/23984
-- The Lexer works bottom-up, so does not have module declaration info
-- when the first top decl processed
fixModuleHeaderComments :: GHC.ParsedSource -> GHC.ParsedSource
fixModuleHeaderComments (GHC.L l p) = GHC.L l p'
where
moveComments :: GHC.EpaLocation -> GHC.LHsDecl GHC.GhcPs -> GHC.EpAnnComments
-> (GHC.LHsDecl GHC.GhcPs, GHC.EpAnnComments)
moveComments GHC.EpaDelta{} dd cs = (dd,cs)
moveComments _loc dd@(GHC.L (GHC.SrcSpanAnn GHC.EpAnnNotUsed _) _) cs = (dd,cs)
moveComments (GHC.EpaSpan r _) (GHC.L (GHC.SrcSpanAnn (GHC.EpAnn anc an csd) ll) a) cs = (dd,css)
where
-- Move any comments on the decl that occur prior to the location
pc = GHC.priorComments csd
fc = GHC.getFollowingComments csd
bf (GHC.L anch _) = GHC.anchor anch > r
(move,keep) = break bf pc
csd' = GHC.EpaCommentsBalanced keep fc
dd = GHC.L (GHC.SrcSpanAnn (GHC.EpAnn anc an csd') ll) a
css = cs <> GHC.EpaComments move
(ds',an') = rebalance (GHC.hsmodDecls p, GHC.hsmodAnn $ GHC.hsmodExt p)
p' = p { GHC.hsmodExt = (GHC.hsmodExt p){ GHC.hsmodAnn = an' },
GHC.hsmodDecls = ds'
}
rebalance :: ([GHC.LHsDecl GHC.GhcPs], GHC.EpAnn GHC.AnnsModule)
-> ([GHC.LHsDecl GHC.GhcPs], GHC.EpAnn GHC.AnnsModule)
rebalance (ds, GHC.EpAnnNotUsed) = (ds, GHC.EpAnnNotUsed)
rebalance (ds, GHC.EpAnn a an cs) = (ds1, GHC.EpAnn a an cs')
where
(ds1,cs') = case break (\(GHC.AddEpAnn k _) -> k == GHC.AnnWhere) (GHC.am_main an) of
(_, (GHC.AddEpAnn _ whereLoc:_)) ->
case GHC.hsmodDecls p of
(d:ds0) -> (d':ds0, cs0)
where (d',cs0) = moveComments whereLoc d cs
ds0 -> (ds0,cs)
_ -> (ds,cs)
-- | 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.
initDynFlags :: GHC.GhcMonad m => FilePath -> m GHC.DynFlags
initDynFlags file = do
-- Based on GHC backpack driver doBackPack
dflags0 <- GHC.getSessionDynFlags
let parser_opts0 = GHC.initParserOpts dflags0
(_, src_opts) <- GHC.liftIO $ GHC.getOptionsFromFile parser_opts0 file
(dflags1, _, _) <- GHC.parseDynamicFilePragma dflags0 src_opts
-- Turn this on last to avoid T10942
let dflags2 = dflags1 `GHC.gopt_set` GHC.Opt_KeepRawTokenStream
-- Prevent parsing of .ghc.environment.* "package environment files"
(dflags3, _, _) <- GHC.parseDynamicFlagsCmdLine
dflags2
[GHC.noLoc "-hide-all-packages"]
_ <- GHC.setSessionDynFlags dflags3
return dflags3
-- | 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.
initDynFlagsPure :: GHC.GhcMonad m => FilePath -> String -> m GHC.DynFlags
initDynFlagsPure fp s = do
-- AZ Note: "I" below appears to be Lennart Spitzner
-- I was told we could get away with using the unsafeGlobalDynFlags.
-- as long as `parseDynamicFilePragma` is impure there seems to be
-- no reason to use it.
dflags0 <- GHC.getSessionDynFlags
let parser_opts0 = GHC.initParserOpts dflags0
let (_, pragmaInfo) = GHC.getOptions parser_opts0 (GHC.stringToStringBuffer $ s) fp
(dflags1, _, _) <- GHC.parseDynamicFilePragma dflags0 pragmaInfo
-- Turn this on last to avoid T10942
let dflags2 = dflags1 `GHC.gopt_set` GHC.Opt_KeepRawTokenStream
-- Prevent parsing of .ghc.environment.* "package environment files"
(dflags3, _, _) <- GHC.parseDynamicFlagsCmdLine
dflags2
[GHC.noLoc "-hide-all-packages"]
_ <- GHC.setSessionDynFlags dflags3
return dflags3
-- ---------------------------------------------------------------------