Distribution/PackageDescription/Parsec.hs

    {-# LANGUAGE CPP                 #-}
    {-# LANGUAGE FlexibleContexts    #-}
    {-# LANGUAGE OverloadedStrings   #-}
    {-# LANGUAGE Rank2Types          #-}
    {-# LANGUAGE ScopedTypeVariables #-}
    {-# LANGUAGE TupleSections       #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.PackageDescription.Parsec
    -- Copyright   :  Isaac Jones 2003-2005
    -- License     :  BSD3
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- This defined parsers and partial pretty printers for the @.cabal@ format.

    module Distribution.PackageDescription.Parsec (
        -- * Package descriptions
        readGenericPackageDescription,
        parseGenericPackageDescription,
        parseGenericPackageDescriptionMaybe,

        -- ** Parsing
        ParseResult,
        runParseResult,

        -- ** Supplementary build information
        readHookedBuildInfo,
        parseHookedBuildInfo,
        ) where

    import Distribution.Compat.Prelude
    import Prelude ()

    import           Control.Monad.State.Strict                   (StateT, execStateT)
    import           Control.Monad.Trans.Class                    (lift)
    import qualified Data.ByteString                              as BS
    import           Data.List                                    (partition)
    import qualified Distribution.Compat.Map.Strict               as Map
    import           Distribution.FieldGrammar
    import           Distribution.PackageDescription
    import           Distribution.PackageDescription.FieldGrammar
    import           Distribution.PackageDescription.Quirks       (patchQuirks)
    import           Distribution.Parsec.Class                    (parsec)
    import           Distribution.Parsec.Common
    import           Distribution.Parsec.ConfVar                  (parseConditionConfVar)
    import           Distribution.Parsec.Field                    (FieldName, getName)
    import           Distribution.Parsec.LexerMonad               (LexWarning, toPWarning)
    import           Distribution.Parsec.Parser
    import           Distribution.Parsec.ParseResult
    import           Distribution.Simple.Utils                    (die', fromUTF8BS, warn)
    import           Distribution.Text                            (display)
    import           Distribution.Types.CondTree
    import           Distribution.Types.ForeignLib
    import           Distribution.Types.UnqualComponentName
                     (UnqualComponentName, mkUnqualComponentName)
    import           Distribution.Utils.Generic                   (breakMaybe, unfoldrM)
    import           Distribution.Verbosity                       (Verbosity)
    import           Distribution.Version
                     (LowerBound (..), Version, asVersionIntervals, mkVersion, orLaterVersion)
    import           System.Directory                             (doesFileExist)

    import           Distribution.Compat.Lens
    import qualified Distribution.Types.GenericPackageDescription.Lens as L
    import qualified Distribution.Types.PackageDescription.Lens        as L

    -- ---------------------------------------------------------------
    -- Parsing

    -- | Helper combinator to do parsing plumbing for files.
    --
    -- Given a parser and a filename, return the parse of the file,
    -- after checking if the file exists.
    --
    -- Argument order is chosen to encourage partial application.
    readAndParseFile
        :: (BS.ByteString -> ParseResult a)  -- ^ File contents to final value parser
        -> Verbosity                         -- ^ Verbosity level
        -> FilePath                          -- ^ File to read
        -> IO a
    readAndParseFile parser verbosity fpath = do
        exists <- doesFileExist fpath
        unless exists $
          die' verbosity $
            "Error Parsing: file \"" ++ fpath ++ "\" doesn't exist. Cannot continue."
        bs <- BS.readFile fpath
        let (warnings, errors, result) = runParseResult (parser bs)
        traverse_ (warn verbosity . showPWarning fpath) warnings
        traverse_ (warn verbosity . showPError fpath) errors
        case result of
            Nothing -> die' verbosity $ "Failing parsing \"" ++ fpath ++ "\"."
            Just x  -> return x

    -- | Parse the given package file.
    readGenericPackageDescription :: Verbosity -> FilePath -> IO GenericPackageDescription
    readGenericPackageDescription = readAndParseFile parseGenericPackageDescription

    ------------------------------------------------------------------------------
    -- | Parses the given file into a 'GenericPackageDescription'.
    --
    -- In Cabal 1.2 the syntax for package descriptions was changed to a format
    -- with sections and possibly indented property descriptions.
    --
    parseGenericPackageDescription :: BS.ByteString -> ParseResult GenericPackageDescription
    parseGenericPackageDescription bs = case readFields' bs' of
        Right (fs, lexWarnings) -> do
            when patched $
                parseWarning zeroPos PWTQuirkyCabalFile "Legacy cabal file"
            parseGenericPackageDescription' lexWarnings fs
        -- TODO: better marshalling of errors
        Left perr -> parseFatalFailure zeroPos (show perr)
      where
        (patched, bs') = patchQuirks bs

    -- | 'Maybe' variant of 'parseGenericPackageDescription'
    parseGenericPackageDescriptionMaybe :: BS.ByteString -> Maybe GenericPackageDescription
    parseGenericPackageDescriptionMaybe =
        trdOf3 . runParseResult . parseGenericPackageDescription
      where
        trdOf3 (_, _, x) = x

    fieldlinesToBS :: [FieldLine ann] -> BS.ByteString
    fieldlinesToBS = BS.intercalate "\n" . map (\(FieldLine _ bs) -> bs)

    -- Monad in which sections are parsed
    type SectionParser = StateT GenericPackageDescription ParseResult

    -- Note [Accumulating parser]
    --
    -- This parser has two "states":
    -- * first we parse fields of PackageDescription
    -- * then we parse sections (libraries, executables, etc)
    parseGenericPackageDescription'
        :: [LexWarning]
        -> [Field Position]
        -> ParseResult GenericPackageDescription
    parseGenericPackageDescription' lexWarnings fs = do
        parseWarnings (fmap toPWarning lexWarnings)
        let (syntax, fs') = sectionizeFields fs

        -- PackageDescription
        let (fields, sectionFields) = takeFields fs'
        pd <- parseFieldGrammar fields packageDescriptionFieldGrammar
        maybeWarnCabalVersion syntax pd

        -- Sections
        let gpd = emptyGpd & L.packageDescription .~ pd

        -- elif conditional is accepted if spec version is >= 2.1
        let hasElif = if specVersion pd >= mkVersion [2,1] then HasElif else NoElif
        execStateT (goSections hasElif sectionFields) gpd
      where
        emptyGpd :: GenericPackageDescription
        emptyGpd = GenericPackageDescription emptyPackageDescription [] Nothing [] [] [] [] []

        newSyntaxVersion :: Version
        newSyntaxVersion = mkVersion [1, 2]

        maybeWarnCabalVersion :: Syntax -> PackageDescription -> ParseResult ()
        maybeWarnCabalVersion syntax pkg
          | syntax == NewSyntax && specVersion pkg < newSyntaxVersion
          = parseWarning (Position 0 0) PWTNewSyntax $
                 "A package using section syntax must specify at least\n"
              ++ "'cabal-version: >= 1.2'."

        maybeWarnCabalVersion syntax pkg
          | syntax == OldSyntax && specVersion pkg >= newSyntaxVersion
          = parseWarning (Position 0 0) PWTOldSyntax $
                 "A package using 'cabal-version: "
              ++ displaySpecVersion (specVersionRaw pkg)
              ++ "' must use section syntax. See the Cabal user guide for details."
          where
            displaySpecVersion (Left version)       = display version
            displaySpecVersion (Right versionRange) =
              case asVersionIntervals versionRange of
                [] {- impossible -}           -> display versionRange
                ((LowerBound version _, _):_) -> display (orLaterVersion version)

        maybeWarnCabalVersion _ _ = return ()

        -- Sections
    goSections :: HasElif -> [Field Position] -> SectionParser ()
    goSections hasElif = traverse_ process
      where
        process (Field (Name pos name) _) =
            lift $ parseWarning pos PWTTrailingFields $
                "Ignoring trailing fields after sections: " ++ show name
        process (Section name args secFields) =
            parseSection name args secFields

        snoc x xs = xs ++ [x]

        parseSection :: Name Position -> [SectionArg Position] -> [Field Position] -> SectionParser ()
        parseSection (Name pos name) args fields
            | name == "library" && null args = do
                lib <- lift $ parseCondTree hasElif (libraryFieldGrammar Nothing) (targetBuildDepends . libBuildInfo) fields
                -- TODO: check that library is defined once
                L.condLibrary ?= lib

            -- Sublibraries
            | name == "library" = do
                -- TODO: check cabal-version
                name' <- parseUnqualComponentName pos args
                lib   <- lift $ parseCondTree hasElif (libraryFieldGrammar $ Just name') (targetBuildDepends . libBuildInfo) fields
                -- TODO check duplicate name here?
                L.condSubLibraries %= snoc (name', lib)

            | name == "foreign-library" = do
                name' <- parseUnqualComponentName pos args
                flib  <- lift $ parseCondTree hasElif (foreignLibFieldGrammar name') (targetBuildDepends . foreignLibBuildInfo) fields
                -- TODO check duplicate name here?
                L.condForeignLibs %= snoc (name', flib)

            | name == "executable" = do
                name' <- parseUnqualComponentName pos args
                exe   <- lift $ parseCondTree hasElif (executableFieldGrammar name') (targetBuildDepends . buildInfo) fields
                -- TODO check duplicate name here?
                L.condExecutables %= snoc (name', exe)

            | name == "test-suite" = do
                name'      <- parseUnqualComponentName pos args
                testStanza <- lift $ parseCondTree hasElif testSuiteFieldGrammar (targetBuildDepends . _testStanzaBuildInfo) fields
                testSuite  <- lift $ traverse (validateTestSuite pos) testStanza
                -- TODO check duplicate name here?
                L.condTestSuites %= snoc (name', testSuite)

            | name == "benchmark" = do
                name'       <- parseUnqualComponentName pos args
                benchStanza <- lift $ parseCondTree hasElif benchmarkFieldGrammar (targetBuildDepends . _benchmarkStanzaBuildInfo) fields
                bench       <- lift $ traverse (validateBenchmark pos) benchStanza
                -- TODO check duplicate name here?
                L.condBenchmarks %= snoc (name', bench)

            | name == "flag" = do
                name'  <- parseName pos args
                name'' <- lift $ runFieldParser' pos parsec name' `recoverWith` mkFlagName ""
                flag   <- lift $ parseFields fields (flagFieldGrammar name'')
                -- Check default flag
                L.genPackageFlags %= snoc flag

            | name == "custom-setup" && null args = do
                sbi <- lift $ parseFields fields  (setupBInfoFieldGrammar False)
                L.packageDescription . L.setupBuildInfo ?= sbi

            | name == "source-repository" = do
                kind <- lift $ case args of
                    [SecArgName spos secName] ->
                        runFieldParser' spos parsec (fromUTF8BS secName) `recoverWith` RepoHead
                    [] -> do
                        parseFailure pos "'source-repository' requires exactly one argument"
                        pure RepoHead
                    _ -> do
                        parseFailure pos $ "Invalid source-repository kind " ++ show args
                        pure RepoHead

                sr <- lift $ parseFields fields (sourceRepoFieldGrammar kind)
                L.packageDescription . L.sourceRepos %= snoc sr

            | otherwise = lift $
                parseWarning pos PWTUnknownSection $ "Ignoring section: " ++ show name

    parseName :: Position -> [SectionArg Position] -> SectionParser String
    parseName pos args = case args of
        [SecArgName _pos secName] ->
             pure $ fromUTF8BS secName
        [SecArgStr _pos secName] ->
             pure $ fromUTF8BS secName
        [] -> do
             lift $ parseFailure pos $ "name required"
             pure ""
        _ -> do
             -- TODO: pretty print args
             lift $ parseFailure pos $ "Invalid name " ++ show args
             pure ""

    parseUnqualComponentName :: Position -> [SectionArg Position] -> SectionParser UnqualComponentName
    parseUnqualComponentName pos args = mkUnqualComponentName <$> parseName pos args

    -- | Parse a non-recursive list of fields.
    parseFields
        :: [Field Position] -- ^ fields to be parsed
        -> ParsecFieldGrammar' a
        -> ParseResult a
    parseFields fields grammar = do
        let (fs0, ss) = partitionFields fields
        traverse_ (traverse_ warnInvalidSubsection) ss
        parseFieldGrammar fs0 grammar

    warnInvalidSubsection :: Section Position -> ParseResult ()
    warnInvalidSubsection (MkSection (Name pos name) _ _) =
        void (parseFailure pos $ "invalid subsection " ++ show name)

    data HasElif = HasElif | NoElif
      deriving (Eq, Show)

    parseCondTree
        :: forall a c.
           HasElif                -- ^ accept @elif@
        -> ParsecFieldGrammar' a  -- ^ grammar
        -> (a -> c)               -- ^ condition extractor
        -> [Field Position]
        -> ParseResult (CondTree ConfVar c a)
    parseCondTree hasElif grammar cond = go
      where
        go fields = do
            let (fs, ss) = partitionFields fields
            x <- parseFieldGrammar fs grammar
            branches <- concat <$> traverse parseIfs ss
            return (CondNode x (cond x) branches) -- TODO: branches

        parseIfs :: [Section Position] -> ParseResult [CondBranch ConfVar c a]
        parseIfs [] = return []
        parseIfs (MkSection (Name _ name) test fields : sections) | name == "if" = do
            test' <- parseConditionConfVar test
            fields' <- go fields
            -- TODO: else
            (elseFields, sections') <- parseElseIfs sections
            return (CondBranch test' fields' elseFields : sections')
        parseIfs (MkSection (Name pos name) _ _ : sections) = do
            parseWarning pos PWTInvalidSubsection $ "invalid subsection " ++ show name
            parseIfs sections

        parseElseIfs
            :: [Section Position]
            -> ParseResult (Maybe (CondTree ConfVar c a), [CondBranch ConfVar c a])
        parseElseIfs [] = return (Nothing, [])
        parseElseIfs (MkSection (Name pos name) args fields : sections) | name == "else" = do
            unless (null args) $
                parseFailure pos $ "`else` section has section arguments " ++ show args
            elseFields <- go fields
            sections' <- parseIfs sections
            return (Just elseFields, sections')

        parseElseIfs (MkSection (Name _ name) test fields : sections) | hasElif == HasElif, name == "elif" = do
            -- TODO: check cabal-version
            test' <- parseConditionConfVar test
            fields' <- go fields
            (elseFields, sections') <- parseElseIfs sections
            -- we parse an empty 'Fields', to get empty value for a node
            a <- parseFieldGrammar mempty grammar
            return (Just $ CondNode a (cond a) [CondBranch test' fields' elseFields], sections')

        parseElseIfs sections = (,) Nothing <$> parseIfs sections

    {- Note [Accumulating parser]

    Note: Outdated a bit

    In there parser, @'FieldDescr' a@ is transformed into @Map FieldName (a ->
    FieldParser a)@.  The weird value is used because we accumulate structure of
    @a@ by folding over the fields.  There are various reasons for that:

    * Almost all fields are optional

    * This is simple approach so declarative bi-directional format (parsing and
    printing) of structure could be specified (list of @'FieldDescr' a@)

    * There are surface syntax fields corresponding to single field in the file:
      @license-file@ and @license-files@

    * This is quite safe approach.

    When/if we re-implement the parser to support formatting preservging roundtrip
    with new AST, this all need to be rewritten.
    -}

    -------------------------------------------------------------------------------
    -- Old syntax
    -------------------------------------------------------------------------------

    -- TODO: move to own module

    -- | "Sectionize" an old-style Cabal file.  A sectionized file has:
    --
    --  * all global fields at the beginning, followed by
    --
    --  * all flag declarations, followed by
    --
    --  * an optional library section, and an arbitrary number of executable
    --    sections (in any order).
    --
    -- The current implementation just gathers all library-specific fields
    -- in a library section and wraps all executable stanzas in an executable
    -- section.
    sectionizeFields :: [Field ann] -> (Syntax, [Field ann])
    sectionizeFields fs = case classifyFields fs of
        Just fields -> (OldSyntax, convert fields)
        Nothing     -> (NewSyntax, fs)
      where
        -- return 'Just' if all fields are simple fields
        classifyFields :: [Field ann] -> Maybe [(Name ann, [FieldLine ann])]
        classifyFields = traverse f
          where
            f (Field name fieldlines) = Just (name, fieldlines)
            f _                      = Nothing

        trim = BS.dropWhile isSpace' . BS.reverse . BS.dropWhile isSpace' . BS.reverse
        isSpace' = (== 32)

        convert :: [(Name ann, [FieldLine ann])] -> [Field ann]
        convert fields =
          let
            toField (name, ls) = Field name ls
            -- "build-depends" is a local field now.  To be backwards
            -- compatible, we still allow it as a global field in old-style
            -- package description files and translate it to a local field by
            -- adding it to every non-empty section
            (hdr0, exes0) = break ((=="executable") . getName . fst) fields
            (hdr, libfs0) = partition (not . (`elem` libFieldNames) . getName . fst) hdr0

            (deps, libfs) = partition ((== "build-depends") . getName . fst)
                                       libfs0

            exes = unfoldr toExe exes0
            toExe [] = Nothing
            toExe ((Name pos n, ls) : r)
              | n == "executable" =
                  let (efs, r') = break ((== "executable") . getName . fst) r
                  in Just (Section (Name pos "executable") [SecArgName pos $ trim $ fieldlinesToBS ls] (map toField $ deps ++ efs), r')
            toExe _ = error "unexpected input to 'toExe'"

            lib = case libfs of
                []                         -> []
                ((Name pos _,  _) : _) ->
                    [Section (Name pos "library") [] (map toField $ deps ++ libfs)]

          in map toField hdr ++ lib ++ exes

    -- | See 'sectionizeFields'.
    data Syntax = OldSyntax | NewSyntax
        deriving (Eq, Show)

    libFieldNames :: [FieldName]
    libFieldNames = fieldGrammarKnownFieldList (libraryFieldGrammar Nothing)

    -------------------------------------------------------------------------------
    -- Suplementary build information
    -------------------------------------------------------------------------------

    readHookedBuildInfo :: Verbosity -> FilePath -> IO HookedBuildInfo
    readHookedBuildInfo = readAndParseFile parseHookedBuildInfo

    parseHookedBuildInfo :: BS.ByteString -> ParseResult HookedBuildInfo
    parseHookedBuildInfo bs = case readFields' bs' of
        Right (fs, lexWarnings) -> do
            when patched $
                parseWarning zeroPos PWTQuirkyCabalFile "Legacy cabal file"
            parseHookedBuildInfo' lexWarnings fs
        -- TODO: better marshalling of errors
        Left perr -> parseFatalFailure zeroPos (show perr)
      where
        (patched, bs') = patchQuirks bs

    parseHookedBuildInfo'
        :: [LexWarning]
        -> [Field Position]
        -> ParseResult HookedBuildInfo
    parseHookedBuildInfo' lexWarnings fs = do
        parseWarnings (fmap toPWarning lexWarnings)
        (mLibFields, exes) <- stanzas fs
        mLib <- parseLib mLibFields
        biExes <- traverse parseExe exes
        return (mLib, biExes)
      where
        parseLib :: Fields Position -> ParseResult (Maybe BuildInfo)
        parseLib fields
            | Map.null fields = pure Nothing
            | otherwise       = Just <$> parseFieldGrammar fields buildInfoFieldGrammar

        parseExe :: (UnqualComponentName, Fields Position) -> ParseResult (UnqualComponentName, BuildInfo)
        parseExe (n, fields) = do
            bi <- parseFieldGrammar fields buildInfoFieldGrammar
            pure (n, bi)

        stanzas :: [Field Position] -> ParseResult (Fields Position, [(UnqualComponentName, Fields Position)])
        stanzas fields = do
            let (hdr0, exes0) = breakMaybe isExecutableField fields
            hdr <- toFields hdr0
            exes <- unfoldrM (traverse toExe) exes0
            pure (hdr, exes)

        toFields :: [Field Position] -> ParseResult (Fields Position)
        toFields fields = do
            let (fields', ss) = partitionFields fields
            traverse_ (traverse_ warnInvalidSubsection) ss
            pure fields'

        toExe
            :: ([FieldLine Position], [Field Position])
            -> ParseResult ((UnqualComponentName, Fields Position), Maybe ([FieldLine Position], [Field Position]))
        toExe (fss, fields) = do
            name <- runFieldParser zeroPos parsec fss
            let (hdr0, rest) = breakMaybe isExecutableField fields
            hdr <- toFields hdr0
            pure ((name, hdr), rest)

        isExecutableField (Field (Name _ name) fss)
            | name == "executable" = Just fss
            | otherwise            = Nothing
        isExecutableField _ = Nothing