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|
module GHC.Types.SourceFile
( HscSource(..)
, hscSourceToIsBoot
, isHsBootOrSig
, isHsigFile
, hscSourceString
)
where
import GHC.Prelude
import GHC.Utils.Binary
import GHC.Unit.Types
-- Note [HscSource types]
-- ~~~~~~~~~~~~~~~~~~~~~~
-- There are three types of source file for Haskell code:
--
-- * HsSrcFile is an ordinary hs file which contains code,
--
-- * HsBootFile is an hs-boot file, which is used to break
-- recursive module imports (there will always be an
-- HsSrcFile associated with it), and
--
-- * HsigFile is an hsig file, which contains only type
-- signatures and is used to specify signatures for
-- modules.
--
-- Syntactically, hs-boot files and hsig files are quite similar: they
-- only include type signatures and must be associated with an
-- actual HsSrcFile. isHsBootOrSig allows us to abstract over code
-- which is indifferent to which. However, there are some important
-- differences, mostly owing to the fact that hsigs are proper
-- modules (you `import Sig` directly) whereas HsBootFiles are
-- temporary placeholders (you `import {-# SOURCE #-} Mod).
-- When we finish compiling the true implementation of an hs-boot,
-- we replace the HomeModInfo with the real HsSrcFile. An HsigFile, on the
-- other hand, is never replaced (in particular, we *cannot* use the
-- HomeModInfo of the original HsSrcFile backing the signature, since it
-- will export too many symbols.)
--
-- Additionally, while HsSrcFile is the only Haskell file
-- which has *code*, we do generate .o files for HsigFile, because
-- this is how the recompilation checker figures out if a file
-- needs to be recompiled. These are fake object files which
-- should NOT be linked against.
data HscSource
= HsSrcFile -- ^ .hs file
| HsBootFile -- ^ .hs-boot file
| HsigFile -- ^ .hsig file
deriving (Eq, Ord, Show)
-- | Tests if an 'HscSource' is a boot file, primarily for constructing elements
-- of 'BuildModule'. We conflate signatures and modules because they are bound
-- in the same namespace; only boot interfaces can be disambiguated with
-- `import {-# SOURCE #-}`.
hscSourceToIsBoot :: HscSource -> IsBootInterface
hscSourceToIsBoot HsBootFile = IsBoot
hscSourceToIsBoot _ = NotBoot
instance Binary HscSource where
put_ bh HsSrcFile = putByte bh 0
put_ bh HsBootFile = putByte bh 1
put_ bh HsigFile = putByte bh 2
get bh = do
h <- getByte bh
case h of
0 -> return HsSrcFile
1 -> return HsBootFile
_ -> return HsigFile
hscSourceString :: HscSource -> String
hscSourceString HsSrcFile = ""
hscSourceString HsBootFile = "[boot]"
hscSourceString HsigFile = "[sig]"
-- See Note [HscSource types]
isHsBootOrSig :: HscSource -> Bool
isHsBootOrSig HsBootFile = True
isHsBootOrSig HsigFile = True
isHsBootOrSig _ = False
isHsigFile :: HscSource -> Bool
isHsigFile HsigFile = True
isHsigFile _ = False
|
