1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
|
{-# LANGUAGE CPP, RankNTypes #-}
{-# OPTIONS_GHC -funbox-strict-fields #-}
-- -----------------------------------------------------------------------------
--
-- (c) The University of Glasgow, 2010
--
-- The Session type and related functionality
--
-- -----------------------------------------------------------------------------
module GhcMonad (
-- * 'Ghc' monad stuff
GhcMonad(..),
Ghc(..),
GhcT(..), liftGhcT,
reflectGhc, reifyGhc,
getSessionDynFlags,
liftIO,
Session(..), withSession, modifySession, withTempSession,
-- ** Warnings
logWarnings, printException,
WarnErrLogger, defaultWarnErrLogger
) where
import GhcPrelude
import MonadUtils
import HscTypes
import DynFlags
import Exception
import ErrUtils
import Control.Monad
import Data.IORef
-- -----------------------------------------------------------------------------
-- | A monad that has all the features needed by GHC API calls.
--
-- In short, a GHC monad
--
-- - allows embedding of IO actions,
--
-- - can log warnings,
--
-- - allows handling of (extensible) exceptions, and
--
-- - maintains a current session.
--
-- If you do not use 'Ghc' or 'GhcT', make sure to call 'GHC.initGhcMonad'
-- before any call to the GHC API functions can occur.
--
class (Functor m, MonadIO m, ExceptionMonad m, HasDynFlags m) => GhcMonad m where
getSession :: m HscEnv
setSession :: HscEnv -> m ()
-- | Call the argument with the current session.
withSession :: GhcMonad m => (HscEnv -> m a) -> m a
withSession f = getSession >>= f
-- | Grabs the DynFlags from the Session
getSessionDynFlags :: GhcMonad m => m DynFlags
getSessionDynFlags = withSession (return . hsc_dflags)
-- | Set the current session to the result of applying the current session to
-- the argument.
modifySession :: GhcMonad m => (HscEnv -> HscEnv) -> m ()
modifySession f = do h <- getSession
setSession $! f h
withSavedSession :: GhcMonad m => m a -> m a
withSavedSession m = do
saved_session <- getSession
m `gfinally` setSession saved_session
-- | Call an action with a temporarily modified Session.
withTempSession :: GhcMonad m => (HscEnv -> HscEnv) -> m a -> m a
withTempSession f m =
withSavedSession $ modifySession f >> m
-- -----------------------------------------------------------------------------
-- | A monad that allows logging of warnings.
logWarnings :: GhcMonad m => WarningMessages -> m ()
logWarnings warns = do
dflags <- getSessionDynFlags
liftIO $ printOrThrowWarnings dflags warns
-- -----------------------------------------------------------------------------
-- | A minimal implementation of a 'GhcMonad'. If you need a custom monad,
-- e.g., to maintain additional state consider wrapping this monad or using
-- 'GhcT'.
newtype Ghc a = Ghc { unGhc :: Session -> IO a }
-- | The Session is a handle to the complete state of a compilation
-- session. A compilation session consists of a set of modules
-- constituting the current program or library, the context for
-- interactive evaluation, and various caches.
data Session = Session !(IORef HscEnv)
instance Functor Ghc where
fmap f m = Ghc $ \s -> f `fmap` unGhc m s
instance Applicative Ghc where
pure a = Ghc $ \_ -> return a
g <*> m = do f <- g; a <- m; return (f a)
instance Monad Ghc where
m >>= g = Ghc $ \s -> do a <- unGhc m s; unGhc (g a) s
instance MonadIO Ghc where
liftIO ioA = Ghc $ \_ -> ioA
instance MonadFix Ghc where
mfix f = Ghc $ \s -> mfix (\x -> unGhc (f x) s)
instance ExceptionMonad Ghc where
gcatch act handle =
Ghc $ \s -> unGhc act s `gcatch` \e -> unGhc (handle e) s
gmask f =
Ghc $ \s -> gmask $ \io_restore ->
let
g_restore (Ghc m) = Ghc $ \s -> io_restore (m s)
in
unGhc (f g_restore) s
instance HasDynFlags Ghc where
getDynFlags = getSessionDynFlags
instance GhcMonad Ghc where
getSession = Ghc $ \(Session r) -> readIORef r
setSession s' = Ghc $ \(Session r) -> writeIORef r s'
-- | Reflect a computation in the 'Ghc' monad into the 'IO' monad.
--
-- You can use this to call functions returning an action in the 'Ghc' monad
-- inside an 'IO' action. This is needed for some (too restrictive) callback
-- arguments of some library functions:
--
-- > libFunc :: String -> (Int -> IO a) -> IO a
-- > ghcFunc :: Int -> Ghc a
-- >
-- > ghcFuncUsingLibFunc :: String -> Ghc a -> Ghc a
-- > ghcFuncUsingLibFunc str =
-- > reifyGhc $ \s ->
-- > libFunc $ \i -> do
-- > reflectGhc (ghcFunc i) s
--
reflectGhc :: Ghc a -> Session -> IO a
reflectGhc m = unGhc m
-- > Dual to 'reflectGhc'. See its documentation.
reifyGhc :: (Session -> IO a) -> Ghc a
reifyGhc act = Ghc $ act
-- -----------------------------------------------------------------------------
-- | A monad transformer to add GHC specific features to another monad.
--
-- Note that the wrapped monad must support IO and handling of exceptions.
newtype GhcT m a = GhcT { unGhcT :: Session -> m a }
liftGhcT :: m a -> GhcT m a
liftGhcT m = GhcT $ \_ -> m
instance Functor m => Functor (GhcT m) where
fmap f m = GhcT $ \s -> f `fmap` unGhcT m s
instance Applicative m => Applicative (GhcT m) where
pure x = GhcT $ \_ -> pure x
g <*> m = GhcT $ \s -> unGhcT g s <*> unGhcT m s
instance Monad m => Monad (GhcT m) where
m >>= k = GhcT $ \s -> do a <- unGhcT m s; unGhcT (k a) s
instance MonadIO m => MonadIO (GhcT m) where
liftIO ioA = GhcT $ \_ -> liftIO ioA
instance ExceptionMonad m => ExceptionMonad (GhcT m) where
gcatch act handle =
GhcT $ \s -> unGhcT act s `gcatch` \e -> unGhcT (handle e) s
gmask f =
GhcT $ \s -> gmask $ \io_restore ->
let
g_restore (GhcT m) = GhcT $ \s -> io_restore (m s)
in
unGhcT (f g_restore) s
instance MonadIO m => HasDynFlags (GhcT m) where
getDynFlags = GhcT $ \(Session r) -> liftM hsc_dflags (liftIO $ readIORef r)
instance ExceptionMonad m => GhcMonad (GhcT m) where
getSession = GhcT $ \(Session r) -> liftIO $ readIORef r
setSession s' = GhcT $ \(Session r) -> liftIO $ writeIORef r s'
-- | Print the error message and all warnings. Useful inside exception
-- handlers. Clears warnings after printing.
printException :: GhcMonad m => SourceError -> m ()
printException err = do
dflags <- getSessionDynFlags
liftIO $ printBagOfErrors dflags (srcErrorMessages err)
-- | A function called to log warnings and errors.
type WarnErrLogger = forall m. GhcMonad m => Maybe SourceError -> m ()
defaultWarnErrLogger :: WarnErrLogger
defaultWarnErrLogger Nothing = return ()
defaultWarnErrLogger (Just e) = printException e
|
