1 -----------------------------------------------------------------------------
3 -- GHCi Interactive debugging commands
5 -- Pepe Iborra (supported by Google SoC) 2006
7 -- ToDo: lots of violation of layering here. This module should
8 -- decide whether it is above the GHC API (import GHC and nothing
11 -----------------------------------------------------------------------------
13 module Debugger (pprintClosureCommand, showTerm, pprTypeAndContents) where
16 import RtClosureInspect
22 import Var hiding ( varName )
29 import InteractiveEval
34 import Control.Exception
43 -------------------------------------
44 -- | The :print & friends commands
45 -------------------------------------
46 pprintClosureCommand :: Session -> Bool -> Bool -> String -> IO ()
47 pprintClosureCommand session bindThings force str = do
48 tythings <- (catMaybes . concat) `liftM`
49 mapM (\w -> GHC.parseName session w >>=
50 mapM (GHC.lookupName session))
52 let ids = [id | AnId id <- tythings]
54 -- Obtain the terms and the recovered type information
55 (terms, substs) <- unzip `liftM` mapM (go session) ids
57 -- Apply the substitutions obtained after recovering the types
58 modifySession session $ \hsc_env ->
59 hsc_env{hsc_IC = foldr (flip substInteractiveContext)
61 (map skolemiseSubst substs)}
62 -- Finally, print the Terms
63 unqual <- GHC.getPrintUnqual session
64 docterms <- mapM (showTerm session) terms
65 (printForUser stdout unqual . vcat)
66 (zipWith (\id docterm -> ppr id <+> char '=' <+> docterm)
71 -- Do the obtainTerm--bindSuspensions-computeSubstitution dance
72 go :: Session -> Id -> IO (Term, TvSubst)
74 term_ <- GHC.obtainTerm cms force id
75 term <- tidyTermTyVars cms term_
76 term' <- if not bindThings then return term
77 else bindSuspensions cms term
78 -- Before leaving, we compare the type obtained to see if it's more specific
79 -- Then, we extract a substitution,
80 -- mapping the old tyvars to the reconstructed types.
81 let Just reconstructed_type = termType term
82 subst = computeRTTIsubst (idType id) (reconstructed_type)
85 tidyTermTyVars :: Session -> Term -> IO Term
86 tidyTermTyVars (Session ref) t = do
87 hsc_env <- readIORef ref
88 let env_tvs = ic_tyvars (hsc_IC hsc_env)
90 tvs = env_tvs `minusVarSet` my_tvs
91 tyvarOccName = nameOccName . tyVarName
92 tidyEnv = (initTidyOccEnv (map tyvarOccName (varSetElems tvs))
93 , env_tvs `intersectVarSet` my_tvs)
94 return$ mapTermType (snd . tidyOpenType tidyEnv) t
96 -- | Give names, and bind in the interactive environment, to all the suspensions
97 -- included (inductively) in a term
98 bindSuspensions :: Session -> Term -> IO Term
99 bindSuspensions cms@(Session ref) t = do
100 hsc_env <- readIORef ref
101 inScope <- GHC.getBindings cms
102 let ictxt = hsc_IC hsc_env
104 alreadyUsedNames = map (occNameString . nameOccName . getName) inScope
105 availNames = map ((prefix++) . show) [(1::Int)..] \\ alreadyUsedNames
106 availNames_var <- newIORef availNames
107 (t', stuff) <- foldTerm (nameSuspensionsAndGetInfos availNames_var) t
108 let (names, tys, hvals) = unzip3 stuff
109 let tys' = map (fst.skolemiseTy) tys
110 let ids = [ mkGlobalId VanillaGlobal name ty vanillaIdInfo
111 | (name,ty) <- zip names tys']
112 new_tyvars = tyVarsOfTypes tys'
113 new_ic = extendInteractiveContext ictxt ids new_tyvars
114 extendLinkEnv (zip names hvals)
115 writeIORef ref (hsc_env {hsc_IC = new_ic })
119 -- Processing suspensions. Give names and recopilate info
120 nameSuspensionsAndGetInfos :: IORef [String] ->
121 TermFold (IO (Term, [(Name,Type,HValue)]))
122 nameSuspensionsAndGetInfos freeNames = TermFold
124 fSuspension = doSuspension freeNames
125 , fTerm = \ty dc v tt -> do
127 let (terms,names) = unzip tt'
128 return (Term ty dc v terms, concat names)
129 , fPrim = \ty n ->return (Prim ty n,[])
133 return (NewtypeWrap ty dc term, names)
135 doSuspension freeNames ct mb_ty hval _name = do
136 name <- atomicModifyIORef freeNames (\x->(tail x, head x))
137 n <- newGrimName name
138 let ty' = fromMaybe (error "unexpected") mb_ty
139 return (Suspension ct mb_ty hval (Just n), [(n,ty',hval)])
142 -- A custom Term printer to enable the use of Show instances
143 showTerm :: Session -> Term -> IO SDoc
144 showTerm cms@(Session ref) term = do
145 dflags <- GHC.getSessionDynFlags cms
146 if dopt Opt_PrintEvldWithShow dflags
147 then cPprTerm (liftM2 (++) (\_y->[cPprShowable]) cPprTermBase) term
148 else cPprTerm cPprTermBase term
150 cPprShowable prec t@Term{ty=ty, val=val} =
151 if not (isFullyEvaluatedTerm t)
154 hsc_env <- readIORef ref
155 dflags <- GHC.getSessionDynFlags cms
157 (new_env, bname) <- bindToFreshName hsc_env ty "showme"
158 writeIORef ref (new_env)
159 let noop_log _ _ _ _ = return ()
160 expr = "show " ++ showSDoc (ppr bname)
161 GHC.setSessionDynFlags cms dflags{log_action=noop_log}
162 mb_txt <- withExtendedLinkEnv [(bname, val)]
163 (GHC.compileExpr cms expr)
164 let myprec = 10 -- application precedence. TODO Infix constructors
166 Just txt_ | txt <- unsafeCoerce# txt_, not (null txt)
167 -> return $ Just$ cparen (prec >= myprec &&
172 writeIORef ref hsc_env
173 GHC.setSessionDynFlags cms dflags
174 cPprShowable prec NewtypeWrap{ty=new_ty,wrapped_term=t} =
175 cPprShowable prec t{ty=new_ty}
176 cPprShowable _ _ = panic "cPprShowable - unreachable"
178 needsParens ('"':_) = False -- some simple heuristics to see whether parens
179 -- are redundant in an arbitrary Show output
180 needsParens ('(':_) = False
181 needsParens txt = ' ' `elem` txt
184 bindToFreshName hsc_env ty userName = do
185 name <- newGrimName userName
186 let ictxt = hsc_IC hsc_env
187 tmp_ids = ic_tmp_ids ictxt
188 id = mkGlobalId VanillaGlobal name (sigmaType ty) vanillaIdInfo
189 new_ic = ictxt { ic_tmp_ids = id : tmp_ids }
190 return (hsc_env {hsc_IC = new_ic }, name)
192 -- Create new uniques and give them sequentially numbered names
193 newGrimName :: String -> IO Name
194 newGrimName userName = do
195 us <- mkSplitUniqSupply 'b'
196 let unique = uniqFromSupply us
197 occname = mkOccName varName userName
198 name = mkInternalName unique occname noSrcSpan
201 pprTypeAndContents :: Session -> [Id] -> IO SDoc
202 pprTypeAndContents session ids = do
203 dflags <- GHC.getSessionDynFlags session
204 let pefas = dopt Opt_PrintExplicitForalls dflags
205 pcontents = dopt Opt_PrintBindContents dflags
209 terms <- mapM (GHC.obtainTermB session depthBound False) ids
210 docs_terms <- mapM (showTerm session) terms
211 return $ vcat $ zipWith (\ty cts -> ty <+> equals <+> cts)
212 (map (pprTyThing pefas . AnId) ids)
214 else return $ vcat $ map (pprTyThing pefas . AnId) ids