2 % (c) The GRASP/AQUA Project, Glasgow University, 1999
4 \section[ParseUtil]{Parser Utilities}
8 parseError -- String -> Pa
10 , mkVanillaCon, mkRecCon,
12 , mkRecConstrOrUpdate -- HsExp -> [HsFieldUpdate] -> P HsExp
15 , mkExtName -- RdrName -> ExtName
17 , checkPrec -- String -> P String
18 , checkContext -- HsType -> P HsContext
19 , checkInstType -- HsType -> P HsType
20 , checkDataHeader -- HsQualType -> P (HsContext,HsName,[HsName])
21 , checkSimple -- HsType -> [HsName] -> P ((HsName,[HsName]))
22 , checkPattern -- HsExp -> P HsPat
23 , checkPatterns -- SrcLoc -> [HsExp] -> P [HsPat]
24 , checkDo -- [HsStmt] -> P [HsStmt]
25 , checkValDef -- (SrcLoc, HsExp, HsRhs, [HsDecl]) -> P HsDecl
26 , checkValSig -- (SrcLoc, HsExp, HsRhs, [HsDecl]) -> P HsDecl
29 #include "HsVersions.h"
32 import HsSyn -- Lots of it
34 import RdrHsSyn ( RdrBinding(..),
35 RdrNameHsType, RdrNameBangType, RdrNameContext,
36 RdrNameHsTyVar, RdrNamePat, RdrNameHsExpr, RdrNameGRHSs,
37 RdrNameHsRecordBinds, RdrNameMonoBinds, RdrNameConDetails
40 import PrelNames ( unitTyCon_RDR )
41 import ForeignCall ( CCallConv(..) )
42 import OccName ( dataName, varName, tcClsName,
43 occNameSpace, setOccNameSpace, occNameUserString )
44 import CStrings ( CLabelString )
45 import FastString ( unpackFS )
46 import UniqFM ( UniqFM, listToUFM )
49 -----------------------------------------------------------------------------
52 parseError :: String -> P a
54 getSrcLocP `thenP` \ loc ->
55 failMsgP (hcat [ppr loc, text ": ", text s])
57 cbot = panic "CCall:result_ty"
59 -----------------------------------------------------------------------------
62 -- When parsing data declarations, we sometimes inadvertently parse
63 -- a constructor application as a type (eg. in data T a b = C a b `D` E a b)
64 -- This function splits up the type application, adds any pending
65 -- arguments, and converts the type constructor back into a data constructor.
67 mkVanillaCon :: RdrNameHsType -> [RdrNameBangType] -> P (RdrName, RdrNameConDetails)
72 split (HsAppTy t u) ts = split t (unbangedType u : ts)
73 split (HsTyVar tc) ts = tyConToDataCon tc `thenP` \ data_con ->
74 returnP (data_con, VanillaCon ts)
75 split _ _ = parseError "Illegal data/newtype declaration"
77 mkRecCon :: RdrName -> [([RdrName],RdrNameBangType)] -> P (RdrName, RdrNameConDetails)
79 = tyConToDataCon con `thenP` \ data_con ->
80 returnP (data_con, RecCon fields)
82 tyConToDataCon :: RdrName -> P RdrName
84 | occNameSpace tc_occ == tcClsName
85 = returnP (setRdrNameOcc tc (setOccNameSpace tc_occ dataName))
87 = parseError (showSDoc (text "not a constructor:" <+> quotes (ppr tc)))
89 tc_occ = rdrNameOcc tc
92 ----------------------------------------------------------------------------
93 -- Various Syntactic Checks
95 checkInstType :: RdrNameHsType -> P RdrNameHsType
98 HsForAllTy tvs ctxt ty ->
99 checkDictTy ty [] `thenP` \ dict_ty ->
100 returnP (HsForAllTy tvs ctxt dict_ty)
102 ty -> checkDictTy ty [] `thenP` \ dict_ty->
103 returnP (HsForAllTy Nothing [] dict_ty)
105 checkContext :: RdrNameHsType -> P RdrNameContext
106 checkContext (HsTupleTy _ ts)
107 = mapP (\t -> checkPred t []) ts `thenP` \ps ->
109 checkContext (HsTyVar t) -- empty contexts are allowed
110 | t == unitTyCon_RDR = returnP []
112 = checkPred t [] `thenP` \p ->
115 checkPred :: RdrNameHsType -> [RdrNameHsType]
116 -> P (HsPred RdrName)
117 checkPred (HsTyVar t) args@(_:_) | not (isRdrTyVar t)
118 = returnP (HsClassP t args)
119 checkPred (HsAppTy l r) args = checkPred l (r:args)
120 checkPred (HsPredTy (HsIParam n ty)) [] = returnP (HsIParam n ty)
121 checkPred _ _ = parseError "Illegal class assertion"
123 checkDictTy :: RdrNameHsType -> [RdrNameHsType] -> P RdrNameHsType
124 checkDictTy (HsTyVar t) args@(_:_) | not (isRdrTyVar t)
125 = returnP (mkHsDictTy t args)
126 checkDictTy (HsAppTy l r) args = checkDictTy l (r:args)
127 checkDictTy _ _ = parseError "Malformed context in instance header"
129 -- Put more comments!
130 -- Checks that the lhs of a datatype declaration
131 -- is of the form Context => T a b ... z
132 checkDataHeader :: RdrNameHsType
133 -> P (RdrNameContext, RdrName, [RdrNameHsTyVar])
135 checkDataHeader (HsForAllTy Nothing cs t) =
136 checkSimple t [] `thenP` \(c,ts) ->
137 returnP (cs,c,map UserTyVar ts)
139 checkSimple t [] `thenP` \(c,ts) ->
140 returnP ([],c,map UserTyVar ts)
142 -- Checks the type part of the lhs of a datatype declaration
143 checkSimple :: RdrNameHsType -> [RdrName] -> P ((RdrName,[RdrName]))
144 checkSimple (HsAppTy l (HsTyVar a)) xs | isRdrTyVar a
145 = checkSimple l (a:xs)
146 checkSimple (HsTyVar tycon) xs | not (isRdrTyVar tycon) = returnP (tycon,xs)
148 checkSimple (HsOpTy (HsTyVar t1) tycon (HsTyVar t2)) []
149 | not (isRdrTyVar tycon) && isRdrTyVar t1 && isRdrTyVar t2
150 = returnP (tycon,[t1,t2])
152 checkSimple t _ = parseError "Illegal left hand side in data/newtype declaration"
154 ---------------------------------------------------------------------------
155 -- Checking statements in a do-expression
156 -- We parse do { e1 ; e2 ; }
157 -- as [ExprStmt e1, ExprStmt e2]
158 -- checkDo (a) checks that the last thing is an ExprStmt
159 -- (b) transforms it to a ResultStmt
161 checkDo [] = parseError "Empty 'do' construct"
162 checkDo [ExprStmt e l] = returnP [ResultStmt e l]
163 checkDo [s] = parseError "The last statment in a 'do' construct must be an expression"
164 checkDo (s:ss) = checkDo ss `thenP` \ ss' ->
167 ---------------------------------------------------------------------------
168 -- Checking Patterns.
170 -- We parse patterns as expressions and check for valid patterns below,
171 -- converting the expression into a pattern at the same time.
173 checkPattern :: SrcLoc -> RdrNameHsExpr -> P RdrNamePat
174 checkPattern loc e = setSrcLocP loc (checkPat e [])
176 checkPatterns :: SrcLoc -> [RdrNameHsExpr] -> P [RdrNamePat]
177 checkPatterns loc es = mapP (checkPattern loc) es
179 checkPat :: RdrNameHsExpr -> [RdrNamePat] -> P RdrNamePat
180 checkPat (HsVar c) args | isRdrDataCon c = returnP (ConPatIn c args)
181 checkPat (HsApp f x) args =
182 checkPat x [] `thenP` \x ->
184 checkPat e [] = case e of
185 EWildPat -> returnP WildPatIn
186 HsVar x -> returnP (VarPatIn x)
187 HsLit l -> returnP (LitPatIn l)
188 HsOverLit l -> returnP (NPatIn l)
189 ELazyPat e -> checkPat e [] `thenP` (returnP . LazyPatIn)
190 EAsPat n e -> checkPat e [] `thenP` (returnP . AsPatIn n)
191 ExprWithTySig e t -> checkPat e [] `thenP` \e ->
192 -- Pattern signatures are parsed as sigtypes,
193 -- but they aren't explicit forall points. Hence
194 -- we have to remove the implicit forall here.
196 HsForAllTy Nothing [] ty -> ty
199 returnP (SigPatIn e t')
201 OpApp (HsVar n) (HsVar plus) _ (HsOverLit lit@(HsIntegral k))
203 -> returnP (NPlusKPatIn n lit)
205 plus_RDR = mkUnqual varName SLIT("+") -- Hack
207 OpApp l op fix r -> checkPat l [] `thenP` \l ->
208 checkPat r [] `thenP` \r ->
210 HsVar c -> returnP (ConOpPatIn l c fix r)
213 HsPar e -> checkPat e [] `thenP` (returnP . ParPatIn)
214 ExplicitList es -> mapP (\e -> checkPat e []) es `thenP` \ps ->
215 returnP (ListPatIn ps)
217 ExplicitTuple es b -> mapP (\e -> checkPat e []) es `thenP` \ps ->
218 returnP (TuplePatIn ps b)
220 RecordCon c fs -> mapP checkPatField fs `thenP` \fs ->
221 returnP (RecPatIn c fs)
223 HsType ty -> returnP (TypePatIn ty)
226 checkPat _ _ = patFail
228 checkPatField :: (RdrName, RdrNameHsExpr, Bool)
229 -> P (RdrName, RdrNamePat, Bool)
230 checkPatField (n,e,b) =
231 checkPat e [] `thenP` \p ->
234 patFail = parseError "Parse error in pattern"
237 ---------------------------------------------------------------------------
238 -- Check Equation Syntax
242 -> Maybe RdrNameHsType
247 checkValDef lhs opt_sig grhss loc
248 = case isFunLhs lhs [] of
250 checkPatterns loc es `thenP` \ps ->
251 returnP (RdrValBinding (FunMonoBind f inf [Match [] ps opt_sig grhss] loc))
254 checkPattern loc lhs `thenP` \lhs ->
255 returnP (RdrValBinding (PatMonoBind lhs grhss loc))
262 checkValSig (HsVar v) ty loc = returnP (RdrSig (Sig v ty loc))
263 checkValSig other ty loc = parseError "Type signature given for an expression"
266 -- A variable binding is parsed as an RdrNameFunMonoBind.
267 -- See comments with HsBinds.MonoBinds
269 isFunLhs :: RdrNameHsExpr -> [RdrNameHsExpr] -> Maybe (RdrName, Bool, [RdrNameHsExpr])
270 isFunLhs (OpApp l (HsVar op) fix r) es | not (isRdrDataCon op)
271 = Just (op, True, (l:r:es))
273 = case isFunLhs l es of
274 Just (op', True, j : k : es') ->
275 Just (op', True, j : OpApp k (HsVar op) fix r : es')
277 isFunLhs (HsVar f) es | not (isRdrDataCon f)
279 isFunLhs (HsApp f e) es = isFunLhs f (e:es)
280 isFunLhs (HsPar e) es = isFunLhs e es
281 isFunLhs _ _ = Nothing
283 ---------------------------------------------------------------------------
284 -- Miscellaneous utilities
286 checkPrec :: Integer -> P ()
287 checkPrec i | 0 <= i && i <= 9 = returnP ()
288 | otherwise = parseError "precedence out of range"
292 -> RdrNameHsRecordBinds
295 mkRecConstrOrUpdate (HsVar c) fs | isRdrDataCon c
296 = returnP (RecordCon c fs)
297 mkRecConstrOrUpdate exp fs@(_:_)
298 = returnP (RecordUpd exp fs)
299 mkRecConstrOrUpdate _ _
300 = parseError "Empty record update"
302 -- Supplying the ext_name in a foreign decl is optional ; if it
303 -- isn't there, the Haskell name is assumed. Note that no transformation
304 -- of the Haskell name is then performed, so if you foreign export (++),
305 -- it's external name will be "++". Too bad; it's important because we don't
306 -- want z-encoding (e.g. names with z's in them shouldn't be doubled)
307 -- (This is why we use occNameUserString.)
309 mkExtName :: RdrName -> CLabelString
310 mkExtName rdrNm = _PK_ (occNameUserString (rdrNameOcc rdrNm))
312 -----------------------------------------------------------------------------
313 -- group function bindings into equation groups
315 -- we assume the bindings are coming in reverse order, so we take the srcloc
316 -- from the *last* binding in the group as the srcloc for the whole group.
318 groupBindings :: [RdrBinding] -> RdrBinding
319 groupBindings binds = group Nothing binds
320 where group :: Maybe RdrNameMonoBinds -> [RdrBinding] -> RdrBinding
321 group (Just bind) [] = RdrValBinding bind
322 group Nothing [] = RdrNullBind
324 -- don't group together FunMonoBinds if they have
325 -- no arguments. This is necessary now that variable bindings
326 -- with no arguments are now treated as FunMonoBinds rather
327 -- than pattern bindings (tests/rename/should_fail/rnfail002).
328 group (Just (FunMonoBind f inf1 mtchs ignore_srcloc))
329 (RdrValBinding (FunMonoBind f' _
330 [mtch@(Match _ (_:_) _ _)] loc)
332 | f == f' = group (Just (FunMonoBind f inf1 (mtch:mtchs) loc)) binds
334 group (Just so_far) binds
335 = RdrValBinding so_far `RdrAndBindings` group Nothing binds
336 group Nothing (bind:binds)
338 RdrValBinding b@(FunMonoBind _ _ _ _) -> group (Just b) binds
339 other -> bind `RdrAndBindings` group Nothing binds