1 -----------------------------------------------------------------------------
3 -- Pretty-printing TyThings
5 -- (c) The GHC Team 2005
7 -----------------------------------------------------------------------------
13 pprTyThingInContextLoc,
17 #include "HsVersions.h"
20 import GHC ( TyThing(..), SrcLoc )
23 -- -----------------------------------------------------------------------------
24 -- Pretty-printing entities that we get from the GHC API
26 -- This should be a good source of sample code for using the GHC API to
27 -- inspect source code entities.
29 -- | Pretty-prints a 'TyThing' with its defining location.
30 pprTyThingLoc :: Bool -> TyThing -> SDoc
31 pprTyThingLoc exts tyThing
32 = showWithLoc loc (pprTyThing exts tyThing)
33 where loc = GHC.nameSrcLoc (GHC.getName tyThing)
35 -- | Pretty-prints a 'TyThing'.
36 pprTyThing :: Bool -> TyThing -> SDoc
37 pprTyThing exts (AnId id) = pprId exts id
38 pprTyThing exts (ADataCon dataCon) = pprDataConSig exts dataCon
39 pprTyThing exts (ATyCon tyCon) = pprTyCon exts tyCon
40 pprTyThing exts (AClass cls) = pprClass exts cls
42 -- | Like 'pprTyThingInContext', but adds the defining location.
43 pprTyThingInContextLoc :: Bool -> TyThing -> SDoc
44 pprTyThingInContextLoc exts tyThing
45 = showWithLoc loc (pprTyThingInContext exts tyThing)
46 where loc = GHC.nameSrcLoc (GHC.getName tyThing)
48 -- | Pretty-prints a 'TyThing' in context: that is, if the entity
49 -- is a data constructor, record selector, or class method, then
50 -- the entity's parent declaration is pretty-printed with irrelevant
52 pprTyThingInContext :: Bool -> TyThing -> SDoc
53 pprTyThingInContext exts (AnId id) = pprIdInContext exts id
54 pprTyThingInContext exts (ADataCon dataCon) = pprDataCon exts dataCon
55 pprTyThingInContext exts (ATyCon tyCon) = pprTyCon exts tyCon
56 pprTyThingInContext exts (AClass cls) = pprClass exts cls
58 -- | Pretty-prints the 'TyThing' header. For functions and data constructors
59 -- the function is equivalent to 'pprTyThing' but for type constructors
60 -- and classes it prints only the header part of the declaration.
61 pprTyThingHdr :: Bool -> TyThing -> SDoc
62 pprTyThingHdr exts (AnId id) = pprId exts id
63 pprTyThingHdr exts (ADataCon dataCon) = pprDataConSig exts dataCon
64 pprTyThingHdr exts (ATyCon tyCon) = pprTyConHdr exts tyCon
65 pprTyThingHdr exts (AClass cls) = pprClassHdr exts cls
67 pprTyConHdr exts tyCon =
68 ptext keyword <+> ppr_bndr tyCon <+> hsep (map ppr vars)
70 vars | GHC.isPrimTyCon tyCon = take (GHC.tyConArity tyCon) GHC.alphaTyVars
71 | otherwise = GHC.tyConTyVars tyCon
73 keyword | GHC.isSynTyCon tyCon = SLIT("type")
74 | GHC.isNewTyCon tyCon = SLIT("newtype")
75 | otherwise = SLIT("data")
77 pprDataConSig exts dataCon =
78 ppr_bndr dataCon <+> dcolon <+> pprType exts (GHC.dataConType dataCon)
80 pprClassHdr exts cls =
81 let (tyVars, funDeps) = GHC.classTvsFds cls
82 in ptext SLIT("class") <+>
83 GHC.pprThetaArrow (GHC.classSCTheta cls) <+>
85 hsep (map ppr tyVars) <+>
86 GHC.pprFundeps funDeps
88 pprIdInContext exts id
89 | GHC.isRecordSelector id = pprRecordSelector exts id
90 | Just cls <- GHC.isClassOpId_maybe id = pprClassOneMethod exts cls id
91 | otherwise = pprId exts id
93 pprRecordSelector exts id
94 = pprAlgTyCon exts tyCon show_con show_label
96 (tyCon,label) = GHC.recordSelectorFieldLabel id
97 show_con dataCon = label `elem` GHC.dataConFieldLabels dataCon
98 show_label label' = label == label'
101 = hang (ppr_bndr id <+> dcolon) 2
102 (pprType exts (GHC.idType id))
104 pprType True ty = ppr ty
105 pprType False ty = ppr (GHC.dropForAlls ty)
108 | GHC.isSynTyCon tyCon
109 = let (_,rhs_type) = GHC.getSynTyConDefn tyCon
110 in hang (pprTyConHdr exts tyCon <+> equals) 2 (pprType exts rhs_type)
112 = pprAlgTyCon exts tyCon (const True) (const True)
114 pprAlgTyCon exts tyCon ok_con ok_label
115 | gadt = pprTyConHdr exts tyCon <+> ptext SLIT("where") $$
116 nest 2 (vcat (ppr_trim show_con datacons))
117 | otherwise = hang (pprTyConHdr exts tyCon)
118 2 (add_bars (ppr_trim show_con datacons))
120 datacons = GHC.tyConDataCons tyCon
121 gadt = any (not . GHC.isVanillaDataCon) datacons
124 | ok_con dataCon = Just (pprDataConDecl exts gadt ok_label dataCon)
125 | otherwise = Nothing
127 pprDataCon exts dataCon = pprAlgTyCon exts tyCon (== dataCon) (const True)
128 where tyCon = GHC.dataConTyCon dataCon
130 pprDataConDecl exts gadt_style show_label dataCon
131 | not gadt_style = ppr_fields tys_w_strs
132 | otherwise = ppr_bndr dataCon <+> dcolon <+>
133 sep [ ppr_tvs, GHC.pprThetaArrow theta, pp_tau ]
135 (tyvars, theta, argTypes, tyCon, res_tys) = GHC.dataConSig dataCon
136 labels = GHC.dataConFieldLabels dataCon
137 qualVars = filter (flip notElem (GHC.tyConTyVars tyCon)) tyvars
138 stricts = GHC.dataConStrictMarks dataCon
139 tys_w_strs = zip stricts argTypes
142 | null qualVars = empty
143 | otherwise = ptext SLIT("forall") <+>
144 hsep (map ppr qualVars) <> dot
146 -- printing out the dataCon as a type signature, in GADT style
147 pp_tau = foldr add pp_res_ty tys_w_strs
148 pp_res_ty = ppr_bndr tyCon <+> hsep (map GHC.pprParendType res_tys)
149 add (str,ty) pp_ty = pprBangTy str ty <+> arrow <+> pp_ty
151 pprParendBangTy (strict,ty)
152 | GHC.isMarkedStrict strict = char '!' <> GHC.pprParendType ty
153 | otherwise = GHC.pprParendType ty
156 | GHC.isMarkedStrict strict = char '!' <> ppr ty
159 maybe_show_label (lbl,(strict,tp))
160 | show_label lbl = Just (ppr lbl <+> dcolon <+> pprBangTy strict tp)
161 | otherwise = Nothing
163 ppr_fields [ty1, ty2]
164 | GHC.dataConIsInfix dataCon && null labels
165 = sep [pprParendBangTy ty1, ppr dataCon, pprParendBangTy ty2]
168 = ppr_bndr dataCon <+> sep (map pprParendBangTy fields)
170 = ppr_bndr dataCon <+>
171 braces (sep (punctuate comma (ppr_trim maybe_show_label
172 (zip labels fields))))
178 hang (pprClassHdr exts cls <+> ptext SLIT("where"))
179 2 (vcat (map (pprClassMethod exts) methods))
181 methods = GHC.classMethods cls
183 pprClassOneMethod exts cls this_one =
184 hang (pprClassHdr exts cls <+> ptext SLIT("where"))
185 2 (vcat (ppr_trim show_meth methods))
187 methods = GHC.classMethods cls
188 show_meth id | id == this_one = Just (pprClassMethod exts id)
189 | otherwise = Nothing
191 pprClassMethod exts id =
192 hang (ppr_bndr id <+> dcolon) 2 (pprType exts (classOpType id))
194 -- Here's the magic incantation to strip off the dictionary
195 -- from the class op type. Stolen from IfaceSyn.tyThingToIfaceDecl.
196 classOpType id = GHC.funResultTy rho_ty
197 where (_sel_tyvars, rho_ty) = GHC.splitForAllTys (GHC.idType id)
199 ppr_trim :: (a -> Maybe SDoc) -> [a] -> [SDoc]
201 = snd (foldr go (False, []) xs)
203 go x (eliding, so_far)
204 | Just doc <- show x = (False, doc : so_far)
205 | otherwise = if eliding then (True, so_far)
206 else (True, ptext SLIT("...") : so_far)
209 add_bars [c] = equals <+> c
210 add_bars (c:cs) = sep ((equals <+> c) : map (char '|' <+>) cs)
212 -- Wrap operators in ()
213 ppr_bndr :: GHC.NamedThing a => a -> SDoc
214 ppr_bndr a = GHC.pprParenSymName a
216 showWithLoc :: SrcLoc -> SDoc -> SDoc
218 = hang doc 2 (char '\t' <> comment <+> GHC.pprDefnLoc loc)
219 -- The tab tries to make them line up a bit
221 comment = ptext SLIT("--")