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.tyConTyVars tyCon
72 keyword | GHC.isSynTyCon tyCon = SLIT("type")
73 | GHC.isNewTyCon tyCon = SLIT("newtype")
74 | otherwise = SLIT("data")
76 pprDataConSig exts dataCon =
77 ppr_bndr dataCon <+> dcolon <+> pprType exts (GHC.dataConType dataCon)
79 pprClassHdr exts cls =
80 let (tyVars, funDeps) = GHC.classTvsFds cls
81 in ptext SLIT("class") <+>
82 GHC.pprThetaArrow (GHC.classSCTheta cls) <+>
84 hsep (map ppr tyVars) <+>
85 GHC.pprFundeps funDeps
87 pprIdInContext exts id
88 | GHC.isRecordSelector id = pprRecordSelector exts id
89 | Just cls <- GHC.isClassOpId_maybe id = pprClassOneMethod exts cls id
90 | otherwise = pprId exts id
92 pprRecordSelector exts id
93 = pprAlgTyCon exts tyCon show_con show_label
95 (tyCon,label) = GHC.recordSelectorFieldLabel id
96 show_con dataCon = label `elem` GHC.dataConFieldLabels dataCon
97 show_label label' = label == label'
100 = hang (ppr_bndr id <+> dcolon) 2
101 (pprType exts (GHC.idType id))
103 pprType True ty = ppr ty
104 pprType False ty = ppr (GHC.dropForAlls ty)
107 | GHC.isSynTyCon tyCon
108 = let (_,rhs_type) = GHC.getSynTyConDefn tyCon
109 in hang (pprTyConHdr exts tyCon <+> equals) 2 (pprType exts rhs_type)
111 = pprAlgTyCon exts tyCon (const True) (const True)
113 pprAlgTyCon exts tyCon ok_con ok_label
114 | gadt = pprTyConHdr exts tyCon <+> ptext SLIT("where") $$
115 nest 2 (vcat (ppr_trim show_con datacons))
116 | otherwise = hang (pprTyConHdr exts tyCon)
117 2 (add_bars (ppr_trim show_con datacons))
119 datacons = GHC.tyConDataCons tyCon
120 gadt = any (not . GHC.isVanillaDataCon) datacons
123 | ok_con dataCon = Just (pprDataConDecl exts gadt ok_label dataCon)
124 | otherwise = Nothing
126 pprDataCon exts dataCon = pprAlgTyCon exts tyCon (== dataCon) (const True)
127 where tyCon = GHC.dataConTyCon dataCon
129 pprDataConDecl exts gadt_style show_label dataCon
130 | not gadt_style = ppr_fields tys_w_strs
131 | otherwise = ppr_bndr dataCon <+> dcolon <+>
132 sep [ ppr_tvs, GHC.pprThetaArrow theta, pp_tau ]
134 (tyvars, theta, argTypes, tyCon, res_tys) = GHC.dataConSig dataCon
135 labels = GHC.dataConFieldLabels dataCon
136 qualVars = filter (flip notElem (GHC.tyConTyVars tyCon)) tyvars
137 stricts = GHC.dataConStrictMarks dataCon
138 tys_w_strs = zip stricts argTypes
141 | null qualVars = empty
142 | otherwise = ptext SLIT("forall") <+>
143 hsep (map ppr qualVars) <> dot
145 -- printing out the dataCon as a type signature, in GADT style
146 pp_tau = foldr add pp_res_ty tys_w_strs
147 pp_res_ty = ppr_bndr tyCon <+> hsep (map GHC.pprParendType res_tys)
148 add (str,ty) pp_ty = pprBangTy str ty <+> arrow <+> pp_ty
150 pprParendBangTy (strict,ty)
151 | GHC.isMarkedStrict strict = char '!' <> GHC.pprParendType ty
152 | otherwise = GHC.pprParendType ty
155 | GHC.isMarkedStrict strict = char '!' <> ppr ty
158 maybe_show_label (lbl,(strict,tp))
159 | show_label lbl = Just (ppr lbl <+> dcolon <+> pprBangTy strict tp)
160 | otherwise = Nothing
162 ppr_fields [ty1, ty2]
163 | GHC.dataConIsInfix dataCon && null labels
164 = sep [pprParendBangTy ty1, ppr dataCon, pprParendBangTy ty2]
167 = ppr_bndr dataCon <+> sep (map pprParendBangTy fields)
169 = ppr_bndr dataCon <+>
170 braces (sep (punctuate comma (ppr_trim maybe_show_label
171 (zip labels fields))))
177 hang (pprClassHdr exts cls <+> ptext SLIT("where"))
178 2 (vcat (map (pprClassMethod exts) methods))
180 methods = GHC.classMethods cls
182 pprClassOneMethod exts cls this_one =
183 hang (pprClassHdr exts cls <+> ptext SLIT("where"))
184 2 (vcat (ppr_trim show_meth methods))
186 methods = GHC.classMethods cls
187 show_meth id | id == this_one = Just (pprClassMethod exts id)
188 | otherwise = Nothing
190 pprClassMethod exts id =
191 hang (ppr_bndr id <+> dcolon) 2 (pprType exts (classOpType id))
193 -- Here's the magic incantation to strip off the dictionary
194 -- from the class op type. Stolen from IfaceSyn.tyThingToIfaceDecl.
195 classOpType id = GHC.funResultTy rho_ty
196 where (_sel_tyvars, rho_ty) = GHC.splitForAllTys (GHC.idType id)
198 ppr_trim :: (a -> Maybe SDoc) -> [a] -> [SDoc]
200 = snd (foldr go (False, []) xs)
202 go x (eliding, so_far)
203 | Just doc <- show x = (False, doc : so_far)
204 | otherwise = if eliding then (True, so_far)
205 else (True, ptext SLIT("...") : so_far)
208 add_bars [c] = equals <+> c
209 add_bars (c:cs) = sep ((equals <+> c) : map (char '|' <+>) cs)
211 -- Wrap operators in ()
212 ppr_bndr :: GHC.NamedThing a => a -> SDoc
213 ppr_bndr a = GHC.pprParenSymName a
215 showWithLoc :: SrcLoc -> SDoc -> SDoc
217 = hang doc 2 (char '\t' <> comment <+> GHC.pprDefnLoc loc)
218 -- The tab tries to make them line up a bit
220 comment = ptext SLIT("--")