----------------------------------------------------------------------------- -- -- Pretty-printing TyThings -- -- (c) The GHC Team 2005 -- ----------------------------------------------------------------------------- module PprTyThing ( pprTyThing, pprTyThingInContext, pprTyThingLoc, pprTyThingInContextLoc, pprTyThingHdr ) where #include "HsVersions.h" import qualified GHC import GHC ( TyThing(..), SrcLoc ) import DataCon ( dataConResTys ) import Outputable -- ----------------------------------------------------------------------------- -- Pretty-printing entities that we get from the GHC API -- This should be a good source of sample code for using the GHC API to -- inspect source code entities. -- | Pretty-prints a 'TyThing' with its defining location. pprTyThingLoc :: Bool -> TyThing -> SDoc pprTyThingLoc exts tyThing = showWithLoc loc (pprTyThing exts tyThing) where loc = GHC.nameSrcLoc (GHC.getName tyThing) -- | Pretty-prints a 'TyThing'. pprTyThing :: Bool -> TyThing -> SDoc pprTyThing exts (AnId id) = pprId exts id pprTyThing exts (ADataCon dataCon) = pprDataConSig exts dataCon pprTyThing exts (ATyCon tyCon) = pprTyCon exts tyCon pprTyThing exts (AClass cls) = pprClass exts cls -- | Like 'pprTyThingInContext', but adds the defining location. pprTyThingInContextLoc :: Bool -> TyThing -> SDoc pprTyThingInContextLoc exts tyThing = showWithLoc loc (pprTyThingInContext exts tyThing) where loc = GHC.nameSrcLoc (GHC.getName tyThing) -- | Pretty-prints a 'TyThing' in context: that is, if the entity -- is a data constructor, record selector, or class method, then -- the entity's parent declaration is pretty-printed with irrelevant -- parts omitted. pprTyThingInContext :: Bool -> TyThing -> SDoc pprTyThingInContext exts (AnId id) = pprIdInContext exts id pprTyThingInContext exts (ADataCon dataCon) = pprDataCon exts dataCon pprTyThingInContext exts (ATyCon tyCon) = pprTyCon exts tyCon pprTyThingInContext exts (AClass cls) = pprClass exts cls -- | Pretty-prints the 'TyThing' header. For functions and data constructors -- the function is equivalent to 'pprTyThing' but for type constructors -- and classes it prints only the header part of the declaration. pprTyThingHdr :: Bool -> TyThing -> SDoc pprTyThingHdr exts (AnId id) = pprId exts id pprTyThingHdr exts (ADataCon dataCon) = pprDataConSig exts dataCon pprTyThingHdr exts (ATyCon tyCon) = pprTyConHdr exts tyCon pprTyThingHdr exts (AClass cls) = pprClassHdr exts cls pprTyConHdr exts tyCon = addFamily (ptext keyword) <+> ppr_bndr tyCon <+> hsep (map ppr vars) where vars | GHC.isPrimTyCon tyCon || GHC.isFunTyCon tyCon = take (GHC.tyConArity tyCon) GHC.alphaTyVars | otherwise = GHC.tyConTyVars tyCon keyword | GHC.isSynTyCon tyCon = SLIT("type") | GHC.isNewTyCon tyCon = SLIT("newtype") | otherwise = SLIT("data") addFamily keytext | GHC.isOpenTyCon tyCon = keytext <> ptext SLIT(" family") | otherwise = keytext pprDataConSig exts dataCon = ppr_bndr dataCon <+> dcolon <+> pprType exts (GHC.dataConType dataCon) pprClassHdr exts cls = let (tyVars, funDeps) = GHC.classTvsFds cls in ptext SLIT("class") <+> GHC.pprThetaArrow (GHC.classSCTheta cls) <+> ppr_bndr cls <+> hsep (map ppr tyVars) <+> GHC.pprFundeps funDeps pprIdInContext exts id | GHC.isRecordSelector id = pprRecordSelector exts id | Just cls <- GHC.isClassOpId_maybe id = pprClassOneMethod exts cls id | otherwise = pprId exts id pprRecordSelector exts id = pprAlgTyCon exts tyCon show_con show_label where (tyCon,label) = GHC.recordSelectorFieldLabel id show_con dataCon = label `elem` GHC.dataConFieldLabels dataCon show_label label' = label == label' pprId exts id = hang (ppr_bndr id <+> dcolon) 2 (pprType exts (GHC.idType id)) pprType True ty = ppr ty pprType False ty = ppr (GHC.dropForAlls ty) pprTyCon exts tyCon | GHC.isSynTyCon tyCon = if GHC.isOpenTyCon tyCon then pprTyConHdr exts tyCon <+> dcolon <+> pprType exts (GHC.synTyConResKind tyCon) else let rhs_type = GHC.synTyConType tyCon in hang (pprTyConHdr exts tyCon <+> equals) 2 (pprType exts rhs_type) | otherwise = pprAlgTyCon exts tyCon (const True) (const True) pprAlgTyCon exts tyCon ok_con ok_label | gadt = pprTyConHdr exts tyCon <+> ptext SLIT("where") $$ nest 2 (vcat (ppr_trim show_con datacons)) | otherwise = hang (pprTyConHdr exts tyCon) 2 (add_bars (ppr_trim show_con datacons)) where datacons = GHC.tyConDataCons tyCon gadt = any (not . GHC.isVanillaDataCon) datacons show_con dataCon | ok_con dataCon = Just (pprDataConDecl exts gadt ok_label dataCon) | otherwise = Nothing pprDataCon exts dataCon = pprAlgTyCon exts tyCon (== dataCon) (const True) where tyCon = GHC.dataConTyCon dataCon pprDataConDecl exts gadt_style show_label dataCon | not gadt_style = ppr_fields tys_w_strs | otherwise = ppr_bndr dataCon <+> dcolon <+> sep [ ppr_tvs, GHC.pprThetaArrow theta, pp_tau ] where (tyvars, theta, argTypes) = GHC.dataConSig dataCon tyCon = GHC.dataConTyCon dataCon labels = GHC.dataConFieldLabels dataCon res_tys = dataConResTys dataCon qualVars = filter (flip notElem (GHC.tyConTyVars tyCon)) tyvars stricts = GHC.dataConStrictMarks dataCon tys_w_strs = zip stricts argTypes ppr_tvs | null qualVars = empty | otherwise = ptext SLIT("forall") <+> hsep (map ppr qualVars) <> dot -- printing out the dataCon as a type signature, in GADT style pp_tau = foldr add pp_res_ty tys_w_strs pp_res_ty = ppr_bndr tyCon <+> hsep (map GHC.pprParendType res_tys) add (str,ty) pp_ty = pprBangTy str ty <+> arrow <+> pp_ty pprParendBangTy (strict,ty) | GHC.isMarkedStrict strict = char '!' <> GHC.pprParendType ty | otherwise = GHC.pprParendType ty pprBangTy strict ty | GHC.isMarkedStrict strict = char '!' <> ppr ty | otherwise = ppr ty maybe_show_label (lbl,(strict,tp)) | show_label lbl = Just (ppr lbl <+> dcolon <+> pprBangTy strict tp) | otherwise = Nothing ppr_fields [ty1, ty2] | GHC.dataConIsInfix dataCon && null labels = sep [pprParendBangTy ty1, ppr dataCon, pprParendBangTy ty2] ppr_fields fields | null labels = ppr_bndr dataCon <+> sep (map pprParendBangTy fields) | otherwise = ppr_bndr dataCon <+> braces (sep (punctuate comma (ppr_trim maybe_show_label (zip labels fields)))) pprClass exts cls | null methods = pprClassHdr exts cls | otherwise = hang (pprClassHdr exts cls <+> ptext SLIT("where")) 2 (vcat (map (pprClassMethod exts) methods)) where methods = GHC.classMethods cls pprClassOneMethod exts cls this_one = hang (pprClassHdr exts cls <+> ptext SLIT("where")) 2 (vcat (ppr_trim show_meth methods)) where methods = GHC.classMethods cls show_meth id | id == this_one = Just (pprClassMethod exts id) | otherwise = Nothing pprClassMethod exts id = hang (ppr_bndr id <+> dcolon) 2 (pprType exts (classOpType id)) where -- Here's the magic incantation to strip off the dictionary -- from the class op type. Stolen from IfaceSyn.tyThingToIfaceDecl. classOpType id = GHC.funResultTy rho_ty where (_sel_tyvars, rho_ty) = GHC.splitForAllTys (GHC.idType id) ppr_trim :: (a -> Maybe SDoc) -> [a] -> [SDoc] ppr_trim show xs = snd (foldr go (False, []) xs) where go x (eliding, so_far) | Just doc <- show x = (False, doc : so_far) | otherwise = if eliding then (True, so_far) else (True, ptext SLIT("...") : so_far) add_bars [] = empty add_bars [c] = equals <+> c add_bars (c:cs) = sep ((equals <+> c) : map (char '|' <+>) cs) -- Wrap operators in () ppr_bndr :: GHC.NamedThing a => a -> SDoc ppr_bndr a = GHC.pprParenSymName a showWithLoc :: SrcLoc -> SDoc -> SDoc showWithLoc loc doc = hang doc 2 (char '\t' <> comment <+> GHC.pprDefnLoc loc) -- The tab tries to make them line up a bit where comment = ptext SLIT("--")