X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FhsSyn%2FHsPat.lhs;h=953d228942a0c85da06b8035a72c430609819740;hb=28a464a75e14cece5db40f2765a29348273ff2d2;hp=c5fa2c74baa2b743094019ff17d655cbb339e939;hpb=d4e38936bf64bcd3dc301ec404406bbff20f01d5;p=ghc-hetmet.git diff --git a/ghc/compiler/hsSyn/HsPat.lhs b/ghc/compiler/hsSyn/HsPat.lhs index c5fa2c7..953d228 100644 --- a/ghc/compiler/hsSyn/HsPat.lhs +++ b/ghc/compiler/hsSyn/HsPat.lhs @@ -5,228 +5,231 @@ \begin{code} module HsPat ( - InPat(..), - OutPat(..), - - irrefutablePat, irrefutablePats, - failureFreePat, isWildPat, - patsAreAllCons, isConPat, - patsAreAllLits, isLitPat, - collectPatBinders, collectPatsBinders, - collectSigTysFromPat, collectSigTysFromPats + Pat(..), InPat, OutPat, LPat, + + HsConDetails(..), hsConArgs, + + mkPrefixConPat, mkCharLitPat, mkNilPat, + + isBangHsBind, + patsAreAllCons, isConPat, isSigPat, isWildPat, + patsAreAllLits, isLitPat, isIrrefutableHsPat ) where #include "HsVersions.h" --- friends: -import HsLit ( HsLit, HsOverLit ) -import HsExpr ( HsExpr ) -import HsTypes ( HsType ) -import BasicTypes ( Fixity, Boxity, tupleParens ) +import {-# SOURCE #-} HsExpr ( SyntaxExpr ) +-- friends: +import HsBinds ( DictBinds, HsBind(..), emptyLHsBinds, pprLHsBinds ) +import HsLit ( HsLit(HsCharPrim), HsOverLit ) +import HsTypes ( LHsType, PostTcType ) +import BasicTypes ( Boxity, tupleParens ) -- others: -import Name ( Name ) -import Var ( Id, TyVar ) +import PprCore ( {- instance OutputableBndr TyVar -} ) +import TysWiredIn ( nilDataCon, charDataCon, charTy ) +import Var ( TyVar ) import DataCon ( DataCon, dataConTyCon ) -import Name ( isDataSymOcc, getOccName, NamedThing ) -import Maybes ( maybeToBool ) +import TyCon ( isProductTyCon ) import Outputable -import TyCon ( maybeTyConSingleCon ) import Type ( Type ) +import SrcLoc ( Located(..), unLoc, noLoc ) \end{code} -Patterns come in distinct before- and after-typechecking flavo(u)rs. + \begin{code} -data InPat name - = WildPatIn -- wild card - | VarPatIn name -- variable - | LitPatIn HsLit -- literal - | LazyPatIn (InPat name) -- lazy pattern - | AsPatIn name -- as pattern - (InPat name) - | SigPatIn (InPat name) - (HsType name) - | ConPatIn name -- constructed type - [InPat name] - | ConOpPatIn (InPat name) - name - Fixity -- c.f. OpApp in HsExpr - (InPat name) - - | NPatIn HsOverLit - - | NPlusKPatIn name -- n+k pattern - HsOverLit -- It'll always be an HsIntegral - Name -- Name of '-' (see RnEnv.lookupSyntaxName) - - -- We preserve prefix negation and parenthesis for the precedence parser. - - | ParPatIn (InPat name) -- parenthesised pattern - - | ListPatIn [InPat name] -- syntactic list - -- must have >= 1 elements - | TuplePatIn [InPat name] Boxity -- tuple (boxed?) - - | RecPatIn name -- record - [(name, InPat name, Bool)] -- True <=> source used punning - --- Generics - | TypePatIn (HsType name) -- Type pattern for generic definitions +type InPat id = LPat id -- No 'Out' constructors +type OutPat id = LPat id -- No 'In' constructors + +type LPat id = Located (Pat id) + +data Pat id + = ------------ Simple patterns --------------- + WildPat PostTcType -- Wild card + | VarPat id -- Variable + | VarPatOut id (DictBinds id) -- Used only for overloaded Ids; the + -- bindings give its overloaded instances + | LazyPat (LPat id) -- Lazy pattern + | AsPat (Located id) (LPat id) -- As pattern + | ParPat (LPat id) -- Parenthesised pattern + | BangPat (LPat id) -- Bang patterng + + ------------ Lists, tuples, arrays --------------- + | ListPat [LPat id] -- Syntactic list + PostTcType -- The type of the elements + + | TuplePat [LPat id] -- Tuple + Boxity -- UnitPat is TuplePat [] + PostTcType + -- You might think that the PostTcType was redundant, but it's essential + -- data T a where + -- T1 :: Int -> T Int + -- f :: (T a, a) -> Int + -- f (T1 x, z) = z + -- When desugaring, we must generate + -- f = /\a. \v::a. case v of (t::T a, w::a) -> + -- case t of (T1 (x::Int)) -> + -- Note the (w::a), NOT (w::Int), because we have not yet + -- refined 'a' to Int. So we must know that the second component + -- of the tuple is of type 'a' not Int. See selectMatchVar + + | PArrPat [LPat id] -- Syntactic parallel array + PostTcType -- The type of the elements + + ------------ Constructor patterns --------------- + | ConPatIn (Located id) + (HsConDetails id (LPat id)) + + | ConPatOut (Located DataCon) + [TyVar] -- Existentially bound type variables + [id] -- Ditto dictionaries + (DictBinds id) -- Bindings involving those dictionaries + (HsConDetails id (LPat id)) + Type -- The type of the pattern + + ------------ Literal and n+k patterns --------------- + | LitPat HsLit -- Used for *non-overloaded* literal patterns: + -- Int#, Char#, Int, Char, String, etc. + + | NPat (HsOverLit id) -- ALWAYS positive + (Maybe (SyntaxExpr id)) -- Just (Name of 'negate') for negative + -- patterns, Nothing otherwise + (SyntaxExpr id) -- Equality checker, of type t->t->Bool + PostTcType -- Type of the pattern + + | NPlusKPat (Located id) -- n+k pattern + (HsOverLit id) -- It'll always be an HsIntegral + (SyntaxExpr id) -- (>=) function, of type t->t->Bool + (SyntaxExpr id) -- Name of '-' (see RnEnv.lookupSyntaxName) + + ------------ Generics --------------- + | TypePat (LHsType id) -- Type pattern for generic definitions -- e.g f{| a+b |} = ... - -- These show up only in class - -- declarations, + -- These show up only in class declarations, -- and should be a top-level pattern --- /Generics - -data OutPat id - = WildPat Type -- wild card - | VarPat id -- variable (type is in the Id) - | LazyPat (OutPat id) -- lazy pattern - | AsPat id -- as pattern - (OutPat id) - - | ListPat -- Syntactic list - Type -- The type of the elements - [OutPat id] - - | TuplePat [OutPat id] -- Tuple - Boxity - -- UnitPat is TuplePat [] - - | ConPat DataCon - Type -- the type of the pattern - [TyVar] -- Existentially bound type variables - [id] -- Ditto dictionaries - [OutPat id] - - -- ConOpPats are only used on the input side - - | RecPat DataCon -- Record constructor - Type -- The type of the pattern - [TyVar] -- Existentially bound type variables - [id] -- Ditto dictionaries - [(Id, OutPat id, Bool)] -- True <=> source used punning - - | LitPat -- Used for *non-overloaded* literal patterns: - -- Int#, Char#, Int, Char, String, etc. - HsLit - Type -- Type of pattern - - | NPat -- Used for literal patterns where there's an equality function to call - HsLit -- The literal is retained so that - -- the desugarer can readily identify - -- equations with identical literal-patterns - -- Always HsInteger, HsRat or HsString. - Type -- Type of pattern, t - (HsExpr id (OutPat id)) -- Of type t -> Bool; detects match - - | NPlusKPat id - Integer - Type -- Type of pattern, t - (HsExpr id (OutPat id)) -- Of type t -> Bool; detects match - (HsExpr id (OutPat id)) -- Of type t -> t; subtracts k + ------------ Pattern type signatures --------------- + | SigPatIn (LPat id) -- Pattern with a type signature + (LHsType id) + | SigPatOut (LPat id) -- Pattern with a type signature + Type + + ------------ Dictionary patterns (translation only) --------------- | DictPat -- Used when destructing Dictionaries with an explicit case [id] -- superclass dicts [id] -- methods \end{code} -Now name in Inpat is not need to be in NAmedThing to be Outputable. -Needed by ../deSugar/Check.lhs - -JJQC-2-12-97 +HsConDetails is use both for patterns and for data type declarations \begin{code} -instance (Outputable name) => Outputable (InPat name) where - ppr = pprInPat - -pprInPat :: (Outputable name) => InPat name -> SDoc - -pprInPat (WildPatIn) = char '_' -pprInPat (VarPatIn var) = ppr var -pprInPat (LitPatIn s) = ppr s -pprInPat (SigPatIn pat ty) = ppr pat <+> dcolon <+> ppr ty -pprInPat (LazyPatIn pat) = char '~' <> ppr pat -pprInPat (AsPatIn name pat) = parens (hcat [ppr name, char '@', ppr pat]) -pprInPat (ParPatIn pat) = parens (pprInPat pat) -pprInPat (ListPatIn pats) = brackets (interpp'SP pats) -pprInPat (TuplePatIn pats bx) = tupleParens bx (interpp'SP pats) -pprInPat (NPlusKPatIn n k _) = parens (hcat [ppr n, char '+', ppr k]) -pprInPat (NPatIn l) = ppr l - -pprInPat (ConPatIn c pats) - | null pats = ppr c - | otherwise = hsep [ppr c, interppSP pats] -- inner ParPats supply the necessary parens. - -pprInPat (ConOpPatIn pat1 op fixity pat2) - = hsep [ppr pat1, ppr op, ppr pat2] -- ParPats put in parens - - -- ToDo: use pprSym to print op (but this involves fiddling various - -- contexts & I'm lazy...); *PatIns are *rarely* printed anyway... (WDP) - -pprInPat (RecPatIn con rpats) - = hsep [ppr con, braces (hsep (punctuate comma (map (pp_rpat) rpats)))] - where - pp_rpat (v, _, True) = ppr v - pp_rpat (v, p, _) = hsep [ppr v, char '=', ppr p] - -pprInPat (TypePatIn ty) = ptext SLIT("{|") <> ppr ty <> ptext SLIT("|}") +data HsConDetails id arg + = PrefixCon [arg] -- C p1 p2 p3 + | RecCon [(Located id, arg)] -- C { x = p1, y = p2 } + | InfixCon arg arg -- p1 `C` p2 + +hsConArgs :: HsConDetails id arg -> [arg] +hsConArgs (PrefixCon ps) = ps +hsConArgs (RecCon fs) = map snd fs +hsConArgs (InfixCon p1 p2) = [p1,p2] \end{code} -\begin{code} -instance (NamedThing id, Outputable id) => Outputable (OutPat id) where - ppr = pprOutPat -\end{code} + +%************************************************************************ +%* * +%* Printing patterns +%* * +%************************************************************************ \begin{code} -pprOutPat (WildPat ty) = char '_' -pprOutPat (VarPat var) = ppr var -pprOutPat (LazyPat pat) = hcat [char '~', ppr pat] -pprOutPat (AsPat name pat) - = parens (hcat [ppr name, char '@', ppr pat]) - -pprOutPat (ConPat name ty [] [] []) - = ppr name - --- Kludge to get infix constructors to come out right --- when ppr'ing desugar warnings. -pprOutPat (ConPat name ty tyvars dicts pats) +instance (OutputableBndr name) => Outputable (Pat name) where + ppr = pprPat + +pprPatBndr :: OutputableBndr name => name -> SDoc +pprPatBndr var -- Print with type info if -dppr-debug is on = getPprStyle $ \ sty -> - parens $ - case pats of - [p1,p2] - | userStyle sty && isDataSymOcc (getOccName name) -> - hsep [ppr p1, ppr name, ppr p2] - _ -> hsep [ppr name, interppSP tyvars, interppSP dicts, interppSP pats] - -pprOutPat (ListPat ty pats) = brackets (interpp'SP pats) -pprOutPat (TuplePat pats boxity) = tupleParens boxity (interpp'SP pats) - -pprOutPat (RecPat con ty tvs dicts rpats) - = hsep [ppr con, interppSP tvs, interppSP dicts, braces (hsep (punctuate comma (map (pp_rpat) rpats)))] - where - pp_rpat (v, _, True) = ppr v - pp_rpat (v, p, _) = hsep [ppr v, char '=', ppr p] + if debugStyle sty then + parens (pprBndr LambdaBind var) -- Could pass the site to pprPat + -- but is it worth it? + else + ppr var + +pprPat :: (OutputableBndr name) => Pat name -> SDoc +pprPat (VarPat var) = pprPatBndr var +pprPat (VarPatOut var bs) = parens (pprPatBndr var <+> braces (ppr bs)) +pprPat (WildPat _) = char '_' +pprPat (LazyPat pat) = char '~' <> ppr pat +pprPat (BangPat pat) = char '!' <> ppr pat +pprPat (AsPat name pat) = parens (hcat [ppr name, char '@', ppr pat]) +pprPat (ParPat pat) = parens (ppr pat) +pprPat (ListPat pats _) = brackets (interpp'SP pats) +pprPat (PArrPat pats _) = pabrackets (interpp'SP pats) +pprPat (TuplePat pats bx _) = tupleParens bx (interpp'SP pats) + +pprPat (ConPatIn con details) = pprUserCon con details +pprPat (ConPatOut con tvs dicts binds details _) + = getPprStyle $ \ sty -> -- Tiresome; in TcBinds.tcRhs we print out a + if debugStyle sty then -- typechecked Pat in an error message, + -- and we want to make sure it prints nicely + ppr con <+> sep [ hsep (map pprPatBndr tvs) <+> hsep (map pprPatBndr dicts), + pprLHsBinds binds, pprConArgs details] + else pprUserCon con details + +pprPat (LitPat s) = ppr s +pprPat (NPat l Nothing _ _) = ppr l +pprPat (NPat l (Just _) _ _) = char '-' <> ppr l +pprPat (NPlusKPat n k _ _) = hcat [ppr n, char '+', ppr k] +pprPat (TypePat ty) = ptext SLIT("{|") <> ppr ty <> ptext SLIT("|}") +pprPat (SigPatIn pat ty) = ppr pat <+> dcolon <+> ppr ty +pprPat (SigPatOut pat ty) = ppr pat <+> dcolon <+> ppr ty +pprPat (DictPat ds ms) = parens (sep [ptext SLIT("{-dict-}"), + brackets (interpp'SP ds), + brackets (interpp'SP ms)]) + +pprUserCon c (InfixCon p1 p2) = ppr p1 <+> ppr c <+> ppr p2 +pprUserCon c details = ppr c <+> pprConArgs details + +pprConArgs (PrefixCon pats) = interppSP pats +pprConArgs (InfixCon p1 p2) = interppSP [p1,p2] +pprConArgs (RecCon rpats) = braces (hsep (punctuate comma (map (pp_rpat) rpats))) + where + pp_rpat (v, p) = hsep [ppr v, char '=', ppr p] + + +-- add parallel array brackets around a document +-- +pabrackets :: SDoc -> SDoc +pabrackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]") +\end{code} + -pprOutPat (LitPat l ty) = ppr l -- ToDo: print more -pprOutPat (NPat l ty e) = ppr l -- ToDo: print more -pprOutPat (NPlusKPat n k ty e1 e2) -- ToDo: print more - = parens (hcat [ppr n, char '+', integer k]) +%************************************************************************ +%* * +%* Building patterns +%* * +%************************************************************************ + +\begin{code} +mkPrefixConPat :: DataCon -> [OutPat id] -> Type -> OutPat id +-- Make a vanilla Prefix constructor pattern +mkPrefixConPat dc pats ty = noLoc $ ConPatOut (noLoc dc) [] [] emptyLHsBinds (PrefixCon pats) ty -pprOutPat (DictPat dicts methods) - = parens (sep [ptext SLIT("{-dict-}"), - brackets (interpp'SP dicts), - brackets (interpp'SP methods)]) +mkNilPat :: Type -> OutPat id +mkNilPat ty = mkPrefixConPat nilDataCon [] ty +mkCharLitPat :: Char -> OutPat id +mkCharLitPat c = mkPrefixConPat charDataCon [noLoc $ LitPat (HsCharPrim c)] charTy \end{code} + %************************************************************************ %* * -%* predicates for checking things about pattern-lists in EquationInfo * +%* Predicates for checking things about pattern-lists in EquationInfo * %* * %************************************************************************ + \subsection[Pat-list-predicates]{Look for interesting things in patterns} Unlike in the Wadler chapter, where patterns are either ``variables'' @@ -251,109 +254,71 @@ patterns are treated specially, of course. The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are. \begin{code} -irrefutablePats :: [OutPat id] -> Bool -irrefutablePats pat_list = all irrefutablePat pat_list - -irrefutablePat (AsPat _ pat) = irrefutablePat pat -irrefutablePat (WildPat _) = True -irrefutablePat (VarPat _) = True -irrefutablePat (LazyPat _) = True -irrefutablePat (DictPat ds ms) = (length ds + length ms) <= 1 -irrefutablePat other = False - -failureFreePat :: OutPat id -> Bool - -failureFreePat (WildPat _) = True -failureFreePat (VarPat _) = True -failureFreePat (LazyPat _) = True -failureFreePat (AsPat _ pat) = failureFreePat pat -failureFreePat (ConPat con tys _ _ pats) = only_con con && all failureFreePat pats -failureFreePat (RecPat con _ _ _ fields) = only_con con && and [ failureFreePat pat | (_,pat,_) <- fields ] -failureFreePat (ListPat _ _) = False -failureFreePat (TuplePat pats _) = all failureFreePat pats -failureFreePat (DictPat _ _) = True -failureFreePat other_pat = False -- Literals, NPat - -only_con con = maybeToBool (maybeTyConSingleCon (dataConTyCon con)) -\end{code} - -\begin{code} isWildPat (WildPat _) = True isWildPat other = False -patsAreAllCons :: [OutPat id] -> Bool +patsAreAllCons :: [Pat id] -> Bool patsAreAllCons pat_list = all isConPat pat_list -isConPat (AsPat _ pat) = isConPat pat -isConPat (ConPat _ _ _ _ _) = True -isConPat (ListPat _ _) = True -isConPat (TuplePat _ _) = True -isConPat (RecPat _ _ _ _ _) = True -isConPat (DictPat ds ms) = (length ds + length ms) > 1 -isConPat other = False - -patsAreAllLits :: [OutPat id] -> Bool -patsAreAllLits pat_list = all isLitPat pat_list - -isLitPat (AsPat _ pat) = isLitPat pat -isLitPat (LitPat _ _) = True -isLitPat (NPat _ _ _) = True -isLitPat (NPlusKPat _ _ _ _ _) = True -isLitPat other = False -\end{code} +isConPat (AsPat _ pat) = isConPat (unLoc pat) +isConPat (ConPatIn _ _) = True +isConPat (ConPatOut _ _ _ _ _ _) = True +isConPat (ListPat _ _) = True +isConPat (PArrPat _ _) = True +isConPat (TuplePat _ _ _) = True +isConPat (DictPat ds ms) = (length ds + length ms) > 1 +isConPat other = False -This function @collectPatBinders@ works with the ``collectBinders'' -functions for @HsBinds@, etc. The order in which the binders are -collected is important; see @HsBinds.lhs@. +isSigPat (SigPatIn _ _) = True +isSigPat (SigPatOut _ _) = True +isSigPat other = False -\begin{code} -collectPatBinders :: InPat a -> [a] -collectPatBinders pat = collect pat [] - -collectPatsBinders :: [InPat a] -> [a] -collectPatsBinders pats = foldr collect [] pats - -collect WildPatIn bndrs = bndrs -collect (VarPatIn var) bndrs = var : bndrs -collect (LitPatIn _) bndrs = bndrs -collect (SigPatIn pat _) bndrs = collect pat bndrs -collect (LazyPatIn pat) bndrs = collect pat bndrs -collect (AsPatIn a pat) bndrs = a : collect pat bndrs -collect (NPlusKPatIn n _ _) bndrs = n : bndrs -collect (NPatIn _) bndrs = bndrs -collect (ConPatIn c pats) bndrs = foldr collect bndrs pats -collect (ConOpPatIn p1 c f p2) bndrs = collect p1 (collect p2 bndrs) -collect (ParPatIn pat) bndrs = collect pat bndrs -collect (ListPatIn pats) bndrs = foldr collect bndrs pats -collect (TuplePatIn pats _) bndrs = foldr collect bndrs pats -collect (RecPatIn c fields) bndrs = foldr (\ (f,pat,_) bndrs -> collect pat bndrs) bndrs fields --- Generics -collect (TypePatIn ty) bndrs = bndrs --- assume the type variables do not need to be bound -\end{code} +patsAreAllLits :: [Pat id] -> Bool +patsAreAllLits pat_list = all isLitPat pat_list -\begin{code} -collectSigTysFromPats :: [InPat name] -> [HsType name] -collectSigTysFromPats pats = foldr collect_pat [] pats - -collectSigTysFromPat :: InPat name -> [HsType name] -collectSigTysFromPat pat = collect_pat pat [] - -collect_pat (SigPatIn pat ty) acc = collect_pat pat (ty:acc) -collect_pat WildPatIn acc = acc -collect_pat (VarPatIn var) acc = acc -collect_pat (LitPatIn _) acc = acc -collect_pat (LazyPatIn pat) acc = collect_pat pat acc -collect_pat (AsPatIn a pat) acc = collect_pat pat acc -collect_pat (NPatIn _) acc = acc -collect_pat (NPlusKPatIn n _ _) acc = acc -collect_pat (ConPatIn c pats) acc = foldr collect_pat acc pats -collect_pat (ConOpPatIn p1 c f p2) acc = collect_pat p1 (collect_pat p2 acc) -collect_pat (ParPatIn pat) acc = collect_pat pat acc -collect_pat (ListPatIn pats) acc = foldr collect_pat acc pats -collect_pat (TuplePatIn pats _) acc = foldr collect_pat acc pats -collect_pat (RecPatIn c fields) acc = foldr (\ (f,pat,_) acc -> collect_pat pat acc) acc fields --- Generics -collect_pat (TypePatIn ty) acc = ty:acc +isLitPat (AsPat _ pat) = isLitPat (unLoc pat) +isLitPat (LitPat _) = True +isLitPat (NPat _ _ _ _) = True +isLitPat (NPlusKPat _ _ _ _) = True +isLitPat other = False + +isBangHsBind :: HsBind id -> Bool +-- In this module because HsPat is above HsBinds in the import graph +isBangHsBind (PatBind { pat_lhs = L _ (BangPat p) }) = True +isBangHsBind bind = False + +isIrrefutableHsPat :: LPat id -> Bool +-- This function returns False if it's in doubt; specifically +-- on a ConPatIn it doesn't know the size of the constructor family +-- But if it returns True, the pattern is definitely irrefutable +isIrrefutableHsPat pat + = go pat + where + go (L _ pat) = go1 pat + + go1 (WildPat _) = True + go1 (VarPat _) = True + go1 (VarPatOut _ _) = True + go1 (LazyPat pat) = True + go1 (BangPat pat) = go pat + go1 (ParPat pat) = go pat + go1 (AsPat _ pat) = go pat + go1 (SigPatIn pat _) = go pat + go1 (SigPatOut pat _) = go pat + go1 (TuplePat pats _ _) = all go pats + go1 (ListPat pats _) = False + go1 (PArrPat pats _) = False -- ? + + go1 (ConPatIn _ _) = False -- Conservative + go1 (ConPatOut (L _ con) _ _ _ details _) + = isProductTyCon (dataConTyCon con) + && all go (hsConArgs details) + + go1 (LitPat _) = False + go1 (NPat _ _ _ _) = False + go1 (NPlusKPat _ _ _ _) = False + + go1 (TypePat _) = panic "isIrrefutableHsPat: type pattern" + go1 (DictPat _ _) = panic "isIrrefutableHsPat: type pattern" \end{code}