X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FhsSyn%2FHsPat.lhs;h=eca7dd1d11e09a9ed84b2e7a36ce9be773ddf3fe;hb=04feba252e40d16101b92948cd1e13c7bc1f3062;hp=da42d1ce89068a8e76977d673a5ec1d601f8c258;hpb=8de16184643ea3c2f9f30b5eaed18db6ef247760;p=ghc-hetmet.git diff --git a/ghc/compiler/hsSyn/HsPat.lhs b/ghc/compiler/hsSyn/HsPat.lhs index da42d1c..eca7dd1 100644 --- a/ghc/compiler/hsSyn/HsPat.lhs +++ b/ghc/compiler/hsSyn/HsPat.lhs @@ -1,217 +1,235 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[PatSyntax]{Abstract Haskell syntax---patterns} \begin{code} -#include "HsVersions.h" - module HsPat ( - InPat(..), - OutPat(..), - - irrefutablePat, irrefutablePats, - failureFreePat, - patsAreAllCons, isConPat, - patsAreAllLits, isLitPat, - collectPatBinders + Pat(..), InPat, OutPat, LPat, + + HsConDetails(..), hsConArgs, + + mkPrefixConPat, mkCharLitPat, mkNilPat, + + isWildPat, + patsAreAllCons, isConPat, isSigPat, + patsAreAllLits, isLitPat, isIrrefutableHsPat ) where -IMP_Ubiq() +#include "HsVersions.h" --- friends: -import HsBasic ( HsLit, Fixity ) -IMPORT_DELOOPER(HsLoop) ( HsExpr ) +import {-# SOURCE #-} HsExpr ( SyntaxExpr ) + +-- friends: +import HsBinds ( DictBinds, emptyLHsBinds, pprLHsBinds ) +import HsLit ( HsLit(HsCharPrim), HsOverLit ) +import HsTypes ( LHsType, PostTcType ) +import BasicTypes ( Boxity, tupleParens ) -- others: -import Id ( dataConTyCon, GenId ) -import Maybes ( maybeToBool ) -import Name ( pprSym, pprNonSym ) -import Outputable ( interppSP, interpp'SP, ifPprShowAll ) -import PprStyle ( PprStyle(..) ) -import Pretty -import TyCon ( maybeTyConSingleCon ) -import PprType ( GenType ) +import PprCore ( {- instance OutputableBndr TyVar -} ) +import TysWiredIn ( nilDataCon, charDataCon, charTy ) +import Var ( TyVar ) +import DataCon ( DataCon, dataConTyCon ) +import TyCon ( isProductTyCon ) +import Outputable +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) - | ConPatIn name -- constructed type - [InPat name] - | ConOpPatIn (InPat name) - name - Fixity -- c.f. OpApp in HsExpr - (InPat name) - - -- We preserve prefix negation and parenthesis for the precedence parser. - - | NegPatIn (InPat name) -- negated pattern - | ParPatIn (InPat name) -- parenthesised pattern - - | ListPatIn [InPat name] -- syntactic list - -- must have >= 1 elements - | TuplePatIn [InPat name] -- tuple - - | RecPatIn name -- record - [(name, InPat name, Bool)] -- True <=> source used punning - -data OutPat tyvar uvar id - = WildPat (GenType tyvar uvar) -- wild card - - | VarPat id -- variable (type is in the Id) - - | LazyPat (OutPat tyvar uvar id) -- lazy pattern - - | AsPat id -- as pattern - (OutPat tyvar uvar id) - - | ConPat Id -- Constructor is always an Id - (GenType tyvar uvar) -- the type of the pattern - [OutPat tyvar uvar id] - - | ConOpPat (OutPat tyvar uvar id) -- just a special case... - Id - (OutPat tyvar uvar id) - (GenType tyvar uvar) - | ListPat -- syntactic list - (GenType tyvar uvar) -- the type of the elements - [OutPat tyvar uvar id] - - | TuplePat [OutPat tyvar uvar id] -- tuple - -- UnitPat is TuplePat [] - - | RecPat Id -- record constructor - (GenType tyvar uvar) -- the type of the pattern - [(Id, OutPat tyvar uvar id, Bool)] -- True <=> source used punning - - | LitPat -- Used for *non-overloaded* literal patterns: - -- Int#, Char#, Int, Char, String, etc. - HsLit - (GenType tyvar uvar) -- type of pattern - - | NPat -- Used for *overloaded* literal patterns - HsLit -- the literal is retained so that - -- the desugarer can readily identify - -- equations with identical literal-patterns - (GenType tyvar uvar) -- type of pattern, t - (HsExpr tyvar uvar id (OutPat tyvar uvar id)) - -- of type t -> Bool; detects match +\begin{code} +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 + + ------------ 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, + -- and should be a top-level pattern + + ------------ 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} +HsConDetails is use both for patterns and for data type declarations + \begin{code} -instance (Outputable name, NamedThing name) => Outputable (InPat name) where - ppr = pprInPat - -pprInPat :: (Outputable name, NamedThing name) => PprStyle -> InPat name -> Pretty - -pprInPat sty (WildPatIn) = ppStr "_" -pprInPat sty (VarPatIn var) = ppr sty var -pprInPat sty (LitPatIn s) = ppr sty s -pprInPat sty (LazyPatIn pat) = ppBeside (ppChar '~') (ppr sty pat) -pprInPat sty (AsPatIn name pat) - = ppBesides [ppLparen, ppr sty name, ppChar '@', ppr sty pat, ppRparen] - -pprInPat sty (ConPatIn c pats) - = if null pats then - ppr sty c - else - ppCat [ppr sty c, interppSP sty pats] -- ParPats put in the parens - -pprInPat sty (ConOpPatIn pat1 op fixity pat2) - = ppCat [ppr sty pat1, ppr sty op, ppr sty 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 sty (NegPatIn pat) - = let - pp_pat = pprInPat sty pat - in - ppBeside (ppChar '-') ( - case pat of - LitPatIn _ -> pp_pat - _ -> ppParens pp_pat - ) - -pprInPat sty (ParPatIn pat) - = ppParens (pprInPat sty pat) - -pprInPat sty (ListPatIn pats) - = ppBesides [ppLbrack, interpp'SP sty pats, ppRbrack] -pprInPat sty (TuplePatIn pats) - = ppParens (interpp'SP sty pats) - -pprInPat sty (RecPatIn con rpats) - = ppCat [ppr sty con, ppCurlies (ppIntersperse pp'SP (map (pp_rpat sty) rpats))] - where - pp_rpat PprForUser (v, _, True) = ppr PprForUser v - pp_rpat sty (v, p, _) = ppCat [ppr sty v, ppStr "=", ppr sty p] +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} + +%************************************************************************ +%* * +%* Printing patterns +%* * +%************************************************************************ + \begin{code} -instance (Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar, Outputable id) - => Outputable (OutPat tyvar uvar id) where - ppr = pprOutPat +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 -> + 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 (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} -\begin{code} -pprOutPat sty (WildPat ty) = ppChar '_' -pprOutPat sty (VarPat var) = ppr sty var -pprOutPat sty (LazyPat pat) = ppBesides [ppChar '~', ppr sty pat] -pprOutPat sty (AsPat name pat) - = ppBesides [ppLparen, ppr sty name, ppChar '@', ppr sty pat, ppRparen] - -pprOutPat sty (ConPat name ty []) - = ppBeside (ppr sty name) - (ifPprShowAll sty (pprConPatTy sty ty)) - -pprOutPat sty (ConPat name ty pats) - = ppBesides [ppLparen, ppr sty name, ppSP, - interppSP sty pats, ppRparen, - ifPprShowAll sty (pprConPatTy sty ty) ] - -pprOutPat sty (ConOpPat pat1 op pat2 ty) - = ppBesides [ppLparen, ppr sty pat1, ppSP, pprSym sty op, ppSP, ppr sty pat2, ppRparen] - -pprOutPat sty (ListPat ty pats) - = ppBesides [ppLbrack, interpp'SP sty pats, ppRbrack] -pprOutPat sty (TuplePat pats) - = ppParens (interpp'SP sty pats) - -pprOutPat sty (RecPat con ty rpats) - = ppBesides [ppr sty con, ppCurlies (ppIntersperse pp'SP (map (pp_rpat sty) rpats))] - where - pp_rpat PprForUser (v, _, True) = ppr PprForUser v - pp_rpat sty (v, p, _) = ppCat [ppr sty v, ppStr "=", ppr sty p] -pprOutPat sty (LitPat l ty) = ppr sty l -- ToDo: print more -pprOutPat sty (NPat l ty e) = ppr sty l -- ToDo: print more +%************************************************************************ +%* * +%* 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 sty (DictPat dicts methods) - = ppSep [ppBesides [ppLparen, ppPStr SLIT("{-dict-}")], - ppBracket (interpp'SP sty dicts), - ppBesides [ppBracket (interpp'SP sty methods), ppRparen]] +mkNilPat :: Type -> OutPat id +mkNilPat ty = mkPrefixConPat nilDataCon [] ty -pprConPatTy sty ty - = ppParens (ppr sty 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'' @@ -236,71 +254,65 @@ patterns are treated specially, of course. The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are. \begin{code} -irrefutablePats :: [OutPat a b c] -> 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 a b c -> 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 (ConOpPat pat1 con pat2 _) = only_con con && failureFreePat pat1 && failureFreePat pat1 -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} +isWildPat (WildPat _) = True +isWildPat other = False -\begin{code} -patsAreAllCons :: [OutPat a b c] -> Bool +patsAreAllCons :: [Pat id] -> Bool patsAreAllCons pat_list = all isConPat pat_list -isConPat (AsPat _ pat) = isConPat pat -isConPat (ConPat _ _ _) = True -isConPat (ConOpPat _ _ _ _) = True -isConPat (ListPat _ _) = True -isConPat (TuplePat _) = True -isConPat (RecPat _ _ _) = True -isConPat (DictPat ds ms) = (length ds + length ms) > 1 -isConPat other = False +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 -patsAreAllLits :: [OutPat a b c] -> Bool +isSigPat (SigPatIn _ _) = True +isSigPat (SigPatOut _ _) = True +isSigPat other = False + +patsAreAllLits :: [Pat id] -> Bool patsAreAllLits pat_list = all isLitPat pat_list -isLitPat (AsPat _ pat) = isLitPat pat -isLitPat (LitPat _ _) = True -isLitPat (NPat _ _ _) = True -isLitPat other = False +isLitPat (AsPat _ pat) = isLitPat (unLoc pat) +isLitPat (LitPat _) = True +isLitPat (NPat _ _ _ _) = True +isLitPat (NPlusKPat _ _ _ _) = True +isLitPat other = 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 (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} -This function @collectPatBinders@ works with the ``collectBinders'' -functions for @HsBinds@, etc. The order in which the binders are -collected is important; see @HsBinds.lhs@. -\begin{code} -collectPatBinders :: InPat a -> [a] - -collectPatBinders WildPatIn = [] -collectPatBinders (VarPatIn var) = [var] -collectPatBinders (LitPatIn _) = [] -collectPatBinders (LazyPatIn pat) = collectPatBinders pat -collectPatBinders (AsPatIn a pat) = a : collectPatBinders pat -collectPatBinders (ConPatIn c pats) = concat (map collectPatBinders pats) -collectPatBinders (ConOpPatIn p1 c f p2) = collectPatBinders p1 ++ collectPatBinders p2 -collectPatBinders (NegPatIn pat) = collectPatBinders pat -collectPatBinders (ParPatIn pat) = collectPatBinders pat -collectPatBinders (ListPatIn pats) = concat (map collectPatBinders pats) -collectPatBinders (TuplePatIn pats) = concat (map collectPatBinders pats) -collectPatBinders (RecPatIn c fields) = concat (map (\ (f,pat,_) -> collectPatBinders pat) fields) -\end{code}