X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FhsSyn%2FHsPat.lhs;h=9e954a67fe4f63a981c60cc792c91b4ddcc8124f;hp=ee21ee3bfa7698e1112998cd47ef8e39721a2c28;hb=432b9c9322181a3644083e3c19b7e240d90659e7;hpb=58d200ac9cb51faa5c94e7919217f170b35b8441 diff --git a/compiler/hsSyn/HsPat.lhs b/compiler/hsSyn/HsPat.lhs index ee21ee3..9e954a6 100644 --- a/compiler/hsSyn/HsPat.lhs +++ b/compiler/hsSyn/HsPat.lhs @@ -1,41 +1,51 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[PatSyntax]{Abstract Haskell syntax---patterns} \begin{code} +{-# OPTIONS -fno-warn-incomplete-patterns #-} +-- The above warning supression flag is a temporary kludge. +-- While working on this module you are encouraged to remove it and fix +-- any warnings in the module. See +-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings +-- for details + module HsPat ( Pat(..), InPat, OutPat, LPat, - HsConDetails(..), hsConArgs, + HsConDetails(..), + HsConPatDetails, hsConPatArgs, + HsRecFields(..), HsRecField(..), hsRecFields, + + HsQuasiQuote(..), - mkPrefixConPat, mkCharLitPat, mkNilPat, mkCoPat, + mkPrefixConPat, mkCharLitPat, mkNilPat, mkCoPat, mkCoPatCoI, isBangHsBind, patsAreAllCons, isConPat, isSigPat, isWildPat, patsAreAllLits, isLitPat, isIrrefutableHsPat ) where -#include "HsVersions.h" - - -import {-# SOURCE #-} HsExpr ( SyntaxExpr ) +import {-# SOURCE #-} HsExpr (SyntaxExpr, LHsExpr, pprLExpr) -- friends: -import HsBinds ( DictBinds, HsBind(..), ExprCoFn, isIdCoercion, pprCoFn, - emptyLHsBinds, pprLHsBinds ) -import HsLit ( HsLit(HsCharPrim), HsOverLit ) -import HsTypes ( LHsType, PostTcType ) -import BasicTypes ( Boxity, tupleParens ) +import HsBinds +import HsLit +import HsTypes +import BasicTypes -- others: +import Coercion import PprCore ( {- instance OutputableBndr TyVar -} ) -import TysWiredIn ( nilDataCon, charDataCon, charTy ) -import Var ( TyVar ) -import DataCon ( DataCon, dataConTyCon ) -import TyCon ( isProductTyCon ) +import TysWiredIn +import Var +import DataCon +import TyCon import Outputable -import Type ( Type ) -import SrcLoc ( Located(..), unLoc, noLoc ) +import Type +import SrcLoc +import FastString \end{code} @@ -48,13 +58,16 @@ type LPat id = Located (Pat id) data Pat id = ------------ Simple patterns --------------- WildPat PostTcType -- Wild card + -- The sole reason for a type on a WildPat is to + -- support hsPatType :: Pat Id -> Type + | 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 + | BangPat (LPat id) -- Bang pattern ------------ Lists, tuples, arrays --------------- | ListPat [LPat id] -- Syntactic list @@ -80,18 +93,30 @@ data Pat id ------------ Constructor patterns --------------- | ConPatIn (Located id) - (HsConDetails id (LPat id)) + (HsConPatDetails id) | ConPatOut { pat_con :: Located DataCon, - pat_tvs :: [TyVar], -- Existentially bound type variables - -- including any bound coercion variables - pat_dicts :: [id], -- Ditto dictionaries + pat_tvs :: [TyVar], -- Existentially bound type variables (tyvars only) + pat_dicts :: [id], -- Ditto *coercion variables* and *dictionaries* + -- One reason for putting coercion variable here, I think, + -- is to ensure their kinds are zonked pat_binds :: DictBinds id, -- Bindings involving those dictionaries - pat_args :: HsConDetails id (LPat id), + pat_args :: HsConPatDetails id, pat_ty :: Type -- The type of the pattern } + ------------ View patterns --------------- + | ViewPat (LHsExpr id) + (LPat id) + PostTcType -- The overall type of the pattern + -- (= the argument type of the view function) + -- for hsPatType. + + ------------ Quasiquoted patterns --------------- + -- See Note [Quasi-quote overview] in TcSplice + | QuasiQuotePat (HsQuasiQuote id) + ------------ Literal and n+k patterns --------------- | LitPat HsLit -- Used for *non-overloaded* literal patterns: -- Int#, Char#, Int, Char, String, etc. @@ -100,7 +125,6 @@ data Pat id (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 @@ -120,30 +144,81 @@ data Pat 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 - ------------ Pattern coercions (translation only) --------------- - | CoPat ExprCoFn -- If co::t1 -> t2, p::t2, + | CoPat HsWrapper -- If co::t1 -> t2, p::t2, -- then (CoPat co p) :: t1 - (Pat id) -- No nested location reqd - Type + (Pat id) -- Why not LPat? Ans: existing locn will do + Type -- Type of whole pattern, t1 + -- During desugaring a (CoPat co pat) turns into a cast with 'co' on + -- the scrutinee, followed by a match on 'pat' \end{code} -HsConDetails is use both for patterns and for data type declarations +HsConDetails is use for patterns/expressions *and* for data type declarations \begin{code} -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] +data HsConDetails arg rec + = PrefixCon [arg] -- C p1 p2 p3 + | RecCon rec -- C { x = p1, y = p2 } + | InfixCon arg arg -- p1 `C` p2 + +type HsConPatDetails id = HsConDetails (LPat id) (HsRecFields id (LPat id)) + +hsConPatArgs :: HsConPatDetails id -> [LPat id] +hsConPatArgs (PrefixCon ps) = ps +hsConPatArgs (RecCon fs) = map hsRecFieldArg (rec_flds fs) +hsConPatArgs (InfixCon p1 p2) = [p1,p2] +\end{code} + +However HsRecFields is used only for patterns and expressions +(not data type declarations) + +\begin{code} +data HsRecFields id arg -- A bunch of record fields + -- { x = 3, y = True } + -- Used for both expressiona and patterns + = HsRecFields { rec_flds :: [HsRecField id arg], + rec_dotdot :: Maybe Int } + -- Nothing => the normal case + -- Just n => the group uses ".." notation, + -- and the first n elts of rec_flds + -- were the user-written ones + -- (In the latter case, the remaining elts of + -- rec_flds are the non-user-written ones) + +data HsRecField id arg = HsRecField { + hsRecFieldId :: Located id, + hsRecFieldArg :: arg, + hsRecPun :: Bool -- Note [Punning] + } + +-- Note [Punning] +-- ~~~~~~~~~~~~~~ +-- If you write T { x, y = v+1 }, the HsRecFields will be +-- HsRecField x x True ... +-- HsRecField y (v+1) False ... +-- That is, for "punned" field x is immediately expanded to x=x +-- but with a punning flag so we can detect it later +-- (e.g. when pretty printing) + +hsRecFields :: HsRecFields id arg -> [id] +hsRecFields rbinds = map (unLoc . hsRecFieldId) (rec_flds rbinds) +\end{code} + +\begin{code} +data HsQuasiQuote id = HsQuasiQuote + id + id + SrcSpan + FastString + +instance OutputableBndr id => Outputable (HsQuasiQuote id) where + ppr = ppr_qq + +ppr_qq :: OutputableBndr id => HsQuasiQuote id -> SDoc +ppr_qq (HsQuasiQuote name quoter _ quote) = + char '$' <> brackets (ppr name) <> + ptext (sLit "[:") <> ppr quoter <> ptext (sLit "|") <> + ppr quote <> ptext (sLit "|]") \end{code} @@ -173,6 +248,7 @@ pprPat (WildPat _) = char '_' pprPat (LazyPat pat) = char '~' <> ppr pat pprPat (BangPat pat) = char '!' <> ppr pat pprPat (AsPat name pat) = parens (hcat [ppr name, char '@', ppr pat]) +pprPat (ViewPat expr pat _) = parens (hcat [pprLExpr expr, text " -> ", ppr pat]) pprPat (ParPat pat) = parens (ppr pat) pprPat (ListPat pats _) = brackets (interpp'SP pats) pprPat (PArrPat pats _) = pabrackets (interpp'SP pats) @@ -189,31 +265,46 @@ pprPat (ConPatOut { pat_con = con, pat_tvs = tvs, pat_dicts = dicts, else pprUserCon con details pprPat (LitPat s) = ppr s -pprPat (NPat l Nothing _ _) = ppr l -pprPat (NPat l (Just _) _ _) = char '-' <> ppr l +pprPat (NPat l Nothing _) = ppr l +pprPat (NPat l (Just _) _) = char '-' <> ppr l pprPat (NPlusKPat n k _ _) = hcat [ppr n, char '+', ppr k] -pprPat (TypePat ty) = ptext SLIT("{|") <> ppr ty <> ptext SLIT("|}") -pprPat (CoPat co pat _) = parens (pprCoFn (ppr pat) co) +pprPat (QuasiQuotePat (HsQuasiQuote name quoter _ quote)) + = char '$' <> brackets (ppr name) <> + ptext (sLit "[:") <> ppr quoter <> ptext (sLit "|") <> + ppr quote <> ptext (sLit "|]") +pprPat (TypePat ty) = ptext (sLit "{|") <> ppr ty <> ptext (sLit "|}") +pprPat (CoPat co pat _) = parens (pprHsWrapper (ppr pat) co) 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 :: (Outputable con, OutputableBndr id) => con -> HsConPatDetails id -> SDoc pprUserCon c (InfixCon p1 p2) = ppr p1 <+> ppr c <+> ppr p2 pprUserCon c details = ppr c <+> pprConArgs details +pprConArgs :: OutputableBndr id => HsConPatDetails id -> SDoc 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] - +pprConArgs (RecCon rpats) = ppr rpats + +instance (OutputableBndr id, Outputable arg) + => Outputable (HsRecFields id arg) where + ppr (HsRecFields { rec_flds = flds, rec_dotdot = Nothing }) + = braces (fsep (punctuate comma (map ppr flds))) + ppr (HsRecFields { rec_flds = flds, rec_dotdot = Just n }) + = braces (fsep (punctuate comma (map ppr (take n flds) ++ [dotdot]))) + where + dotdot = ptext (sLit "..") <+> ifPprDebug (ppr (drop n flds)) + +instance (OutputableBndr id, Outputable arg) + => Outputable (HsRecField id arg) where + ppr (HsRecField { hsRecFieldId = f, hsRecFieldArg = arg, + hsRecPun = pun }) + = ppr f <+> (if pun then empty else equals <+> ppr arg) -- add parallel array brackets around a document -- pabrackets :: SDoc -> SDoc -pabrackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]") +pabrackets p = ptext (sLit "[:") <> p <> ptext (sLit ":]") \end{code} @@ -237,10 +328,14 @@ mkNilPat ty = mkPrefixConPat nilDataCon [] ty mkCharLitPat :: Char -> OutPat id mkCharLitPat c = mkPrefixConPat charDataCon [noLoc $ LitPat (HsCharPrim c)] charTy -mkCoPat :: ExprCoFn -> OutPat id -> Type -> OutPat id -mkCoPat co lpat@(L loc pat) ty - | isIdCoercion co = lpat - | otherwise = L loc (CoPat co pat ty) +mkCoPat :: HsWrapper -> Pat id -> Type -> Pat id +mkCoPat co pat ty + | isIdHsWrapper co = pat + | otherwise = CoPat co pat ty + +mkCoPatCoI :: CoercionI -> Pat id -> Type -> Pat id +mkCoPatCoI IdCo pat _ = pat +mkCoPatCoI (ACo co) pat ty = mkCoPat (WpCast co) pat ty \end{code} @@ -274,41 +369,49 @@ patterns are treated specially, of course. The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are. \begin{code} +isWildPat :: Pat id -> Bool isWildPat (WildPat _) = True -isWildPat other = False +isWildPat _ = False patsAreAllCons :: [Pat id] -> Bool patsAreAllCons pat_list = all isConPat pat_list +isConPat :: Pat id -> Bool 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 +isConPat _ = False +isSigPat :: Pat id -> Bool isSigPat (SigPatIn _ _) = True isSigPat (SigPatOut _ _) = True -isSigPat other = False +isSigPat _ = False patsAreAllLits :: [Pat id] -> Bool patsAreAllLits pat_list = all isLitPat pat_list +isLitPat :: Pat id -> Bool isLitPat (AsPat _ pat) = isLitPat (unLoc pat) isLitPat (LitPat _) = True -isLitPat (NPat _ _ _ _) = True +isLitPat (NPat _ _ _) = True isLitPat (NPlusKPat _ _ _ _) = True -isLitPat other = False +isLitPat _ = 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 +isBangHsBind (PatBind { pat_lhs = L _ (BangPat _) }) = True +isBangHsBind _ = False + +isIrrefutableHsPat :: OutputableBndr id => LPat id -> Bool +-- (isIrrefutableHsPat p) is true if matching against p cannot fail, +-- in the sense of falling through to the next pattern. +-- (NB: this is not quite the same as the (silly) defn +-- in 3.17.2 of the Haskell 98 report.) +-- +-- isIrrefutableHsPat 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 @@ -319,27 +422,31 @@ isIrrefutableHsPat pat go1 (WildPat _) = True go1 (VarPat _) = True go1 (VarPatOut _ _) = True - go1 (LazyPat pat) = True + go1 (LazyPat _) = True go1 (BangPat pat) = go pat go1 (CoPat _ pat _) = go1 pat go1 (ParPat pat) = go pat go1 (AsPat _ pat) = go pat + go1 (ViewPat _ 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 (ListPat _ _) = False + go1 (PArrPat _ _) = False -- ? go1 (ConPatIn _ _) = False -- Conservative go1 (ConPatOut{ pat_con = L _ con, pat_args = details }) = isProductTyCon (dataConTyCon con) - && all go (hsConArgs details) + && all go (hsConPatArgs details) go1 (LitPat _) = False - go1 (NPat _ _ _ _) = False + go1 (NPat _ _ _) = False go1 (NPlusKPat _ _ _ _) = False - go1 (TypePat _) = panic "isIrrefutableHsPat: type pattern" - go1 (DictPat _ _) = panic "isIrrefutableHsPat: type pattern" + go1 (QuasiQuotePat {}) = urk pat -- Gotten rid of by renamer, before + -- isIrrefutablePat is called + go1 (TypePat {}) = urk pat + + urk pat = pprPanic "isIrrefutableHsPat:" (ppr pat) \end{code}