X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FhsSyn%2FHsPat.lhs;h=6027377e3688ca39d3bc5804eef341420ed87568;hb=fbe64026eac8b559693868f38e6a9e6dad8a8ec6;hp=96d308229dc4a2a5838c90d1ee72778190a90dca;hpb=5cf27e8f1731c52fe63a5b9615f927484164c61b;p=ghc-hetmet.git diff --git a/ghc/compiler/hsSyn/HsPat.lhs b/ghc/compiler/hsSyn/HsPat.lhs index 96d3082..6027377 100644 --- a/ghc/compiler/hsSyn/HsPat.lhs +++ b/ghc/compiler/hsSyn/HsPat.lhs @@ -1,217 +1,229 @@ % -% (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(..), + Pat(..), InPat, OutPat, + + HsConDetails(..), hsConArgs, - unfailablePats, unfailablePat, - patsAreAllCons, isConPat, + mkPrefixConPat, mkCharLitPat, mkNilPat, + + isWildPat, + patsAreAllCons, isConPat, isSigPat, patsAreAllLits, isLitPat, - irrefutablePat, - collectPatBinders + collectPatBinders, collectPatsBinders, + collectSigTysFromPat, collectSigTysFromPats ) where -import Ubiq +#include "HsVersions.h" + --- friends: -import HsLit ( HsLit ) -import HsLoop ( HsExpr ) +import {-# SOURCE #-} HsExpr ( HsExpr ) +-- friends: +import HsLit ( HsLit(HsCharPrim), HsOverLit ) +import HsTypes ( HsType, SyntaxName, PostTcType ) +import BasicTypes ( Boxity, tupleParens ) -- others: -import Id ( GenId, dataConSig ) -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 TysWiredIn ( nilDataCon, charDataCon, charTy ) +import Var ( TyVar ) +import DataCon ( DataCon ) +import Outputable +import Type ( Type ) \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 - (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 = Pat id -- No 'Out' constructors +type OutPat id = Pat id -- No 'In' constructors + +data Pat id + = ------------ Simple patterns --------------- + WildPat PostTcType -- Wild card + | VarPat id -- Variable + | LazyPat (Pat id) -- Lazy pattern + | AsPat id (Pat id) -- As pattern + | ParPat (Pat id) -- Parenthesised pattern + + ------------ Lists, tuples, arrays --------------- + | ListPat [Pat id] -- Syntactic list + PostTcType -- The type of the elements + + | TuplePat [Pat id] -- Tuple + Boxity -- UnitPat is TuplePat [] + + | PArrPat [Pat id] -- Syntactic parallel array + PostTcType -- The type of the elements + + ------------ Constructor patterns --------------- + | ConPatIn id + (HsConDetails id (Pat id)) + + | ConPatOut DataCon + (HsConDetails id (Pat id)) + Type -- The type of the pattern + [TyVar] -- Existentially bound type variables + [id] -- Ditto dictionaries + + ------------ Literal and n+k patterns --------------- + | LitPat HsLit -- Used for *non-overloaded* literal patterns: + -- Int#, Char#, Int, Char, String, etc. + + | NPatIn HsOverLit -- Always positive + (Maybe SyntaxName) -- Just (Name of 'negate') for negative + -- patterns, Nothing otherwise + + | NPatOut HsLit -- Used for literal patterns where there's an equality function to call + -- The literal is retained so that the desugarer can readily identify + -- equations with identical literal-patterns + -- Always HsInteger, HsRat or HsString. + -- Always HsInteger, HsRat or HsString. + -- *Unlike* NPatIn, for negative literals, the + -- literal is acutally negative! + Type -- Type of pattern, t + (HsExpr id) -- Of type t -> Bool; detects match + + | NPlusKPatIn id -- n+k pattern + HsOverLit -- It'll always be an HsIntegral + SyntaxName -- Name of '-' (see RnEnv.lookupSyntaxName) + + | NPlusKPatOut id + Integer + (HsExpr id) -- Of type t -> Bool; detects match + (HsExpr id) -- Of type t -> t; subtracts k + + + ------------ Generics --------------- + | TypePat (HsType 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 (Pat id) -- Pattern with a type signature + (HsType id) + + | SigPatOut (Pat id) -- Pattern p + Type -- Type, t, of the whole pattern + (HsExpr id) -- Coercion function, + -- of type t -> typeof(p) + + ------------ 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 +data HsConDetails id arg + = PrefixCon [arg] -- C p1 p2 p3 + | RecCon [(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} -pprInPat :: (Outputable name, NamedThing name) => PprStyle -> InPat name -> Pretty -pprInPat sty (WildPatIn) = ppStr "_" -pprInPat sty (VarPatIn var) = pprNonSym 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] +%************************************************************************ +%* * +%* Printing patterns +%* * +%************************************************************************ -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 +\begin{code} +instance (OutputableBndr name) => Outputable (Pat name) where + ppr = pprPat -pprInPat sty (ConOpPatIn pat1 op pat2) - = ppCat [ppr sty pat1, ppr sty op, ppr sty pat2] -- ParPats put in parens +pprPat :: (OutputableBndr name) => Pat name -> SDoc +pprPat (VarPat 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 (WildPat _) = char '_' +pprPat (LazyPat pat) = char '~' <> ppr pat +pprPat (AsPat name pat) = parens (hcat [ppr name, char '@', ppr pat]) +pprPat (ParPat pat) = parens (pprPat 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 c details) = pprConPat c details +pprPat (ConPatOut c details _ _ _) = pprConPat c details + +pprPat (LitPat s) = ppr s +pprPat (NPatIn l _) = ppr l +pprPat (NPatOut l _ _) = ppr l +pprPat (NPlusKPatIn n k _) = hcat [ppr n, char '+', ppr k] +pprPat (NPlusKPatOut n k _ _) = hcat [ppr n, char '+', integer 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 dicts methods) + = parens (sep [ptext SLIT("{-dict-}"), + brackets (interpp'SP dicts), + brackets (interpp'SP methods)]) + + + +pprConPat con (PrefixCon pats) = ppr con <+> interppSP pats -- inner ParPats supply the necessary parens. +pprConPat con (InfixCon pat1 pat2) = hsep [ppr pat1, ppr con, 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 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) - = ppBesides [ppr sty con, ppSP, ppChar '{', ppInterleave ppComma (map (pp_rpat sty) rpats), ppChar '}'] +pprConPat con (RecCon rpats) + = ppr con <+> braces (hsep (punctuate comma (map (pp_rpat) rpats))) where - pp_rpat PprForUser (v, _, True) = ppr PprForUser v - pp_rpat sty (v, p, _) = ppCat [ppr sty v, ppStr "=", ppr sty p] -\end{code} + pp_rpat (v, p) = hsep [ppr v, char '=', ppr p] -\begin{code} -instance (Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar, - NamedThing id, Outputable id) - => Outputable (OutPat tyvar uvar id) where - ppr = pprOutPat + +-- 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) = pprNonSym 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, ppChar '{', ppInterleave ppComma (map (pp_rpat sty) rpats), ppChar '}'] - 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 = ConPatOut dc (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 :: Int -> OutPat id +mkCharLitPat c = mkPrefixConPat charDataCon [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'' @@ -234,76 +246,102 @@ At least the numeric ones may be overloaded. A pattern is in {\em exactly one} of the above three categories; `as' patterns are treated specially, of course. +The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are. \begin{code} -unfailablePats :: [OutPat a b c] -> Bool -unfailablePats pat_list = all unfailablePat pat_list - -unfailablePat (AsPat _ pat) = unfailablePat pat -unfailablePat (WildPat _) = True -unfailablePat (VarPat _) = True -unfailablePat (LazyPat _) = True -unfailablePat (DictPat ds ms) = (length ds + length ms) <= 1 -unfailablePat other = False +isWildPat (WildPat _) = True +isWildPat other = False -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 (ConPatIn _ _) = True +isConPat (ConPatOut _ _ _ _ _) = True isConPat (ListPat _ _) = True -isConPat (TuplePat _) = True -isConPat (RecPat _ _ _) = 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 pat +isLitPat (LitPat _) = True +isLitPat (NPatIn _ _) = True +isLitPat (NPatOut _ _ _) = True +isLitPat (NPlusKPatIn _ _ _) = True +isLitPat (NPlusKPatOut _ _ _ _) = True +isLitPat other = False \end{code} -A pattern is irrefutable if a match on it cannot fail -(at any depth). -\begin{code} -irrefutablePat :: OutPat a b c -> Bool - -irrefutablePat (WildPat _) = True -irrefutablePat (VarPat _) = True -irrefutablePat (LazyPat _) = True -irrefutablePat (AsPat _ pat) = irrefutablePat pat -irrefutablePat (ConPat con tys pats) = only_con con && all irrefutablePat pats -irrefutablePat (ConOpPat pat1 con pat2 _) = only_con con && irrefutablePat pat1 && irrefutablePat pat1 -irrefutablePat (RecPat con _ fields) = only_con con && and [ irrefutablePat pat | (_,pat,_) <- fields ] -irrefutablePat (ListPat _ _) = False -irrefutablePat (TuplePat pats) = all irrefutablePat pats -irrefutablePat (DictPat _ _) = True -irrefutablePat other_pat = False -- Literals, NPat - -only_con con = maybeToBool (maybeTyConSingleCon tycon) - where - (_,_,_,tycon) = dataConSig con -\end{code} +%************************************************************************ +%* * +%* Gathering stuff out of patterns +%* * +%************************************************************************ This function @collectPatBinders@ works with the ``collectBinders'' functions for @HsBinds@, etc. The order in which the binders are collected is important; see @HsBinds.lhs@. + +It collects the bounds *value* variables in renamed patterns; type variables +are *not* collected. + \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 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) +collectPatBinders :: Pat a -> [a] +collectPatBinders pat = collect pat [] + +collectPatsBinders :: [Pat a] -> [a] +collectPatsBinders pats = foldr collect [] pats + +collect (WildPat _) bndrs = bndrs +collect (VarPat var) bndrs = var : bndrs +collect (LazyPat pat) bndrs = collect pat bndrs +collect (AsPat a pat) bndrs = a : collect pat bndrs +collect (ParPat pat) bndrs = collect pat bndrs + +collect (ListPat pats _) bndrs = foldr collect bndrs pats +collect (PArrPat pats _) bndrs = foldr collect bndrs pats +collect (TuplePat pats _) bndrs = foldr collect bndrs pats + +collect (ConPatIn c ps) bndrs = foldr collect bndrs (hsConArgs ps) +collect (ConPatOut c ps _ _ ds) bndrs = ds ++ foldr collect bndrs (hsConArgs ps) + +collect (LitPat _) bndrs = bndrs +collect (NPatIn _ _) bndrs = bndrs +collect (NPatOut _ _ _) bndrs = bndrs + +collect (NPlusKPatIn n _ _) bndrs = n : bndrs +collect (NPlusKPatOut n _ _ _) bndrs = n : bndrs + +collect (SigPatIn pat _) bndrs = collect pat bndrs +collect (SigPatOut pat _ _) bndrs = collect pat bndrs +collect (TypePat ty) bndrs = bndrs +collect (DictPat ids1 ids2) bndrs = ids1 ++ ids2 ++ bndrs \end{code} + +\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 (TypePat ty) acc = ty:acc + +collect_pat (LazyPat pat) acc = collect_pat pat acc +collect_pat (AsPat a pat) acc = collect_pat pat acc +collect_pat (ParPat pat) acc = collect_pat pat acc +collect_pat (ListPat pats _) acc = foldr collect_pat acc pats +collect_pat (PArrPat pats _) acc = foldr collect_pat acc pats +collect_pat (TuplePat pats _) acc = foldr collect_pat acc pats +collect_pat (ConPatIn c ps) acc = foldr collect_pat acc (hsConArgs ps) +collect_pat other acc = acc -- Literals, vars, wildcard +\end{code} +