\section[PatSyntax]{Abstract Haskell syntax---patterns}
\begin{code}
-{-# OPTIONS -w #-}
+{-# 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
HsConPatDetails, hsConPatArgs,
HsRecFields(..), HsRecField(..), hsRecFields,
+ HsQuasiQuote(..),
+
mkPrefixConPat, mkCharLitPat, mkNilPat, mkCoPat, mkCoPatCoI,
- isBangHsBind,
+ isBangHsBind, hsPatNeedsParens,
patsAreAllCons, isConPat, isSigPat, isWildPat,
- patsAreAllLits, isLitPat, isIrrefutableHsPat
+ patsAreAllLits, isLitPat, isIrrefutableHsPat, hasViewPat
) where
-#include "HsVersions.h"
-
import {-# SOURCE #-} HsExpr (SyntaxExpr, LHsExpr, pprLExpr)
-- friends:
import HsBinds
import HsLit
import HsTypes
-import HsDoc
import BasicTypes
-- others:
import Coercion
import Outputable
import Type
import SrcLoc
+import FastString
\end{code}
-- (= 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.
\begin{code}
data HsRecFields id arg -- A bunch of record fields
-- { x = 3, y = True }
- -- Used for both expressiona and patterns
+ -- Used for both expressions and patterns
= HsRecFields { rec_flds :: [HsRecField id arg],
rec_dotdot :: Maybe Int }
-- Nothing => the normal case
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 '$' <> brackets (ppr name) <>
+ ptext (sLit "[:") <> ppr quoter <> ptext (sLit "|") <>
+ ppr quote <> ptext (sLit "|]")
+\end{code}
+
%************************************************************************
%* *
pprPat (LazyPat pat) = char '~' <> ppr pat
pprPat (BangPat pat) = char '!' <> ppr pat
pprPat (AsPat name pat) = parens (hcat [ppr name, char '@', ppr pat])
-pprPat (ViewPat expr pat _) = parens (hcat [pprLExpr expr, text " -> ", ppr pat])
-pprPat (ParPat pat) = parens (ppr pat)
+pprPat (ViewPat expr pat _) = parens (hcat [pprLExpr expr, text " -> ", ppr pat])
+pprPat (ParPat pat) = parens (ppr pat)
pprPat (ListPat pats _) = brackets (interpp'SP pats)
pprPat (PArrPat pats _) = pabrackets (interpp'SP pats)
pprPat (TuplePat pats bx _) = tupleParens bx (interpp'SP pats)
pprPat (NPat l Nothing _) = ppr l
pprPat (NPat l (Just _) _) = char '-' <> ppr l
pprPat (NPlusKPat n k _ _) = hcat [ppr n, char '+', ppr k]
-pprPat (TypePat ty) = ptext SLIT("{|") <> ppr ty <> ptext SLIT("|}")
+pprPat (QuasiQuotePat (HsQuasiQuote name quoter _ quote))
+ = char '$' <> 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
+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) = ppr rpats
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))
+ dotdot = ptext (sLit "..") <+> ifPprDebug (ppr (drop n flds))
instance (OutputableBndr id, Outputable arg)
=> Outputable (HsRecField id arg) where
-- 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}
| otherwise = CoPat co pat ty
mkCoPatCoI :: CoercionI -> Pat id -> Type -> Pat id
-mkCoPatCoI IdCo pat ty = pat
-mkCoPatCoI (ACo co) pat ty = mkCoPat (WpCo co) pat ty
+mkCoPatCoI IdCo pat _ = pat
+mkCoPatCoI (ACo co) pat ty = mkCoPat (WpCast co) pat ty
\end{code}
The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are.
\begin{code}
+hasViewPat :: LPat id -> Bool
+hasViewPat (L _ p) = go p where
+ go (WildPat _) = False
+ go (VarPat _) = False
+ go (VarPatOut _ _) = False
+ go (LazyPat p) = hasViewPat p
+ go (AsPat _ p) = hasViewPat p
+ go (ParPat p) = hasViewPat p
+ go (BangPat p) = hasViewPat p
+ go (ListPat p _) = any hasViewPat p
+ go (TuplePat p _ _) = any hasViewPat p
+ go (PArrPat p _) = any hasViewPat p
+ go (ConPatIn _ p) = go' p
+ go (ConPatOut _ _ _ _ p _) = go' p
+ go (ViewPat _ _ _) = True
+ go (QuasiQuotePat _) = False
+ go (LitPat _) = False
+ go (NPat _ _ _) = False
+ go (NPlusKPat _ _ _ _) = False
+ go (TypePat _) = False
+ go (SigPatIn p _) = hasViewPat p
+ go (SigPatOut p _) = hasViewPat p
+ go (CoPat _ _ _) = False
+ go' p = case p of
+ PrefixCon ps -> any hasViewPat ps
+ RecCon (HsRecFields fs _) -> any (hasViewPat . hsRecFieldArg) fs
+ InfixCon p1 p2 -> hasViewPat p1 || hasViewPat p2
+
+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 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 (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
+isBangHsBind (PatBind { pat_lhs = L _ (BangPat _) }) = True
+isBangHsBind _ = False
-isIrrefutableHsPat :: LPat id -> Bool
+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
isIrrefutableHsPat pat
= go pat
where
- go (L _ pat) = go1 pat
+ go (L _ pat) = go1 pat
- go1 (WildPat _) = True
- go1 (VarPat _) = True
- go1 (VarPatOut _ _) = True
- go1 (LazyPat pat) = True
+ go1 (WildPat {}) = True
+ go1 (VarPat {}) = True
+ go1 (VarPatOut {}) = True
+ go1 (LazyPat {}) = True
go1 (BangPat pat) = go pat
go1 (CoPat _ pat _) = go1 pat
go1 (ParPat 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 (ConPatIn {}) = False -- Conservative
go1 (ConPatOut{ pat_con = L _ con, pat_args = details })
= isProductTyCon (dataConTyCon con)
&& all go (hsConPatArgs details)
- go1 (LitPat _) = False
- go1 (NPat _ _ _) = False
- go1 (NPlusKPat _ _ _ _) = False
-
- go1 (TypePat _) = panic "isIrrefutableHsPat: type pattern"
+ go1 (LitPat {}) = False
+ go1 (NPat {}) = False
+ go1 (NPlusKPat {}) = False
+
+ go1 (QuasiQuotePat {}) = urk pat -- Gotten rid of by renamer, before
+ -- isIrrefutablePat is called
+ go1 (TypePat {}) = urk pat
+
+ urk pat = pprPanic "isIrrefutableHsPat:" (ppr pat)
+
+hsPatNeedsParens :: Pat a -> Bool
+hsPatNeedsParens (WildPat {}) = False
+hsPatNeedsParens (VarPat {}) = False
+hsPatNeedsParens (VarPatOut {}) = True
+hsPatNeedsParens (LazyPat {}) = False
+hsPatNeedsParens (BangPat {}) = False
+hsPatNeedsParens (CoPat {}) = True
+hsPatNeedsParens (ParPat {}) = False
+hsPatNeedsParens (AsPat {}) = False
+hsPatNeedsParens (ViewPat {}) = True
+hsPatNeedsParens (SigPatIn {}) = True
+hsPatNeedsParens (SigPatOut {}) = True
+hsPatNeedsParens (TuplePat {}) = False
+hsPatNeedsParens (ListPat {}) = False
+hsPatNeedsParens (PArrPat {}) = False
+hsPatNeedsParens (ConPatIn _ ds) = conPatNeedsParens ds
+hsPatNeedsParens (ConPatOut {}) = True
+hsPatNeedsParens (LitPat {}) = False
+hsPatNeedsParens (NPat {}) = False
+hsPatNeedsParens (NPlusKPat {}) = True
+hsPatNeedsParens (QuasiQuotePat {}) = True
+hsPatNeedsParens (TypePat {}) = False
+
+conPatNeedsParens :: HsConDetails a b -> Bool
+conPatNeedsParens (PrefixCon args) = not (null args)
+conPatNeedsParens (InfixCon {}) = False
+conPatNeedsParens (RecCon {}) = False
\end{code}
projects / ghc-hetmet.git / blobdiff