From 276f03b24f6929186e481431e482aee5db6ed7d1 Mon Sep 17 00:00:00 2001
From: sof <unknown>
Date: Mon, 5 Jul 1999 17:06:21 +0000
Subject: [PATCH] [project @ 1999-07-05 17:06:21 by sof] Tidied up the handling
of the code that emits the precedence level predicates that gets used in
applications of showParen and readParen.
---
ghc/compiler/typecheck/TcGenDeriv.lhs | 65 ++++++++++++++++-----------
1 file changed, 40 insertions(+), 25 deletions(-)
diff --git a/ghc/compiler/typecheck/TcGenDeriv.lhs b/ghc/compiler/typecheck/TcGenDeriv.lhs
index 3385fbdda627..a95ffe91a725 100644
--- a/ghc/compiler/typecheck/TcGenDeriv.lhs
+++ b/ghc/compiler/typecheck/TcGenDeriv.lhs
@@ -34,7 +34,9 @@ import HsSyn ( InPat(..), HsExpr(..), MonoBinds(..),
import RdrHsSyn ( mkOpApp, RdrNameMonoBinds, RdrNameHsExpr, RdrNamePat )
import RdrName ( RdrName, mkSrcUnqual )
import RnMonad ( Fixities )
-import BasicTypes ( RecFlag(..), Fixity(..), FixityDirection(..) )
+import BasicTypes ( RecFlag(..), Fixity(..), FixityDirection(..)
+ , maxPrecedence, defaultFixity
+ )
import FieldLabel ( fieldLabelName )
import DataCon ( isNullaryDataCon, dataConTag,
dataConRawArgTys, fIRST_TAG,
@@ -57,7 +59,7 @@ import TysPrim ( charPrimTy, intPrimTy, wordPrimTy, addrPrimTy,
floatPrimTy, doublePrimTy
)
import Util ( mapAccumL, zipEqual, zipWithEqual,
- zipWith3Equal, nOfThem )
+ zipWith3Equal, nOfThem, assocDefault )
import Panic ( panic, assertPanic )
import Maybes ( maybeToBool, assocMaybe )
import Constants
@@ -897,7 +899,7 @@ gen_Read_binds fixities tycon
then d_Expr
else HsVar (last bs_needed)] True
- [lp,rp] = getLRPrecs fixities dc_nm
+ [lp,rp] = getLRPrecs is_infix fixities dc_nm
quals
| is_infix = let (h:t) = field_quals in (h:con_qual:t)
@@ -905,8 +907,11 @@ gen_Read_binds fixities tycon
stmts = quals ++ [ReturnStmt result_expr]
+ {-
+ c.f. Figure 18 in Haskell 1.1 report.
+ -}
paren_prec_limit
- | not is_infix = 9
+ | not is_infix = fromInt maxPrecedence
| otherwise = getFixity fixities dc_nm
read_paren_arg -- parens depend on precedence...
@@ -939,7 +944,7 @@ gen_Show_binds fixs_assoc tycon
([wildPat, con_pat], show_con)
| otherwise =
([a_Pat, con_pat],
- showParen_Expr (HsPar (genOpApp a_Expr gt_RDR (HsLit (HsInt paren_prec_limit))))
+ showParen_Expr (HsPar (genOpApp a_Expr ge_RDR (HsLit (HsInt paren_prec_limit))))
(HsPar (nested_compose_Expr show_thingies)))
where
data_con_RDR = qual_orig_name data_con
@@ -994,7 +999,7 @@ gen_Show_binds fixs_assoc tycon
mk_showString_app str = HsApp (HsVar showString_RDR)
(HsLit (mkHsString str))
- prec_cons = getLRPrecs fixs_assoc dc_nm
+ prec_cons = getLRPrecs is_infix fixs_assoc dc_nm
real_show_thingies
| is_infix =
@@ -1017,41 +1022,51 @@ gen_Show_binds fixs_assoc tycon
(con_left_assoc, con_right_assoc) = isLRAssoc fixs_assoc dc_nm
+ {-
+ c.f. Figure 16 and 17 in Haskell 1.1 report
+ -}
paren_prec_limit
- | not is_infix = 9
- | otherwise = getFixity fixs_assoc dc_nm
+ | not is_infix = fromInt maxPrecedence + 1
+ | otherwise = getFixity fixs_assoc dc_nm + 1
\end{code}
\begin{code}
-getLRPrecs :: Fixities -> Name -> [Integer]
-getLRPrecs fixs_assoc nm = [lp, rp]
+getLRPrecs :: Bool -> Fixities -> Name -> [Integer]
+getLRPrecs is_infix fixs_assoc nm = [lp, rp]
where
- ( con_left_assoc, con_right_assoc) = isLRAssoc fixs_assoc nm
- paren_prec_limit = 9
+ {-
+ Figuring out the fixities of the arguments to a constructor,
+ cf. Figures 16-18 in Haskell 1.1 report.
+ -}
+ (con_left_assoc, con_right_assoc) = isLRAssoc fixs_assoc nm
+ paren_con_prec = getFixity fixs_assoc nm
+ maxPrec = fromInt maxPrecedence
lp
- | con_left_assoc = paren_prec_limit
- | otherwise = paren_prec_limit + 1
+ | not is_infix = maxPrec + 1
+ | con_left_assoc = paren_con_prec
+ | otherwise = paren_con_prec + 1
rp
- | con_right_assoc = paren_prec_limit
- | otherwise = paren_prec_limit + 1
+ | not is_infix = maxPrec + 1
+ | con_right_assoc = paren_con_prec
+ | otherwise = paren_con_prec + 1
-
getFixity :: Fixities -> Name -> Integer
getFixity fixs_assoc nm =
- case assocMaybe fixs_assoc nm of
- Nothing -> 9
- Just (Fixity x _) -> fromInt x + 1
+ case lookupFixity fixs_assoc nm of
+ Fixity x _ -> fromInt x
isLRAssoc :: Fixities -> Name -> (Bool, Bool)
isLRAssoc fixs_assoc nm =
- case assocMaybe fixs_assoc nm of
- Just (Fixity _ InfixL) -> (True, False)
- Just (Fixity _ InfixR) -> (False, True)
- Just (Fixity _ _) -> (False, False)
- _ -> (True, False)
+ case lookupFixity fixs_assoc nm of
+ Fixity _ InfixN -> (False, False)
+ Fixity _ InfixR -> (False, True)
+ Fixity _ InfixL -> (True, False)
+
+lookupFixity :: Fixities -> Name -> Fixity
+lookupFixity fixs_assoc nm = assocDefault defaultFixity fixs_assoc nm
\end{code}
--
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