Fix a bug in alternative layout

[ghc-hetmet.git] / compiler / parser / Lexer.x

diff --git a/compiler/parser/Lexer.x b/compiler/parser/Lexer.x
index fbc4821..1bb8a63 100644 (file)
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -1998,26 +1998,29 @@ alternativeLayoutRuleToken t
                     setALRContext (ALRLayout expectingOCurly thisCol : context)
                     setNextToken t
                     return (L thisLoc ITocurly)
+             -- We do the [] cases earlier than in the spec, as we
+             -- have an actual EOF token
+             (ITeof, ALRLayout _ _ : ls, _) ->
+                 do setALRContext ls
+                    setNextToken t
+                    return (L thisLoc ITccurly)
+             (ITeof, _, _) ->
+                 return t
+             -- the other ITeof case omitted; general case below covers it
              (ITin, ALRLayout ALRLayoutLet _ : ls, _)
               | newLine ->
                  do setPendingImplicitTokens [t]
                     setALRContext ls
                     return (L thisLoc ITccurly)
-             (_, ls@(ALRLayout _ col : _), _)
-              | newLine && thisCol <= col ->
-                 do let f ls'@(ALRLayout _ col' : ls'')
-                         | thisCol < col' = case f ls'' of
-                                            (ts, ls''') ->
-                                                (L thisLoc ITccurly : ts, ls''')
-                         | thisCol == col' = ([L thisLoc ITsemi], ls')
-                         | otherwise       = ([], ls')
-                        f ls' = ([], ls')
-                    case f ls of
-                        (t' : ts, ls') ->
-                            do setPendingImplicitTokens ts
-                               setNextToken t
-                               return t'
-                        _ -> panic "Layout rule: [] when considering newline"
+             (_, ALRLayout _ col : ls, _)
+              | newLine && thisCol == col ->
+                 do setNextToken t
+                    return (L thisLoc ITsemi)
+              | newLine && thisCol < col ->
+                 do setALRContext ls
+                    -- Note that we use lastLoc, as we may need to close
+                    -- more layouts, or give a semicolon
+                    return (L lastLoc ITccurly)
              (u, _, _)
               | isALRopen u ->
                  do setALRContext (ALRNoLayout (containsCommas u) : context)
@@ -2040,7 +2043,7 @@ alternativeLayoutRuleToken t
                  do setALRContext ls
                     setPendingImplicitTokens [t]
                     return (L thisLoc ITccurly)
-             (ITin, _ : ls, _) ->
+             (ITin, ALRLayout _ _ : ls, _) ->
                  do setALRContext ls
                     setNextToken t
                     return (L thisLoc ITccurly)
@@ -2055,13 +2058,6 @@ alternativeLayoutRuleToken t
                     setPendingImplicitTokens [t]
                     return (L thisLoc ITccurly)
              -- the other ITwhere case omitted; general case below covers it
-             -- The first [] case comes before the general case, as we
-             -- have an actual EOF token
-             (ITeof, ALRLayout _ _ : ls, _) ->
-                 do setALRContext ls
-                    setNextToken t
-                    return (L thisLoc ITccurly)
-             -- the other ITeof case omitted; general case below covers it
              (_, _, _) -> return t
 
 isALRopen :: Token -> Bool
@@ -2070,6 +2066,8 @@ isALRopen ITif     = True
 isALRopen IToparen = True
 isALRopen ITobrack = True
 isALRopen ITocurly = True
+-- GHC Extensions:
+isALRopen IToubxparen = True
 isALRopen _        = False
 
 isALRclose :: Token -> Bool
@@ -2078,11 +2076,15 @@ isALRclose ITthen   = True
 isALRclose ITcparen = True
 isALRclose ITcbrack = True
 isALRclose ITccurly = True
+-- GHC Extensions:
+isALRclose ITcubxparen = True
 isALRclose _        = False
 
 containsCommas :: Token -> Bool
 containsCommas IToparen = True
 containsCommas ITobrack = True
+-- GHC Extensions:
+containsCommas IToubxparen = True
 containsCommas _        = False
 
 topNoLayoutContainsCommas :: [ALRContext] -> Bool