Migrate cvs diff from fptools-assoc branch

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

diff --git a/compiler/parser/Lexer.x b/compiler/parser/Lexer.x
index 1ede5f6..0b02f41 100644 (file)
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -216,6 +216,11 @@ $white_no_nl+                              ;
   "{-#" $whitechar* (INCLUDE|include)   { lex_string_prag ITinclude_prag }
 }
 
+<0,option_prags,glaexts> {
+       -- This is to catch things like {-# OPTIONS OPTIONS_HUGS ... 
+  "{-#" $whitechar* $idchar+            { nested_comment }
+}
+
 -- '0' state: ordinary lexemes
 -- 'glaexts' state: glasgow extensions (postfix '#', etc.)
 
@@ -583,6 +588,9 @@ reservedSymsFM = listToUFM $
        ,("→",   ITrarrow,    bit glaExtsBit)
        ,("←",   ITlarrow,    bit glaExtsBit)
        ,("⋯",        ITdotdot,       bit glaExtsBit)
+        -- ToDo: ideally, → and ∷ should be "specials", so that they cannot
+        -- form part of a large operator.  This would let us have a better
+        -- syntax for kinds: ɑ∷*→* would be a legal kind signature. (maybe).
 #endif
        ]
 
@@ -1210,6 +1218,7 @@ alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
 alexGetChar (AI loc ofs s) 
   | atEnd s   = Nothing
   | otherwise = adj_c `seq` loc' `seq` ofs' `seq` s' `seq` 
+               --trace (show (ord c)) $
                Just (adj_c, (AI loc' ofs' s'))
   where (c,s') = nextChar s
         loc'   = advanceSrcLoc loc c
@@ -1259,6 +1268,7 @@ alexGetChar' :: AlexInput -> Maybe (Char,AlexInput)
 alexGetChar' (AI loc ofs s) 
   | atEnd s   = Nothing
   | otherwise = c `seq` loc' `seq` ofs' `seq` s' `seq` 
+               --trace (show (ord c)) $
                Just (c, (AI loc' ofs' s'))
   where (c,s') = nextChar s
         loc'   = advanceSrcLoc loc c
@@ -1443,15 +1453,13 @@ lexToken = do
        span `seq` setLastToken span bytes
        t span buf bytes
 
--- ToDo: Alex reports the buffer at the start of the erroneous lexeme,
--- but it would be more informative to report the location where the
--- error was actually discovered, especially if this is a decoding
--- error.
-reportLexError loc1 loc2 buf str = 
+reportLexError loc1 loc2 buf str
+  | atEnd buf = failLocMsgP loc1 loc2 (str ++ " at end of input")
+  | otherwise =
   let 
        c = fst (nextChar buf)
   in
   if c == '\0' -- decoding errors are mapped to '\0', see utf8DecodeChar#
-    then failLocMsgP loc2 loc2 "UTF-8 decoding error"
+    then failLocMsgP loc2 loc2 (str ++ " (UTF-8 decoding error)")
     else failLocMsgP loc1 loc2 (str ++ " at character " ++ show c)
 }