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)
}