fooZ fooZZ
:+ Zczp
() Z0T
- (,,,,) Z4T
-
+ (,,,,) Z4T 5-tuple
+ (#,,,,#) Z4H unboxed 5-tuple
+ (NB: the number is one different to the number of
+ elements. No real reason except that () is a zero-tuple,
+ while (,) is a 2-tuple.)
\begin{code}
-- alreadyEncoded is used in ASSERTs to check for encoded
encode :: UserString -> EncodedString
encode cs = case maybe_tuple cs of
- Just n -> 'Z' : show n ++ "T" -- Tuples go to Z2T etc
+ Just n -> n -- Tuples go to Z2T etc
Nothing -> go cs
where
go [] = []
go (c:cs) = encode_ch c ++ go cs
--- ToDo: Unboxed tuples too, perhaps?
-maybe_tuple ('(' : cs) = check_tuple (0::Int) cs
-maybe_tuple other = Nothing
+maybe_tuple ('(' : '#' : cs) = case count_commas (0::Int) cs of
+ (n, '#' : ')' : cs) -> Just ('Z' : shows n "H")
+ other -> Nothing
+maybe_tuple ('(' : cs) = case count_commas (0::Int) cs of
+ (n, ')' : cs) -> Just ('Z' : shows n "T")
+ other -> Nothing
+maybe_tuple other = Nothing
-check_tuple :: Int -> String -> Maybe Int
-check_tuple n (',' : cs) = check_tuple (n+1) cs
-check_tuple n ")" = Just n
-check_tuple n other = Nothing
+count_commas :: Int -> String -> (Int, String)
+count_commas n (',' : cs) = count_commas (n+1) cs
+count_commas n cs = (n,cs)
encodeFS :: UserFS -> EncodedFS
encodeFS fast_str | all unencodedChar str = fast_str
where
go n (c : rest) | isDigit c = go (10*n + digitToInt c) rest
go n ('T' : rest) = '(' : replicate n ',' ++ ')' : decode rest
+ go n ('H' : rest) = '(' : '#' : replicate n ',' ++ '#' : ')' : decode rest
go n ('U' : rest) = chr n : decode rest
go n other = pprPanic "decode_escape" (ppr n <+> text (c:rest))