X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=utils%2Fext-core%2FEncoding.hs;fp=utils%2Fext-core%2FEncoding.hs;h=c276932013a8ca46bf16c7cc0c3106ef6b758d0e;hb=6b085eeada6c3c93599fa4b6d77572abc419c08c;hp=0000000000000000000000000000000000000000;hpb=87c93cf56c83abf0148c91d5972dbe65dc72c38a;p=ghc-hetmet.git diff --git a/utils/ext-core/Encoding.hs b/utils/ext-core/Encoding.hs new file mode 100644 index 0000000..c276932 --- /dev/null +++ b/utils/ext-core/Encoding.hs @@ -0,0 +1,204 @@ +module Encoding where + +import Data.Char +import Numeric + +-- tjc: TODO: Copied straight out of Encoding.hs. +-- Ugh, maybe we can avoid this copy-pasta... + +-- ----------------------------------------------------------------------------- +-- The Z-encoding + +{- +This is the main name-encoding and decoding function. It encodes any +string into a string that is acceptable as a C name. This is done +right before we emit a symbol name into the compiled C or asm code. +Z-encoding of strings is cached in the FastString interface, so we +never encode the same string more than once. + +The basic encoding scheme is this. + +* Tuples (,,,) are coded as Z3T + +* Alphabetic characters (upper and lower) and digits + all translate to themselves; + except 'Z', which translates to 'ZZ' + and 'z', which translates to 'zz' + We need both so that we can preserve the variable/tycon distinction + +* Most other printable characters translate to 'zx' or 'Zx' for some + alphabetic character x + +* The others translate as 'znnnU' where 'nnn' is the decimal number + of the character + + Before After + -------------------------- + Trak Trak + foo_wib foozuwib + > zg + >1 zg1 + foo# foozh + foo## foozhzh + foo##1 foozhzh1 + fooZ fooZZ + :+ ZCzp + () Z0T 0-tuple + (,,,,) Z5T 5-tuple + (# #) Z1H unboxed 1-tuple (note the space) + (#,,,,#) Z5H unboxed 5-tuple + (NB: There is no Z1T nor Z0H.) +-} + +type UserString = String -- As the user typed it +type EncodedString = String -- Encoded form + + +zEncodeString :: UserString -> EncodedString +zEncodeString cs = case maybe_tuple cs of + Just n -> n -- Tuples go to Z2T etc + Nothing -> go cs + where + go [] = [] + go (c:cs) = encode_ch c ++ go cs + +unencodedChar :: Char -> Bool -- True for chars that don't need encoding +unencodedChar 'Z' = False +unencodedChar 'z' = False +unencodedChar c = c >= 'a' && c <= 'z' + || c >= 'A' && c <= 'Z' + || c >= '0' && c <= '9' + +encode_ch :: Char -> EncodedString +encode_ch c | unencodedChar c = [c] -- Common case first + +-- Constructors +encode_ch '(' = "ZL" -- Needed for things like (,), and (->) +encode_ch ')' = "ZR" -- For symmetry with ( +encode_ch '[' = "ZM" +encode_ch ']' = "ZN" +encode_ch ':' = "ZC" +encode_ch 'Z' = "ZZ" + +-- Variables +encode_ch 'z' = "zz" +encode_ch '&' = "za" +encode_ch '|' = "zb" +encode_ch '^' = "zc" +encode_ch '$' = "zd" +encode_ch '=' = "ze" +encode_ch '>' = "zg" +encode_ch '#' = "zh" +encode_ch '.' = "zi" +encode_ch '<' = "zl" +encode_ch '-' = "zm" +encode_ch '!' = "zn" +encode_ch '+' = "zp" +encode_ch '\'' = "zq" +encode_ch '\\' = "zr" +encode_ch '/' = "zs" +encode_ch '*' = "zt" +encode_ch '_' = "zu" +encode_ch '%' = "zv" +encode_ch c = 'z' : if isDigit (head hex_str) then hex_str + else '0':hex_str + where hex_str = showHex (ord c) "U" + -- ToDo: we could improve the encoding here in various ways. + -- eg. strings of unicode characters come out as 'z1234Uz5678U', we + -- could remove the 'U' in the middle (the 'z' works as a separator). + + showHex = showIntAtBase 16 intToDigit + -- needed because prior to GHC 6.2, Numeric.showHex added a "0x" prefix + +zDecodeString :: EncodedString -> UserString +zDecodeString [] = [] +zDecodeString ('Z' : d : rest) + | isDigit d = decode_tuple d rest + | otherwise = decode_upper d : zDecodeString rest +zDecodeString ('z' : d : rest) + | isDigit d = decode_num_esc d rest + | otherwise = decode_lower d : zDecodeString rest +zDecodeString (c : rest) = c : zDecodeString rest + +decode_upper, decode_lower :: Char -> Char + +decode_upper 'L' = '(' +decode_upper 'R' = ')' +decode_upper 'M' = '[' +decode_upper 'N' = ']' +decode_upper 'C' = ':' +decode_upper 'Z' = 'Z' +decode_upper ch = {-pprTrace "decode_upper" (char ch)-} ch + +decode_lower 'z' = 'z' +decode_lower 'a' = '&' +decode_lower 'b' = '|' +decode_lower 'c' = '^' +decode_lower 'd' = '$' +decode_lower 'e' = '=' +decode_lower 'g' = '>' +decode_lower 'h' = '#' +decode_lower 'i' = '.' +decode_lower 'l' = '<' +decode_lower 'm' = '-' +decode_lower 'n' = '!' +decode_lower 'p' = '+' +decode_lower 'q' = '\'' +decode_lower 'r' = '\\' +decode_lower 's' = '/' +decode_lower 't' = '*' +decode_lower 'u' = '_' +decode_lower 'v' = '%' +decode_lower ch = {-pprTrace "decode_lower" (char ch)-} ch + +-- Characters not having a specific code are coded as z224U (in hex) +decode_num_esc :: Char -> EncodedString -> UserString +decode_num_esc d rest + = go (digitToInt d) rest + where + go n (c : rest) | isHexDigit c = go (16*n + digitToInt c) rest + go n ('U' : rest) = chr n : zDecodeString rest + go n other = error ("decode_num_esc: " ++ show n ++ ' ':other) + +decode_tuple :: Char -> EncodedString -> UserString +decode_tuple d rest + = go (digitToInt d) rest + where + -- NB. recurse back to zDecodeString after decoding the tuple, because + -- the tuple might be embedded in a longer name. + go n (c : rest) | isDigit c = go (10*n + digitToInt c) rest + go 0 ('T':rest) = "()" ++ zDecodeString rest + go n ('T':rest) = '(' : replicate (n-1) ',' ++ ")" ++ zDecodeString rest + go 1 ('H':rest) = "(# #)" ++ zDecodeString rest + go n ('H':rest) = '(' : '#' : replicate (n-1) ',' ++ "#)" ++ zDecodeString rest + go n other = error ("decode_tuple: " ++ show n ++ ' ':other) + +{- +Tuples are encoded as + Z3T or Z3H +for 3-tuples or unboxed 3-tuples respectively. No other encoding starts + Z + +* "(# #)" is the tycon for an unboxed 1-tuple (not 0-tuple) + There are no unboxed 0-tuples. + +* "()" is the tycon for a boxed 0-tuple. + There are no boxed 1-tuples. +-} + +maybe_tuple :: UserString -> Maybe EncodedString + +maybe_tuple "(# #)" = Just("Z1H") +maybe_tuple ('(' : '#' : cs) = case count_commas (0::Int) cs of + (n, '#' : ')' : _) -> Just ('Z' : shows (n+1) "H") + _ -> Nothing +maybe_tuple "()" = Just("Z0T") +maybe_tuple ('(' : cs) = case count_commas (0::Int) cs of + (n, ')' : _) -> Just ('Z' : shows (n+1) "T") + _ -> Nothing +maybe_tuple _ = Nothing + +count_commas :: Int -> String -> (Int, String) +count_commas n (',' : cs) = count_commas (n+1) cs +count_commas n cs = (n,cs) +