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Diffstat (limited to 'compiler/parser/LexCore.hs')
| -rw-r--r-- | compiler/parser/LexCore.hs | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/compiler/parser/LexCore.hs b/compiler/parser/LexCore.hs new file mode 100644 index 0000000000..1a545a3e43 --- /dev/null +++ b/compiler/parser/LexCore.hs @@ -0,0 +1,130 @@ +module LexCore where + +import ParserCoreUtils +import Ratio +import Char +import qualified Numeric( readFloat, readDec ) + +isNameChar c = isAlpha c || isDigit c || (c == '_') || (c == '\'') +isKeywordChar c = isAlpha c || (c == '_') + +lexer :: (Token -> P a) -> P a +lexer cont [] = cont TKEOF [] +lexer cont ('\n':cs) = \line -> lexer cont cs (line+1) +lexer cont ('-':'>':cs) = cont TKrarrow cs + +lexer cont (c:cs) + | isSpace c = lexer cont cs + | isLower c || (c == '_') = lexName cont TKname (c:cs) + | isUpper c = lexName cont TKcname (c:cs) + | isDigit c || (c == '-') = lexNum cont (c:cs) + +lexer cont ('%':cs) = lexKeyword cont cs +lexer cont ('\'':cs) = lexChar cont cs +lexer cont ('\"':cs) = lexString [] cont cs +lexer cont ('#':cs) = cont TKhash cs +lexer cont ('(':cs) = cont TKoparen cs +lexer cont (')':cs) = cont TKcparen cs +lexer cont ('{':cs) = cont TKobrace cs +lexer cont ('}':cs) = cont TKcbrace cs +lexer cont ('=':cs) = cont TKeq cs +lexer cont (':':':':cs) = cont TKcoloncolon cs +lexer cont ('*':cs) = cont TKstar cs +lexer cont ('.':cs) = cont TKdot cs +lexer cont ('\\':cs) = cont TKlambda cs +lexer cont ('@':cs) = cont TKat cs +lexer cont ('?':cs) = cont TKquestion cs +lexer cont (';':cs) = cont TKsemicolon cs +lexer cont (c:cs) = failP "invalid character" [c] + + + +lexChar cont ('\\':'x':h1:h0:'\'':cs) + | isHexEscape [h1,h0] = cont (TKchar (hexToChar h1 h0)) cs +lexChar cont ('\\':cs) = failP "invalid char character" ('\\':(take 10 cs)) +lexChar cont ('\'':cs) = failP "invalid char character" ['\''] +lexChar cont ('\"':cs) = failP "invalid char character" ['\"'] +lexChar cont (c:'\'':cs) = cont (TKchar c) cs + + +lexString s cont ('\\':'x':h1:h0:cs) + | isHexEscape [h1,h0] = lexString (s++[hexToChar h1 h0]) cont cs +lexString s cont ('\\':cs) = failP "invalid string character" ['\\'] +lexString s cont ('\'':cs) = failP "invalid string character" ['\''] +lexString s cont ('\"':cs) = cont (TKstring s) cs +lexString s cont (c:cs) = lexString (s++[c]) cont cs + +isHexEscape = all (\c -> isHexDigit c && (isDigit c || isLower c)) + +hexToChar h1 h0 = chr (digitToInt h1 * 16 + digitToInt h0) + + +lexNum cont cs = + case cs of + ('-':cs) -> f (-1) cs + _ -> f 1 cs + where f sgn cs = + case span isDigit cs of + (digits,'.':c:rest) + | isDigit c -> cont (TKrational (fromInteger sgn * r)) rest' + where ((r,rest'):_) = readFloat (digits ++ ('.':c:rest)) + -- When reading a floating-point number, which is + -- a bit complicated, use the Haskell 98 library function + (digits,rest) -> cont (TKinteger (sgn * (read digits))) rest + +lexName cont cstr cs = cont (cstr name) rest + where (name,rest) = span isNameChar cs + +lexKeyword cont cs = + case span isKeywordChar cs of + ("module",rest) -> cont TKmodule rest + ("data",rest) -> cont TKdata rest + ("newtype",rest) -> cont TKnewtype rest + ("forall",rest) -> cont TKforall rest + ("rec",rest) -> cont TKrec rest + ("let",rest) -> cont TKlet rest + ("in",rest) -> cont TKin rest + ("case",rest) -> cont TKcase rest + ("of",rest) -> cont TKof rest + ("coerce",rest) -> cont TKcoerce rest + ("note",rest) -> cont TKnote rest + ("external",rest) -> cont TKexternal rest + ("_",rest) -> cont TKwild rest + _ -> failP "invalid keyword" ('%':cs) + + +#if __GLASGOW_HASKELL__ >= 504 +-- The readFloat in the Numeric library will do the job + +readFloat :: (RealFrac a) => ReadS a +readFloat = Numeric.readFloat + +#else +-- Haskell 98's Numeric.readFloat used to have a bogusly restricted signature +-- so it was incapable of reading a rational. +-- So for GHCs that have that old bogus library, here is the code, written out longhand. + +readFloat r = [(fromRational ((n%1)*10^^(k-d)),t) | (n,d,s) <- readFix r, + (k,t) <- readExp s] ++ + [ (0/0, t) | ("NaN",t) <- lex r] ++ + [ (1/0, t) | ("Infinity",t) <- lex r] + where + readFix r = [(read (ds++ds'), length ds', t) + | (ds,d) <- lexDigits r, + (ds',t) <- lexFrac d ] + + lexFrac ('.':ds) = lexDigits ds + lexFrac s = [("",s)] + + readExp (e:s) | e `elem` "eE" = readExp' s + readExp s = [(0,s)] + + readExp' ('-':s) = [(-k,t) | (k,t) <- Numeric.readDec s] + readExp' ('+':s) = Numeric.readDec s + readExp' s = Numeric.readDec s + +lexDigits :: ReadS String +lexDigits s = case span isDigit s of + (cs,s') | not (null cs) -> [(cs,s')] + otherwise -> [] +#endif |