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|
module Tokenize where
import Operations
---- import UseGrammar (isLiteral,identC)
import CFIdent
import Char
-- lexers = tokenizers, to prepare input for GF grammars. AR 4/1/2002
-- an entry for each is included in Custom.customTokenizer
-- just words
tokWords :: String -> [CFTok]
tokWords = map tS . words
tokLits :: String -> [CFTok]
tokLits = map mkCFTok . words
tokVars :: String -> [CFTok]
tokVars = map mkCFTokVar . words
mkCFTok :: String -> CFTok
mkCFTok s = case s of
'"' :cs@(_:_) -> tL $ init cs
'\'':cs@(_:_) -> tL $ init cs --- 's Gravenhage
_:_ | all isDigit s -> tI s
_ -> tS s
mkCFTokVar :: String -> CFTok
mkCFTokVar s = case s of
'?':_:_ -> tM s --- "?" --- compat with prCF
'x':'_':_ -> tV s
'x':[] -> tV s
'$':xs@(_:_) -> if last s == '$' then tV (init xs) else tS s
_ -> tS s
mkLit :: String -> CFTok
mkLit s = if (all isDigit s) then (tI s) else (tL s)
mkTL :: String -> CFTok
mkTL s = if (all isDigit s) then (tI s) else (tL ("'" ++ s ++ "'"))
-- Haskell lexer, usable for much code
lexHaskell :: String -> [CFTok]
lexHaskell ss = case lex ss of
[(w@(_:_),ws)] -> tS w : lexHaskell ws
_ -> []
-- somewhat shaky text lexer
lexText :: String -> [CFTok]
lexText = uncap . lx where
lx s = case s of
p : cs | isMPunct p -> tS [p] : uncap (lx cs)
p : cs | isPunct p -> tS [p] : lx cs
s : cs | isSpace s -> lx cs
_ : _ -> getWord s
_ -> []
getWord s = tS w : lx ws where (w,ws) = span isNotSpec s
isMPunct c = elem c ".!?"
isPunct c = elem c ",:;()\""
isNotSpec c = not (isMPunct c || isPunct c || isSpace c)
uncap (TS (c:cs) : ws) = tC (c:cs) : ws
uncap s = s
-- lexer for C--, a mini variant of C
lexC2M :: String -> [CFTok]
lexC2M = lexC2M' False
lexC2M' :: Bool -> String -> [CFTok]
lexC2M' isHigherOrder s = case s of
'#':cs -> lexC $ dropWhile (/='\n') cs
'/':'*':cs -> lexC $ dropComment cs
c:cs | isSpace c -> lexC cs
c:cs | isAlpha c -> getId s
c:cs | isDigit c -> getLit s
c:d:cs | isSymb [c,d] -> tS [c,d] : lexC cs
c:cs | isSymb [c] -> tS [c] : lexC cs
_ -> [] --- covers end of file and unknown characters
where
lexC = lexC2M' isHigherOrder
getId s = mkT i : lexC cs where (i,cs) = span isIdChar s
getLit s = tI i : lexC cs where (i,cs) = span isDigit s
isIdChar c = isAlpha c || isDigit c || elem c "'_"
isSymb = reservedAnsiCSymbol
dropComment s = case s of
'*':'/':cs -> cs
_:cs -> dropComment cs
_ -> []
mkT i = if (isRes i) then (tS i) else
if isHigherOrder then (tV i) else (tL ("'" ++ i ++ "'"))
isRes = reservedAnsiC
reservedAnsiCSymbol s = case lookupTree show s ansiCtree of
Ok True -> True
_ -> False
reservedAnsiC s = case lookupTree show s ansiCtree of
Ok False -> True
_ -> False
-- for an efficient lexer: precompile this!
ansiCtree = buildTree $ [(s,True) | s <- reservedAnsiCSymbols] ++
[(s,False) | s <- reservedAnsiCWords]
reservedAnsiCSymbols = words $
"<<= >>= << >> ++ -- == <= >= *= += -= %= /= &= ^= |= " ++
"^ { } = , ; + * - ( ) < > & % ! ~"
reservedAnsiCWords = words $
"auto break case char const continue default " ++
"do double else enum extern float for goto if int " ++
"long register return short signed sizeof static struct switch typedef " ++
"union unsigned void volatile while " ++
"main printin putchar" --- these are not ansi-C
-- turn unknown tokens into string literals; not recursively for literals 123, 'foo'
unknown2string :: (String -> Bool) -> [CFTok] -> [CFTok]
unknown2string isKnown = map mkOne where
mkOne t@(TS s) = if isKnown s then t else mkTL s
mkOne t@(TC s) = if isKnown s then t else mkTL s
mkOne t = t
lexTextLiteral isKnown = unknown2string (eitherUpper isKnown) . lexText
lexHaskellLiteral isKnown = unknown2string isKnown . lexHaskell
eitherUpper isKnown w@(c:cs) = isKnown (toLower c : cs) || isKnown (toUpper c : cs)
eitherUpper isKnown w = isKnown w
|
