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module HpcLexer where
import Data.Char
data Token
= ID String
| SYM Char
| INT Int
| STR String
| CAT String
deriving (Eq,Show)
initLexer :: String -> [Token]
initLexer str = [ t | (_,_,t) <- lexer str 1 1 ]
lexer :: String -> Int -> Int -> [(Int,Int,Token)]
lexer (c:cs) line column
| c == '\n' = lexer cs (succ line) 1
| c == '\"' = lexerSTR cs line (succ column)
| c == '[' = lexerCAT cs "" line (succ column)
| c `elem` "{};-:"
= (line,column,SYM c) : lexer cs line (succ column)
| isSpace c = lexer cs line (succ column)
| isAlpha c = lexerKW cs [c] line (succ column)
| isDigit c = lexerINT cs [c] line (succ column)
| otherwise = error "lexer failure"
lexer [] _ _ = []
lexerKW :: String -> String -> Int -> Int -> [(Int,Int,Token)]
lexerKW (c:cs) s line column
| isAlpha c = lexerKW cs (s ++ [c]) line (succ column)
lexerKW other s line column = (line,column,ID s) : lexer other line column
lexerINT :: String -> String -> Int -> Int -> [(Int,Int,Token)]
lexerINT (c:cs) s line column
| isDigit c = lexerINT cs (s ++ [c]) line (succ column)
lexerINT other s line column = (line,column,INT (read s)) : lexer other line column
-- not technically correct for the new column count, but a good approximation.
lexerSTR :: String -> Int -> Int -> [(Int,Int,Token)]
lexerSTR cs line column
= case lex ('"' : cs) of
[(str,rest)] -> (line,succ column,STR (read str))
: lexer rest line (length (show str) + column + 1)
_ -> error "bad string"
lexerCAT :: String -> String -> Int -> Int -> [(Int,Int,Token)]
lexerCAT (c:cs) s line column
| c == ']' = (line,column,CAT s) : lexer cs line (succ column)
| otherwise = lexerCAT cs (s ++ [c]) line (succ column)
lexerCAT [] _ _ _ = error "lexer failure in CAT"
test :: IO ()
test = do
t <- readFile "EXAMPLE.tc"
print (initLexer t)
|
