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import Text.Combinators.Parsec
data ThueProgram = ThueProgram { thueRules :: [Rule]
, thueInitialState :: State }
deriving (Show)
data Rule = Rule { original :: State
, replacement :: State }
deriving (Show)
type State = String
parseThue :: String -> Either ParseError ThueProgram
parseThue = parse thue "error"
thue = do
rs <- many rule
separatorLine
i <- initialState
eof
return (ThueProgram rs i)
rule = do
o <- ruleState
separator
r <- state
eol
return (Rule o r)
separatorLine = whiteSpace >> separator >> whiteSpace >> eol
separator = string "::="
initialState = do
s <- state `sepEndBy` eol
return (concat s)
ruleState = many ruleStateChar
ruleStateChar = noneOf "\n\r:"
<|> try (do { char ':'; notFollowedBy (string ":="); return ':'})
state = many stateChar
stateChar = noneOf "\n\r"
whiteSpace = many (oneOf "\t ")
eol = try (string "\r\n")
<|> try (string "\n\r")
<|> try (string "\r")
<|> try (string "\n")
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