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|
module Thue.Parser (
ThueProgram(..),
ThueRule(..),
ThueState,
parseThue
) where
import Control.Applicative( some )
import Text.ParserCombinators.Parsec
data ThueProgram = ThueProgram { thueRules :: [ThueRule]
, thueInitialState :: ThueState }
deriving (Show, Eq)
data ThueRule = ThueRule { original :: ThueState
, replacement :: ThueState }
deriving (Show, Eq)
type ThueState = 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 (ThueRule o r)
separatorLine = whiteSpace >> separator >> whiteSpace >> eol
separator = string "::="
<?> "rule separator"
initialState = do
s <- state `sepEndBy` eol
return (concat s)
ruleState = some ruleStateChar
ruleStateChar = noneOf "\n\r:"
<|> try (char ':' >> notFollowedBy (string ":=") >> return ':')
<?> "state character"
state = many stateChar
stateChar = noneOf "\n\r"
<?> "state character"
whiteSpace = many (oneOf "\t ")
eol = try (string "\r\n")
<|> try (string "\n\r")
<|> try (string "\r")
<|> try (string "\n")
<?> "end of line"
|
