Indeed the second solution is more elegant (and the examples very simple to follow, they should be added to Parsec's documentation!).
For the records, before reading this I was using the ductape solution below:
161
162 -- take a string till t, on that runs parser p.
163 -- The last parameters sets wheter t will be consumed or
164 -- not. FILE HANDLING FOR ERRORS?
165 parseTill :: Parser a -> Parser b -> Parser b
166 parseTill ter p = manyTill anyChar ter >>= \sndPar ->
167 case parse p "" sndPar of
168 Left a -> fail "todo: check how error msg are propagted"
169 Right b -> return b
Thanks again
-F
On Sun, 11 Mar 2012 10:53:50 +0000
Stephen Tetley
Hi Franco
Actually the simple case of finding formatting tags in free text was easier in Parsec than my email last night suggested. Perhaps it is artificially easy because you can identify tag start and ends with a single character so you can use `satisfy`.
import Text.Parsec import Text.Parsec.String import Control.Applicative hiding ( (<|>), many )
data Text1 = FreeText String | Formatted String deriving (Eq,Ord,Show)
type Text = [Text1]
runText :: String -> Either ParseError Text runText = runP lexer () "no-input"
notLAngle :: Char -> Bool notLAngle = (/= '<')
notRAngle :: Char -> Bool notRAngle = (/= '>')
lexer :: Parser Text lexer = many (formatted <|> free)
formatted :: Parser Text1 formatted = Formatted <$> between (char '<') (char '>') (many1 (satisfy notRAngle))
free :: Parser Text1 free = FreeText <$> many1 (satisfy notLAngle)
demo01 = runText "[ someconditions | this is some
text.]" demo02 = runText " more text."
--
Franco