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|
{-# LANGUAGE CPP #-}
-- |
-- Module : Documentation.Haddock.Parser.Util
-- Copyright : (c) Mateusz Kowalczyk 2013-2014,
-- Simon Hengel 2013
-- License : BSD-like
--
-- Maintainer : haddock@projects.haskell.org
-- Stability : experimental
-- Portability : portable
--
-- Various utility functions used by the parser.
module Documentation.Haddock.Parser.Util (
unsnoc
, strip
, takeUntil
, makeLabeled
, takeHorizontalSpace
, skipHorizontalSpace
) where
import Control.Applicative
import Control.Monad (mfilter)
import Data.Attoparsec.ByteString.Char8 hiding (parse, take, endOfLine)
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as BS
import Prelude hiding (takeWhile)
#if MIN_VERSION_bytestring(0,10,2)
import Data.ByteString.Char8 (unsnoc)
#else
unsnoc :: ByteString -> Maybe (ByteString, Char)
unsnoc bs
| BS.null bs = Nothing
| otherwise = Just (BS.init bs, BS.last bs)
#endif
-- | Remove all leading and trailing whitespace
strip :: String -> String
strip = (\f -> f . f) $ dropWhile isSpace . reverse
skipHorizontalSpace :: Parser ()
skipHorizontalSpace = skipWhile (`elem` " \t\f\v\r")
takeHorizontalSpace :: Parser BS.ByteString
takeHorizontalSpace = takeWhile (`elem` " \t\f\v\r")
makeLabeled :: (String -> Maybe String -> a) -> String -> a
makeLabeled f input = case break isSpace $ removeEscapes $ strip input of
(uri, "") -> f uri Nothing
(uri, label) -> f uri (Just $ dropWhile isSpace label)
where
-- As we don't parse these any further, we don't do any processing to the
-- string so we at least remove escape character here. Perhaps we should
-- actually be parsing the label at the very least?
removeEscapes "" = ""
removeEscapes ('\\':'\\':xs) = '\\' : removeEscapes xs
removeEscapes ('\\':xs) = removeEscapes xs
removeEscapes (x:xs) = x : removeEscapes xs
takeUntil :: ByteString -> Parser ByteString
takeUntil end_ = dropEnd <$> requireEnd (scan (False, end) p) >>= gotSome
where
end = BS.unpack end_
p :: (Bool, String) -> Char -> Maybe (Bool, String)
p acc c = case acc of
(True, _) -> Just (False, end)
(_, []) -> Nothing
(_, x:xs) | x == c -> Just (False, xs)
_ -> Just (c == '\\', end)
dropEnd = BS.reverse . BS.drop (length end) . BS.reverse
requireEnd = mfilter (BS.isSuffixOf end_)
gotSome xs
| BS.null xs = fail "didn't get any content"
| otherwise = return xs
|
