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{-
Copyright (C) 2006-2010 John MacFarlane <jgm@berkeley.edu>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-}
{- |
Module : Text.Pandoc.CharacterReferences
Copyright : Copyright (C) 2006-2010 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <jgm@berkeley.edu>
Stability : alpha
Portability : portable
Functions for parsing character references.
-}
module Text.Pandoc.CharacterReferences (
characterReference,
decodeCharacterReferences,
) where
import Text.ParserCombinators.Parsec
import Text.HTML.TagSoup.Entity ( lookupNamedEntity, lookupNumericEntity )
import Data.Maybe ( fromMaybe )
-- | Parse character entity.
characterReference :: GenParser Char st Char
characterReference = try $ do
char '&'
character <- numRef <|> entity
char ';'
return character
numRef :: GenParser Char st Char
numRef = do
char '#'
num <- hexNum <|> decNum
return $ fromMaybe '?' $ lookupNumericEntity num
hexNum :: GenParser Char st [Char]
hexNum = do
x <- oneOf "Xx"
num <- many1 hexDigit
return (x:num)
decNum :: GenParser Char st [Char]
decNum = many1 digit
entity :: GenParser Char st Char
entity = do
body <- many1 alphaNum
return $ fromMaybe '?' $ lookupNamedEntity body
-- | Convert entities in a string to characters.
decodeCharacterReferences :: String -> String
decodeCharacterReferences str =
case parse (many (characterReference <|> anyChar)) str str of
Left err -> error $ "\nError: " ++ show err
Right result -> result
|
