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|
--------------------------------------------------------------------
-- |
-- Module : Text.Feed.Import
-- Copyright : (c) Galois, Inc. 2008
-- License : BSD3
--
-- Maintainer: Sigbjorn Finne <sof@galois.com>
-- Stability : provisional
-- Description: Convert from XML to Feeds.
--
--------------------------------------------------------------------
module Text.Feed.Import
( parseFeedFromFile -- :: FilePath -> IO Feed
, parseFeedString -- :: String -> IO Feed
-- if you know your format, use these directly:
, readRSS2 -- :: XML.Element -> Maybe Feed
, readRSS1 -- :: XML.Element -> Maybe Feed
, readAtom -- :: XML.Element -> Maybe Feed
) where
import Text.Atom.Feed.Import as Atom
import Text.RSS.Import as RSS
import Text.RSS1.Import as RSS1
import Text.Feed.Types
import Text.XML.Light as XML
import Control.Monad
import System.IO.UTF8 as UTF8 ( readFile )
-- | 'parseFeedFromFile fp' reads in the contents of the file at @fp@;
-- the assumed encoding is UTF-8.
parseFeedFromFile :: FilePath -> IO Feed
parseFeedFromFile fp = do
ls <- UTF8.readFile fp
case parseFeedString ls of
Nothing -> fail ("parseFeedFromFile: not a well-formed XML content in: " ++ fp)
Just f -> return f
-- | 'parseFeedString str' tries to parse the string @str@ as
-- one of the feed formats. First as Atom, then RSS2 before
-- giving RSS1 a try. @Nothing@ is, rather unhelpfully, returned
-- as an indication of error.
parseFeedString :: String -> Maybe Feed
parseFeedString str =
case parseXMLDoc str of
Nothing -> Nothing
Just e ->
readAtom e `mplus`
readRSS2 e `mplus`
readRSS1 e `mplus`
Just (XMLFeed e)
-- | 'readRSS2 elt' tries to derive an RSS2.x, RSS-0.9x feed document
-- from the XML element @e@.
readRSS2 :: XML.Element -> Maybe Feed
readRSS2 e = fmap RSSFeed $ RSS.elementToRSS e
-- | 'readRSS1 elt' tries to derive an RSS1.0 feed document
-- from the XML element @e@.
readRSS1 :: XML.Element -> Maybe Feed
readRSS1 e = fmap RSS1Feed $ RSS1.elementToFeed e
-- | 'readAtom elt' tries to derive an Atom feed document
-- from the XML element @e@.
readAtom :: XML.Element -> Maybe Feed
readAtom e = fmap AtomFeed $ Atom.elementFeed e
|
