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{-# LANGUAGE FlexibleContexts #-}
module Text.Pandoc.Readers.OPML ( readOPML ) where
import Control.Monad.State.Strict
import Data.Char (toUpper)
import Data.Default
import Data.Generics
import Data.Maybe (fromMaybe)
import Data.Text (Text, pack, unpack)
import Text.HTML.TagSoup.Entity (lookupEntity)
import Text.Pandoc.Builder
import Text.Pandoc.Class (PandocMonad)
import Text.Pandoc.Options
import Text.Pandoc.Readers.HTML (readHtml)
import Text.Pandoc.Readers.Markdown (readMarkdown)
import Text.Pandoc.Shared (crFilter, blocksToInlines')
import Text.XML.Light
type OPML m = StateT OPMLState m
data OPMLState = OPMLState{
opmlSectionLevel :: Int
, opmlDocTitle :: Inlines
, opmlDocAuthors :: [Inlines]
, opmlDocDate :: Inlines
, opmlOptions :: ReaderOptions
} deriving Show
instance Default OPMLState where
def = OPMLState{ opmlSectionLevel = 0
, opmlDocTitle = mempty
, opmlDocAuthors = []
, opmlDocDate = mempty
, opmlOptions = def
}
readOPML :: PandocMonad m => ReaderOptions -> Text -> m Pandoc
readOPML opts inp = do
(bs, st') <- runStateT
(mapM parseBlock $ normalizeTree $
parseXML (unpack (crFilter inp))) def{ opmlOptions = opts }
return $
setTitle (opmlDocTitle st') $
setAuthors (opmlDocAuthors st') $
setDate (opmlDocDate st') $
doc $ mconcat bs
-- normalize input, consolidating adjacent Text and CRef elements
normalizeTree :: [Content] -> [Content]
normalizeTree = everywhere (mkT go)
where go :: [Content] -> [Content]
go (Text (CData CDataRaw _ _):xs) = xs
go (Text (CData CDataText s1 z):Text (CData CDataText s2 _):xs) =
Text (CData CDataText (s1 ++ s2) z):xs
go (Text (CData CDataText s1 z):CRef r:xs) =
Text (CData CDataText (s1 ++ convertEntity r) z):xs
go (CRef r:Text (CData CDataText s1 z):xs) =
Text (CData CDataText (convertEntity r ++ s1) z):xs
go (CRef r1:CRef r2:xs) =
Text (CData CDataText (convertEntity r1 ++ convertEntity r2) Nothing):xs
go xs = xs
convertEntity :: String -> String
convertEntity e = Data.Maybe.fromMaybe (map toUpper e) (lookupEntity e)
-- convenience function to get an attribute value, defaulting to ""
attrValue :: String -> Element -> String
attrValue attr elt =
fromMaybe "" (lookupAttrBy (\x -> qName x == attr) (elAttribs elt))
-- exceptT :: PandocMonad m => Either PandocError a -> OPML m a
-- exceptT = either throwError return
asHtml :: PandocMonad m => String -> OPML m Inlines
asHtml s = do
opts <- gets opmlOptions
Pandoc _ bs <- readHtml def{ readerExtensions = readerExtensions opts } (pack s)
return $ blocksToInlines' bs
asMarkdown :: PandocMonad m => String -> OPML m Blocks
asMarkdown s = do
opts <- gets opmlOptions
Pandoc _ bs <- readMarkdown def{ readerExtensions = readerExtensions opts } (pack s)
return $ fromList bs
getBlocks :: PandocMonad m => Element -> OPML m Blocks
getBlocks e = mconcat <$> mapM parseBlock (elContent e)
parseBlock :: PandocMonad m => Content -> OPML m Blocks
parseBlock (Elem e) =
case qName (elName e) of
"ownerName" -> mempty <$ modify (\st ->
st{opmlDocAuthors = [text $ strContent e]})
"dateModified" -> mempty <$ modify (\st ->
st{opmlDocDate = text $ strContent e})
"title" -> mempty <$ modify (\st ->
st{opmlDocTitle = text $ strContent e})
"outline" -> gets opmlSectionLevel >>= sect . (+1)
"?xml" -> return mempty
_ -> getBlocks e
where sect n = do headerText <- asHtml $ attrValue "text" e
noteBlocks <- asMarkdown $ attrValue "_note" e
modify $ \st -> st{ opmlSectionLevel = n }
bs <- getBlocks e
modify $ \st -> st{ opmlSectionLevel = n - 1 }
let headerText' = case map toUpper (attrValue "type" e) of
"LINK" -> link
(attrValue "url" e) "" headerText
_ -> headerText
return $ header n headerText' <> noteBlocks <> bs
parseBlock _ = return mempty
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