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module NestingXML where
import Data.Conduit
import Data.XML.Types
import Control.Monad.Reader
type NestingXML o m a = ReaderT Int (ConduitM Event o m) a
runNestingXML :: NestingXML o m a -> Int -> ConduitM Event o m a
runNestingXML = runReaderT
nesting :: Monad m => NestingXML o m Int
nesting = ask
awaitXML :: Monad m => NestingXML o m (Maybe Event)
awaitXML = do
xml <- lift await
let f = case xml of
Just (EventBeginElement _ _) -> (+1)
Just (EventEndElement _) -> (subtract 1)
_ -> id
local f (return xml)
awaitCloser :: Monad m => Int -> NestingXML o m ()
awaitCloser lvl = do
fix $ \loop -> do
awaitXML
lvl' <- nesting
when (lvl' >= lvl) loop
nextElement :: Monad m => NestingXML o m (Maybe Event)
nextElement = do
lvl <- nesting
fix $ \loop -> do
xml <- awaitXML
case xml of
Nothing -> return Nothing
Just (EventBeginElement _ _) -> return xml
Just _ -> do
lvl' <- nesting
if (lvl'>=lvl) then loop
else return Nothing
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