minor formatting and documentation additions

src/Network/XMPP/Stream.hs

@@ -24,6 +24,7 @@ import           Text.XML.Stream.Parse as XP
 
 -- import Text.XML.Stream.Elements
 
+-- Unpickles and returns a stream element. Throws a StreamXMLError on failure.
 streamUnpickleElem :: PU [Node] a
                    -> Element
                    -> ErrorT StreamError (Pipe Event Void IO) a
@@ -32,16 +33,20 @@ streamUnpickleElem p x = do
         Left l -> throwError $ StreamXMLError l
         Right r -> return r
 
+-- This is the conduit sink that handles the stream XML events. We extend it
+-- with ErrorT capabilities.
 type StreamSink a = ErrorT StreamError (Pipe Event Void IO) a
 
+-- Discards all events before the first EventBeginElement.
 throwOutJunk :: Monad m => Sink Event m ()
 throwOutJunk = do
     next <- CL.peek
     case next of
-    Nothing -> return ()
+        Nothing -> return () -- This will only happen if the stream is closed.
         Just (EventBeginElement _ _) -> return ()
         _ -> CL.drop 1 >> throwOutJunk
 
+-- Returns an (empty) Element from a stream of XML events.
 openElementFromEvents :: StreamSink Element
 openElementFromEvents = do
     lift throwOutJunk
@@ -50,6 +55,7 @@ openElementFromEvents = do
         Just (EventBeginElement name attrs) -> return $ Element name attrs []
         _ -> throwError $ StreamConnectionError
 
+-- Sends the initial stream:stream element and pulls the server features.
 xmppStartStream :: XMPPConMonad (Either StreamError ())
 xmppStartStream = runErrorT $ do
     hostname' <- gets sHostname
@@ -61,6 +67,8 @@ xmppStartStream = runErrorT $ do
     modify (\s -> s {sFeatures = features})
     return ()
 
+-- Creates a new connection source (of Events) using the raw source (of bytes)
+-- and calls xmppStartStream.
 xmppRestartStream :: XMPPConMonad (Either StreamError ())
 xmppRestartStream = do
     raw <- gets sRawSrc
@@ -68,20 +76,18 @@ xmppRestartStream = do
     modify (\s -> s{sConSrc = newsrc})
     xmppStartStream
 
-
+-- Reads the (partial) stream:stream and the server features from the stream.
 xmppStream :: StreamSink ServerFeatures
 xmppStream = do
     xmppStreamHeader
     xmppStreamFeatures
-
+  where
     xmppStreamHeader :: StreamSink ()
     xmppStreamHeader = do
         lift $ throwOutJunk
         (ver, _, _) <- streamUnpickleElem pickleStream =<< openElementFromEvents
         unless (ver == "1.0") . throwError $ StreamWrongVersion ver
         return ()
-
-
     xmppStreamFeatures :: StreamSink ServerFeatures
     xmppStreamFeatures = do
         e <- lift $ elements =$ CL.head
@@ -89,33 +95,35 @@ xmppStreamFeatures = do
             Nothing -> liftIO $ Ex.throwIO StreamConnectionError
             Just r -> streamUnpickleElem pickleStreamFeatures r
 
--- Pickling
+-- Pickler/Unpickler for the stream, with the version, from and to attributes.
-
 pickleStream :: PU [Node] (Text, Maybe Text, Maybe Text)
-pickleStream = xpElemAttrs (Name "stream"  (Just "http://etherx.jabber.org/streams") (Just "stream"))
+pickleStream = xpElemAttrs
+    (Name "stream" (Just "http://etherx.jabber.org/streams") (Just "stream"))
     (xpTriple
          (xpAttr "version" xpId)
          (xpOption $ xpAttr "from" xpId)
          (xpOption $ xpAttr "to" xpId)
     )
 
-pickleTLSFeature :: PU [Node] Bool
+-- Pickler/Unpickler for the stream features - TLS, SASL, and the rest.
-pickleTLSFeature = xpElemNodes "{urn:ietf:params:xml:ns:xmpp-tls}starttls"
-                      (xpElemExists "required")
-
-pickleSaslFeature :: PU [Node] [Text]
-pickleSaslFeature =  xpElemNodes "{urn:ietf:params:xml:ns:xmpp-sasl}mechanisms"
-                       (xpAll $ xpElemNodes
-                        "{urn:ietf:params:xml:ns:xmpp-sasl}mechanism" (xpContent xpId) )
-
 pickleStreamFeatures :: PU [Node] ServerFeatures
-pickleStreamFeatures = xpWrap ( \(tls, sasl, rest) -> SF tls (mbl sasl) rest)
+pickleStreamFeatures = xpWrap
+    (\(tls, sasl, rest) -> SF tls (mbl sasl) rest)
     (\(SF tls sasl rest) -> (tls, lmb sasl, rest))
-                               $
+    (xpElemNodes (Name
-    xpElemNodes (Name "features"  (Just "http://etherx.jabber.org/streams") (Just "stream"))
+         "features" (Just "http://etherx.jabber.org/streams") (Just "stream"))
          (xpTriple
               (xpOption pickleTLSFeature)
               (xpOption pickleSaslFeature)
               (xpAll xpElemVerbatim)
          )
-
+    )
+  where
+    pickleTLSFeature :: PU [Node] Bool
+    pickleTLSFeature = xpElemNodes "{urn:ietf:params:xml:ns:xmpp-tls}starttls"
+        (xpElemExists "required")
+    pickleSaslFeature :: PU [Node] [Text]
+    pickleSaslFeature =  xpElemNodes
+        "{urn:ietf:params:xml:ns:xmpp-sasl}mechanisms"
+        (xpAll $ xpElemNodes
+             "{urn:ietf:params:xml:ns:xmpp-sasl}mechanism" (xpContent xpId))