{- Copyright (C) 2009 John Millikin <jmillikin@gmail.com>
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 3 of the License, or
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, see <http://www.gnu.org/licenses/>.
-}
module Network.Protocol.XMPP.Util (
eventsToTree
,convertAttr
,convertQName
,mkElement
,mkAttr
,mkQName
) where
import qualified Text.XML.HXT.DOM.XmlNode as XN
import qualified Text.XML.HXT.DOM.Interface as DOM
import qualified Text.XML.LibXML.SAX as SAX
-------------------------------------------------------------------------------
-- For converting incremental XML event lists to HXT trees
-------------------------------------------------------------------------------
-- This function assumes the input list is valid. No validation is performed.
eventsToTree :: [SAX.Event] -> DOM.XmlTree
eventsToTree es = XN.mkRoot [] (eventsToTrees es)
eventsToTrees :: [SAX.Event] -> [DOM.XmlTree]
eventsToTrees es = concatMap blockToTrees (splitBlocks es)
-- Split event list into a sequence of "blocks", which are the events including
-- and between a pair of tags. <start><start2/></start> and <start/> are both
-- single blocks.
splitBlocks :: [SAX.Event] -> [[SAX.Event]]
splitBlocks es = ret where (_, _, ret) = foldl splitBlocks' (0, [], []) es
splitBlocks' :: (Int, [SAX.Event], [[SAX.Event]])
-> SAX.Event
-> (Int, [SAX.Event], [[SAX.Event]])
splitBlocks' (depth, accum, allAccum) e =
if depth' == 0 then
(depth', [], allAccum ++ [accum'])
else
(depth', accum', allAccum)
where
accum' = accum ++ [e]
depth' = depth + case e of
(SAX.BeginElement _ _) -> 1
(SAX.EndElement _) -> (- 1)
_ -> 0
blockToTrees :: [SAX.Event] -> [DOM.XmlTree]
blockToTrees [] = []
blockToTrees (begin:rest) = let end = (last rest) in case (begin, end) of
(SAX.BeginElement qname attrs, SAX.EndElement _) ->
[XN.mkElement (convertQName qname)
(map convertAttr attrs)
(eventsToTrees (init rest))]
(SAX.Characters s, _) -> [XN.mkText s]
(_, SAX.ParseError text) -> error text
_ -> []
convertAttr :: SAX.Attribute -> DOM.XmlTree
convertAttr (SAX.Attribute qname value) = XN.NTree
(XN.mkAttrNode (convertQName qname))
[XN.mkText value]
convertQName :: SAX.QName -> DOM.QName
convertQName (SAX.QName ns _ local) = mkQName ns local
-------------------------------------------------------------------------------
-- Utility function for building XML trees
-------------------------------------------------------------------------------
mkElement :: (String, String) -> [(String, String, String)] -> [DOM.XmlTree] -> DOM.XmlTree
mkElement (ns, localpart) attrs children = let
qname = mkQName ns localpart
attrs' = [mkAttr ans alp text | (ans, alp, text) <- attrs]
in XN.mkElement qname attrs' children
mkAttr :: String -> String -> String -> DOM.XmlTree
mkAttr ns localpart text = XN.mkAttr (mkQName ns localpart) [XN.mkText text]
mkQName :: String -> String -> DOM.QName
mkQName ns localpart = case ns of
"" -> DOM.mkName localpart
_ -> DOM.mkNsName localpart ns