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|
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
{- |
Module : Text.Pandoc.XML.Light
Copyright : Copyright (C) 2021 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <jgm@berkeley.edu>
Stability : alpha
Portability : portable
xml-light, which we used in pandoc's the XML-based readers, has
some limitations: in particular, it produces nodes with String
instead of Text, and the parser falls over on processing instructions
(see #7091).
This module exports much of the API of xml-light, but using Text instead
of String. In addition, the xml-light parsers are replaced by xml-conduit's
well-tested parser. (The xml-conduit types are mapped to types
isomorphic to xml-light's, to avoid the need for massive code modifications
elsewhere.) Bridge functions to map xml-light types to this module's
types are also provided (since libraries like texmath still use xml-light).
Another advantage of the xml-conduit parser is that it gives us
detailed information on xml parse errors.
In the future we may want to move to using xml-conduit or another
xml library in the code base, but this change gives us
better performance and accuracy without much change in the
code that used xml-light.
-}
module Text.Pandoc.XML.Light
( module Text.Pandoc.XML.Light.Types
, module Text.Pandoc.XML.Light.Proc
, module Text.Pandoc.XML.Light.Output
-- * Replacement for xml-light's Text.XML.Input
, parseXMLElement
, parseXMLContents
) where
import qualified Control.Exception as E
import qualified Text.XML as Conduit
import Text.XML.Unresolved (InvalidEventStream(..))
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import qualified Data.Map as M
import Data.Maybe (mapMaybe)
import Text.Pandoc.XML.Light.Types
import Text.Pandoc.XML.Light.Proc
import Text.Pandoc.XML.Light.Output
-- Drop in replacement for parseXMLDoc in xml-light.
parseXMLElement :: TL.Text -> Either T.Text Element
parseXMLElement t =
elementToElement . Conduit.documentRoot <$>
either (Left . T.pack . E.displayException) Right
(Conduit.parseText Conduit.def{ Conduit.psRetainNamespaces = True } t)
parseXMLContents :: TL.Text -> Either T.Text [Content]
parseXMLContents t =
case Conduit.parseText Conduit.def{ Conduit.psRetainNamespaces = True } t of
Left e ->
case E.fromException e of
Just (ContentAfterRoot _) ->
elContent <$> parseXMLElement ("<wrapper>" <> t <> "</wrapper>")
_ -> Left . T.pack . E.displayException $ e
Right x -> Right [Elem . elementToElement . Conduit.documentRoot $ x]
elementToElement :: Conduit.Element -> Element
elementToElement (Conduit.Element name attribMap nodes) =
Element (nameToQname name) attrs (mapMaybe nodeToContent nodes) Nothing
where
attrs = map (\(n,v) -> Attr (nameToQname n) v) $
M.toList attribMap
nameToQname (Conduit.Name localName mbns mbpref) =
case mbpref of
Nothing ->
case T.stripPrefix "xmlns:" localName of
Just rest -> QName rest mbns (Just "xmlns")
Nothing -> QName localName mbns mbpref
_ -> QName localName mbns mbpref
nodeToContent :: Conduit.Node -> Maybe Content
nodeToContent (Conduit.NodeElement el) =
Just (Elem (elementToElement el))
nodeToContent (Conduit.NodeContent t) =
Just (Text (CData CDataText t Nothing))
nodeToContent _ = Nothing
|
