1 files changed, 24 insertions, 1 deletions
diff --git a/src/Text/Pandoc/XML.hs b/src/Text/Pandoc/XML.hs
index e21525018..7a1c8bdd8 100644
--- a/src/Text/Pandoc/XML.hs
+++ b/src/Text/Pandoc/XML.hs
@@ -33,9 +33,13 @@ module Text.Pandoc.XML ( stripTags,
                          inTags,
                          selfClosingTag,
                          inTagsSimple,
-                         inTagsIndented  ) where
+                         inTagsIndented,
+                         toEntities,
+                         fromEntities ) where
 
 import Text.Pandoc.Pretty
+import Data.Char (ord, isAscii)
+import Text.HTML.TagSoup.Entity (lookupEntity)
 
 -- | Remove everything between <...>
 stripTags :: String -> String
@@ -89,3 +93,22 @@ inTagsSimple tagType = inTags False tagType []
 -- | Put the supplied contents in indented block btw start and end tags.
 inTagsIndented :: String -> Doc -> Doc
 inTagsIndented tagType = inTags True tagType []
+
+-- | Escape all non-ascii characters using numerical entities.
+toEntities :: String -> String
+toEntities [] = ""
+toEntities (c:cs)
+  | isAscii c = c : toEntities cs
+  | otherwise = "&#" ++ show (ord c) ++ ";" ++ toEntities cs
+
+-- Unescapes XML entities
+fromEntities :: String -> String
+fromEntities ('&':xs) =
+  case lookupEntity ent of
+        Just c  -> c : fromEntities rest
+        Nothing -> '&' : fromEntities rest
+    where (ent, rest) = case break (==';') xs of
+                             (zs,';':ys) -> (zs,ys)
+                             _           -> ("",xs)
+fromEntities (x:xs) = x : fromEntities xs
+fromEntities [] = []