XML module: added CData support. Escape stuff that needs to be escaped in XML.

src/GF/Data/XML.hs

@@ -12,8 +12,8 @@ module GF.Data.XML (XML(..), Attr, comments, showsXMLDoc, showsXML) where
 
 import GF.Data.Utilities
 
-data XML = Data String | Tag String [Attr] [XML] | Comment String
- deriving (Eq,Show)
+data XML = Data String | CData String | Tag String [Attr] [XML] | Comment String
+ deriving (Ord,Eq,Show)
 
 type Attr = (String,String)
 
@@ -26,6 +26,7 @@ showsXMLDoc xml = showString header . showsXML xml
 
 showsXML :: XML -> ShowS
 showsXML (Data s) = showString s
+showsXML (CData s) = showString "<![CDATA[" . showString s .showString "]]>"
 showsXML (Tag t as []) = showChar '<' . showString t . showsAttrs as . showString "/>"
 showsXML (Tag t as cs) = 
     showChar '<' . showString t . showsAttrs as . showChar '>' 
@@ -38,9 +39,11 @@ showsAttrs = concatS . map (showChar ' ' .) . map showsAttr
 showsAttr :: Attr -> ShowS
 showsAttr (n,v) = showString n . showString "=\"" . showString (escape v) . showString "\""
 
--- FIXME: escape strange charachters with &#xxx;
 escape :: String -> String
 escape = concatMap escChar
   where
-  escChar c | c `elem` ['"','\\'] = '\\':[c]
-            | otherwise = [c]
+  escChar '<'  = "&lt;"
+  escChar '>'  = "&gt;"
+  escChar '&'  = "&amp;"
+  escChar '"'  = "&quot;"
+  escChar c    = [c]