Introduced a new map, reverseEntityTable, for lookups

of entity by character, in Entities.hs. This yields a 
small performance improvement.


git-svn-id: https://pandoc.googlecode.com/svn/trunk@534 788f1e2b-df1e-0410-8736-df70ead52e1b

1 files changed, 8 insertions, 6 deletions

diff --git a/src/Text/Pandoc/Entities.hs b/src/Text/Pandoc/Entities.hs
index 8e184432b..0b77ea334 100644
--- a/src/Text/Pandoc/Entities.hs
+++ b/src/Text/Pandoc/Entities.hs
@@ -43,11 +43,7 @@ import qualified Data.Map as Map
 
 -- | Returns a string containing an entity reference for the character.
 charToEntity :: Char -> String
-charToEntity char = 
-  let matches = Map.filter (== char) entityTable in
-  if Map.null matches
-     then charToNumericalEntity char
-     else head $ Map.keys matches
+charToEntity char = Map.findWithDefault (charToNumericalEntity char) char reverseEntityTable
 
 -- | Returns a string containing a numerical entity reference for the char.
 charToNumericalEntity :: Char -> String
@@ -113,7 +109,13 @@ decodeEntities str =
 	Right result    -> result
 
 entityTable :: Map.Map String Char
-entityTable =  Map.fromList [
+entityTable = Map.fromList entityTableList
+
+reverseEntityTable :: Map.Map Char String
+reverseEntityTable = Map.fromList $ map (\(a,b) -> (b,a)) entityTableList 
+
+entityTableList :: [(String, Char)]
+entityTableList =  [
 	(""", chr 34),
 	("&", chr 38),
 	("<", chr 60),