From 0114f68d21b99a5bd1a96225e74440f05da2ce1c Mon Sep 17 00:00:00 2001
From: fiddlosopher <fiddlosopher@788f1e2b-df1e-0410-8736-df70ead52e1b>
Date: Wed, 14 Feb 2007 18:02:51 +0000
Subject: 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
---
 src/Text/Pandoc/Entities.hs | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

(limited to 'src/Text/Pandoc/Entities.hs')

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 =  [
 	("&quot;", chr 34),
 	("&amp;", chr 38),
 	("&lt;", chr 60),
-- 
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