From d3efa4aa8a7a051c87734be3f923490913d3f2d9 Mon Sep 17 00:00:00 2001
From: fiddlosopher <fiddlosopher@788f1e2b-df1e-0410-8736-df70ead52e1b>
Date: Thu, 15 Feb 2007 01:22:02 +0000
Subject: Use lookAhead parser for the "first pass" looking for reference keys
 in Markdown parser, instead of parsing normally, then using setInput to reset
 input.  Slight performance improvement.

git-svn-id: https://pandoc.googlecode.com/svn/trunk@536 788f1e2b-df1e-0410-8736-df70ead52e1b
---
 src/Text/Pandoc/Readers/Markdown.hs | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index a94a0a06e..91f437372 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/src/Text/Pandoc/Readers/Markdown.hs
@@ -171,12 +171,10 @@ parseMarkdown = do
   -- need to parse raw HTML, since markdown allows it
   (title, author, date) <- option ([],[],"") titleBlock
   oldState <- getState
-  oldInput <- getInput
   -- go through once just to get list of reference keys
-  manyTill (referenceKey <|> (do{anyLine; return Null})) eof 
-  newState <- getState
-  let keysUsed = stateKeysUsed newState
-  setInput oldInput
+  keysUsed <- lookAhead $ (do {manyTill (referenceKey <|> (do{anyLine; return Null})) eof; 
+                               newState <- getState;
+                               return $ stateKeysUsed newState}) 
   setState (oldState { stateKeysUsed = keysUsed })
   blocks <- parseBlocks  -- go through again, for real
   let blocks' = filter (/= Null) blocks
-- 
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