From a7fe4ea5ed6254bf4832d2a506934b16a294936a Mon Sep 17 00:00:00 2001
From: John Schember <john@nachtimwald.com>
Date: Thu, 27 Jan 2011 20:24:12 -0500
Subject: [PATCH] TXT Input: Make preserve_spaces fast and only use &nbsp; when
 necessary.

---
 src/calibre/ebooks/txt/processor.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/ebooks/txt/processor.py b/src/calibre/ebooks/txt/processor.py
index 206a18b3e4..546d3f1842 100644
--- a/src/calibre/ebooks/txt/processor.py
+++ b/src/calibre/ebooks/txt/processor.py
@@ -103,7 +103,7 @@ def separate_paragraphs_print_formatted(txt):
     return txt
 
 def preserve_spaces(txt):
-    txt = txt.replace(' ', '&nbsp;')
+    txt = re.sub('(?P<space>[ ]{2,})', lambda mo: ' ' + ('&nbsp;' * (len(mo.group('space')) - 1)), txt)
     txt = txt.replace('\t', '&nbsp;&nbsp;&nbsp;&nbsp;')
     return txt