imaputil.py: factorize the flag map

Instead of repeating a mapping table twice, once for each direction, it is only
stored once.  This is safer and faster.

As the patch stands, it makes no custom flags available.  The behaviour
is exactly as before.

Patch-written-by: Dan Christensen <jdc@uwo.ca>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

offlineimap/imaputil.py

@@ -147,30 +147,26 @@ def imapsplit(imapstring):
     debug("imapsplit() returning:", retval)
     return retval
             
+flagmap = [('\\Seen', 'S'),
+           ('\\Answered', 'R'),
+           ('\\Flagged', 'F'),
+           ('\\Deleted', 'T'),
+           ('\\Draft', 'D')]
+
 def flagsimap2maildir(flagstring):
-    flagmap = {'\\seen': 'S',
-               '\\answered': 'R',
-               '\\flagged': 'F',
-               '\\deleted': 'T',
-               '\\draft': 'D'}
     retval = []
     imapflaglist = [x.lower() for x in flagstring[1:-1].split()]
-    for imapflag in imapflaglist:
-        if flagmap.has_key(imapflag):
-            retval.append(flagmap[imapflag])
+    for imapflag, maildirflag in flagmap:
+        if imapflag.lower() in imapflaglist:
+            retval.append(maildirflag)
     retval.sort()
     return retval
 
-def flagsmaildir2imap(list):
-    flagmap = {'S': '\\Seen',
-               'R': '\\Answered',
-               'F': '\\Flagged',
-               'T': '\\Deleted',
-               'D': '\\Draft'}
+def flagsmaildir2imap(maildirflaglist):
     retval = []
-    for mdflag in list:
-        if flagmap.has_key(mdflag):
-            retval.append(flagmap[mdflag])
+    for imapflag, maildirflag in flagmap:
+        if maildirflag in maildirflaglist:
+            retval.append(imapflag)
     retval.sort()
     return '(' + ' '.join(retval) + ')'