[Python-checkins] python/dist/src/Lib difflib.py,1.14,1.15

[nnorwitz@users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Lib
In directory sc8-pr-cvs1:/tmp/cvs-serv25889/Lib

Modified Files:
	difflib.py 
Log Message:
Fix SF bug #763023, difflib.py: ratio() zero division not caught

Backport candidate


Index: difflib.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/difflib.py,v
retrieving revision 1.14
retrieving revision 1.15
diff -C2 -d -r1.14 -r1.15
*** difflib.py	17 Jun 2003 16:53:25 -0000	1.14
--- difflib.py	1 Jul 2003 14:57:08 -0000	1.15
***************
*** 30,33 ****
--- 30,38 ----
             'unified_diff']
  
+ def _calculate_ratio(matches, length):
+     if length:
+         return 2.0 * matches / length
+     return 1.0
+ 
  class SequenceMatcher:
  
***************
*** 612,616 ****
          matches = reduce(lambda sum, triple: sum + triple[-1],
                           self.get_matching_blocks(), 0)
!         return 2.0 * matches / (len(self.a) + len(self.b))
  
      def quick_ratio(self):
--- 617,621 ----
          matches = reduce(lambda sum, triple: sum + triple[-1],
                           self.get_matching_blocks(), 0)
!         return _calculate_ratio(matches, len(self.a) + len(self.b))
  
      def quick_ratio(self):
***************
*** 641,645 ****
              if numb > 0:
                  matches = matches + 1
!         return 2.0 * matches / (len(self.a) + len(self.b))
  
      def real_quick_ratio(self):
--- 646,650 ----
              if numb > 0:
                  matches = matches + 1
!         return _calculate_ratio(matches, len(self.a) + len(self.b))
  
      def real_quick_ratio(self):
***************
*** 653,657 ****
          # can't have more matches than the number of elements in the
          # shorter sequence
!         return 2.0 * min(la, lb) / (la + lb)
  
  def get_close_matches(word, possibilities, n=3, cutoff=0.6):
--- 658,662 ----
          # can't have more matches than the number of elements in the
          # shorter sequence
!         return _calculate_ratio(min(la, lb), la + lb)
  
  def get_close_matches(word, possibilities, n=3, cutoff=0.6):