Catastrophic Backtrack Examples

examples.txt

Some samples I collected from sites around the web on this topic.

^(A+)*B
^([a-zA-Z0-9]+\s?)*$
(a+)+b

There seems to be a pretty common theme of 

>>> r = re.compile('^(A+)+B$',re.DEBUG)
AT AT_BEGINNING
MAX_REPEAT 1 MAXREPEAT
  SUBPATTERN 1
    MAX_REPEAT 1 MAXREPEAT
      LITERAL 65
LITERAL 66
AT AT_END