From: brabuhr@...
Date: 2007-02-03T07:29:31+09:00
Subject: Re: bug is ruby regexp

On 2/2/07, James Edward Gray II <james@grayproductions.net> wrote:
> On Feb 2, 2007, at 9:54 AM, Nick Black wrote:
> > I spotted this problem in ruby's regexp today: ...
> >
> > (irb):2: invalid regular expression: /[9-13]/
> >        from (irb):4
> >        from :0
> > irb(main):005:0>
>
> A character class ([...]) with a range of 9-1 is not valid in a
> regular expression because 1 does not come after 9 in your character
> encoding.

For comparative reference:

$ perl -e 'print "foo" if 9 =~ /[9-13]/'
Invalid [] range "9-1" in regex; marked by <-- HERE in m/[9-1 <-- HERE
3]/ at -e line 1.

$ python -c "import re; re.match('[9-13]', '9')"
Traceback (most recent call last):
  File "<string>", line 1, in ?
  File "/usr/lib/python2.4/sre.py", line 129, in match
    return _compile(pattern, flags).match(string)
  File "/usr/lib/python2.4/sre.py", line 227, in _compile
    raise error, v # invalid expression
sre_constants.error: bad character range