Alf P. Steinbach wrote:
* Steven D'Aprano:
On Sat, 06 Feb 2010 16:05:15 -0800, hzh...@gmail.com wrote:
Thanks for your reply.
So there isn't such a routine just because some of the regular
expressions cannot be enumerated. However, some of them can be
enumerated. I guess I have to write a function myself.
How do you expect to tell the ones that can be enumerated apart from
those that can't be?
Regular expressions are programs in a "regex" programming language.
What you are asking for is the same as saying:
"Is there a program that can enumerate every possible set of data that
is usable as valid input for a given program?"
This, in turn, is equivalent to the Halting Problem -- if you can
solve one, you can solve the other. You might like to google on the
Halting Problem before you spend too much time on this.
Hm, well, text editors /regularly/ do repeated regular expression
searches, producing match after match after match, on request.
[snip]
I'm not sure you understood what the OP was requesting: a way of
generating the strings which would match a given regex.
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