emulating an and operator in regular expressions

[Craig Ringer]

On Mon, 2005-01-03 at 08:52, Ross La Haye wrote:
> How can an and operator be emulated in regular expressions in Python?
> Specifically, I want to return a match on a string if and only if 2 or more
> substrings all appear in the string.  For example, for a string s = 'Jones
> John' and substrings sg0 = 'Jones' and sg1 = 'John', I want to return a
> match, but for substrings sg0 = 'Jones' and sg2 = 'Frank' I do not want to
> return a match.  Because the expression 'A and B' is logically equivalent to
> 'not (not A or not B)' I thought I could try something along those lines,
> but can't crack it.

My first thought would be to express your 'A and B' regex as:

(A.*B)|(B.*A)

with whatever padding, etc, is necessary. You can even substitute in the
sub-regex for A and B to avoid writing them out twice.

--
Craig Ringer

--
Craig Ringer