Compare regular expressions

[Paddy]

On Apr 17, 9:17 am, "Diez B. Roggisch" <d... at nospam.web.de> wrote:
> Paddy schrieb:
>
>
>
> > On Apr 16, 10:50 am, Thomas Dybdahl Ahle <lob... at gmail.com> wrote:
> >> Hi, I'm writing a program with a large data stream to which modules can
> >> connect using regular expressions.
>
> >> Now I'd like to not have to test all expressions every time I get a line,
> >> as most of the time, one of them having a match means none of the others
> >> can have so.
>
> >> But ofcource there are also cases where a regular expression can
> >> "contain" another expression, like in:
> >> "^strange line (\w+) and (\w+)$" and "^strange line (\w+) (?:.*?)$" in
> >> which case I'd like to first test the seccond and only if it mathces test
> >> the seccond.
>
> >> Do anybody know if such a test is possible?
> >> if exp0.contains(exp1): ...
>
> > you could OR all the individual RE's test them all at once then find
> > out which matched.
>
> > big_re = "|".join( r"(?P<__match_%i__>%s)" % (i, r)
> >                    for i,r in enumerate(regexps) )
>
> > now if one of the regexps matches then the corresponding named
> > group should have a non-empty string value.
>
> This doesn't answer the question if two of the sub-expressions matched.
>
> Diez

Or three, or four...
If the frequencies of occurence are right and the OP wants all, then
he could use the above to get any then follow up with a search for
all
the rest to the right of the matching regexp portion to get any more.
But thats complex. Better to just do individual matches in a loop
I'd think.

- Paddy.