Re: Operator for "these expressions, in any order"

use Algorithm::Permute;

my @patterns = ();

my $p = new Algorithm::Permute(['X', 'Y', 'Z']);
while (@res = $p->next) {
    push @patterns, join('', @res);
}

my $pattern = join '|', @patterns;

print "$pattern\n";

# give the pattern a test...
while (<DATA>) {
    chomp;
    print "$_ is ", /^(?:$pattern)$/ ? 'good' : 'bad', "\n";
}

__DATA__
XYX
XYZ
ZYY
ZXY
ZYX
XXYZ
[download]

And the output is ...

ZYX|YZX|YXZ|ZXY|XZY|XYZ

XYX is bad
XYZ is good
ZYY is bad
ZXY is good
ZYX is good
XXYZ is bad
[download]

Comment on Re: Operator for "these expressions, in any order" Select or Download Code

Replies are listed 'Best First'.
Re: Operator for "these expressions, in any order" by Abigail-II (Bishop) on Feb 17, 2004 at 15:58 UTC
Unfortunally, the size of the resulting regex grows exponentially. There are 6 permutations for 3 choices, 24 for 4, 120 for 5, 720 for 6, and 3628800 for 10. Abigail	[reply]
Re: Re: Operator for "these expressions, in any order" by thor (Priest) on Feb 17, 2004 at 17:21 UTC
Not to be a stickler, but it's not exponential growth. It's worse than that. For instance, 24 = 16, but 4! = 24. Choose any base j, and there's a number n such that jn < n!. Of course, this only strenghens your point...:). thor	[reply]
Re: Re: Operator for "these expressions, in any order" by Roger (Parson) on Feb 17, 2004 at 15:59 UTC
Yes I know. That's why I like Randal's solution better. :-)	[reply]
Re: Re: Operator for "these expressions, in any order" by jsalvata (Initiate) on Feb 17, 2004 at 23:23 UTC
I thought I already provided this answer myself. However, this does not address the capture-groups issue I mentioned in my question: if X, Y and Z all had capture groups, obtaining their values (and knowing which regexp each comes from) would require some funky code that I need to avoid. Let me clarify my problem: the issue is not how to build a matching regexp, but how to keep the capture groups reasonable. The reason for this is that X Y Z would be build from regexps entered by the program users, who would also provide a result pattern, possibly containing $1 $2,... So I need the correspondence between the capture groups in the input regexps and the vars to be easy to describe.	[reply]