Re: Evaluating code in a regex at runtime: (??{...})

[Athanasius]

in reply to Evaluating code in a regex at runtime: (??{...})

Note that the contents of the match are still accessible via a named capture group:

#! perl
use Modern::Perl;

('a' x 100) =~ /(?<match>(??{'(.)' x 100}))/;

say $+{match};

Output:

12:28 >perl 504_SoPW.pl
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

12:28 >

See Capture groups.

Hope that helps,

[LanX]

> Note that the contents of the match are still accessible via a named capture group:

> ...  ('a' x 100) =~ /(?<match>(??{'(.)' x 100}))/;

ehm ... what you're showing also works with unnamed capture groups:

  DB<113> ('a' x 10) =~ /((??{'(.)' x 10}))/; print "<$1>"
 => 1
<aaaaaaaaaa>

The OP's point was about dynamically generated capture groups, but yours is outside the embedded Perl code.

[Athanasius]

Yes, you’re right. So in dave_the_m’s example, all we need to do is add another set of parentheses:

/(....)...(...)...((??{foo()}))....(...)/
 ^        ^       ^                ^
 1        2       3                4

and the dynamically generated capture group is assigned to $3. For example:

use Modern::Perl;

my $str  = 'abcd$$$$$ef';
my @caps = $str =~ /(a)b(c)d((??{'(.)' x 5}))e(f)/;

say join(', ', @caps);

Output:

18:33 >perl 504_SoPW.pl
a, c, $$$$$, f

18:38 >

What we (apparently) can’t get is multiple capture groups matches assigned to different capture groups (whether named or unnamed) from the same dynamic match. Correct?

[LanX]

> What we (apparently) can’t get is multiple capture groups assigned to different capture groups (whether named or unnamed) from the same dynamic match. Correct?

apparently yes, like documented:

  DB<131> 'aaa' =~ /(?<outer>(??{'(?<inner>.)' x 1}))/; keys %+
 => "outer"

But of course there are workarounds ... if necessary.