use strict;
my $str = '$string = \'
[if true]
[if true]
[if false]
[else]
[/if]
[elseif false]
[if true]
[/if]
[else]
[/if]
[elseif false]
[/if]
[if false]
[if false]
[else]
[/if]
[else]
[if true]
[/if]
[/if]
\';';
my $regex = qr~\[if \s+ [^]]* ]
(?<content> [^[]*+ (?> (?R) [^[]* )*+ )
(?: \[elseif \s+ [^]]* ] \g<content> )*+
(?: \[else] \g<content> )?+
\[/if]~xp;
if ( $str =~ /$regex/g ) {
print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n";
# print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n";
# print "Capture Group 2 is $2 ... and so on\n";
}
# ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p'
# Named capture groups can be called via $+{name}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html