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copied!<h3>Update:</h3> <p>Your timings are a little suspect:</p> <pre><code>#!/usr/bin/perl use strict; use warnings; my $text = '{{abcdefg}}' x 100_000; my @match_pos; my ($start_count, $end_count); while ( $text =~ /({{)|(}})/g ) { push @match_pos, $-[0]; if ( defined $1 ) { ++$start_count; } else { ++$end_count; } } </code></pre> <p>Let's time it:</p> <pre> C:\Temp> timethis zxc.pl TimeThis : Command Line : zxc.pl TimeThis : Elapsed Time : 00:00:00.985 </pre> <p>Replacing <code>$-[0]</code> with <code>length $`</code> takes too long to complete (I pressed <kbd>CTRL-C</kbd> after a minute).</p> <p>If I make <code>2_000</code> copies of the simple pattern above, the timings end up being the same (about .2 seconds). So, I would recommend using <code>$-[0]</code> for scalability.</p> <h3>Previous discussion</h3> <p>From <a href="http://perldoc.perl.org/perlvar.html" rel="nofollow noreferrer"><code>perldoc perlvar</code></a>:</p> <pre><code># @LAST_MATCH_START # @- </code></pre> <blockquote> <p><code>$-[0]</code> is the offset of the start of the last successful match. <code>$-[n]</code> is the offset of the start of the substring matched by n-th subpattern, or undef if the subpattern did not match.</p> </blockquote> <p>See also <code>@+</code>.</p> <p>The <code>s</code> option in your regex is unnecessary because there is no <code>.</code> in the pattern.</p> <p>Have you looked at <a href="http://search.cpan.org/perldoc/Text::Balanced" rel="nofollow noreferrer"><code>Text::Balanced</code></a>?</p> <p>You could also use <a href="http://perldoc.perl.org/functions/pos.html" rel="nofollow noreferrer"><code>pos</code></a>, although I am not sure if it will satisfy your performance requirements.</p> <pre><code>#!/usr/bin/perl use strict; use warnings; use File::Slurp; my $text = read_file \*DATA; my @match_pos; my ($start_count, $end_count); while ( $text =~ /({{)|(}})/g ) { push @match_pos, pos($text) - 2; # push @match_pos, $-[0]; # seems to be slightly faster if ( defined $1 ) { ++$start_count; } else { ++$end_count; } } for my $i ( @match_pos ) { print substr($text, $i, 2), "\n"; } __DATA__ Copy & paste the source of the complicated Wikipedia page here to test. </code></pre>

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