Create a regular expression to identify evergreen content in Google Analytics

evergreen-regex.pl

#!/usr/bin/env perl
use Modern::Perl;
use DateTime;

my $past = DateTime->now->subtract(months => 6);

my $past_year = $past->year();
my $past_month = $past->month();
my $past_2_year = $past->subtract(years => 1)->format_cldr('yy');
my $y_str;
for my $y (@{[0..$past_2_year]}) {
	$y_str .= sprintf("%02d", $y) . "|";
}
chop $y_str;
local $" = "|";
say "^(20($y_str)-[0-9]+|$past_year-0?(@{[1..$past_month]}))-[0-9]+\$";