#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };
use experimental qw( signatures );

use String::Eertree;

sub rosetta_old($str) {
    my @pal;
    for my $n (1 .. length $str) {
        for my $m (1 .. length $str) {
            my $strrev = "";
            my $strpal = substr $str, $n - 1, $m;
            if ($strpal ne "") {
                for my $p (reverse 1 .. length $strpal) {
                    $strrev .= substr $strpal, $p - 1, 1;
                }
                ($strpal eq $strrev) and push @pal, $strpal;
            }
        }
    }
    my %seen;
    return grep ! $seen{$_}++, @pal
}

sub rosetta($str) {
    my (@pal, %seen);
    for my $n (0 .. length($str) - 1) {
        for my $m (1 .. length $str) {
            my $strpal = substr $str, $n, $m;
            push @pal, $strpal
                if $strpal eq reverse($strpal) && ! $seen{$strpal}++;
        }
    }
    return @pal
}

my $s = join "", map chr(ord('a') + int rand 26), 1 .. 55 * 2;
say $s;
my @p1 = 'String::Eertree'->new(string => "$s")->uniq_palindromes;
my @p2 = rosetta_old($s);
my @p3 = rosetta($s);

use Test2::V0 -no_srand => 1;
say "Eertree:     @p1";
say "Rosetta old: @p2";
say "Rosetta new: @p3";
like \@p2, bag { item $_ for @p1; end() };
like \@p3, bag { item $_ for @p1; end() };

use Benchmark qw{ cmpthese };
cmpthese(-3, {
    eertree => sub { 'String::Eertree'->new(string => $s)->uniq_palindromes },
    rosetta_old => sub { rosetta_old($s) },
    rosetta_new => sub { rosetta($s) },
});

done_testing();