#!/usr/bin/perl
use warnings;
use strict;
use feature qw/state/;

use Test::More tests => 4;
use Benchmark qw/cmpthese/;

my $length = 100_000;
my $string = join q(), map int rand 10, 1 .. $length;
my $mask   = join q(), map int rand 2,  1 .. $length;

my $result = bitwise($string, $mask);
is arraywise ($string, $mask), $result, 'array';
is substrwise($string, $mask), $result, 'substr';
is packwise  ($string, $mask), $result, 'pack';
is regexwise ($string, $mask), $result, 'regex';

sub bitwise {
    my $string = shift;
    state $mask;
    ($mask = shift) =~ y/01/\x00\xff/ unless defined $mask;

    my $result = $string & $mask;
    $result =~ tr/\x00//d;
    return $result;
}


sub arraywise {
    my $string = shift;
    state $mask = shift;
    my @chars = split //, $string;
    return join q(), @chars[grep substr($mask, $_, 1), 0 .. length $mask];
}

sub regexwise {
    my $string = shift;
    state $regex;
    unless (defined $regex) {
        $regex = '^' . join(q(), map $_ ? '(.)' : '.', split //, shift) . '$';
    }
    my $result = join q(), $string =~ m/$regex/o;
    return $result;
}


sub packwise {
    my $string = shift;
    state $mask;
    unless (defined $mask) {
        $mask = shift;
        my $template;
        while ($mask =~ /((.)\2*)/g) {
            $template .= (qw(x a))[$2] . length $1;
        }
        $mask = $template;
    }
    return join q(), unpack $mask, $string;
}


sub substrwise {
    my $string = shift;
    state $mask;
    my @mask;
    unless (defined $mask) {
        $mask = shift;
        while ( $mask =~ /0+/g ) {
            push @mask, [ $-[0], ( $+[0] - $-[0] ) ];
        }
    }
    for (1 .. @mask) {
        my $replace = ''; #'*' x $mask[-$_][1]; #check to see
        substr $string, $mask[-$_][0], $mask[-$_][1], $replace;
    }
    return $string;
}

cmpthese(-3, {
              bitwise    => sub { bitwise   ($string, $mask) },
              arraywise  => sub { arraywise ($string, $mask) },
              substrwise => sub { substrwise($string, $mask) },
              packwise   => sub { packwise  ($string, $mask) },
              regexwise  => sub { regexwise ($string, $mask) },
             });