#!/usr/bin/perl

use 5.6.0;

use strict;
use warnings FATAL => 'all';

use Benchmark qw( cmpthese );

my $s1 = do_rand(0, 100_000);
my $s2 = do_rand(1, 100_000);

my $subs =  {
    'split1'     => sub { my $s3 = split1( $s1, $s2 ) },
    'mrm_6'      => sub { mrm_6( \$s1, \$s2 ); $s1 },
    'mrm_7'      => sub { mrm_7( \$s1, \$s2 ); $s1 },
    'mrm_8'      => sub { mrm_8( \$s1, \$s2 ); $s1 },
};

cmpthese( -5, $subs );

use Test::More;

plan 'tests' => scalar keys %{$subs};

my $s3;
foreach my $subname ( keys %{$subs} ) {
    my $sub = $subs->{$subname};
    if ( defined $s3 ) {
	is( $sub->(), $s3, "$subname gets same value" );
    }
    else {
	$s3 = $sub->();
	ok( defined $s3, "$subname gets some value" );
    }
}

sub split1 {
    my ($s1, $s2) = @_;

    my @s1 = split //, $s1;
    my @s2 = split //, $s2;

    foreach my $idx ( 0 .. $#s1 ) { 
	if ( $s1[$idx] eq chr(0) ) { 
	    $s1[$idx] = $s2[$idx];
	} 
    } 

    return join '', @s1;
}

sub mrm_6 {
    # from mrn_5, testing bytes::misc explicitly instead of importing
    # also in-place using of $s2
    my ( $s1, $s2 ) = @_;
    use bytes ();
    my $pos = 0;
    while ( -1 < ( $pos = bytes::index( $$s1, '\0', $pos ) ) ) {
        bytes::substr( $$s1, $pos, 1, bytes::substr( $$s2, $pos, 1 ) );
    }
}

sub mrm_7 {
    # from mrn_5, testing bytes::misc explicitly instead of importing
    # also in-place using of $s2
    my ( $s1, $s2 ) = @_;
    use bytes ();
    my $pos = 0;
    while ( -1 < ( $pos = bytes::index( $$s1, "\000", $pos ) ) ) {
        bytes::substr( $$s1, $pos, 1, bytes::substr( $$s2, $pos, 1 ) );
    }
}

sub mrm_8 {
    # from mrn_5, testing bytes::misc explicitly instead of importing
    # also in-place using of $s2
    my ( $s1, $s2 ) = @_;
    use bytes ();
    my $pos = 0;
    my $chr = chr 0;
    while ( -1 < ( $pos = bytes::index( $$s1, $chr, $pos ) ) ) {
        bytes::substr( $$s1, $pos, 1, bytes::substr( $$s2, $pos, 1 ) );
    }
}


# This makes sure that $s1 has chr(0)'s in it and $s2 does not.
sub do_rand {
    my $min = shift;
    my $len = shift;
    my $n = "";
    for (1 .. $len)
    {
        $n .= chr( rand(255-$min)+$min );
    }
    return $n;
}

#sub do_rand {
#    my $n = (shift) ? int(rand(255)) : int(rand(254)) + 1;
#    return chr( $n );
#}

__END__