use strict;
use warnings;
use Data::Dumper;
use Carp;

sub arrange {
  my $href=shift;
  my @range=@{$href->{range}};
  my @sub=@{$href->{subrange}};
  my $ary=$href->{arr};
  my @ret;

  my $extent= $range[1] - $range[0];
  croak "Range @range extent ".($extent+1)." different from array length:".scalar(@$ary)
    if $#$ary!=abs($extent);
  my $subextent = $sub[1] - $sub[0];
  croak "Bad subextent @sub from range @range\n"
    if abs($subextent)>abs($extent);
  for (@sub) {
    croak "Bad subrange @sub from range @range"
      if ($_<$range[0] and $_<$range[1])
      or ($_>$range[0] and $_>$range[1]);
  }
  my $dx=$subextent>=0 ? 1 : -1;
  $dx=-$dx if $extent<0;
  my $idx=$sub[0];
  while ($#ret!=abs($subextent)) {
    push @ret,$ary->[$idx-$range[0]];
    $idx+=$dx;
  }
  $href->{ret}=\@ret;
  unless (defined wantarray) {
    warn Dumper($href);
  } else{
    return wantarray ? @ret : \@ret;
  }
}

foreach my $t ([6,5],[6,7],[8,9],[1,2]) {
  foreach my $r ([5,8],[8,5]) {
    eval {
      arrange({
        arr => [qw(cero uno dos tres)],
        range => $r,
        subrange =>$t
      });
      1
    } or warn "Test @$t failed on range @$r:\n$@";
  }
}