Your benchmark seems to show that accessing an array if 55x faster than accessing a position in the string. This is what I would expect because unicode strings (utf8) don't have fixed-width characters and perl has to go searching for character boundaries.

For comparison purposes, could you add construction of an inversion list to your benchmark? 

sub build_inversion_list_and_index {
  my @invlist;
  my $match;
  for (0..$max_codepoint) {
    next unless $match xor (chr($_) =~ /[[:$class:]]/);
    push @invlist, $_;
    $match= !$match;
  }
  my @index= ( 0 );
  for (my $i= 0; $i < @invlist; $i+= 2) {
    push @index, $index[-1] + $invlist[$i+1] - $invlist[$i];
  }
  shift @index;
  return \@invlist, \@index;
}

[download]
and random selection from the inversion list: 
sub get_nth_char($i, $invlist, $index) {
  return undef if $i >= $index[-1];
  my ($min, $max, $mid)= (0, $#$index);
  while (1) {
    $mid= ($min+$max) >> 1;
    if ($i > $index[$mid]) { $min= $mid+1 }
    elsif ($mid > 0 && $i < $index[$mid-1]) { $max= $mid-1 }
    else { return $invlist[$mid*2] + ($i - ($mid > 0? $index[$mid-1] :
+ 0)) }
  }
}

[download]

In reply to Re^4: Inspect the members of a Posix Character Class by NERDVANA
in thread Inspect the members of a Posix Character Class by NERDVANA

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