Re^3: In need of a sequence iterator.

The $count can get upto 255 (and theoretically beyond with unicode). The numbers are eventually packed to form a binary string of codepoints that increment, magic string auto-increment style, but starting at chr(0) and modulo alphabet size.

I'm currently limiting my thinking to 8-bit ascii bytes, but notionally the alphabet could be larger with unicode.

The actual keys involved (made up from an arbitrary alphabet) are translated to chr(0) ... chr(alphabet max).

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Comment on Re^3: In need of a sequence iterator.

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Re^4: In need of a sequence iterator. by hv (Prior) on Dec 03, 2004 at 12:53 UTC
Ah ok, well you could use the string approach directly on the packed strings by changing the replace to `/chr(ord($1)+1)/e` or use a hash to describe successorship in the arbitrary alphabet: `my $alphabet = "0123456789ABCDEF"; my %successor = $alphabet =~ /(.)(?=(.))/g; my $zero = substr($alphabet, 0, 1); ... sub genIterator { my($len, $count) = @_; my $cur = ''; my $lastdig = substr($alphabet, $count - 1, 1); return sub { if (length($cur) < $len) { $cur .= $zero; } else { $cur =~ s/([^$lastdig])$lastdig*\z/$successor{$1}/ or $cur = undef; } $cur; } }` [download] Hugo	[reply] [d/l] [select]

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Re^4: In need of a sequence iterator.
by hv (Prior) on Dec 03, 2004 at 12:53 UTC

Ah ok, well you could use the string approach directly on the packed strings by changing the replace to /chr(ord($1)+1)/e or use a hash to describe successorship in the arbitrary alphabet:

  my $alphabet = "0123456789ABCDEF";
  my %successor = $alphabet =~ /(.)(?=(.))/g;
  my $zero = substr($alphabet, 0, 1);
  ...
  sub genIterator {
    my($len, $count) = @_;
    my $cur = '';
    my $lastdig = substr($alphabet, $count - 1, 1);
    return sub {
      if (length($cur) < $len) {
        $cur .= $zero;
      } else {
        $cur =~ s/([^$lastdig])$lastdig*\z/$successor{$1}/
            or $cur = undef;
      }
      $cur;
    }
  }
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