VERSION

Version 0.135

SYNOPSIS

Occasionally it is useful for an iterator to go in both directions, forward and backward. One example would be token processing. When looping though tokens it is sometimes necessary to advance forward looking for a match to a rule. If the match fails, a bi-directional iterator can be moved back so that the next rule can be tried.

  use Array::Iterator::BiDirectional;
  # create an instance of the iterator
  my $i = Array::Iterator::BiDirectional->new(1 .. 100);
  while ($some_condition_exists) {
      # get the latest item from
      # the iterator
      my $current = $i->get_next();
      # ...
      if ($something_happens) {
          # back up the iterator
          $current = $i->get_previous();
      }
  }

METHODS

This is a subclass of Array::Iterator, only those methods that have been added are documented here, refer to the Array::Iterator documentation for more information.

has_previous([$n])

This method works much like "hasNext" does, it will return true (1) unless the beginning of the array has been reached, and false (0) otherwise.

Optional argument has the same meaning except that it specifies $nth previous element.

previous

This method is much like "next". It will return the previous item in the iterator, and throw an exception if it attempts to reach past the beginning of the array.

get_previous

This method is much like "get_next". It will return the previous item in the iterator, and return undef if it attempts to reach past the beginning of the array.

look_back([$n])

This is the counterpart to "peek", it will return the previous items in the iterator, but will not affect the internal counter.

Optional argument has the same meaning except that it specifies $nth previous element.

SEE ALSO

This is a subclass of Array::Iterator, please refer to it for more documentation.

ORIGINAL AUTHOR

stevan little, <stevan@iinteractive.com>

ORIGINAL COPYRIGHT AND LICENSE

Copyright 2004 by Infinity Interactive, Inc.

<http://www.iinteractive.com>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.