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lib/AVLTree.pm  view on Meta::CPAN

  # which hold some data. We can deal with these by definying a custom
  # comparison function based on one of the attributes of these data items, 
  # e.g. 'id':
 
  sub compare {
    my ($i1, $i2) = @_;
    my ($id1, $id2) = ($i1->{id}, $i2->{id});

    croak "Cannot compare items based on id"
      unless defined $id1 and defined $id2;
  
    return $id1<$id2?-1:($id1>$id2)?1:0;
  }

  # Now can do the same as with numbers
  my $tree = AVLTree->new(\&compare);

  my $insert_ok = $tree->insert({ id => 10, data => 'ten' });
  croak "Could not insert item" unless $insert_ok;

  $insert_ok = $tree->insert({ id => 20, data => 'twenty' });
  
  ...

  my $id = 10;
  my $result = $tree->find({ id => $id });
  if($result) {
    printf "Item with id %d found\nData: %s\n", $id, $result->{data};
  } else {
    print "Item with id $id not found\n";
  }

  # forward tree traversal
  my $item = $tree->first();
  print "First item: ", $item, "\n";

  while($item = $tree->next()) {
    print $item, "\n";
  }

  # and similarly for reverse iteratio, using last/prev methods

  ...

=head1 METHODS

=head2 C<new>

  Arg [1]     : (required) A reference to a subroutine
  
  Example     : my $tree->new(\&compare);
                carp "Unable to instantiate tree" unless defined $tree;

  Description : Creates a new AVL tree object.
                The objects hold by the tree are implicitly defined
                by the provided callback.

  Returntype  : AVLTreePtr or undef if unable to instantiate
  Exceptions  : None
  Caller      : General
  Status      : Unstable, interface might change to accomodate suitable defaults, 
                e.g. numbers

=head2 C<find>

  Arg [1]     : Item to search, can be defined just in terms of the attribute
                with which the items in the tree are compared. 
  
  Example     : $tree->find({ id => 10 }); # objects in the tree can hold data as well
                if($result) {
                  printf "Item with id %d found\nData: %s\n", $id, $result->{data};
                } else { print "Item with id $id not found\n"; }

  Description : Query if an item exists in the tree.

  Returntype  : The item, if found, as stored in the tree or undef
                if the item was not found or the query was not provided
                or it was undefined.
  Exceptions  : None
  Caller      : General
  Status      : Unstable

=head2 C<insert>

  Arg [1]     : An item to insert in the tree.
  
  Example     : my $ok = $tree->insert({ id => 10, data => 'ten' });
                croak "Unable to insert 10" unless $ok;

  Description : Insert an item in the tree, use the provided, upon tree construction,
                comparison function to determine the position of the item in the tree

  Returntype  : Bool, true if the item was successfully installed, false otherwise 
  Exceptions  : None
  Caller      : General
  Status      : Unstable

=head2 C<remove>

  Arg[1]      : An item to remove from the tree
  
  Example     : my $ok = $tree->remove({ id => 10 });
                croak "Unable to remove 10" unless $ok;

  Description : Remove an item from the tree.

  Returntype  : Bool, true if the item was successfully installed, false otherwise 
  Exceptions  : None
  Caller      : General
  Status      : Unstable

=head2 C<size>

  Arg[...]    : None
  
  Example     : print "Size of the tree is: %d\n", $tree->size();

  Description : Returns the size of the tree (number of nodes)

  Returntype  : Int, the size of the tree
 

lib/AVLTree.pm  view on Meta::CPAN

  Description : Returns the next element as specified by the order defined by the tree.

  Returntype  : The item, if found, as stored in the tree or undef
                if the tree is empty.
  Exceptions  : None
  Caller      : General
  Status      : Unstable

=head2 C<prev>

  Arg [...]   : None

  Example     : my $item = $tree->last;
                print $item, "\n";
                while($item = $tree->prev) { print $item, "\n"; }

  Description : Returns the previous element as specified by the order defined by the tree.

  Returntype  : The item, if found, as stored in the tree or undef
                if the tree is empty.
  Exceptions  : None
  Caller      : General
  Status      : Unstable

=head1 DEPENDENCIES

AVLTree requires Carp and Test::More, Test::Deep and Test::LeakTrace to run the tests during installation.
If you want to run the benchmarks in the scripts directory, you need to install the Benchmark 
and List::Util modules.

=head1 EXPORT

None

=head1 SEE ALSO

If you want to get a deeper insight into the module, you should of course take a look at the excellent AVL 
tree library developed by Julienne Walker L<http://www.eternallyconfuzzled.com/jsw_home.aspx>. 

There are of course other modules which provide this functionality, see e.g. Tree::AVL, Btrees.
You can appreciate the power of this module by running some benchmarking against the above.
If you've installed from source, go to the installation directory and:  

  cd scripts
  perl benchmarking.pl

Preliminary experiments suggest speed gains of one order of magnitude.

To the best of my knowledge, there are no modules using Perl XS attempting to implement AVL
trees in the most efficient possible way. The closest thing is Tree::Fat, a Perl extension
to implement Fat-Node trees.

=head1 AUTHOR

Alessandro Vullo, C<< <avullo at cpan.org> >>

=head1 BUGS

Please report any bugs or feature requests to C<bug-avltree at rt.cpan.org>, or through
the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=AVLTree>.  I will be notified, and then you'll
automatically be notified of progress on your bug as I make changes.

=head1 CONTRIBUTING

You can obtain the most recent development version of this module via the GitHub
repository at https://github.com/avullo/AVLTree. Please feel free to submit bug
reports, patches etc.

=head1 SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc AVLTree

You can also look for information at:

=over 4

=item * RT: CPAN's request tracker (report bugs here)

L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=AVLTree>

=item * AnnoCPAN: Annotated CPAN documentation

L<http://annocpan.org/dist/AVLTree>

=item * CPAN Ratings

L<http://cpanratings.perl.org/d/AVLTree>

=item * Search CPAN

L<http://search.cpan.org/dist/AVLTree/>

=back

=head1 ACKNOWLEDGEMENTS

I am very grateful to Julienne Walker for generously providing the source 
code of his production quality C library for handling AVL balanced trees.

Julienne's library can be found at:

http://www.eternallyconfuzzled.com/Libraries.aspx

=head1 LICENSE AND COPYRIGHT

Copyright [2017-2018] Alessandro Vullo.

This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.

See L<http://dev.perl.org/licenses/> for more information.

=cut