NAME

       Tree::Simple::Visitor::Sort - A Visitor for sorting a Tree::Simple object hierarchy

SYNOPSIS

         use Tree::Simple::Visitor::Sort;

         # create a visitor object
         my $visitor = Tree::Simple::Visitor::Sort->new();

         $tree->accept($visitor);
         # the tree is now sorted ascii-betically

         # set the sort function to
         # use a numeric comparison
         $visitor->setSortFunction($visitor->NUMERIC);

         $tree->accept($visitor);
         # the tree is now sorted numerically

         # set a custom sort function
         $visitor->setSortFunction(sub {
               my ($left, $right) = @_;
               lc($left->getNodeValue()->{name}) cmp lc($right->getNodeValue()->{name});
         });

         $tree->accept($visitor);
         # the tree's node are now sorted appropriately

DESCRIPTION

       This implements a recursive multi-level sort of a Tree::Simple hierarchy. I think this
       deserves some more explanation, and the best way to do that is visually.

       Given the tree:

           1
               1.3
               1.2
                   1.2.2
                   1.2.1
               1.1
           4
               4.1
           2
               2.1
           3
               3.3
               3.2
               3.1

       A normal sort would produce the following tree:

           1
               1.1
               1.2
                   1.2.1
                   1.2.2
               1.3
           2
               2.1
           3
               3.1
               3.2
               3.3
           4
               4.1

       A sort using the built-in REVERSE sort function would produce the following tree:

           4
               4.1
           3
               3.3
               3.2
               3.1
           2
               2.1
           1
               1.3
               1.2
                   1.2.2
                   1.2.1
               1.1

       As you can see, no node is moved up or down from it's current depth, but sorted with it's
       siblings. Flexible customized sorting is possible within this framework, however, this
       cannot be used for tree-balancing or anything as complex as that.

METHODS

       new There are no arguments to the constructor the object will be in its default state. You
           can use the "setNodeFilter" and "setSortFunction" methods to customize its behavior.

       includeTrunk ($boolean)
           Based upon the value of $boolean, this will tell the visitor to include the trunk of
           the tree in the sort as well.

       setNodeFilter ($filter_function)
           This method accepts a CODE reference as it's $filter_function argument and throws an
           exception if it is not a code reference. This code reference is used to filter the
           tree nodes as they are sorted. This can be used to gather specific information from a
           more complex tree node. The filter function should accept a single argument, which is
           the current Tree::Simple object.

       setSortFunction ($sort_function)
           This method accepts a CODE reference as it's $sort_function argument and throws an
           exception if it is not a code reference.  The $sort_function is used by perl's builtin
           "sort" routine to sort each level of the tree. The $sort_function is passed two
           Tree::Simple objects, and must return 1 (greater than), 0 (equal to) or -1 (less
           than). The sort function will override and bypass any node filters which have been
           applied (see "setNodeFilter" method above), they cannot be used together.

           Several pre-built sort functions are provided. All of these functions assume that
           calling "getNodeValue" on the Tree::Simple object will return a suitable sortable
           value.

           REVERSE
               This is the reverse of the normal sort using "cmp".

           NUMERIC
               This uses the numeric comparison operator "<=>" to sort.

           REVERSE_NUMERIC
               The reverse of the above.

           ALPHABETICAL
               This lowercases the node value before using "cmp" to sort. This results in a true
               alphabetical sorting.

           REVERSE_ALPHABETICAL
               The reverse of the above.

           If you need to implement one of these sorting routines, but need special handling of
           your Tree::Simple objects (such as would be done with a node filter), I suggest you
           read the source code and copy and modify your own sort routine. If it is requested
           enough I will provide this feature in future versions, but for now I am not sure there
           is a large need.

       visit ($tree)
           This is the method that is used by Tree::Simple's "accept" method. It can also be used
           on its own, it requires the $tree argument to be a Tree::Simple object (or derived
           from a Tree::Simple object), and will throw and exception otherwise.

           It should be noted that this is a destructive action, since the sort happens in place
           and does not produce a copy of the tree.

BUGS

       None that I am aware of. Of course, if you find a bug, let me know, and I will be sure to
       fix it.

CODE COVERAGE

       See the CODE COVERAGE section in Tree::Simple::VisitorFactory for more information.

SEE ALSO

       These Visitor classes are all subclasses of Tree::Simple::Visitor, which can be found in
       the Tree::Simple module, you should refer to that module for more information.

ACKNOWLEDGEMENTS

       Thanks to Vitor Mori for the idea and much of the code for this Visitor.

AUTHORS

       Vitor Mori, <vvvv767@hotmail.com>

       stevan little, <stevan@iinteractive.com>

COPYRIGHT AND LICENSE

       Copyright 2004, 2005 by Vitor Mori & 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.