2 package Tree::Simple::Visitor::Sort;
9 use Scalar::Util qw(blessed);
11 use base qw(Tree::Simple::Visitor);
15 my $class = ref($_class) || $_class;
17 bless($visitor, $class);
24 $self->{sort_function} = undef;
25 $self->SUPER::_init();
28 sub REVERSE { sub ($$) { $_[1]->getNodeValue() cmp $_[0]->getNodeValue() }};
29 sub NUMERIC { sub ($$) { $_[0]->getNodeValue() <=> $_[1]->getNodeValue() }};
30 sub REVERSE_NUMERIC { sub ($$) { $_[1]->getNodeValue() <=> $_[0]->getNodeValue() }};
31 sub ALPHABETICAL { sub ($$) { lc($_[0]->getNodeValue()) cmp lc($_[1]->getNodeValue()) }};
32 sub REVERSE_ALPHABETICAL { sub ($$) { lc($_[1]->getNodeValue()) cmp lc($_[0]->getNodeValue()) }};
35 my ($self, $sort_function) = @_;
36 (defined($sort_function) && ref($sort_function) eq "CODE")
37 || die "Insufficient Arguments : You must supply a CODE reference for the sort function";
38 $self->{sort_function} = $sort_function;
42 my ($self, $tree) = @_;
43 (blessed($tree) && $tree->isa("Tree::Simple"))
44 || die "Insufficient Arguments : You must supply a valid Tree::Simple object";
46 # No childs, nothing to sort
47 return if $tree->isLeaf();
50 if ($self->{sort_function}) {
51 $sort_function = $self->{sort_function};
55 my $filter_func = $self->getNodeFilter();
57 $sort_function = sub { $filter_func->($a) cmp $filter_func->($b) };
60 $sort_function = sub { $a->getNodeValue() cmp $b->getNodeValue() };
65 $self->_sortTree($sort_function, $tree);
69 my ($self, $sort_function, $tree) = @_;
71 # sort children, using the sort filter
72 my @childs = sort { $sort_function->($a, $b) } $tree->getAllChildren();
74 # Create the new sequence
75 foreach my $child (@childs) {
76 # get the removed child
77 $child = $tree->removeChild($child);
78 # and be sure that is the one
80 $tree->addChild($child);
81 # only sort the child if
83 $self->_sortTree($sort_function, $child) unless $child->isLeaf();
93 Tree::Simple::Visitor::Sort - A Visitor for sorting a Tree::Simple object heirarchy
97 use Tree::Simple::Visitor::Sort;
99 # create a visitor object
100 my $visitor = Tree::Simple::Visitor::Sort->new();
102 $tree->accept($visitor);
103 # the tree is now sorted ascii-betically
105 # set the sort function to
106 # use a numeric comparison
107 $visitor->setSortFunction($visitor->NUMERIC);
109 $tree->accept($visitor);
110 # the tree is now sorted numerically
112 # set a custom sort function
113 $visitor->setSortFunction(sub {
114 my ($left, $right) = @_;
115 lc($left->getNodeValue()->{name}) cmp lc($right->getNodeValue()->{name});
118 $tree->accept($visitor);
119 # the tree's node are now sorted appropriately
123 This implements a recursive multi-level sort of a Tree::Simple heirarchy. I think this deserves some more explaination, and the best way to do that is visually.
142 A normal sort would produce the following tree:
159 A sort using the built-in REVERSE sort function would produce the following tree:
176 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.
184 There are no arguments to the constructor the object will be in its default state. You can use the C<setNodeFilter> and C<setSortFunction> methods to customize its behavior.
186 =item B<includeTrunk ($boolean)>
188 Based upon the value of C<$boolean>, this will tell the visitor to include the trunk of the tree in the sort as well.
190 =item B<setNodeFilter ($filter_function)>
192 This method accepts a CODE reference as it's C<$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.
194 =item B<setSortFunction ($sort_function)>
196 This method accepts a CODE reference as it's C<$sort_function> argument and throws an exception if it is not a code reference. The C<$sort_function> is used by perl's builtin C<sort> routine to sort each level of the tree. The C<$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 C<setNodeFilter> method above), they cannot be used together.
198 Several pre-built sort functions are provided. All of these functions assume that calling C<getNodeValue> on the Tree::Simple object will return a suitable sortable value.
204 This is the reverse of the normal sort using C<cmp>.
208 This uses the numeric comparison operator C<E<lt>=E<gt>> to sort.
210 =item REVERSE_NUMERIC
212 The reverse of the above.
216 This lowercases the node value before using C<cmp> to sort. This results in a true alphabetical sorting.
218 =item REVERSE_ALPHABETICAL
220 The reverse of the above.
224 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.
226 =item B<visit ($tree)>
228 This is the method that is used by Tree::Simple's C<accept> method. It can also be used on its own, it requires the C<$tree> argument to be a Tree::Simple object (or derived from a Tree::Simple object), and will throw and exception otherwise.
230 It should be noted that this is a I<destructive> action, since the sort happens I<in place> and does not produce a copy of the tree.
236 None that I am aware of. Of course, if you find a bug, let me know, and I will be sure to fix it.
240 See the B<CODE COVERAGE> section in L<Tree::Simple::VisitorFactory> for more inforamtion.
244 These Visitor classes are all subclasses of B<Tree::Simple::Visitor>, which can be found in the B<Tree::Simple> module, you should refer to that module for more information.
246 =head1 ACKNOWLEDGEMENTS
250 =item Thanks to Vitor Mori for the idea and much of the code for this Visitor.
256 Vitor Mori, E<lt>vvvv767@hotmail.comE<gt>
258 stevan little, E<lt>stevan@iinteractive.comE<gt>
260 =head1 COPYRIGHT AND LICENSE
262 Copyright 2004, 2005 by Vitor Mori & Infinity Interactive, Inc.
264 L<http://www.iinteractive.com>
266 This library is free software; you can redistribute it and/or modify
267 it under the same terms as Perl itself.