1Tree::Simple::Visitor::USsoerrt(C3o)ntributed Perl DocumTernetea:t:iSoinmple::Visitor::Sort(3)
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6 Tree::Simple::Visitor::Sort - A Visitor for sorting a Tree::Simple
7 object hierarchy
8
10 use Tree::Simple::Visitor::Sort;
11 # create a visitor object
13 my $visitor = Tree::Simple::Visitor::Sort->new();
14 $tree->accept($visitor);
16 # the tree is now sorted ascii-betically
17 # set the sort function to
19 # use a numeric comparison
20 $visitor->setSortFunction($visitor->NUMERIC);
21 $tree->accept($visitor);
23 # the tree is now sorted numerically
24 # set a custom sort function
26 $visitor->setSortFunction(sub {
27 my ($left, $right) = @_;
28 lc($left->getNodeValue()->{name}) cmp lc($right->getNodeValue()->{name});
29 });
30 $tree->accept($visitor);
32 # the tree's node are now sorted appropriately
33
35 This implements a recursive multi-level sort of a Tree::Simple
36 hierarchy. I think this deserves some more explanation, and the best
37 way to do that is visually.
38 Given the tree:
40 1
42 1.3
43 1.2
44 1.2.2
45 1.2.1
46 1.1
47 4
48 4.1
49 2
50 2.1
51 3
52 3.3
53 3.2
54 3.1
55 A normal sort would produce the following tree:
57 1
59 1.1
60 1.2
61 1.2.1
62 1.2.2
63 1.3
64 2
65 2.1
66 3
67 3.1
68 3.2
69 3.3
70 4
71 4.1
72 A sort using the built-in REVERSE sort function would produce the
74 following tree:
75 4
77 4.1
78 3
79 3.3
80 3.2
81 3.1
82 2
83 2.1
84 1
85 1.3
86 1.2
87 1.2.2
88 1.2.1
89 1.1
90 As you can see, no node is moved up or down from it's current depth,
92 but sorted with it's siblings. Flexible customized sorting is possible
93 within this framework, however, this cannot be used for tree-balancing
94 or anything as complex as that.
95
97 new There are no arguments to the constructor the object will be in its
98 default state. You can use the "setNodeFilter" and
99 "setSortFunction" methods to customize its behavior.
100 includeTrunk ($boolean)
102 Based upon the value of $boolean, this will tell the visitor to
103 include the trunk of the tree in the sort as well.
104 setNodeFilter ($filter_function)
106 This method accepts a CODE reference as it's $filter_function
107 argument and throws an exception if it is not a code reference.
108 This code reference is used to filter the tree nodes as they are
109 sorted. This can be used to gather specific information from a more
110 complex tree node. The filter function should accept a single
111 argument, which is the current Tree::Simple object.
112 setSortFunction ($sort_function)
114 This method accepts a CODE reference as it's $sort_function
115 argument and throws an exception if it is not a code reference.
116 The $sort_function is used by perl's builtin "sort" routine to sort
117 each level of the tree. The $sort_function is passed two
118 Tree::Simple objects, and must return 1 (greater than), 0 (equal
119 to) or -1 (less than). The sort function will override and bypass
120 any node filters which have been applied (see "setNodeFilter"
121 method above), they cannot be used together.
122 Several pre-built sort functions are provided. All of these
124 functions assume that calling "getNodeValue" on the Tree::Simple
125 object will return a suitable sortable value.
126 REVERSE
128 This is the reverse of the normal sort using "cmp".
129 NUMERIC
131 This uses the numeric comparison operator "<=>" to sort.
132 REVERSE_NUMERIC
134 The reverse of the above.
135 ALPHABETICAL
137 This lowercases the node value before using "cmp" to sort. This
138 results in a true alphabetical sorting.
139 REVERSE_ALPHABETICAL
141 The reverse of the above.
142 If you need to implement one of these sorting routines, but need
144 special handling of your Tree::Simple objects (such as would be
145 done with a node filter), I suggest you read the source code and
146 copy and modify your own sort routine. If it is requested enough I
147 will provide this feature in future versions, but for now I am not
148 sure there is a large need.
149 visit ($tree)
151 This is the method that is used by Tree::Simple's "accept" method.
152 It can also be used on its own, it requires the $tree argument to
153 be a Tree::Simple object (or derived from a Tree::Simple object),
154 and will throw and exception otherwise.
155 It should be noted that this is a destructive action, since the
157 sort happens in place and does not produce a copy of the tree.
158
160 <https://github.com/ronsavage/Tree-Simple-VisitorFactory>
161
163 Bugs should be reported via the CPAN bug tracker at
164 <https://github.com/ronsavage/Tree-Simple-VisitorFactory/issues>
166
168 See the CODE COVERAGE section in Tree::Simple::VisitorFactory for more
169 information.
170
172 These Visitor classes are all subclasses of Tree::Simple::Visitor,
173 which can be found in the Tree::Simple module, you should refer to that
174 module for more information.
175
177 Thanks to Vitor Mori for the idea and much of the code for this
178 Visitor.
179
181 Vitor Mori, <vvvv767@hotmail.com>
182 stevan little, <stevan@iinteractive.com>
184
186 Copyright 2004, 2005 by Vitor Mori & Infinity Interactive, Inc.
187 <http://www.iinteractive.com>
189 This library is free software; you can redistribute it and/or modify it
191 under the same terms as Perl itself.
192perl v5.36.0 2023-01-20 Tree::Simple::Visitor::Sort(3)