1Tree::Simple::Visitor::UFsreormNCeosntterdiHbausthe(d3T)Preerel::DSoicmupmleen:t:aVtiisointor::FromNestedHash(3)
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6 Tree::Simple::Visitor::FromNestedHash - A Visitor for creating
7 Tree::Simple objects from nested hash trees.
8
10 use Tree::Simple::Visitor::FromNestedHash;
11 my $visitor = Tree::Simple::Visitor::FromNestedHash->new();
13 # given this nested hash tree
15 my $hash_tree = {
16 Root => {
17 Child1 => {
18 GrandChild1 => {},
19 GrandChild2 => {}
20 },
21 Child2 => {}
22 }
23 };
24 # set the array tree we
26 # are going to convert
27 $visitor->setHashTree($hash_tree);
28 $tree->accept($visitor);
30 # this then creates the equivalent Tree::Simple object:
32 # Tree::Simple->new("Root")
33 # ->addChildren(
34 # Tree::Simple->new("Child1")
35 # ->addChildren(
36 # Tree::Simple->new("GrandChild1"),
37 # Tree::Simple->new("GrandChild2")
38 # ),
39 # Tree::Simple->new("Child2"),
40 # );
41
43 Given a tree constructed from nested hashes, this Visitor will create
44 the equivalent Tree::Simple hierarchy.
45
47 new There are no arguments to the constructor the object will be in its
48 default state. You can use the "setNodeFilter" methods to customize
49 its behavior.
50 setNodeFilter ($filter_function)
52 This method accepts a CODE reference as its $filter_function
53 argument and throws an exception if it is not a code reference.
54 This code reference is used to filter the tree nodes as they are
55 created, the $filter_function is passed the node value extracted
56 from the hash prior to it being inserted into the tree being built.
57 The $filter_function is expected to return the value desired for
58 inclusion into the tree.
59 setHashTree ($hash_tree)
61 This method is used to set the $hash_tree that our Tree::Simple
62 hierarchy will be constructed from. It must be in the following
63 form:
64 {
66 Root => {
67 Child1 => {
68 GrandChild1 => {},
69 GrandChild2 => {}
70 },
71 Child2 => {}
72 }
73 }
74 Basically each key in the hash is considered a node, values are
76 ignored unless it is a hash reference with at least one key in it,
77 in which case it is interpreted as containing the children of the
78 node created from the key.
79 The tree is validated prior being accepted, if it fails validation
81 an exception will be thrown. The rules are as follows;
82 The hash tree must not be empty.
84 It makes not sense to create a tree out of nothing, so it is
85 assumed that this is a sign of something wrong.
86 The hash tree must be a single rooted tree.
88 The hash tree should have only one key in the first level. If
89 it has more than one, then it is not a single rooted tree.
90 NOTE: Hash keys are sorted ascii-betically before being added to
92 the tree, this results in a somewhat more predictable hierarchy.
93 visit ($tree)
95 This is the method that is used by the Tree::Simple "accept"
96 method. It can also be used on its own, it requires the $tree
97 argument to be a Tree::Simple object (or derived from a
98 Tree::Simple object), and will throw and exception otherwise.
99
101 <https://github.com/ronsavage/Tree-Simple-VisitorFactory>
102
104 Bugs should be reported via the CPAN bug tracker at
105 <https://github.com/ronsavage/Tree-Simple-VisitorFactory/issues>
107
109 See the CODE COVERAGE section in Tree::Simple::VisitorFactory for more
110 information.
111
113 These Visitor classes are all subclasses of Tree::Simple::Visitor,
114 which can be found in the Tree::Simple module, you should refer to that
115 module for more information.
116
118 stevan little, <stevan@iinteractive.com>
119
121 Copyright 2004, 2005 by Infinity Interactive, Inc.
122 <http://www.iinteractive.com>
124 This library is free software; you can redistribute it and/or modify it
126 under the same terms as Perl itself.
127perl v5.32.1 2021-T0r2e-e0:2:Simple::Visitor::FromNestedHash(3)