/usr/share/perl5/Tree/Simple/Visitor.pm is in libtree-simple-perl 1.26-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 | package Tree::Simple::Visitor;
use strict;
use warnings;
our $VERSION = '1.26';
use Scalar::Util qw(blessed);
## class constants
use constant RECURSIVE => 0x01;
use constant CHILDREN_ONLY => 0x10;
### constructor
sub new {
my ($_class, $func, $depth) = @_;
if (defined($depth)){
($depth =~ /\d+/ && ($depth == RECURSIVE || $depth == CHILDREN_ONLY))
|| die "Insufficient Arguments : Depth arguement must be either ".
"RECURSIVE or CHILDREN_ONLY";
}
my $class = ref($_class) || $_class;
# if we have not supplied a $func
# it is automatically RECURSIVE
$depth = RECURSIVE unless defined $func;
my $visitor = {
depth => $depth || 0
};
bless($visitor, $class);
$visitor->_init();
if (defined $func) {
$visitor->setNodeFilter($func);
$visitor->includeTrunk(1);
}
return $visitor;
}
### methods
sub _init {
my ($self) = @_;
$self->{_include_trunk} = 0;
$self->{_filter_function} = undef;
$self->{_results} = [];
}
sub includeTrunk {
my ($self, $boolean) = @_;
$self->{_include_trunk} = ($boolean ? 1 : 0) if defined $boolean;
return $self->{_include_trunk};
}
# node filter methods
sub getNodeFilter {
my ($self) = @_;
return $self->{_filter_function};
}
sub clearNodeFilter {
my ($self) = @_;
$self->{_filter_function} = undef;
}
sub setNodeFilter {
my ($self, $filter_function) = @_;
(defined($filter_function) && ref($filter_function) eq "CODE")
|| die "Insufficient Arguments : filter function argument must be a subroutine reference";
$self->{_filter_function} = $filter_function;
}
# results methods
sub setResults {
my ($self, @results) = @_;
$self->{results} = \@results;
}
sub getResults {
my ($self) = @_;
return wantarray ?
@{$self->{results}}
:
$self->{results};
}
# visit routine
sub visit {
my ($self, $tree) = @_;
(blessed($tree) && $tree->isa("Tree::Simple"))
|| die "Insufficient Arguments : You must supply a valid Tree::Simple object";
# get all things set up
my @results;
my $func;
if ($self->{_filter_function}) {
$func = sub { push @results => $self->{_filter_function}->(@_) };
}
else {
$func = sub { push @results => $_[0]->getNodeValue() };
}
# always apply the function
# to the tree's node
$func->($tree) if (defined($self->{_include_trunk}) && $self->{_include_trunk});
# then recursively to all its children
# if the object is configured that way
$tree->traverse($func) if ($self->{depth} == RECURSIVE);
# or just visit its immediate children
# if the object is configured that way
if ($self->{depth} == CHILDREN_ONLY) {
$func->($_) foreach $tree->getAllChildren();
}
# now store the results we got
$self->setResults(@results);
}
1;
__END__
=head1 NAME
Tree::Simple::Visitor - Visitor object for Tree::Simple objects
=head1 SYNOPSIS
use Tree::Simple;
use Tree::Simple::Visitor;
# create a visitor instance
my $visitor = Tree::Simple::Visitor->new();
# create a tree to visit
my $tree = Tree::Simple->new(Tree::Simple->ROOT)
->addChildren(
Tree::Simple->new("1.0"),
Tree::Simple->new("2.0")
->addChild(
Tree::Simple->new("2.1.0")
),
Tree::Simple->new("3.0")
);
# by default this will collect all the
# node values in depth-first order into
# our results
$tree->accept($visitor);
# get our results and print them
print join ", ", $visitor->getResults(); # prints "1.0, 2.0, 2.1.0, 3.0"
# for more complex node objects, you can specify
# a node filter which will be used to extract the
# information desired from each node
$visitor->setNodeFilter(sub {
my ($t) = @_;
return $t->getNodeValue()->description();
});
# NOTE: this object has changed, but it still remains
# backwards compatible to the older version, see the
# DESCRIPTION section below for more details
=head1 DESCRIPTION
This object has been revised into what I think is more intelligent approach to Visitor objects.
This is now a more suitable base class for building your own Visitors. It is also the base class
for the visitors found in the B<Tree::Simple::VisitorFactory> distribution, which includes a
number of useful pre-built Visitors.
While I have changed a number of things about this module, I have kept it backwards compatible
to the old way of using it. So the original example code still works:
my @accumulator;
my $visitor = Tree::Simple::Visitor->new(sub {
my ($tree) = @_;
push @accumulator, $tree->getNodeValue();
},
Tree::Simple::Visitor->RECURSIVE);
$tree->accept($visitor);
print join ", ", @accumulator; # prints "1.0, 2.0, 2.1.0, 3.0"
But is better expressed as this:
my $visitor = Tree::Simple::Visitor->new();
$tree->accept($visitor);
print join ", ", $visitor->getResults(); # prints "1.0, 2.0, 2.1.0, 3.0"
This object is still pretty much a wrapper around the Tree::Simple C<traverse> method,
and can be thought of as a depth-first traversal Visitor object.
=head1 METHODS
=over 4
=item B<new ($func, $depth)>
The new style interface means that all arguments to the constructor are now optional.
As a means of defining the usage of the old and new, when no arguments are sent to the
constructor, it is assumed that the new style interface is being used. In the new style,
the C<$depth> is always assumed to be equivalent to C<RECURSIVE> and the C<$func> argument
can be set with C<setNodeFilter> instead. This is the recommended way of doing things now.
If you have been using the old way, it is still there, and I will maintain backwards
compatibility for a few more version before removing it entirely. If you are using this
module (and I do not even know if anyone actually is) you have been warned. Please contact
me if this will be a problem.
The old style constructor documentation is retained her for reference:
The first argument to the constructor is a code reference to a function which expects a
B<Tree::Simple> object as its only argument. The second argument is optional, it can be
used to set the depth to which the function is applied. If no depth is set, the function
is applied to the current B<Tree::Simple> instance. If C<$depth> is set to C<CHILDREN_ONLY>,
then the function will be applied to the current B<Tree::Simple> instance and all its
immediate children. If C<$depth> is set to C<RECURSIVE>, then the function will be applied
to the current B<Tree::Simple> instance and all its immediate children, and all of their
children recursively on down the tree. If no C<$depth> is passed to the constructor,
then the function will only be applied to the current B<Tree::Simple> object and none
of its children.
=item B<includeTrunk ($boolean)>
Based upon the value of C<$boolean>, this will tell the visitor to collect the trunk of the
tree as well. It is defaulted to false (C<0>) in the new style interface, but is defaulted
to true (C<1>) in the old style interface.
=item B<getNodeFilter>
This method returns the CODE reference set with C<setNodeFilter> argument.
=item B<clearNodeFilter>
This method clears node filter field.
=item B<setNodeFilter ($filter_function)>
This method accepts a CODE reference as its C<$filter_function> argument. This code reference
is used to filter the tree nodes as they are collected. This can be used to customize output,
or 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.
=item B<getResults>
This method returns the accumulated results of the application of the node filter to the tree.
=item B<setResults>
This method should not really be used outside of this class, as it just would not make any sense
to. It is included in this class and in this documentation to facilitate subclassing of this
class for your own needs. If you desire to clear the results, then you can simply call
C<setResults> with no argument.
=item B<visit ($tree)>
The C<visit> method accepts a B<Tree::Simple> and applies the function set in C<new> or
C<setNodeFilter> appropriately. The results of this application can be retrieved with C<getResults>
=back
=head1 CONSTANTS
These constants are part of the old-style interface, and therefore will eventually be deprecated.
=over 4
=item B<RECURSIVE>
If passed this constant in the constructor, the function will be applied recursively down the
hierarchy of B<Tree::Simple> objects.
=item B<CHILDREN_ONLY>
If passed this constant in the constructor, the function will be applied to the immediate children
of the B<Tree::Simple> object.
=back
=head1 BUGS
None that I am aware of. The code is pretty thoroughly tested (see B<CODE COVERAGE> section in
B<Tree::Simple>) and is based on an (non-publicly released) module which I had used in production
systems for about 2 years without incident. Of course, if you find a bug, let me know, and I will
be sure to fix it.
=head1 SEE ALSO
I have written a set of pre-built Visitor objects, available on CPAN as
B<Tree::Simple::VisitorFactory>.
=head1 AUTHOR
stevan little, E<lt>stevan@iinteractive.comE<gt>
=head1 REPOSITORY
L<https://github.com/ronsavage/Tree-Simple>.
=head1 COPYRIGHT AND LICENSE
Copyright 2004-2006 by Infinity Interactive, Inc.
L<http://www.iinteractive.com>
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=cut
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