perlfan,
Doing a DFS as an iterator is pretty simple. If this code example isn't sufficient, let me know.
#!/usr/bin/perl
use strict;
use warnings;
{
my %seen;
my %tree = (
A => ['B', 'C'], B => ['D', 'E'], C => ['F', 'G'],
E => ['H', 'I'], G => ['J', 'K'], H => ['L', 'M', 'N'],
I => ['O', 'P'], K => ['Q'],
);
sub get_root { 'A' }
sub get_children {
my ($node) = @_;
return $tree{$node} ? @{$tree{$node}} : ();
}
sub visited {
my ($node, $val) = @_;
return $seen{$node} = $val if defined $val;
return $seen{$node};
}
}
sub gen_tree_iter {
my @nodes = get_root();
return sub {
{
my $node = shift @nodes;
return undef if ! defined $node;
redo if visited($node);
visited($node => 1);
unshift @nodes, get_children($node);
return $node;
}
};
}
my $iter = gen_tree_iter();
while (my $node = $iter->()) {
print "Visiting $node\n";
}
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