in reply to Re^3: how to construct tree from parent pointer list
in thread how to construct tree from parent pointer list

Hi, Can you explain what the pieces of this does 

sub visit_preorder {
   my ($cb, node, $depth) = @_;
   $depth ||= 0;
   $cb->($node, $depth);
   visit_preorder($cb, $_, $depth+1) for $node->children();
}

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For example, what is '$cb' ? What I am trying to do is output the tree in a flattened format once the tree is built. Something like : Fruit|Apple|Granny Smith.. Fruit being the parent of Apple, Apple being the parent of Granny Smith..

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Re^5: how to construct tree from parent pointer list
by ikegami (Patriarch) on Jun 30, 2009 at 19:21 UTC

    For example, what is '$cb'

    The first argument. It's expected to be a code reference.

    What I am trying to do is output the tree in a flattened format once the tree is built.

    Based on the code from Re: Tree path analyzer regex problem (maybe other issues)?, a reply in an older thread of yours, 

    sub leaves {
    my $node = shift;
    my @children = $node->children();

    if (!@children) {
        print(join('|', @_), "\n");
    } else {
        for my $child (@children) {
            leaves($child, @_, $child->value());
        }
    }
}

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