Tree from Hash

hashtree.rb

class Tree
  attr_accessor :children, :node_name

  def initialize(name, children=[])
    @node_name = name
    @children = children
  end
  
  def visit_all(&block)
    visit &block
    visit_children &block
  end

  def visit_children(&block)
    children.each {|c| c.visit_all &block}
  end

  def visit(&block)
    block.call self
  end
end

def tree_from_hash(h)
  tree_from_hash = []
  for name in h.keys do
    tree_from_hash.push(Tree.new(name, tree_from_hash(h[name])))
  end
end

ruby_tree = tree_from_hash({'grandpa'=>{'dad'=>{'child 1'=>{}}}})[0]

puts "Visiting a node"
ruby_tree.visit {|node| puts node.node_name}
puts

puts "Visiting only children"
ruby_tree.visit_children {|node| puts node.node_name}
puts

puts "Visiting entire tree"
ruby_tree.visit_all {|node| puts node.node_name}