serializing_trees.rb

# http://eli.thegreenplace.net/2011/09/29/an-interesting-tree-serialization-algorithm-from-dwarf

def load array
  root = Node.new array.shift.first
  stack = [root]

  array.each do |pair|
    if pair.nil?
      stack.pop
    else
      node = Node.new pair.first
      stack.last.add_child node
      stack.push node if pair.last
    end
  end

  root
end

def dump root
  array = []

  serialize = -> node do
    if node.children.empty?
      array.push [node.value, false]
    else
      array.push [node.value, true]
      node.children.each { |node| serialize[node] }
      array.push nil
    end
  end
  serialize[root]

  array
end