show ruby classes

class_tree.rb

#!/usr/bin/env ruby
class TreeNodeData < Array
  def <<(ary)
    raise ArgumentError unless ary.size == 2
    super
  end

  def child_data
    self[0]
  end

  def parent_data
    self[1]
  end

  def root?
    self.parent_data.nil?
  end
end

class Tree
  def initialize
    @data = Array.new
  end

  def <<(ary)
    @data << TreeNodeData.new(ary)
  end

  def to_s(indent='  ')
    @indent = indent
    root_nodes = @data.select(&:root?)
    puts_hierarchy(root_nodes)
  end

  private
  def puts_hierarchy(nodes, depth=0)
    return nodes if nodes.size.zero?
    nodes.sort_by{ |x| x.child_data.to_s }.each do |node|
      puts "#{@indent*depth}#{node.child_data}"
      children = @data.select { |elm| elm.parent_data == node.child_data }
      puts_hierarchy(children, depth+1)
    end
  end
end

if __FILE__ == $0
  tree = Tree.new
  Module.constants.each do |elm|
    const = eval(elm.to_s)
    tree << [const, const.superclass] if const.respond_to? :superclass
  end

  puts tree
end