DOT言語のDSL

dot_dsl.rb

class Digraph
  attr_reader :name

  def initialize(name)
    @name = name
    @nodes = []
  end

  def method_missing(name, *args)
    node = @nodes.select { |node| node.name == name }.first
    if node.nil?
      node = Node.new(name)
      @nodes << node
    end
    node
  end
end

class Node
  attr_reader :name

  def initialize(name)
    @name = name
  end

  def >>(other)
    puts "#{self.name} -> #{other.name};"
    other
  end

  def <=>(other)
    puts "#{self.name} -> #{other.name} [dir = both];"
    other
  end
end

def digraph(name, &block)
  digraph = Digraph.new(name)
  puts "digraph #{digraph.name} {"
  digraph.instance_eval(&block)
  puts "}"
  digraph
end

digraph "sample" do
  a >> b >> c >> d
  b <=> d
end