gistfile1.rb

class BasicGraph

  include_package 'clojure.lang'

  attr_reader :nodes, :edges

  def self.empty
    BasicGraph.new(PersistentHashMap::EMPTY, PersistentHashMap::EMPTY)
  end

  def add_node(node, id)
    BasicGraph.new(@nodes.assoc(id, node), @edges)
  end

  def add_edge(source_id, target_id, edge)
    if (@nodes.containsKey(source_id) && @nodes.containsKey(target_id))
      BasicGraph.new(@nodes, @edges.assoc([source_id, target_id], edge))
    else
      self
    end
  end


  private

  attr_accessor :nodes, :edges

  def initialize(nodes, edges)
    @nodes = nodes
    @edges = edges
  end
end