each_strongly_connected_component_from

# File lib/tsort.rb, line 199
  def each_strongly_connected_component_from(node, id_map={}, stack=[]) # :yields: nodes
    minimum_id = node_id = id_map[node] = id_map.size
    stack_length = stack.length
    stack << node

    tsort_each_child(node) {|child|
      if id_map.include? child
        child_id = id_map[child]
        minimum_id = child_id if child_id && child_id < minimum_id
      else
        sub_minimum_id =
          each_strongly_connected_component_from(child, id_map, stack) {|c|
            yield c
          }
        minimum_id = sub_minimum_id if sub_minimum_id < minimum_id
      end
    }

    if node_id == minimum_id
      component = stack.slice!(stack_length .. -1)
      component.each {|n| id_map[n] = nil}
      yield component
    end

    minimum_id
  end