class LegacyFacter::Core::DirectedGraph

def acyclic?
  cycles.empty?
end

def cycles
  cycles = []
  each_strongly_connected_component do |component|
    cycles << component if component.size > 1
  end
  cycles
end

def tsort
  missing = Set.new(values.flatten) - Set.new(keys)
  unless missing.empty?
    raise MissingVertex, "Cannot sort elements; cannot depend on missing elements #{missing.to_a}"
  end
  super
rescue TSort::Cyclic
  raise CycleError, "Cannot sort elements; found the following cycles: #{cycles.inspect}"
end

def tsort_each_child(node)
  fetch(node, []).each do |child|
    yield child
  end
end