# File lib/rdoc/stats.rb, line 106
  def calculate
    return if @doc_items

    ucm = RDoc::TopLevel.unique_classes_and_modules
    constants = []
    ucm.each { |cm| constants.concat cm.constants }

    methods = []
    ucm.each { |cm| methods.concat cm.method_list }

    attributes = []
    ucm.each { |cm| attributes.concat cm.attributes }

    @num_attributes, @undoc_attributes = doc_stats attributes
    @num_classes,    @undoc_classes    = doc_stats RDoc::TopLevel.unique_classes
    @num_constants,  @undoc_constants  = doc_stats constants
    @num_methods,    @undoc_methods    = doc_stats methods
    @num_modules,    @undoc_modules    = doc_stats RDoc::TopLevel.unique_modules

    @num_items =
      @num_attributes +
      @num_classes +
      @num_constants +
      @num_methods +
      @num_modules +
      @num_params

    @undoc_items =
      @undoc_attributes +
      @undoc_classes +
      @undoc_constants +
      @undoc_methods +
      @undoc_modules +
      @undoc_params

    @doc_items = @num_items - @undoc_items
  end