class RuboCop::Cop::Metrics::Utils::AbcSizeCalculator

> ABC is .. a software size metric .. computed by counting the number > of assignments, branches and conditions for a section of code. > c2.com/cgi/wiki?AbcMetric

We separate the calculator from the cop so that the calculation, the formula itself, is easier to test.

Constants

BRANCH_NODES

> Branch – an explicit forward program branch out of scope – a > function call, class method call .. > c2.com/cgi/wiki?AbcMetric

CONDITION_NODES

> Condition – a logical/Boolean test, == != <= >= < > else case > default try catch ? and unary conditionals. > c2.com/cgi/wiki?AbcMetric

Public Class Methods

calculate(node, discount_repeated_attributes: false) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 30
def self.calculate(node, discount_repeated_attributes: false)
  new(node, discount_repeated_attributes: discount_repeated_attributes).calculate
end
new(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 34
def initialize(node)
  @assignment = 0
  @branch = 0
  @condition = 0
  @node = node
  reset_repeated_csend
end

Public Instance Methods

calculate() click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 42
def calculate
  visit_depth_last(@node) { |child| calculate_node(child) }

  [
    Math.sqrt((@assignment**2) + (@branch**2) + (@condition**2)).round(2),
    "<#{@assignment}, #{@branch}, #{@condition}>"
  ]
end
else_branch?(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 65
def else_branch?(node)
  %i[case if].include?(node.type) && node.else? && node.loc.else.is?('else')
end
evaluate_branch_nodes(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 51
def evaluate_branch_nodes(node)
  if node.comparison_method?
    @condition += 1
  else
    @branch += 1
    @condition += 1 if node.csend_type? && !discount_for_repeated_csend?(node)
  end
end
evaluate_condition_node(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 60
def evaluate_condition_node(node)
  @condition += 1 if else_branch?(node)
  @condition += 1
end

Private Instance Methods

argument?(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 127
def argument?(node)
  node.argument_type? && capturing_variable?(node.children.first)
end
assignment?(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 86
def assignment?(node)
  return compound_assignment(node) if node.masgn_type? || node.shorthand_asgn?

  node.for_type? ||
    (node.respond_to?(:setter_method?) && node.setter_method?) ||
    simple_assignment?(node) ||
    argument?(node)
end
branch?(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 123
def branch?(node)
  BRANCH_NODES.include?(node.type)
end
calculate_node(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 76
def calculate_node(node)
  @assignment += 1 if assignment?(node)

  if branch?(node)
    evaluate_branch_nodes(node)
  elsif condition?(node)
    evaluate_condition_node(node)
  end
end
capturing_variable?(name) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 119
def capturing_variable?(name)
  name && !name.start_with?('_')
end
compound_assignment(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 95
def compound_assignment(node)
  # Methods setter cannot be detected for multiple assignments
  # and shorthand assigns, so we'll count them here instead
  children = node.masgn_type? ? node.children[0].children : node.children

  will_be_miscounted = children.count do |child|
    child.respond_to?(:setter_method?) && !child.setter_method?
  end
  @assignment += will_be_miscounted

  false
end
condition?(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 131
def condition?(node)
  return false if iterating_block?(node) == false

  CONDITION_NODES.include?(node.type)
end
simple_assignment?(node) click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 108
def simple_assignment?(node)
  if !node.equals_asgn?
    false
  elsif node.lvasgn_type?
    reset_on_lvasgn(node)
    capturing_variable?(node.children.first)
  else
    true
  end
end
visit_depth_last(node) { |node| ... } click to toggle source
# File lib/rubocop/cop/metrics/utils/abc_size_calculator.rb, line 71
def visit_depth_last(node, &block)
  node.each_child_node { |child| visit_depth_last(child, &block) }
  yield node
end