Class: RuboCop::Cop::Metrics::PerceivedComplexity


Tries to produce a complexity score that’s a measure of the complexity the reader experiences when looking at a method. For that reason it considers when nodes as something that doesn’t add as much complexity as an if or a &&. Except if it’s one of those special case/when constructs where there’s no expression after case. Then the cop treats it as an if/elsif/elsif…​ and lets all the when nodes count. In contrast to the CyclomaticComplexity cop, this cop considers else nodes as adding complexity.


def my_method                   # 1
  if cond                       # 1
    case var                    # 2 (0.8 + 4 * 0.2, rounded)
    when 1 then func_one
    when 2 then func_two
    when 3 then func_three
    when 4..10 then func_other
  else                          # 1
    do_something until a && b   # 2
  end                           # ===
end                             # 7 complexity points

Constant Summary

::RuboCop::Cop::Base - Inherited


Utils::IteratingBlock - Included


CyclomaticComplexity - Inherited


Class Attribute Summary

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,

Returns if class supports autocorrect.


Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited


List of cops that should not try to autocorrect at the same time as this cop.



.callbacks_needed, .cop_name, .department,

Returns an url to view this cops documentation online.


Call for abstract Cop classes.


Override and return the Force class(es) you need to join.


Returns true if the cop name or the cop namespace matches any of the given names.


Register a version requirement for the given gem name.


::RuboCop::ExcludeLimit - Extended


Sets up a configuration option to have an exclude limit tracked.


Instance Attribute Summary

Instance Method Summary

CyclomaticComplexity - Inherited

Utils::IteratingBlock - Included


Returns the name of the method called with a block if node is a block node, or a block-pass node.


Returns nil if node is neither a block node or a block-pass node.


Returns true iff name is a known iterating type (e.g.

::RuboCop::Cop::MethodComplexity - Included

Utils::RepeatedCsendDiscount - Included

::RuboCop::Cop::AllowedPattern - Included

::RuboCop::Cop::AllowedMethods - Included

::RuboCop::Cop::Base - Inherited


Adds an offense that has no particular location.


Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.


Called before any investigation.


Configuration Helpers.

#cop_name, #excluded_file?,

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:


Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.


Alias for Base#cop_name.


Called after all on_…​


Called before all on_…​


Called instead of all on_…​


There should be very limited reasons for a Cop to do it’s own parsing.


Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,

Reserved for Cop::Cop.


Called to complete an investigation.

#correct, #current_corrector,

Reserved for Commissioner:

#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,

Actually private methods.


::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#complexity_score_for(node) (private)

[ GitHub ]

# File 'lib/rubocop/cop/metrics/perceived_complexity.rb', line 36

def complexity_score_for(node)
  case node.type
  when :case
    # If cond is nil, that means each when has an expression that
    # evaluates to true or false. It's just an alternative to
    # if/elsif/elsif... so the when nodes count.
    nb_branches = node.when_branches.length + (node.else_branch ? 1 : 0)
    if node.condition.nil?
      # Otherwise, the case node gets 0.8 complexity points and each
      # when gets 0.2.
      ((nb_branches * 0.2) + 0.8).round
  when :if
    node.else? && !node.elsif? ? 2 : 1