Class: RuboCop::Cop::Lint::MultipleComparison

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Defined in:
lib/rubocop/cop/lint/multiple_comparison.rb

Overview

In math and Python, we can use x < y < z style comparison to compare multiple value. However, we can’t use the comparison in Ruby. However, the comparison is not syntax error. This cop checks the bad usage of comparison operators.

Examples:


# bad
x < y < z
10 <= x <= 20

# good
x < y && y < z
10 <= x && x <= 20

Constant Summary collapse

MSG = 
'Use the `&&` operator to compare multiple values.'
COMPARISON_METHODS = 
%i[< > <= >=].freeze
SET_OPERATION_OPERATORS = 
%i[& | ^].freeze
RESTRICT_ON_SEND = 
COMPARISON_METHODS

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #begin_investigation, callbacks_needed, #callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

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

Instance Method Details

#multiple_compare?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/multiple_comparison.rb', line 29

def_node_matcher :multiple_compare?, <<~PATTERN
  (send (send _ {:< :> :<= :>=} $_) {:#{COMPARISON_METHODS.join(' :')}} _)
PATTERN

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/multiple_comparison.rb', line 33

def on_send(node)
  return unless (center = multiple_compare?(node))
  # It allows multiple comparison using `&`, `|`, and `^` set operation operators.
  # e.g. `x >= y & y < z`
  return if center.send_type? && SET_OPERATION_OPERATORS.include?(center.method_name)

  add_offense(node) do |corrector|
    new_center = "#{center.source} && #{center.source}"

    corrector.replace(center, new_center)
  end
end