Class: RuboCop::Cop::Lint::BinaryOperatorWithIdenticalOperands

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/lint/binary_operator_with_identical_operands.rb

Overview

Checks for places where binary operator has identical operands.

It covers arithmetic operators: -, /, %; comparison operators: ==, ===, =~, >, >=, <, ⇐; bitwise operators: |, ^, &; boolean operators: &&, || and "spaceship" operator - <⇒.

Simple arithmetic operations are allowed by this cop: +, , *, << and >>. Although these can be rewritten in a different way, it should not be necessary to do so. This does not include operations such as - or / where the result will always be the same (x - x will always be 0; x / x will always be 1), and thus are legitimate offenses.

Examples:

# bad
x / x
x.top >= x.top

if a.x != 0 && a.x != 0
  do_something
end

def child?
  left_child || left_child
end

# good
x + x
1 << 1

Cop Safety Information:

  • This cop is unsafe as it does not consider side effects when calling methods and thus can generate false positives, for example:

    if wr.take_char == '\0' && wr.take_char == '\0'
  # ...
end

Constant Summary collapse

MSG = 
'Binary operator `%<op>s` has identical operands.'
ALLOWED_MATH_OPERATORS = 
%i[+ * ** << >>].to_set.freeze

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

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

#on_and(node) ⇒ Object Also known as: on_or 



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# File 'lib/rubocop/cop/lint/binary_operator_with_identical_operands.rb', line 61

def on_and(node)
  add_offense(node, message: format(MSG, op: node.operator)) if node.lhs == node.rhs
end

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/binary_operator_with_identical_operands.rb', line 52

def on_send(node)
  return unless node.binary_operation?

  lhs, operation, rhs = *node
  return if ALLOWED_MATH_OPERATORS.include?(node.method_name)

  add_offense(node, message: format(MSG, op: operation)) if lhs == rhs
end