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Class: RuboCop::Cop::Style::YodaExpression

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/yoda_expression.rb

Overview

Forbids Yoda expressions, i.e. binary operations (using *, +, &, |, and ^ operators) where the order of expression is reversed, eg. 1 + x. This cop complements Style/YodaCondition cop, which has a similar purpose.

This cop is disabled by default to respect user intentions such as:

config.server_port = 9000 + ENV["TEST_ENV_NUMBER"].to_i

Examples:

SupportedOperators: ['*', '+', '&', '|', '^'] (default)

# bad
10 * y
1 + x
1 & z
1 | x
1 ^ x
1 + CONST

# good
y * 10
x + 1
z & 1
x | 1
x ^ 1
CONST + 1
60 * 24

Cop Safety Information:

  • This cop is unsafe because binary operators can be defined differently on different classes, and are not guaranteed to have the same result if reversed.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

support_autocorrect?

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.
.support_multiple_source?

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.
.builtin?

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

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

Naming.
.callbacks_needed, .cop_name, .department,
.documentation_url

Cops (other than builtin) are encouraged to implement this.
.exclude_from_registry

Call for abstract Cop classes.
.inherited,
.joining_forces

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

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

Register a version requirement for the given gem name.
.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

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

Instance Attribute Summary

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #target_satisfies_all_gem_version_requirements?

::RuboCop::Cop::AutocorrectLogic - Included

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

Instance Method Summary

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.
#add_offense

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.
#begin_investigation

Called before any investigation.
#callbacks_needed,
#cop_config

Configuration Helpers.
#cop_name, #excluded_file?,
#external_dependency_checksum

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

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.
#name

Alias for Base#cop_name.
#offenses,
#on_investigation_end

Called after all on_…​
#on_new_investigation

Called before all on_…​
#on_other_file

Called instead of all on_…​
#parse

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

Called between investigations.
#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.
#complete_investigation

Called to complete an investigation.
#correct, #current_corrector,
#current_offense_locations

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, #reset_investigation, #use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

#disable_offense, #disable_offense_at_end_of_line, #disable_offense_before_and_after, #disable_offense_with_eol_or_surround_comment, #max_line_length,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #surrounding_heredoc, #surrounding_percent_array

::RuboCop::Cop::IgnoredNode - Included

#ignore_node, #ignored_node?, #part_of_ignored_node?, #ignored_nodes

Constructor Details

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

Instance Method Details

#constant_portion?(node) ⇒ Boolean (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/yoda_expression.rb', line 73



def constant_portion?(node)
  node.numeric_type? || node.const_type?
end


  








  

    #offended_ancestor?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/yoda_expression.rb', line 81



def offended_ancestor?(node)
  node.each_ancestor(:send).any? { |ancestor| @offended_nodes&.include?(ancestor) }
end


  








  

    #offended_nodes   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/yoda_expression.rb', line 85



def offended_nodes
  @offended_nodes ||= Set.new.compare_by_identity
end


  








  

    #on_new_investigation  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/yoda_expression.rb', line 47



def on_new_investigation
  @offended_nodes = nil
end


  








  

    #on_send(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/yoda_expression.rb', line 51



def on_send(node)
  return unless supported_operators.include?(node.method_name.to_s)

  lhs = node.receiver
  rhs = node.first_argument
  return unless yoda_expression_constant?(lhs, rhs)
  return if offended_ancestor?(node)

  message = format(MSG, source: rhs.source)
  add_offense(node, message: message) do |corrector|
    corrector.swap(lhs, rhs)
  end

  offended_nodes.add(node)
end


  








  

    #supported_operators   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/yoda_expression.rb', line 77



def supported_operators
  Array(cop_config['SupportedOperators'])
end


  








  

    #yoda_expression_constant?(lhs, rhs)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/yoda_expression.rb', line 69



def yoda_expression_constant?(lhs, rhs)
  constant_portion?(lhs) && !constant_portion?(rhs)
end