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Class: RuboCop::Cop::Style::YodaCondition

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:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/yoda_condition.rb

Overview

Enforces or forbids Yoda conditions, i.e. comparison operations where the order of expression is reversed. eg. 5 == x

Examples:

EnforcedStyle: forbid_for_all_comparison_operators (default)

# bad
99 == foo
"bar" != foo
42 >= foo
10 < bar
99 == CONST

# good
foo == 99
foo == "bar"
foo <= 42
bar > 10
CONST == 99
"#{interpolation}" == foo
/#{interpolation}/ == foo

EnforcedStyle: forbid_for_equality_operators_only

# bad
99 == foo
"bar" != foo

# good
99 >= foo
3 < a && a < 5

EnforcedStyle: require_for_all_comparison_operators

# bad
foo == 99
foo == "bar"
foo <= 42
bar > 10

# good
99 == foo
"bar" != foo
42 >= foo
10 < bar

EnforcedStyle: require_for_equality_operators_only

# bad
99 >= foo
3 < a && a < 5

# good
99 == foo
"bar" != foo

Cop Safety Information:

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

    For example:

    class MyKlass
      def ==(other)
        true
      end
    end
    
    obj = MyKlass.new
    obj == 'string'   #=> true
    'string' == obj   #=> false

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::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.

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

Returns an url to view this cops documentation online.

.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

Instance Method Summary

::RuboCop::Cop::RangeHelp - Included

#add_range, #column_offset_between,
#contents_range

A range containing only the contents of a literal with delimiters (e.g.

#directions,
#effective_column

Returns the column attribute of the range, except if the range is on the first line and there’s a byte order mark at the beginning of that line, in which case 1 is subtracted from the column value.

#final_pos, #move_pos, #move_pos_str, #range_between, #range_by_whole_lines, #range_with_comments, #range_with_comments_and_lines, #range_with_surrounding_comma, #range_with_surrounding_space, #source_range

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

::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

Actually private methods.

#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

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

Instance Attribute Details

#enforce_yoda?Boolean (readonly, private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 107

def enforce_yoda?
  style == :require_for_all_comparison_operators ||
    style == :require_for_equality_operators_only
end

#equality_only?Boolean (readonly, private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 112

def equality_only?
  style == :forbid_for_equality_operators_only ||
    style == :require_for_equality_operators_only
end

Instance Method Details

#actual_code_range(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 149

def actual_code_range(node)
  range_between(node.source_range.begin_pos, node.source_range.end_pos)
end

#constant_portion?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 145

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

#corrected_code(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 138

def corrected_code(node)
  lhs = node.receiver
  rhs = node.first_argument

  "#{rhs.source} #{reverse_comparison(node.method_name)} #{lhs.source}"
end

#file_constant_equal_program_name?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 90

def_node_matcher :file_constant_equal_program_name?, <<~PATTERN
  (send #source_file_path_constant? {:== :!=} (gvar #program_name?))
PATTERN

#interpolation?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 173

def interpolation?(node)
  return true if node.dstr_type?

  node.regexp_type? && node.interpolation?
end

#message(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 134

def message(node)
  format(MSG, source: node.source)
end

#non_equality_operator?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 157

def non_equality_operator?(node)
  !EQUALITY_OPERATORS.include?(node.method_name)
end

#noncommutative_operator?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 161

def noncommutative_operator?(node)
  NONCOMMUTATIVE_OPERATORS.include?(node.method_name)
end

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 94

def on_send(node)
  return unless yoda_compatible_condition?(node)
  return if (equality_only? && non_equality_operator?(node)) ||
            file_constant_equal_program_name?(node) ||
            valid_yoda?(node)

  add_offense(node) do |corrector|
    corrector.replace(actual_code_range(node), corrected_code(node))
  end
end

#program_name?(name) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 169

def program_name?(name)
  PROGRAM_NAMES.include?(name)
end

#reverse_comparison(operator) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 153

def reverse_comparison(operator)
  REVERSE_COMPARISON.fetch(operator.to_s, operator)
end

#source_file_path_constant?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 165

def source_file_path_constant?(node)
  node.source == '__FILE__'
end

#valid_yoda?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 122

def valid_yoda?(node)
  return true unless (rhs = node.first_argument)

  lhs = node.receiver
  return true if (constant_portion?(lhs) && constant_portion?(rhs)) ||
                 (!constant_portion?(lhs) && !constant_portion?(rhs)) ||
                 interpolation?(lhs)

  enforce_yoda? ? constant_portion?(lhs) : constant_portion?(rhs)
end

#yoda_compatible_condition?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/yoda_condition.rb', line 117

def yoda_compatible_condition?(node)
  node.comparison_method? && !noncommutative_operator?(node)
end