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Class: RuboCop::Cop::Style::NegatedIfElseCondition

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/negated_if_else_condition.rb

Overview

Checks for uses of if-else and ternary operators with a negated condition which can be simplified by inverting condition and swapping branches.

Examples:

# bad
if !x
  do_something
else
  do_something_else
end

# good
if x
  do_something_else
else
  do_something
end

# bad
!x ? do_something : do_something_else

# good
x ? do_something_else : do_something

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::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::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

Class Method Details

.autocorrect_incompatible_with

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 41

def self.autocorrect_incompatible_with
  [Style::InverseMethods, Style::Not]
end

Instance Method Details

#correct_negated_condition(corrector, node) (private)

[ GitHub ]

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

def correct_negated_condition(corrector, node)
  receiver, method_name, rhs = *node
  replacement =
    if node.negation_method?
      receiver.source
    else
      inverted_method = method_name.to_s.sub('!', '=')
      "#{receiver.source} #{inverted_method} #{rhs.source}"
    end

  corrector.replace(node, replacement)
end

#corrected_ancestor?(node) ⇒ Boolean (private)

[ GitHub ]

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

def corrected_ancestor?(node)
  node.each_ancestor(:if).any? { |ancestor| @corrected_nodes&.include?(ancestor) }
end

#double_negation?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 39

def_node_matcher :double_negation?, '(send (send _ :!) :!)'

#else_range(node) (private)

Collect the entire else branch, including whitespace and comments

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 125

def else_range(node)
  if node.ternary?
    node.else_branch
  else
    range_between(node.loc.else.end_pos, node.loc.end.begin_pos)
  end
end

#if_else?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 68

def if_else?(node)
  else_branch = node.else_branch
  !node.elsif? && else_branch && (!else_branch.if_type? || !else_branch.elsif?)
end

#if_range(node) (private)

Collect the entire if branch, including whitespace and comments

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 116

def if_range(node)
  if node.ternary?
    node.if_branch
  else
    range_between(node.condition.source_range.end_pos, node.loc.else.begin_pos)
  end
end

#message(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 84

def message(node)
  type = node.ternary? ? 'ternary' : 'if-else'

  format(MSG, type: type)
end

#negated_condition?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 79

def negated_condition?(node)
  node.send_type? &&
    (node.negation_method? || NEGATED_EQUALITY_METHODS.include?(node.method_name))
end

#on_if(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 49

def on_if(node)
  return unless if_else?(node)
  return unless (condition = unwrap_begin_nodes(node.condition))
  return if double_negation?(condition) || !negated_condition?(condition)

  message = message(node)
  add_offense(node, message: message) do |corrector|
    unless corrected_ancestor?(node)
      correct_negated_condition(corrector, condition)
      swap_branches(corrector, node)

      @corrected_nodes ||= Set.new.compare_by_identity
      @corrected_nodes.add(node)
    end
  end
end

#on_new_investigation

[ GitHub ]

  
# File 'lib/rubocop/cop/style/negated_if_else_condition.rb', line 45

def on_new_investigation
  @corrected_nodes = nil
end

#swap_branches(corrector, node) (private)

[ GitHub ]

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

def swap_branches(corrector, node)
  if node.if_branch.nil?
    corrector.remove(range_by_whole_lines(node.loc.else, include_final_newline: true))
  else
    corrector.swap(if_range(node), else_range(node))
  end
end

#unwrap_begin_nodes(node) (private)

[ GitHub ]

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

def unwrap_begin_nodes(node)
  node = node.children.first while node && (node.begin_type? || node.kwbegin_type?)

  node
end