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Class: RuboCop::Cop::Style::NonNilCheck

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/non_nil_check.rb

Overview

Checks for non-nil checks, which are usually redundant.

With IncludeSemanticChanges set to false by default, this cop does not report offenses for !x.nil? and does no changes that might change behavior. Also IncludeSemanticChanges set to false with EnforcedStyle: comparison of Style/NilComparison cop, this cop does not report offenses for x != nil and does no changes to !x.nil? style.

With IncludeSemanticChanges set to true, this cop reports offenses for !x.nil? and autocorrects that and x != nil to solely x, which is usually OK, but might change behavior.

Examples:

# bad
if x != nil
end

# good
if x
end

# Non-nil checks are allowed if they are the final nodes of predicate.
# good
def signed_in?
  !current_user.nil?
end

IncludeSemanticChanges: false (default)

# good
if !x.nil?
end

IncludeSemanticChanges: true

# bad
if !x.nil?
end

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.

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 a 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

::RuboCop::Cop::Base - Inherited

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

Actually private methods.
#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, #range_overlaps_offense?, #string_continuation, #string_continuation?, #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 Attribute Details

#include_semantic_changes? ⇒ Boolean (readonly, private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 119



def include_semantic_changes?
  cop_config['IncludeSemanticChanges']
end


  







Instance Method Details



  

    #autocorrect(corrector, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 93



def autocorrect(corrector, node)
  case node.method_name
  when :!=
    autocorrect_comparison(corrector, node)
  when :!
    autocorrect_non_nil(corrector, node, node.receiver)
  when :nil?
    autocorrect_unless_nil(corrector, node, node.receiver)
  end
end


  








  

    #autocorrect_comparison(corrector, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 123



def autocorrect_comparison(corrector, node)
  expr = node.source

  new_code = if include_semantic_changes?
               expr.sub(/\s*!=\s*nil/, '')
             else
               expr.sub(/^(\S*)\s*!=\s*nil/, '!\1.nil?')
             end

  return if expr == new_code

  corrector.replace(node, new_code)
end


  








  

    #autocorrect_non_nil(corrector, node, inner_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 137



def autocorrect_non_nil(corrector, node, inner_node)
  if inner_node.receiver
    corrector.replace(node, inner_node.receiver.source)
  else
    corrector.replace(node, 'self')
  end
end


  








  

    #autocorrect_unless_nil(corrector, node, receiver)   (private)
  

  [ GitHub ]


  

  


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



def autocorrect_unless_nil(corrector, node, receiver)
  corrector.replace(node.parent.loc.keyword, 'if')
  corrector.replace(node, receiver.source)
end


  








  

    #message(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 110



def message(node)
  if node.method?(:!=) && !include_semantic_changes?
    prefer = "!#{node.receiver.source}.nil?"
    format(MSG_FOR_REPLACEMENT, prefer: prefer, current: node.source)
  else
    MSG_FOR_REDUNDANCY
  end
end


  








  

    #nil_check?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 59



def_node_matcher :nil_check?, '(send _ :nil?)'


  








  

    #nil_comparison_style   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 150



def nil_comparison_style
  nil_comparison_conf = config.for_cop('Style/NilComparison')

  nil_comparison_conf['Enabled'] && nil_comparison_conf['EnforcedStyle']
end


  








  

    #not_and_nil_check?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 62



def_node_matcher :not_and_nil_check?, '(send (send _ :nil?) :!)'


  








  

    #not_equal_to_nil?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 53



def_node_matcher :not_equal_to_nil?, '(send _ :!= nil)'


  








  

    #on_def(node)  
    Also known as: #on_defs
  

  [ GitHub ]


  

  


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



def on_def(node)
  body = node.body

  return unless node.predicate_method? && body

  if body.begin_type?
    ignore_node(body.children.last)
  else
    ignore_node(body)
  end
end


  








  

    #on_defs(node)  
  



  

    


Alias for #on_def.



  



  [ GitHub ]


  

  


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



alias on_defs on_def


  








  

    #on_send(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 64



def on_send(node)
  return if ignored_node?(node) ||
            (!include_semantic_changes? && nil_comparison_style == 'comparison')
  return unless register_offense?(node)

  message = message(node)
  add_offense(node, message: message) { |corrector| autocorrect(corrector, node) }
end


  








  

    #register_offense?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 88



def register_offense?(node)
  not_equal_to_nil?(node) ||
    (include_semantic_changes? && (not_and_nil_check?(node) || unless_and_nil_check?(node)))
end


  








  

    #unless_and_nil_check?(send_node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 104



def unless_and_nil_check?(send_node)
  parent = send_node.parent

  nil_check?(send_node) && unless_check?(parent) && !parent.ternary? && parent.unless?
end


  








  

    #unless_check?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/non_nil_check.rb', line 56



def_node_matcher :unless_check?, '(if (send _ :nil?) ...)'