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

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Defined in:
lib/rubocop/cop/style/non_nil_check.rb

Overview

This cop 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 collapse

MSG_FOR_REPLACEMENT =
'Prefer `%<prefer>s` over `%<current>s`.'
MSG_FOR_REDUNDANCY =
'Explicit non-nil checks are usually redundant.'
RESTRICT_ON_SEND =
%i[!= nil? !].freeze

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #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, joining_forces, lint?, match?, #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?, #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

#nil_check?(node) ⇒ Object


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

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

#not_and_nil_check?(node) ⇒ Object


62
# 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) ⇒ Object


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

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

#on_def(node) ⇒ Object Also known as: on_defs


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# 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_send(node) ⇒ Object


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# 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

#unless_check?(node) ⇒ Object


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

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