123456789_123456789_123456789_123456789_123456789_

Class: RuboCop::Cop::Lint::RedundantSafeNavigation

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/lint/redundant_safe_navigation.rb

Overview

Checks for redundant safe navigation calls. Use cases where a constant, named in camel case for classes and modules is nil are rare, and an offense is not detected when the receiver is a constant. The detection also applies to literal receivers, except for nil.

For all receivers, the instance_of?, kind_of?, is_a?, eql?, respond_to?, and equal? methods are checked by default. These are customizable with AllowedMethods option.

The AllowedMethods option specifies nil-safe methods, in other words, it is a method that is allowed to skip safe navigation. Note that the AllowedMethod option is not an option that specifies methods for which to suppress (allow) this cop’s check.

In the example below, the safe navigation operator (&.) is unnecessary because NilClass has methods like respond_to? and is_a?.

Examples:

# bad
CamelCaseConst&.do_something

# bad
do_something if attrs&.respond_to?(:[])

# good
do_something if attrs.respond_to?(:[])

# bad
while node&.is_a?(BeginNode)
  node = node.parent
end

# good
CamelCaseConst.do_something

# good
while node.is_a?(BeginNode)
  node = node.parent
end

# good - without `&.` this will always return `true`
foo&.respond_to?(:to_a)

# bad - for `nil`s conversion methods return default values for the type
foo&.to_h || {}
foo&.to_h { |k, v| [k, v] } || {}
foo&.to_a || []
foo&.to_i || 0
foo&.to_f || 0.0
foo&.to_s || ''

# good
foo.to_h
foo.to_h { |k, v| [k, v] }
foo.to_a
foo.to_i
foo.to_f
foo.to_s

AllowedMethods: [nil_safe_method]

# bad
do_something if attrs&.nil_safe_method(:[])

# good
do_something if attrs.nil_safe_method(:[])
do_something if attrs&.not_nil_safe_method(:[])

Cop Safety Information:

  • This cop is unsafe, because autocorrection can change the return type of the expression. An offending expression that previously could return nil will be autocorrected to never return nil.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

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::AllowedMethods - 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 Method Details

#assume_receiver_instance_exists?(receiver) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 133

def assume_receiver_instance_exists?(receiver)
  return true if receiver.const_type? && !receiver.source.match?(SNAKE_CASE)

  receiver.literal? && !receiver.nil_type?
end

#check?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 139

def check?(node)
  parent = node.parent
  return false unless parent

  condition?(parent, node) ||
    parent.and_type? ||
    parent.or_type? ||
    (parent.send_type? && parent.negation_method?)
end

#condition?(parent, node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 149

def condition?(parent, node)
  (parent.conditional? || parent.post_condition_loop?) && parent.condition == node
end

#conversion_with_default?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 95

def_node_matcher :conversion_with_default?, <<~PATTERN
  {
    (or $(csend _ :to_h) (hash))
    (or (block $(csend _ :to_h) ...) (hash))
    (or $(csend _ :to_a) (array))
    (or $(csend _ :to_i) (int 0))
    (or $(csend _ :to_f) (float 0.0))
    (or $(csend _ :to_s) (str empty?))
  }
PATTERN

#on_csend(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 107

def on_csend(node)
  unless assume_receiver_instance_exists?(node.receiver)
    return unless check?(node) && allowed_method?(node.method_name)
    return if respond_to_nil_specific_method?(node)
  end

  range = node.loc.dot
  add_offense(range) { |corrector| corrector.replace(range, '.') }
end

#on_or(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 117

def on_or(node)
  conversion_with_default?(node) do |send_node|
    range = send_node.loc.dot.begin.join(node.source_range.end)

    add_offense(range, message: MSG_LITERAL) do |corrector|
      corrector.replace(send_node.loc.dot, '.')

      range_with_default = node.lhs.source_range.end.begin.join(node.source_range.end)
      corrector.remove(range_with_default)
    end
  end
end

#respond_to_nil_specific_method?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 90

def_node_matcher :respond_to_nil_specific_method?, <<~PATTERN
  (csend _ :respond_to? (sym %NIL_SPECIFIC_METHODS))
PATTERN