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Class: RuboCop::Cop::Lint::SelfAssignment

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/self_assignment.rb

Overview

Checks for self-assignments.

Examples:

# bad
foo = foo
foo, bar = foo, bar
Foo = Foo
hash['foo'] = hash['foo']
obj.attr = obj.attr

# good
foo = bar
foo, bar = bar, foo
Foo = Bar
hash['foo'] = hash['bar']
obj.attr = obj.attr2

# good (method calls possibly can return different results)
hash[foo] = hash[foo]

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::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

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

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

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

Instance Method Details

#handle_attribute_assignment(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 101

def handle_attribute_assignment(node)
  first_argument = node.first_argument
  return unless first_argument.respond_to?(:arguments) && first_argument.arguments.empty?

  if first_argument.call_type? &&
     node.receiver == first_argument.receiver &&
     first_argument.method_name.to_s == node.method_name.to_s.delete_suffix('=')
    add_offense(node)
  end
end

#handle_key_assignment(node) (private)

[ GitHub ]

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

def handle_key_assignment(node)
  value_node = node.arguments[1]

  if value_node.send_type? && value_node.method?(:[]) &&
     node.receiver == value_node.receiver &&
     !node.first_argument.call_type? &&
     node.first_argument == value_node.first_argument
    add_offense(node)
  end
end

#multiple_self_assignment?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 74

def multiple_self_assignment?(node)
  lhs = node.lhs
  rhs = node.rhs
  return false unless rhs.array_type?
  return false unless lhs.children.size == rhs.children.size

  lhs.children.zip(rhs.children).all? do |lhs_item, rhs_item|
    rhs_matches_lhs?(rhs_item, lhs_item)
  end
end

#on_and_asgn(node)

Alias for #on_or_asgn.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 70

alias on_and_asgn on_or_asgn

#on_casgn(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 56

def on_casgn(node)
  return unless node.rhs&.const_type?

  add_offense(node) if node.namespace == node.rhs.namespace &&
                       node.short_name == node.rhs.short_name
end

#on_csend(node)

Alias for #on_send.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 43

alias on_csend on_send

#on_cvasgn(node)

Alias for #on_lvasgn.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 53

alias on_cvasgn on_lvasgn

#on_gvasgn(node)

Alias for #on_lvasgn.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 54

alias on_gvasgn on_lvasgn

#on_ivasgn(node)

Alias for #on_lvasgn.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 52

alias on_ivasgn on_lvasgn

#on_lvasgn(node) Also known as: #on_ivasgn, #on_cvasgn, #on_gvasgn

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 45

def on_lvasgn(node)
  return unless node.rhs

  rhs_type = ASSIGNMENT_TYPE_TO_RHS_TYPE[node.type]

  add_offense(node) if node.rhs.type == rhs_type && node.rhs.source == node.lhs.to_s
end

#on_masgn(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 63

def on_masgn(node)
  add_offense(node) if multiple_self_assignment?(node)
end

#on_or_asgn(node) Also known as: #on_and_asgn

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 67

def on_or_asgn(node)
  add_offense(node) if rhs_matches_lhs?(node.rhs, node.lhs)
end

#on_send(node) Also known as: #on_csend

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 36

def on_send(node)
  if node.method?(:[]=)
    handle_key_assignment(node) if node.arguments.size == 2
  elsif node.assignment_method?
    handle_attribute_assignment(node) if node.arguments.size == 1
  end
end

#rhs_matches_lhs?(rhs, lhs) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/self_assignment.rb', line 85

def rhs_matches_lhs?(rhs, lhs)
  rhs.type == ASSIGNMENT_TYPE_TO_RHS_TYPE[lhs.type] &&
    rhs.children.first == lhs.children.first
end