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Class: RuboCop::Cop::Style::RedundantSelfAssignment

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/redundant_self_assignment.rb

Overview

Checks for places where redundant assignments are made for in place modification methods.

Examples:

# bad
args = args.concat(ary)
hash = hash.merge!(other)

# good
args.concat(foo)
args += foo
hash.merge!(other)

# bad
self.foo = foo.concat(ary)

# good
foo.concat(ary)
self.foo += ary

Cop Safety Information:

  • This cop is unsafe, because it can produce false positives for user defined methods having one of the expected names, but not modifying its receiver in place.

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 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::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

Instance Method Details

#correction_range(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 114

def correction_range(node)
  range_between(node.source_range.begin_pos, node.first_argument.source_range.begin_pos)
end

#method_returning_self?(method_name) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 83

def method_returning_self?(method_name)
  METHODS_RETURNING_SELF.include?(method_name)
end

#on_cvasgn(node)

Alias for #on_lvasgn.

[ GitHub ]

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

alias on_cvasgn on_lvasgn

#on_gvasgn(node)

Alias for #on_lvasgn.

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 69

alias on_gvasgn on_lvasgn

#on_ivasgn(node)

Alias for #on_lvasgn.

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 67

alias on_ivasgn on_lvasgn

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

[ GitHub ]

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

def on_lvasgn(node)
  return unless (rhs = node.rhs)
  return unless rhs.send_type? && method_returning_self?(rhs.method_name)
  return unless (receiver = rhs.receiver)

  receiver_type = ASSIGNMENT_TYPE_TO_RECEIVER_TYPE[node.type]
  return unless receiver.type == receiver_type && receiver.children.first == node.lhs

  message = format(MSG, method_name: rhs.method_name)
  add_offense(node.loc.operator, message: message) do |corrector|
    corrector.replace(node, rhs.source)
  end
end

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 71

def on_send(node)
  return unless node.assignment_method?
  return unless redundant_assignment?(node)

  message = format(MSG, method_name: node.first_argument.method_name)
  add_offense(node.loc.operator, message: message) do |corrector|
    corrector.remove(correction_range(node))
  end
end

#redundant_assignment?(node) ⇒ Boolean (private)

[ GitHub ]

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

def redundant_assignment?(node)
  receiver_name = node.method_name.to_s[0...-1].to_sym

  redundant_self_assignment?(node, receiver_name) ||
    redundant_nonself_assignment?(node, node.receiver, receiver_name)
end

#redundant_nonself_assignment?(node, receiver, method_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 98

def_node_matcher :redundant_nonself_assignment?, <<~PATTERN
  (send
    %1 _
    (send
      (send
        %1 %2) #method_returning_self?
      ...))
PATTERN

#redundant_self_assignment?(node, method_name) (private)

[ GitHub ]

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

def_node_matcher :redundant_self_assignment?, <<~PATTERN
  (send
    (self) _
    (send
      (send
        {(self) nil?} %1) #method_returning_self?
      ...))
PATTERN