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Class: RuboCop::Cop::Style::For

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::ConfigurableEnforcedStyle, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/for.rb

Overview

Looks for uses of the for keyword or each method. The preferred alternative is set in the EnforcedStyle configuration parameter. An each call with a block on a single line is always allowed.

Note
 each is preferred in idiomatic Ruby because for leaks its loop variable into the surrounding scope.

Examples:

EnforcedStyle: each (default)

# bad
def foo
  for n in [1, 2, 3] do
    puts n
  end
end

# good
def foo
  [1, 2, 3].each do |n|
    puts n
  end
end

EnforcedStyle: for

# bad
def foo
  [1, 2, 3].each do |n|
    puts n
  end
end

# good
def foo
  for n in [1, 2, 3] do
    puts n
  end
end

Cop Safety Information:

  • This cop’s autocorrection is unsafe because the scope of variables is different between each and for.

Constant Summary

::RuboCop::Cop::Base - Inherited

DEPARTMENT_SEVERITIES, EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

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

  • .autocorrect_incompatible_with

    Style/RedundantBegin removes the begin of a block body in the same pass, leaving a rescue or ensure clause directly in the for body.

::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

Reserved for Commissioner.

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.
transform

Instance Attribute Summary

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#detected_style, #detected_style=, #no_acceptable_style?, #style_configured?

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #disabled_autocorrect?,
#preview?

Whether the user opted in to unstable behavior, with --preview or AllCops: Preview.
#processed_source, #project_index, #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?,
#skipped_unsafe_correction_with_disable_uncorrectable?

Whether a correction exists but is skipped because it is unsafe in a safe autocorrect run, while --disable-uncorrectable asks for a todo comment on everything this run cannot correct.
#contextual_autocorrect_held_back?

When LSP is enabled or the --editor-mode option is on, it is considered as editing source code, and autocorrection with AutoCorrect: contextual will not be performed.

Instance Method Summary

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#alternative_style, #alternative_styles, #ambiguous_style_detected,
#conflicting_styles_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.
#correct_style_detected, #no_acceptable_style!, #opposite_style_detected, #style,
#style_detected

rubocop:disable-next Metrics.
#style_parameter_name, #supported_styles, #unexpected_style_detected,
#unrecognized_style_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.

::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

 — grouped under the Commissioner heading above.
#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_gem_version

Returns the version of a gem in the target, by default its locked version (i.e. from Gemfile.lock or gems.locked).
#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, #covering_disabled_range, #current_corrector,
#current_offense_locations

Reserved for Commissioner:
#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?,
#enabled_lines?

A multi-line offense is suppressed by a directive on any line of its range, not only its first line, matching the intuition that the directive is attached to the offending code.
#file_name_matches_any?, #find_message, #find_severity, #matches_absolute_include_pattern?, #new_offense, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.
#suppression_reason

The -- reason on the directive that suppresses offenses on this range, or nil when the directive carries none.
#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, #eol_comment, #eol_comment_would_be_inside_literal?, #heredoc_range, #line_with_eol_comment_too_long?, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #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

Class Method Details

.autocorrect_incompatible_with

Style/RedundantBegin removes the begin of a block body in the same pass, leaving a rescue or ensure clause directly in the for body. Style/ItBlockParameter replaces block parameter references in the body with it in the same pass, while they become for loop variables.

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/for.rb', line 61



def self.autocorrect_incompatible_with
  [Style::RedundantBegin, Style::ItBlockParameter]
end


  







Instance Method Details



  

    #convertible_to_each?(node)  ⇒ Boolean  (private)
  



  

    


The loop variable becomes a block parameter, which can only be a local
variable, and the body can’t refer to an implicit block parameter
(_1 or it) once the block has an explicit one.



  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 103



def convertible_to_each?(node)
  return false unless node.variable.each_node.all? { |n| n.type?(:lvasgn, :mlhs, :splat) }
  return true unless node.body

  node.body.each_node(:send, :lvar).none? { |ref| implicit_parameter?(ref, node) }
end


  








  

    #convertible_to_for?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 129



def convertible_to_for?(node)
  return false if node.type?(:numblock, :itblock)
  return true unless node.arguments?

  arguments = node.arguments
  return false if arguments.children.one? && arguments.children.first.restarg_type?

  arguments.each_descendant.all? { |arg| arg.type?(:arg, :restarg, :mlhs) }
end


  








  

    #do_end_block_in_collection?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 143



def do_end_block_in_collection?(node)
  node.receiver.each_node(:any_block).any?(&:keywords?)
end


  








  

    #implicit_parameter?(ref, for_node)  ⇒ Boolean  (private)
  



  

    


Inside a numbered or it block, _1 and it are local variables
rather than method calls.



  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 112



def implicit_parameter?(ref, for_node)
  return false unless implicit_parameter_reference?(ref)

  ref.each_ancestor.take_while { |ancestor| !ancestor.equal?(for_node) }
     .none?(&:any_block_type?)
end


  








  

    #implicit_parameter_reference?(ref)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


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



def implicit_parameter_reference?(ref)
  return IMPLICIT_PARAMETERS.include?(ref.name) if ref.lvar_type?

  IMPLICIT_PARAMETERS.include?(ref.method_name) && !ref.receiver && !ref.arguments?
end


  








  

    #on_block(node)  
    Also known as: #on_numblock, #on_itblock
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 78



def on_block(node)
  return unless suspect_enumerable?(node)

  if style == :for
    return unless node.receiver
    return unless convertible_to_for?(node)
    return if rescue_or_ensure_body?(node) || do_end_block_in_collection?(node)

    add_offense(node, message: PREFER_FOR) do |corrector|
      EachToForCorrector.new(node).call(corrector)
      opposite_style_detected
    end
  else
    correct_style_detected
  end
end


  








  

    #on_for(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 65



def on_for(node)
  if style == :each
    add_offense(node, message: PREFER_EACH) do |corrector|
      opposite_style_detected
      next unless convertible_to_each?(node)

      ForToEachCorrector.new(node).call(corrector)
    end
  else
    correct_style_detected
  end
end


  








  

    #on_itblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 96



alias on_itblock on_block


  








  

    #on_numblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 95



alias on_numblock on_block


  








  

    #rescue_or_ensure_body?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 139



def rescue_or_ensure_body?(node)
  node.body&.type?(:rescue, :ensure)
end


  








  

    #suspect_enumerable?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/for.rb', line 125



def suspect_enumerable?(node)
  node.multiline? && node.method?(:each) && !node.send_node.arguments?
end