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Class: RuboCop::Cop::Style::Lambda

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::RescueNode, ::RuboCop::Cop::PatternMatchingHelp, ::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/lambda.rb

Overview

(by default) checks for uses of the lambda literal syntax for single line lambdas, and the method call syntax for multiline lambdas. It is configurable to enforce one of the styles for both single line and multiline lambdas as well.

Examples:

EnforcedStyle: line_count_dependent (default)

# bad
f = lambda { |x| x }
f = ->(x) do
      x
    end

# good
f = ->(x) { x }
f = lambda do |x|
      x
    end

EnforcedStyle: lambda

# bad
f = ->(x) { x }
f = ->(x) do
      x
    end

# good
f = lambda { |x| x }
f = lambda do |x|
      x
    end

EnforcedStyle: literal

# bad
f = lambda { |x| x }
f = lambda do |x|
      x
    end

# good
f = ->(x) { x }
f = ->(x) do
      x
    end

Constant Summary

::RuboCop::Cop::Base - Inherited

DEPARTMENT_SEVERITIES, EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

::RuboCop::Cop::PatternMatchingHelp - Included

PATTERN_TYPES

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

::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::RescueNode - Included

#modifier_locations, #rescue_modifier?, #rescued_exceptions

::RuboCop::Cop::PatternMatchingHelp - Included

#in_pattern?

::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

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/lambda.rb', line 66



def self.autocorrect_incompatible_with
  [Style::SymbolProc]
end


  







Instance Method Details



  

    #arguments_with_whitespace(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 138



def arguments_with_whitespace(node)
  node.loc.begin.end.join(node.arguments.loc.end)
end


  








  

    #autocorrect_method_to_literal(corrector, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 127



def autocorrect_method_to_literal(corrector, node)
  corrector.replace(node.send_node, '->')

  return unless node.arguments?

  arg_str = "(#{lambda_arg_string(node.arguments)})"

  corrector.insert_after(node.send_node, arg_str)
  corrector.remove(arguments_with_whitespace(node))
end


  








  

    #lambda_arg_string(args)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 142



def lambda_arg_string(args)
  # Block-local (shadow) arguments are separated from regular arguments by a
  # `;`; joining everything with `,` would turn them into extra parameters
  # and change the lambda's arity.
  regular, shadow = args.children.partition { |arg| !arg.shadowarg_type? }
  arg_string = regular.map(&:source).join(', ')
  arg_string += "; #{shadow.map(&:source).join(', ')}" unless shadow.empty?
  arg_string
end


  








  

    #message(node, selector)   (private)
  

  [ GitHub ]


  

  


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



def message(node, selector)
  message = selector == '->' ? METHOD_MESSAGE : LITERAL_MESSAGE

  format(message, modifier: message_line_modifier(node))
end


  








  

    #message_line_modifier(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 118



def message_line_modifier(node)
  case style
  when :line_count_dependent
    node.multiline? ? 'multiline' : 'single line'
  else
    'all'
  end
end


  








  

    #offending_selector?(node, selector)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 91



def offending_selector?(node, selector)
  lines = node.multiline? ? :multiline : :single_line

  selector == OFFENDING_SELECTORS[:style][style][lines]
end


  








  

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

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 70



def on_block(node)
  return unless node.lambda?

  selector = node.send_node.source

  return unless offending_selector?(node, selector)
  return if uncorrectable_lambda_literal?(node)

  add_offense(node.send_node, message: message(node, selector)) do |corrector|
    if node.send_node.lambda_literal?
      LambdaLiteralToMethodCorrector.new(node).call(corrector)
    else
      autocorrect_method_to_literal(corrector, node)
    end
  end
end


  








  

    #on_itblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 87



alias on_itblock on_block


  








  

    #on_numblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 86



alias on_numblock on_block


  








  

    #rescue_or_ensure_clause?(body)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 105



def rescue_or_ensure_clause?(body)
  return false unless body
  return true if body.ensure_type?

  body.rescue_type? && !rescue_modifier?(body.resbody_branches.first)
end


  








  

    #uncorrectable_lambda_literal?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/lambda.rb', line 97



def uncorrectable_lambda_literal?(node)
  return false unless node.send_node.lambda_literal?
  return true if in_pattern?(node)
  return false unless rescue_or_ensure_clause?(node.body)

  LambdaLiteralToMethodCorrector.new(node).replace_delimiters?
end