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Class: RuboCop::Cop::Style::MapJoin

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

Overview

Checks for map { |x| x.to_s }.join and similar calls where the map is redundant because Array#join implicitly calls #to_s on each element.

Examples:

# bad
array.map(&:to_s).join(', ')

# bad
array.map { |x| x.to_s }.join(', ')

# bad
array.collect(&:to_s).join

# good
array.join(', ')

# good
array.join

Cop Safety Information:

  • This cop is unsafe because it cannot guarantee that the receiver is an Array by static analysis. If the receiver does not have an Array#join-compatible implementation (i.e. one that calls #to_s on elements), the correction may change behavior.

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

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

::RuboCop::ExcludeLimit - Extended

exclude_limit

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

Instance Attribute Summary

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #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?

Instance Method Summary

::RuboCop::Cop::RangeHelp - Included

#add_range,
#arguments_range

A range containing the first to the last argument of a method call or method definition.
#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_gem_version

Returns a gems locked versions (i.e.
#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

#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

Instance Method Details

#map_to_s_block_join?(node)

map { |x| x.to_s }.join(…​)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/map_join.rb', line 49



def_node_matcher :map_to_s_block_join?, <<~PATTERN
  (call
    $(block
      (call _ ${:map :collect})
      (args (arg _x))
      (send (lvar _x) :to_s))
    :join ...)
PATTERN


  








  

    #map_to_s_itblock_join?(node)  
  



  

    


map { it.to_s }.join(…​)



  



  [ GitHub ]


  

  


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



def_node_matcher :map_to_s_itblock_join?, <<~PATTERN
  (call
    $(itblock
      (call _ ${:map :collect})
      :it
      (send (lvar :it) :to_s))
    :join ...)
PATTERN


  








  

    #map_to_s_join?(node)  
  



  

    


map(&:to_s).join(…​)



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/map_join.rb', line 41



def_node_matcher :map_to_s_join?, <<~PATTERN
  (call
    $(call _ ${:map :collect} (block_pass (sym :to_s)))
    :join ...)
PATTERN


  








  

    #map_to_s_numblock_join?(node)  
  



  

    


map { _1.to_s }.join(…​)



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/map_join.rb', line 60



def_node_matcher :map_to_s_numblock_join?, <<~PATTERN
  (call
    $(numblock
      (call _ ${:map :collect})
      1
      (send (lvar :_1) :to_s))
    :join ...)
PATTERN


  








  

    #no_receiver_range(map_node, join_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/map_join.rb', line 117



def no_receiver_range(map_node, join_node)
  range_between(map_node.source_range.begin_pos, join_node.loc.dot.end_pos)
end


  








  

    #on_csend(node)  
  



  

    


Alias for #on_send.



  



  [ GitHub ]


  

  


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



alias on_csend on_send


  








  

    #on_send(node)  
    Also known as: #on_csend
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/map_join.rb', line 80



def on_send(node)
  map_to_s_join?(node) { |m, n| register_offense(node, m, n) } ||
    map_to_s_block_join?(node) { |m, n| register_offense(node, m, n) } ||
    map_to_s_numblock_join?(node) { |m, n| register_offense(node, m, n) } ||
    map_to_s_itblock_join?(node) { |m, n| register_offense(node, m, n) }
end


  








  

    #register_offense(join_node, map_node, method_name)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/map_join.rb', line 90



def register_offense(join_node, map_node, method_name)
  map_send = map_node.any_block_type? ? map_node.send_node : map_node
  message = format(MSG, method: method_name)

  add_offense(map_send.loc.selector, message: message) do |corrector|
    remove_map_call(corrector, join_node, map_node, map_send)
  end
end


  








  

    #removal_range(receiver, map_node, map_send)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/map_join.rb', line 108



def removal_range(receiver, map_node, map_send)
  start_pos = if receiver.last_line < map_send.loc.dot.line
                receiver.source_range.end_pos
              else
                map_send.loc.dot.begin_pos
              end
  range_between(start_pos, map_node.source_range.end_pos)
end


  








  

    #remove_map_call(corrector, join_node, map_node, map_send)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/map_join.rb', line 99



def remove_map_call(corrector, join_node, map_node, map_send)
  receiver = map_send.receiver
  if receiver
    corrector.replace(removal_range(receiver, map_node, map_send), '')
  else
    corrector.replace(no_receiver_range(map_node, join_node), '')
  end
end