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Class: RuboCop::Cop::Style::TallyMethod

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::TargetRubyVersion, ::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/tally_method.rb

Overview

Checks for manual counting patterns that can be replaced by Enumerable#tally.

The cop detects the following patterns:

  • each_with_object(Hash.new(0)) { |item, counts| counts[item] += 1 }

  • group_by(&:itself).transform_values(&:count)

  • group_by { |x| x }.transform_values(&:size)

  • group_by { |x| x }.transform_values { |v| v.length }

Examples:

# bad
array.each_with_object(Hash.new(0)) { |item, counts| counts[item] += 1 }

# bad
array.group_by(&:itself).transform_values(&:count)

# bad
array.group_by { |item| item }.transform_values(&:size)

# bad
array.group_by { |item| item }.transform_values { |v| v.length }

# good
array.tally

Cop Safety Information:

  • This cop is unsafe because it cannot guarantee that the receiver is an Enumerable by static analysis, so the correction may not be actually equivalent.

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::TargetRubyVersion - Extended

maximum_target_ruby_version, minimum_target_ruby_version, required_maximum_ruby_version, required_minimum_ruby_version, support_target_ruby_version?

::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

#check_each_with_object(node) (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 140



def check_each_with_object(node)
  block_node = node.block_node
  return unless block_node
  return unless tally_each_with_object?(block_node)

  add_offense(node.loc.selector, message: MSG_EACH_WITH_OBJECT) do |corrector|
    corrector.replace(replacement_range(node, block_node), 'tally')
  end
end


  








  

    #check_transform_values(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 150



def check_transform_values(node)
  if tally_group_by_symbol?(node) || tally_group_by_identity_block?(node)
    register_group_by_offense(node, node)
  elsif (block_node = node.block_node) && tally_group_by_transform_block?(block_node)
    register_group_by_offense(node, block_node)
  end
end


  








  

    #group_by_send_node(transform_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 166



def group_by_send_node(transform_node)
  receiver = transform_node.receiver
  if receiver.type?(:any_block)
    receiver.send_node
  else
    receiver
  end
end


  








  

    #on_csend(node)  
  



  

    


Alias for #on_send.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 136



alias on_csend on_send


  








  

    #on_send(node)  
    Also known as: #on_csend
  

  [ GitHub ]


  

  


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



def on_send(node)
  if node.method?(:each_with_object)
    check_each_with_object(node)
  elsif node.method?(:transform_values)
    check_transform_values(node)
  end
end


  








  

    #register_group_by_offense(transform_node, end_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 158



def register_group_by_offense(transform_node, end_node)
  group_by_node = group_by_send_node(transform_node)

  add_offense(group_by_node.loc.selector, message: MSG_GROUP_BY) do |corrector|
    corrector.replace(replacement_range(group_by_node, end_node), 'tally')
  end
end


  








  

    #replacement_range(start_node, end_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 175



def replacement_range(start_node, end_node)
  range_between(start_node.loc.selector.begin_pos, end_node.source_range.end_pos)
end


  








  

    #tally_each_with_object?(node)  
  



  

    


Pattern 1: collection.each_with_object(Hash.new(0)) { |elem, hash| hash[elem] += 1 }



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 50



def_node_matcher :tally_each_with_object?, <<~PATTERN
  {
    (block
      (call _ :each_with_object
        (send (const {nil? cbase} :Hash) :new (int 0)))
      (args (arg _elem) (arg _hash))
      (op_asgn
        (send (lvar _hash) :[] (lvar _elem)) :+ (int 1)))
    (numblock
      (call _ :each_with_object
        (send (const {nil? cbase} :Hash) :new (int 0)))
      2
      (op_asgn
        (send (lvar :_2) :[] (lvar :_1)) :+ (int 1)))
  }
PATTERN


  








  

    #tally_group_by_identity_block?(node)  
  



  

    


Pattern 3: collection.group_by { |x| x }.transform_values(&:count/size/length)



  



  [ GitHub ]


  

  


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



def_node_matcher :tally_group_by_identity_block?, <<~PATTERN
  (call
    {
      (block (call _ :group_by) (args (arg _x)) (lvar _x))
      (numblock (call _ :group_by) 1 (lvar :_1))
      (itblock (call _ :group_by) :it (lvar :it))
    }
    :transform_values
    (block_pass (sym %COUNTING_METHODS)))
PATTERN


  








  

    #tally_group_by_symbol?(node)  
  



  

    


Pattern 2: collection.group_by(&:itself).transform_values(&:count/size/length)



  



  [ GitHub ]


  

  


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



def_node_matcher :tally_group_by_symbol?, <<~PATTERN
  (call
    (call _ :group_by (block_pass (sym :itself)))
    :transform_values
    (block_pass (sym %COUNTING_METHODS)))
PATTERN


  








  

    #tally_group_by_transform_block?(node)  
  



  

    


Pattern 4: collection.group_by(&:itself).transform_values { |v| v.count/size/length }
           collection.group_by { |x| x }.transform_values { |v| v.count/size/length }



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/tally_method.rb', line 92



def_node_matcher :tally_group_by_transform_block?, <<~PATTERN
  {
    (block
      (call
        {
          (call _ :group_by (block_pass (sym :itself)))
          (block (call _ :group_by) (args (arg _x)) (lvar _x))
          (numblock (call _ :group_by) 1 (lvar :_1))
          (itblock (call _ :group_by) :it (lvar :it))
        }
        :transform_values)
      (args (arg _v))
      (send (lvar _v) %COUNTING_METHODS))
    (numblock
      (call
        {
          (call _ :group_by (block_pass (sym :itself)))
          (block (call _ :group_by) (args (arg _x)) (lvar _x))
          (numblock (call _ :group_by) 1 (lvar :_1))
          (itblock (call _ :group_by) :it (lvar :it))
        }
        :transform_values)
      1
      (send (lvar :_1) %COUNTING_METHODS))
    (itblock
      (call
        {
          (call _ :group_by (block_pass (sym :itself)))
          (block (call _ :group_by) (args (arg _x)) (lvar _x))
          (numblock (call _ :group_by) 1 (lvar :_1))
          (itblock (call _ :group_by) :it (lvar :it))
        }
        :transform_values)
      :it
      (send (lvar :it) %COUNTING_METHODS))
  }
PATTERN