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Class: RuboCop::Cop::Style::EachWithObject

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/each_with_object.rb

Overview

Looks for inject / reduce calls where the passed in object is returned at the end and so could be replaced by each_with_object without the need to return the object at the end.

However, we can’t replace with each_with_object if the accumulator parameter is assigned to within the block.

Examples:

# bad
[1, 2].inject({}) { |a, e| a[e] = e; a }

# good
[1, 2].each_with_object({}) { |e, a| a[e] = e }

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 an 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

#accumulator_param_assigned_to?(body, args) ⇒ Boolean (private)

if the accumulator parameter is assigned to in the block, then we can’t convert to each_with_object

[ GitHub ]

  
# File 'lib/rubocop/cop/style/each_with_object.rb', line 102

def accumulator_param_assigned_to?(body, args)
  first_arg, = *args
  accumulator_var, = *first_arg

  body.each_descendant.any? do |n|
    next unless n.assignment?

    lhs, _rhs = *n
    lhs.equal?(accumulator_var)
  end
end

#autocorrect_block(corrector, node, return_value) (private)

[ GitHub ]

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

def autocorrect_block(corrector, node, return_value)
  corrector.replace(node.send_node.loc.selector, 'each_with_object')

  first_arg, second_arg = *node.arguments

  corrector.replace(first_arg, second_arg.source)
  corrector.replace(second_arg, first_arg.source)

  if return_value_occupies_whole_line?(return_value)
    corrector.remove(whole_line_expression(return_value))
  else
    corrector.remove(return_value)
  end
end

#autocorrect_numblock(corrector, node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/each_with_object.rb', line 84

def autocorrect_numblock(corrector, node)
  corrector.replace(node.send_node.loc.selector, 'each_with_object')

  # We don't remove the return value to avoid a clobbering error.
  node.body.each_descendant do |var|
    next unless var.lvar_type?

    corrector.replace(var, '_2') if var.source == '_1'
    corrector.replace(var, '_1') if var.source == '_2'
  end
end

#each_with_object_block_candidate?(node) (private)

[ GitHub ]

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

def_node_matcher :each_with_object_block_candidate?, <<~PATTERN
  (block $(call _ {:inject :reduce} _) $_ $_)
PATTERN

#each_with_object_numblock_candidate?(node) (private)

[ GitHub ]

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

def_node_matcher :each_with_object_numblock_candidate?, <<~PATTERN
  (numblock $(call _ {:inject :reduce} _) 2 $_)
PATTERN

#first_argument_returned?(args, return_value) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/each_with_object.rb', line 121

def first_argument_returned?(args, return_value)
  first_arg, = *args
  accumulator_var, = *first_arg
  return_var, = *return_value

  accumulator_var == return_var
end

#on_block(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/each_with_object.rb', line 26

def on_block(node)
  each_with_object_block_candidate?(node) do |method, args, body|
    _, method_name, method_arg = *method
    return if simple_method_arg?(method_arg)

    return_value = return_value(body)
    return unless return_value
    return unless first_argument_returned?(args, return_value)
    return if accumulator_param_assigned_to?(body, args)

    message = format(MSG, method: method_name)
    add_offense(method.loc.selector, message: message) do |corrector|
      autocorrect_block(corrector, node, return_value)
    end
  end
end

#on_numblock(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/each_with_object.rb', line 43

def on_numblock(node)
  each_with_object_numblock_candidate?(node) do |method, body|
    _, method_name, method_arg = *method
    return if simple_method_arg?(method_arg)

    return unless return_value(body)&.source == '_1'

    message = format(MSG, method: method_name)
    add_offense(method.loc.selector, message: message) do |corrector|
      autocorrect_numblock(corrector, node)
    end
  end
end

#return_value(body) (private)

[ GitHub ]

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

def return_value(body)
  return unless body

  return_value = body.begin_type? ? body.children.last : body
  return_value if return_value&.lvar_type?
end

#return_value_occupies_whole_line?(node) ⇒ Boolean (private)

[ GitHub ]

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

def return_value_occupies_whole_line?(node)
  whole_line_expression(node).source.strip == node.source
end

#simple_method_arg?(method_arg) ⇒ Boolean (private)

[ GitHub ]

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

def simple_method_arg?(method_arg)
  method_arg&.basic_literal?
end

#whole_line_expression(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/each_with_object.rb', line 133

def whole_line_expression(node)
  range_by_whole_lines(node.source_range, include_final_newline: true)
end