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Class: RuboCop::Cop::Style::CollectionCompact

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/collection_compact.rb

Overview

Checks for places where custom logic on rejection nils from arrays and hashes can be replaced with {Array,Hash}#{compact,compact!}.

Examples:

# bad
array.reject(&:nil?)
array.reject { |e| e.nil? }
array.select { |e| !e.nil? }
array.grep_v(nil)
array.grep_v(NilClass)

# good
array.compact

# bad
hash.reject!(&:nil?)
array.delete_if(&:nil?)
hash.reject! { |k, v| v.nil? }
array.delete_if { |e| e.nil? }
hash.select! { |k, v| !v.nil? }

# good
hash.compact!

AllowedReceivers: ['params']

# good
params.reject(&:nil?)

Cop Safety Information:

  • It is unsafe by default because false positives may occur in the nil check of block arguments to the receiver object. Additionally, we can’t know the type of the receiver object for sure, which may result in false positives as well.

    For example, [[1, 2], [3, nil]].reject { |first, second| second.nil? } and [[1, 2], [3, nil]].compact are not compatible. This will work fine when the receiver is a hash object.

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::TargetRubyVersion - Extended

::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::AllowedReceivers - Included

::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

#good_method_name(node) (private)

[ GitHub ]

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

def good_method_name(node)
  if node.bang_method? || node.method?(:delete_if)
    'compact!'
  else
    'compact'
  end
end

#grep_v_with_nil?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 85

def_node_matcher :grep_v_with_nil?, <<~PATTERN
  (send _ :grep_v {(nil) (const {nil? cbase} :NilClass)})
PATTERN

#offense_range(node) (private)

Metrics/PerceivedComplexity

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 106

def offense_range(node)
  if reject_method_with_block_pass?(node) || grep_v_with_nil?(node)
    range(node, node)
  else
    block_node = node.parent

    return unless block_node&.block_type?
    unless (args, receiver = reject_method?(block_node) || select_method?(block_node))
      return
    end
    return unless args.last.source == receiver.source

    range(node, block_node)
  end
end

#on_csend(node)

Alias for #on_send.

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 101

alias on_csend on_send

#on_send(node) Also known as: #on_csend

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 89

def on_send(node)
  return unless (range = offense_range(node))
  return if allowed_receiver?(node.receiver)
  if (target_ruby_version <= 3.0 || node.method?(:delete_if)) && to_enum_method?(node)
    return
  end

  good = good_method_name(node)
  message = format(MSG, good: good, bad: range.source)

  add_offense(range, message: message) { |corrector| corrector.replace(range, good) }
end

#range(begin_pos_node, end_pos_node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 137

def range(begin_pos_node, end_pos_node)
  range_between(begin_pos_node.loc.selector.begin_pos, end_pos_node.source_range.end_pos)
end

#reject_method?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 64

def_node_matcher :reject_method?, <<~PATTERN
  (block
    (call
      !nil? {:reject :delete_if :reject!})
    $(args ...)
    (call
      $(lvar _) :nil?))
PATTERN

#reject_method_with_block_pass?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 57

def_node_matcher :reject_method_with_block_pass?, <<~PATTERN
  (call !nil? {:reject :delete_if :reject!}
    (block_pass
      (sym :nil?)))
PATTERN

#select_method?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 74

def_node_matcher :select_method?, <<~PATTERN
  (block
    (call
      !nil? {:select :select!})
    $(args ...)
    (call
      (call
        $(lvar _) :nil?) :!))
PATTERN

#to_enum_method?(node) ⇒ Boolean (private)

Metrics/PerceivedComplexity

[ GitHub ]

  
# File 'lib/rubocop/cop/style/collection_compact.rb', line 123

def to_enum_method?(node)
  return false unless node.receiver.send_type?

  TO_ENUM_METHODS.include?(node.receiver.method_name)
end