Class: RuboCop::Cop::Style::SelectByKind

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
RangeHelp
Defined in:
lib/rubocop/cop/style/select_by_kind.rb

Overview

Looks for places where a subset of an Enumerable (array, range, set, etc.; see note below) is calculated based on a class type check, and suggests grep or grep_v instead.

NOTE: Hashes do not behave as you may expect with grep, which means that hash.grep is not equivalent to hash.select. Although RuboCop is limited by static analysis, this cop attempts to avoid registering an offense when the receiver is a hash (hash literal, Hash.new, ‘Hash#[]`, or to_h/to_hash).

Examples:

# bad (select or find_all)
array.select { |x| x.is_a?(Foo) }
array.select { |x| x.kind_of?(Foo) }

# bad (reject)
array.reject { |x| x.is_a?(Foo) }

# bad (negative form)
array.reject { |x| !x.is_a?(Foo) }

# good
array.grep(Foo)
array.grep_v(Foo)

Constant Summary collapse

MSG = 
'Prefer `%<replacement>s` to `%<original_method>s` with a kind check.'
RESTRICT_ON_SEND = 
%i[select filter find_all reject].freeze
SELECT_METHODS = 
%i[select filter find_all].freeze
CLASS_CHECK_METHODS = 
%i[is_a? kind_of?].to_set.freeze

Constants included from RangeHelp

RangeHelp::BYTE_ORDER_MARK, RangeHelp::NOT_GIVEN

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, #always_autocorrect?, autocorrect_incompatible_with, badge, #begin_investigation, #callbacks_needed, callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #cop_config, #cop_name, cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #parser_engine, #ready, #relevant_file?, requires_gem, #string_literals_frozen_by_default?, support_autocorrect?, support_multiple_source?, #target_gem_version, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#calls_lvar?(node, name) ⇒ Object 



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# File 'lib/rubocop/cop/style/select_by_kind.rb', line 72

def_node_matcher :calls_lvar?, <<~PATTERN
  (send (lvar %1) %CLASS_CHECK_METHODS _)
PATTERN

#class_check?(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/select_by_kind.rb', line 45

def_node_matcher :class_check?, <<~PATTERN
  {
    (block call (args (arg $_)) ${(send (lvar _) %CLASS_CHECK_METHODS _)})
    (block call (args (arg $_)) ${(send (send (lvar _) %CLASS_CHECK_METHODS _) :!)})
    (numblock call $1 ${(send (lvar _) %CLASS_CHECK_METHODS _)})
    (numblock call $1 ${(send (send (lvar _) %CLASS_CHECK_METHODS _) :!)})
    (itblock call $_ ${(send (lvar _) %CLASS_CHECK_METHODS _)})
    (itblock call $_ ${(send (send (lvar _) %CLASS_CHECK_METHODS _) :!)})
  }
PATTERN

#creates_hash?(node) ⇒ Object

Returns true if a node appears to return a hash



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# File 'lib/rubocop/cop/style/select_by_kind.rb', line 58

def_node_matcher :creates_hash?, <<~PATTERN
  {
    (call (const _ :Hash) {:new :[]} ...)
    (block (call (const _ :Hash) :new ...) ...)
    (call _ { :to_h :to_hash } ...)
  }
PATTERN

#env_const?(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/select_by_kind.rb', line 67

def_node_matcher :env_const?, <<~PATTERN
  (const {nil? cbase} :ENV)
PATTERN

#negated_calls_lvar?(node, name) ⇒ Object 



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# File 'lib/rubocop/cop/style/select_by_kind.rb', line 77

def_node_matcher :negated_calls_lvar?, <<~PATTERN
  (send (send (lvar %1) %CLASS_CHECK_METHODS _) :!)
PATTERN

#on_send(node) ⇒ Object Also known as: on_csend 



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# File 'lib/rubocop/cop/style/select_by_kind.rb', line 81

def on_send(node)
  return unless (block_node = node.block_node)
  return if block_node.body&.begin_type?
  return if receiver_allowed?(block_node.receiver)
  return unless (class_check_send_node = extract_send_node(block_node))

  replacement = replacement(class_check_send_node, node)
  class_constant = find_class_constant(class_check_send_node)

  register_offense(node, block_node, class_constant, replacement)
end