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

cop_dir_for, #exclude_limit, read_limits

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