Class: RuboCop::Cop::Style::SelectByRegexp

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

Overview

Looks for places where an subset of an Enumerable (array, range, set, etc.; see note below) is calculated based on a ‘Regexp` match, 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`).

NOTE: ‘grep` and `grep_v` were optimized when used without a block in Ruby 3.0, but may be slower in previous versions. See bugs.ruby-lang.org/issues/17030

Examples:

# bad (select or find_all)
array.select { |x| x.match? /regexp/ }
array.select { |x| /regexp/.match?(x) }
array.select { |x| x =~ /regexp/ }
array.select { |x| /regexp/ =~ x }

# bad (reject)
array.reject { |x| x.match? /regexp/ }
array.reject { |x| /regexp/.match?(x) }
array.reject { |x| x =~ /regexp/ }
array.reject { |x| /regexp/ =~ x }

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

Constant Summary collapse

MSG = 
'Prefer `%<replacement>s` to `%<original_method>s` with a regexp match.'
RESTRICT_ON_SEND = 
%i[select find_all reject].freeze
REPLACEMENTS = 
{ select: 'grep', find_all: 'grep', reject: 'grep_v' }.freeze
OPPOSITE_REPLACEMENTS = 
{ select: 'grep_v', find_all: 'grep_v', reject: 'grep' }.freeze
REGEXP_METHODS = 
%i[match? =~ !~].to_set.freeze

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, support_autocorrect?, support_multiple_source?, #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_regexp.rb', line 79

def_node_matcher :calls_lvar?, <<~PATTERN
  {
    (send (lvar %1) ...)
    (send ... (lvar %1))
    (match-with-lvasgn regexp (lvar %1))
  }
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_regexp.rb', line 65

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_regexp.rb', line 74

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

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

rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity



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# File 'lib/rubocop/cop/style/select_by_regexp.rb', line 88

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 (regexp_method_send_node = extract_send_node(block_node))
  return if match_predicate_without_receiver?(regexp_method_send_node)

  replacement = replacement(regexp_method_send_node, node)
  return if target_ruby_version <= 2.2 && replacement == 'grep_v'

  regexp = find_regexp(regexp_method_send_node, block_node)

  register_offense(node, block_node, regexp, replacement)
end

#regexp_match?(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/select_by_regexp.rb', line 56

def_node_matcher :regexp_match?, <<~PATTERN
  {
    (block call (args (arg $_)) ${(send _ %REGEXP_METHODS _) match-with-lvasgn})
    (numblock call $1 ${(send _ %REGEXP_METHODS _) match-with-lvasgn})
  }
PATTERN