Class: RuboCop::Cop::Style::Sample

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

Overview

Identifies usages of shuffle.first, shuffle.last, and shuffle[] and change them to use sample instead.

NOTE: An offense involving a random: argument is registered but not autocorrected: shuffle and sample consume the given generator differently, so for a seeded generator the correction would select different elements.

Examples:

# bad
[1, 2, 3].shuffle.first
[1, 2, 3].shuffle.first(2)
[1, 2, 3].shuffle.last
[2, 1, 3].shuffle.at(0)
[2, 1, 3].shuffle.slice(0)
[1, 2, 3].shuffle[2]
[1, 2, 3].shuffle[0, 2]    # sample(2) will do the same
[1, 2, 3].shuffle[0..2]    # sample(3) will do the same
[1, 2, 3].shuffle(random: Random.new).first

# good
[1, 2, 3].shuffle
[1, 2, 3].sample
[1, 2, 3].sample(3)
[1, 2, 3].shuffle[1, 3]    # sample(3) might return a longer Array
[1, 2, 3].shuffle[1..3]    # sample(3) might return a longer Array
[1, 2, 3].shuffle[foo, bar]
[1, 2, 3].shuffle(random: Random.new)

Constant Summary collapse

MSG = 
'Use `%<correct>s` instead of `%<incorrect>s`.'
RESTRICT_ON_SEND = 
%i[first last [] at slice].freeze

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source, #project_index

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?, #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?, #skipped_unsafe_correction_with_disable_uncorrectable?

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

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



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

def on_send(node)
  sample_candidate?(node) do |shuffle_node, shuffle_arg, method, method_args|
    return unless offensive?(method, method_args)

    range = source_range(shuffle_node, node)
    message = message(shuffle_arg, method, method_args, range)

    if shuffle_arg.empty?
      add_offense(range, message: message) do |corrector|
        corrector.replace(range, correction(shuffle_arg, method, method_args))
      end
    else
      add_offense(range, message: message)
    end
  end
end

#sample_candidate?(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/sample.rb', line 41

def_node_matcher :sample_candidate?, <<~PATTERN
  (call $(call _ :shuffle $...) ${:#{RESTRICT_ON_SEND.join(' :')}} $...)
PATTERN