Class: RuboCop::Cop::Performance::Sample

Inherits:
Cop
  • Object
show all
Defined in:
lib/rubocop/cop/performance/sample.rb

Overview

This cop is used to identify usages of shuffle.first and change them to use sample instead.

Examples:

# bad
[1, 2, 3].shuffle.first
[1, 2, 3].shuffle.last
[1, 2, 3].shuffle[0]
[1, 2, 3].shuffle[0, 3]
[1, 2, 3].shuffle(random: Random.new(1))

# good
[1, 2, 3].shuffle
[1, 2, 3].sample
[1, 2, 3].sample(3)
[1, 2, 3].sample(random: Random.new(1))

Constant Summary collapse

MSG = 
'Use `sample` instead of `shuffle%s`.'
RANGE_TYPES = 
[:irange, :erange]
VALID_ARRAY_SELECTORS = 
[:first, :last, :[], nil]

Constants included from Util

Util::ASGN_NODES, Util::EQUALS_ASGN_NODES, Util::OPERATOR_METHODS, Util::PROC_NEW_NODE, Util::SHORTHAND_ASGN_NODES

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods inherited from Cop

#add_offense, all, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, cop_type, #correct, #debug?, #display_cop_names?, #display_style_guide?, inherited, #initialize, #join_force?, lint?, match?, non_rails, qualified_cop_name, rails?, #relevant_file?, #style_guide_url

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

begins_its_line?, block_length, command?, comment_line?, const_name, directions, first_part_of_call_chain, lambda?, lambda_or_proc?, line_range, move_pos, numeric_range_size, on_node, operator?, parentheses?, proc?, range_with_surrounding_comma, range_with_surrounding_space, source_range, strip_quotes, within_node?

Methods included from PathUtil

hidden?, issue_deprecation_warning, match_path?, relative_path

Constructor Details

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

Instance Method Details

#autocorrect(node) ⇒ Object 



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# File 'lib/rubocop/cop/performance/sample.rb', line 37

def autocorrect(node)
  _receiver, _method, params, selector = *node
  _receiver, _method, params, selector = *node.parent if params.nil?

  return if params && RANGE_TYPES.include?(params.type)

  range = if params && (params.hash_type? || params.lvar_type?)
            range_of_shuffle(node)
          else
            Parser::Source::Range.new(node.loc.expression.source_buffer,
                                      node.loc.selector.begin_pos,
                                      node.parent.loc.selector.end_pos)
          end

  lambda do |corrector|
    corrector.replace(range, 'sample')
    return if selector.nil?
    corrector.insert_after(range, "(#{selector.loc.expression.source})")
  end
end

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/performance/sample.rb', line 27

def on_send(node)
  _receiver, first_method, params, = *node
  return unless first_method == :shuffle
  _receiver, second_method, params, = *node.parent if params.nil?
  return unless VALID_ARRAY_SELECTORS.include?(second_method)
  return if second_method.nil? && params.nil?

  add_offense(node, range_of_shuffle(node), message(node, params))
end