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]

# good
[1, 2, 3].sample

Constant Summary collapse

MSG = 
'Use `sample` instead of `shuffle.%s`.'
MSG_SELECTOR = 
'Use `sample` instead of `shuffle[%s]`.'
ARRAY_SELECTORS = 
[:first, :last, :[]]

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_name_with_namespace, cop_type, #correct, #debug?, #display_cop_names?, #display_style_guide?, inherited, #initialize, #join_force?, lint?, #message, 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 44

def autocorrect(node)
  receiver, = *node
  location_of_shuffle = receiver.loc.selector.begin_pos
  range = Parser::Source::Range.new(node.loc.expression.source_buffer,
                                    location_of_shuffle,
                                    node.loc.selector.end_pos)

  @corrections << lambda do |corrector|
    corrector.replace(range, 'sample')
  end
end

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/performance/sample.rb', line 22

def on_send(node)
  receiver, second_method, selector = *node
  return unless ARRAY_SELECTORS.include?(second_method)
  return if receiver.nil?
  _array, first_method = *receiver
  return unless first_method == :shuffle

  begin_of_offense = receiver.loc.selector.begin_pos
  end_of_offense = node.loc.selector.end_pos
  range = Parser::Source::Range.new(node.loc.expression.source_buffer,
                                    begin_of_offense,
                                    end_of_offense)

  message = if second_method == :[]
              format(MSG_SELECTOR, selector.loc.expression.source)
            else
              format(MSG, second_method)
            end

  add_offense(node, range, message)
end