Class: RuboCop::Cop::Performance::Detect

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

Overview

This cop is used to identify usages of select.first, select.last, find_all.first, and find_all.last and change them to use detect instead.

Examples:

# bad
[].select { |item| true }.first
[].select { |item| true }.last
[].find_all { |item| true }.first
[].find_all { |item| true }.last

# good
[].detect { |item| true }
[].reverse.detect { |item| true }

Constant Summary collapse

MSG =
'Use `%s` instead of `%s.%s`.'
REVERSE_MSG =
'Use `reverse.%s` instead of `%s.%s`.'
SELECT_METHODS =
[:select, :find_all]
DANGEROUS_METHODS =
[:first, :last]

Constants included from Util

Util::ASGN_NODES, Util::BASIC_LITERALS, Util::EQUALS_ASGN_NODES, Util::LITERALS, 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?, #details, #display_cop_names?, #display_style_guide?, #excluded_file?, #extra_details?, inherited, #initialize, #join_force?, lint?, match?, #message, non_rails, qualified_cop_name, rails?, #reference_url, #relevant_file?, #style_guide_url

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search

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/detect.rb', line 52

def autocorrect(node)
  receiver, first_method = *node

  replacement = if first_method == :last
                  "reverse.#{preferred_method}"
                else
                  preferred_method
                end

  first_range = Parser::Source::Range.new(
    receiver.loc.expression.source,
    receiver.loc.end.end_pos,
    receiver.loc.end.end_pos).join(node.loc.selector)

  receiver, _args, _body = *receiver if receiver.block_type?

  lambda do |corrector|
    corrector.remove(first_range)
    corrector.replace(receiver.loc.selector, replacement)
  end
end

#on_send(node) ⇒ Object


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

def on_send(node)
  receiver, second_method = *node
  return if receiver.nil?
  return unless DANGEROUS_METHODS.include?(second_method)

  receiver, _args, body = *receiver if receiver.block_type?

  caller, first_method, args = *receiver

  # check that we have usual block or block pass
  return if body.nil? && (args.nil? || !args.block_pass_type?)

  return unless SELECT_METHODS.include?(first_method)

  return if lazy?(caller)

  range = receiver.loc.selector.join(node.loc.selector)

  message = second_method == :last ? REVERSE_MSG : MSG
  add_offense(node, range, format(message,
                                  preferred_method,
                                  first_method,
                                  second_method))
end