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.

‘ActiveRecord` compatibility: `ActiveRecord` does not implement a `detect` method and `find` has its own meaning. Correcting ActiveRecord methods with this cop should be considered unsafe.

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

Constants included from Util

Util::ASGN_NODES, Util::BYTE_ORDER_MARK, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::OPERATOR_METHODS, 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?, #highlights, inherited, #initialize, #join_force?, lint?, match?, #message, #messages, non_rails, #parse, qualified_cop_name, #reference_url, #relevant_file?, #style_guide_url, #target_ruby_version

Methods included from Sexp

#s

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search_body

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, comment_line?, directions, double_quotes_acceptable?, double_quotes_required?, effective_column, ends_its_line?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, move_pos, needs_escaping?, numeric_range_size, on_node, operator?, parentheses?, parenthesized_call?, range_with_surrounding_comma, range_with_surrounding_space, source_range, strip_quotes, to_string_literal, to_symbol_literal, within_node?

Methods included from PathUtil

absolute?, 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 44

def autocorrect(node)
  receiver, first_method = *node

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

  first_range = receiver.source_range.end.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 33

def on_send(node)
  return unless should_run?
  receiver, second_method, *args = *node
  return if accept_second_call?(receiver, second_method, args)

  receiver, _args, body = *receiver if receiver.block_type?
  return if accept_first_call?(receiver, body)

  offense(node, receiver, second_method)
end