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

Inherits:
Cop
  • Object
show all
Includes:
SafeMode
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 `%<prefer>s` instead of ' \
'`%<first_method>s.%<second_method>s`.'.freeze
REVERSE_MSG = 
'Use `reverse.%<prefer>s` instead of ' \
'`%<first_method>s.%<second_method>s`.'.freeze

Constants included from Util

Util::ASGN_NODES, Util::BYTE_ORDER_MARK, Util::CONDITIONAL_NODES, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::LOGICAL_OPERATOR_NODES, Util::MODIFIER_NODES, 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, autocorrect_incompatible_with, badge, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, #correct, department, #duplicate_location?, #excluded_file?, #find_location, #highlights, inherited, #initialize, #join_force?, lint?, match?, #message, #messages, non_rails, #parse, qualified_cop_name, #relevant_file?, #target_rails_version, #target_ruby_version

Methods included from AST::Sexp

#s

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search, #node_search_all, #node_search_body, #node_search_first

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?, comment_line?, double_quotes_required?, effective_column, ends_its_line?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, needs_escaping?, on_node, operator?, parentheses?, parenthesized_call?, precede?, range_between, range_by_whole_lines, range_with_surrounding_comma, range_with_surrounding_space, same_line?, source_range, strip_quotes, stripped_source_upto, symbol_without_quote?, to_string_literal, to_supported_styles, to_symbol_literal, within_node?

Methods included from PathUtil

absolute?, find_file_upwards, match_path?, pwd, relative_path, reset_pwd, smart_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 54

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 40

def on_send(node)
  return if rails_safe_mode?

  detect_candidate?(node) do |receiver, second_method, args|
    return unless args.empty?
    return unless receiver

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

    register_offense(node, receiver, second_method)
  end
end