Class: RuboCop::Cop::Performance::InefficientHashSearch

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

Overview

This cop checks for inefficient searching of keys and values within hashes.

`Hash#keys.include?` is less efficient than `Hash#key?` because the former allocates a new array and then performs an O(n) search through that array, while `Hash#key?` does not allocate any array and performs a faster O(1) search for the key.

`Hash#values.include?` is less efficient than `Hash#value?`. While they both perform an O(n) search through all of the values, calling `values` allocates a new array while using `value?` does not.

Examples:

# bad
{ a: 1, b: 2 }.keys.include?(:a)
{ a: 1, b: 2 }.keys.include?(:z)
h = { a: 1, b: 2 }; h.keys.include?(100)

# good
{ a: 1, b: 2 }.key?(:a)
{ a: 1, b: 2 }.has_key?(:z)
h = { a: 1, b: 2 }; h.key?(100)

# bad
{ a: 1, b: 2 }.values.include?(2)
{ a: 1, b: 2 }.values.include?('garbage')
h = { a: 1, b: 2 }; h.values.include?(nil)

# good
{ a: 1, b: 2 }.value?(2)
{ a: 1, b: 2 }.has_value?('garbage')
h = { a: 1, b: 2 }; h.value?(nil)

Constant Summary

Constants included from Util

Util::LITERAL_REGEX

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?, #messages, non_rails, #parse, qualified_cop_name, #relevant_file?, #target_rails_version, #target_ruby_version

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 AST::Sexp

#s

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?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, needs_escaping?, on_node, parentheses?, same_line?, to_string_literal, to_supported_styles, tokens

Methods included from PathUtil

absolute?, hidden_dir?, hidden_file_in_not_hidden_dir?, 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/inefficient_hash_search.rb', line 52

def autocorrect(node)
  lambda do |corrector|
    # Replace `keys.include?` or `values.include?` with the appropriate
    # `key?`/`value?` method.
    corrector.replace(
      node.loc.expression,
      "#{autocorrect_hash_expression(node)}."\
      "#{autocorrect_method(node)}(#{autocorrect_argument(node)})"
    )
  end
end

#on_send(node) ⇒ Object



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# File 'lib/rubocop/cop/performance/inefficient_hash_search.rb', line 44

def on_send(node)
  inefficient_include?(node) do |receiver|
    return if receiver.nil?

    add_offense(node)
  end
end