Class: RuboCop::Cop::Style::EachWithObject

Inherits:
Cop
  • Object
show all
Defined in:
lib/rubocop/cop/style/each_with_object.rb

Overview

This cop looks for inject / reduce calls where the passed in object is returned at the end and so could be replace by each_with_object without the need to return the object at the end.

However, we can't replace with each_with_object if the accumulator parameter is assigned to within the block.

Examples:

# bad
[1, 2].inject({}) { |a, e| a[e] = e; a }

# good
[1, 2].each_with_object({}) { |e, a| a[e] = e }

Constant Summary collapse

MSG =
'Use `each_with_object` instead of `%s`.'
METHODS =
[:inject, :reduce]

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

#on_block(node) ⇒ Object


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# File 'lib/rubocop/cop/style/each_with_object.rb', line 23

def on_block(node)
  method, args, body = *node

  # filter out super and zsuper nodes
  return unless method.type == :send

  _, method_name, method_arg = *method

  return unless METHODS.include? method_name
  return if method_arg && BASIC_LITERALS.include?(method_arg.type)

  return_value = return_value(body)
  return unless return_value

  return unless first_argument_returned?(args, return_value)

  # if the accumulator parameter is assigned to in the block,
  # then we can't convert to each_with_object
  first_arg, = *args
  accumulator_var, = *first_arg
  return if body.each_descendant.any? do |n|
    next unless n.assignment?
    lhs, _rhs = *n
    lhs.equal?(accumulator_var)
  end

  add_offense(method, :selector, format(MSG, method_name))
end