Class: RuboCop::Cop::Performance::FlatMap

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

Overview

This cop is used to identify usages of

Examples:

# bad
[1, 2, 3, 4].map { |e| [e, e] }.flatten(1)
[1, 2, 3, 4].collect { |e| [e, e] }.flatten(1)

# good
[1, 2, 3, 4].flat_map { |e| [e, e] }
[1, 2, 3, 4].map { |e| [e, e] }.flatten
[1, 2, 3, 4].collect { |e| [e, e] }.flatten

Constant Summary collapse

MSG = 
'Use `flat_map` instead of `%s...%s`.'
FLATTEN_MULTIPLE_LEVELS = 
' Beware, `flat_map` only flattens 1 level ' \
'and `flatten` can be used to flatten ' \
'multiple levels.'
FLATTEN = 
[:flatten, :flatten!]

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/flat_map.rb', line 46

def autocorrect(node)
  receiver, _flatten, flatten_param = *node
  flatten_level, = *flatten_param
  return if flatten_level.nil?

  array, = *receiver

  lambda do |corrector|
    range = Parser::Source::Range.new(node.loc.expression.source_buffer,
                                      node.loc.dot.begin_pos,
                                      node.loc.expression.end_pos)

    corrector.remove(range)
    corrector.replace(array.loc.selector, 'flat_map')
  end
end

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/performance/flat_map.rb', line 24

def on_send(node)
  left, second_method, flatten_param = *node
  return unless FLATTEN.include?(second_method)
  flatten_level, = *flatten_param
  expression, = *left
  _array, first_method = *expression
  return unless first_method == :map || first_method == :collect

  message = MSG
  if cop_config['EnabledForFlattenWithoutParams'] && flatten_level.nil?
    message = MSG + FLATTEN_MULTIPLE_LEVELS
  else
    return unless flatten_level == 1
  end

  range = Parser::Source::Range.new(node.loc.expression.source_buffer,
                                    expression.loc.selector.begin_pos,
                                    node.loc.selector.end_pos)

  add_offense(node, range, format(message, first_method, second_method))
end