Class: RuboCop::Cop::Style::EmptyLiteral

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

Overview

This cop checks for the use of a method, the result of which would be a literal, like an empty array, hash or string.

Constant Summary collapse

ARR_MSG =
'Use array literal `[]` instead of `Array.new`.'
HASH_MSG =
'Use hash literal `{}` instead of `Hash.new`.'
STR_MSG =
"Use string literal `''` instead of `String.new`."
ARRAY_NODE =

Empty array node

(send (const nil :Array) :new)

s(:send, s(:const, nil, :Array), :new)
HASH_NODE =

Empty hash node

(send (const nil :Hash) :new)

s(:send, s(:const, nil, :Hash), :new)
STR_NODE =

Empty string node

(send (const nil :String) :new)

s(:send, s(:const, nil, :String), :new)

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/style/empty_literal.rb', line 45

def autocorrect(node)
  name = case node
         when ARRAY_NODE
           '[]'
         when HASH_NODE
           # `some_method {}` is not same as `some_method Hash.new`
           # because the braces are interpreted as a block, so we avoid
           # the correction. Parentheses around the arguments would
           # solve the problem, but we let the user add those manually.
           return if first_arg_in_method_call_without_parentheses?(node)
           '{}'
         when STR_NODE
           "''"
         end
  ->(corrector) { corrector.replace(node.loc.expression, name) }
end

#first_arg_in_method_call_without_parentheses?(node) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/cop/style/empty_literal.rb', line 62

def first_arg_in_method_call_without_parentheses?(node)
  return false unless node.parent && node.parent.send_type?

  _receiver, _method_name, *args = *node.parent
  node.object_id == args.first.object_id && !parentheses?(node.parent)
end

#on_send(node) ⇒ Object


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# File 'lib/rubocop/cop/style/empty_literal.rb', line 31

def on_send(node)
  case node
  when ARRAY_NODE
    add_offense(node, :expression, ARR_MSG)
  when HASH_NODE
    # If Hash.new takes a block, it can't be changed to {}.
    return if node.parent && node.parent.block_type?

    add_offense(node, :expression, HASH_MSG)
  when STR_NODE
    add_offense(node, :expression, STR_MSG)
  end
end