Class: RuboCop::Cop::Style::ZeroLengthPredicate

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

Overview

This cop checks for receiver.length == 0 predicates and the negated versions receiver.length > 0 and receiver.length != 0. These can be replaced with receiver.empty? and !receiver.empty? respectively.

Examples:


@bad
[1, 2, 3].length == 0
0 == "foobar".length
hash.size > 0

@good
[1, 2, 3].empty?
"foobar".empty?
!hash.empty?

Constant Summary collapse

ZERO_MSG = 
'Use `empty?` instead of `%s %s %s`.'.freeze
NONZERO_MSG = 
'Use `!empty?` instead of `%s %s %s`.'.freeze

Constants included from Util

Util::ASGN_NODES, Util::BYTE_ORDER_MARK, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, 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, #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?, #highlights, inherited, #initialize, #join_force?, lint?, match?, #message, #messages, non_rails, #parse, qualified_cop_name, #reference_url, #relevant_file?, #style_guide_url, #target_ruby_version

Methods included from Sexp

#s

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search_body

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, comment_line?, directions, double_quotes_acceptable?, double_quotes_required?, effective_column, ends_its_line?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, move_pos, needs_escaping?, numeric_range_size, on_node, operator?, parentheses?, parenthesized_call?, range_with_surrounding_comma, range_with_surrounding_space, source_range, strip_quotes, to_string_literal, to_symbol_literal, within_node?

Methods included from PathUtil

absolute?, 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/zero_length_predicate.rb', line 55

def autocorrect(node)
  lambda do |corrector|
    corrector.replace(node.loc.expression, replacement(node))
  end
end

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/zero_length_predicate.rb', line 27

def on_send(node)
  zero_length_predicate = zero_length_predicate(node)

  if zero_length_predicate
    add_offense(node, :expression,
                format(ZERO_MSG, *zero_length_predicate))
  end

  nonzero_length_predicate = nonzero_length_predicate(node)

  if nonzero_length_predicate
    add_offense(node, :expression,
                format(NONZERO_MSG, *nonzero_length_predicate))
  end
end

#replacement(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/zero_length_predicate.rb', line 61

def replacement(node)
  receiver = zero_length_receiver(node)
  return "#{receiver.source}.empty?" if receiver

  "!#{other_receiver(node).source}.empty?"
end