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 numeric comparisons that can be replaced by a predicate method, such as receiver.length == 0, receiver.length > 0, receiver.length != 0, receiver.length < 1 and receiver.size == 0 that can be replaced by receiver.empty? and !receiver.empty.

Examples:


@bad
[1, 2, 3].length == 0
0 == "foobar".length
array.length < 1
{a: 1, b: 2}.length != 0
string.length > 0
hash.size > 0

@good
[1, 2, 3].empty?
"foobar".empty?
array.empty?
!{a: 1, b: 2}.empty?
!string.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::CONDITIONAL_NODES, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::LOGICAL_OPERATOR_NODES, Util::MODIFIER_NODES, 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, 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?, #message, #messages, non_rails, #parse, qualified_cop_name, #relevant_file?, #target_rails_version, #target_ruby_version

Methods included from AST::Sexp

#s

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 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?, compatible_external_encoding_for?, directions, double_quotes_required?, effective_column, ends_its_line?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_distance, line_range, move_pos, needs_escaping?, on_node, operator?, parentheses?, parenthesized_call?, preceed?, range_between, range_by_whole_lines, range_with_surrounding_comma, range_with_surrounding_space, same_line?, source_range, strip_quotes, stripped_source_upto, symbol_without_quote?, to_string_literal, to_supported_styles, to_symbol_literal, within_node?

Methods included from PathUtil

absolute?, match_path?, relative_path, 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/style/zero_length_predicate.rb', line 63

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 33

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)

  # rubocop:disable Style/GuardClause
  if nonzero_length_predicate
    add_offense(node, :expression,
                format(NONZERO_MSG, *nonzero_length_predicate))
  end
  # rubocop:enable Style/GuardClause
end

#replacement(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/zero_length_predicate.rb', line 69

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

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