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Class: RuboCop::Cop::Style::NumericPredicate

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/numeric_predicate.rb

Overview

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Examples:

EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0

# good
foo.zero?
foo.negative?
bar.baz.positive?

EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

# good
foo == 0
0 > foo
bar.baz > 0

AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0

# bad
0 > foo
bar.baz > 0

AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?

# bad
foo.negative?
bar.baz.positive?

Cop Safety Information:

  • This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.

.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.

.badge

Naming.

.callbacks_needed, .cop_name, .department,
.documentation_url

Returns an url to view this cops documentation online.

.exclude_from_registry

Call for abstract Cop classes.

.inherited,
.joining_forces

Override and return the Force class(es) you need to join.

.match?

Returns true if the cop name or the cop namespace matches any of the given names.

.new,
.requires_gem

Register a version requirement for the given gem name.

.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.

transform

Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::AllowedPattern - Included

::RuboCop::Cop::AllowedMethods - Included

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.

#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.

#begin_investigation

Called before any investigation.

#callbacks_needed,
#cop_config

Configuration Helpers.

#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:

#inspect
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.

#name

Alias for Base#cop_name.

#offenses,
#on_investigation_end

Called after all on_…​

#on_new_investigation

Called before all on_…​

#on_other_file

Called instead of all on_…​

#parse

There should be very limited reasons for a Cop to do it’s own parsing.

#parser_engine,
#ready

Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.

#complete_investigation

Called to complete an investigation.

#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:

#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.

#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#allowed_method_name?(name) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 107

def allowed_method_name?(name)
  allowed_method?(name) || matches_allowed_pattern?(name)
end

#check(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 111

def check(node)
  numeric, operator =
    if style == :predicate
      comparison(node) || inverted_comparison(node, &invert)
    else
      predicate(node)
    end

  return unless numeric && operator && replacement_supported?(operator)

  [numeric, replacement(node, numeric, operator)]
end

#comparison(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 174

def_node_matcher :comparison, <<~PATTERN
  (send [$(...) !gvar_type?] ${:== :> :<} (int 0))
PATTERN

#invert (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 154

def invert
  lambda do |comparison, numeric|
    comparison = { :> => :<, :< => :> }[comparison] || comparison

    [numeric, comparison]
  end
end

#inverted_comparison(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 179

def_node_matcher :inverted_comparison, <<~PATTERN
  (send (int 0) ${:== :> :<} [$(...) !gvar_type?])
PATTERN

#negated?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 162

def negated?(node)
  return false unless (parent = node.parent)

  parent.send_type? && parent.method?(:!)
end

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 90

def on_send(node)
  numeric, replacement = check(node)
  return unless numeric

  return if allowed_method_name?(node.method_name) ||
            node.each_ancestor(:send, :block).any? do |ancestor|
              allowed_method_name?(ancestor.method_name)
            end

  message = format(MSG, prefer: replacement, current: node.source)
  add_offense(node, message: message) do |corrector|
    corrector.replace(node, replacement)
  end
end

#parenthesized_source(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 134

def parenthesized_source(node)
  if require_parentheses?(node)
    "(#{node.source})"
  else
    node.source
  end
end

#predicate(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 169

def_node_matcher :predicate, <<~PATTERN
  (send $(...) ${:zero? :positive? :negative?})
PATTERN

#replacement(node, numeric, operation) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 124

def replacement(node, numeric, operation)
  if style == :predicate
    [parenthesized_source(numeric), REPLACEMENTS.invert[operation.to_s]].join('.')
  elsif negated?(node)
    "(#{numeric.source} #{REPLACEMENTS[operation.to_s]} 0)"
  else
    [numeric.source, REPLACEMENTS[operation.to_s], 0].join(' ')
  end
end

#replacement_supported?(operator) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 146

def replacement_supported?(operator)
  if %i[> <].include?(operator)
    target_ruby_version >= 2.3
  else
    true
  end
end

#require_parentheses?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/numeric_predicate.rb', line 142

def require_parentheses?(node)
  node.send_type? && node.binary_operation? && !node.parenthesized?
end