Class: RuboCop::Cop::Lint::AmbiguousOperatorPrecedence

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/lint/ambiguous_operator_precedence.rb


Looks for expressions containing multiple binary operators where precedence is ambiguous due to lack of parentheses. For example, in 1 + 2 * 3, the multiplication will happen before the addition, but lexically it appears that the addition will happen first.

The cop does not consider unary operators (ie. !a or -b) or comparison operators (ie. a =~ b) because those are not ambiguous.

Ranges are handled by Lint/AmbiguousRange.


# bad
a + b * c
a || b && c
a ** b + c

# good (different precedence)
a + (b * c)
a || (b && c)
(a ** b) + c

# good (same precedence)
a + b + c
a * b / c % d

Constant Summary

::RuboCop::Cop::Base - Inherited


Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,

Returns if class supports autocorrect.


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


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



.callbacks_needed, .cop_name, .department,

Returns an url to view this cops documentation online.


Call for abstract Cop classes.


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


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


Register a version requirement for the given gem name.


::RuboCop::ExcludeLimit - Extended


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


Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::Base - Inherited


Adds an offense that has no particular location.


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.


Called before any investigation.


Configuration Helpers.

#cop_name, #excluded_file?,

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


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.


Alias for Base#cop_name.


Called after all on_…​


Called before all on_…​


Called instead of all on_…​


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


Called between investigations.

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

Reserved for Cop::Cop.


Called to complete an investigation.

#correct, #current_corrector,

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,

Actually private methods.


::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

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

Instance Method Details

#autocorrect(corrector, node) (private)

[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 105

def autocorrect(corrector, node)
  corrector.wrap(node, '(', ')')

#greater_precedence?(node1, node2) ⇒ Boolean (private)

[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 89

def greater_precedence?(node1, node2)
  node1_precedence = precedence(node1)
  node2_precedence = precedence(node2)
  return false unless node1_precedence && node2_precedence

  node2_precedence > node1_precedence


[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 54

def on_and(node)
  return unless (parent = node.parent)

  return if parent.begin_type? # if the `and` is in a `begin`, it's parenthesized already
  return unless parent.or_type?

  add_offense(node) do |corrector|
    autocorrect(corrector, node)


[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 47

def on_new_investigation
  # Cache the precedence of each node being investigated
  # so that we only need to calculate it once
  @node_precedences = {}


[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 65

def on_send(node)
  return if node.parenthesized?

  return unless (parent = node.parent)
  return unless operator?(parent)
  return unless greater_precedence?(node, parent)

  add_offense(node) do |corrector|
    autocorrect(corrector, node)

#operator?(node) ⇒ Boolean (private)

[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 85

def operator?(node)
  (node.send_type? && RESTRICT_ON_SEND.include?(node.method_name)) || node.operator_keyword?

#operator_name(node) (private)

[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 97

def operator_name(node)
  if node.send_type?

#precedence(node) (private)

[ GitHub ]

# File 'lib/rubocop/cop/lint/ambiguous_operator_precedence.rb', line 79

def precedence(node)
  @node_precedences.fetch(node) do
    PRECEDENCE.index { |operators| operators.include?(operator_name(node)) }