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Class: RuboCop::Cop::Lint::UselessOr

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:
self, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/useless_or.rb

Overview

Checks for useless OR (|| and or) expressions.

Some methods always return a truthy value, even when called on nil (e.g. nil.to_i evaluates to 0). Therefore, OR expressions appended after these methods will never evaluate.

Examples:

# bad
x.to_a || fallback
x.to_c || fallback
x.to_d || fallback
x.to_i || fallback
x.to_f || fallback
x.to_h || fallback
x.to_r || fallback
x.to_s || fallback
x.to_sym || fallback
x.intern || fallback
x.inspect || fallback
x.hash || fallback
x.object_id || fallback
x.__id__ || fallback

x.to_s or fallback

# good - if fallback is same as return value of method called on nil
x.to_a # nil.to_a returns []
x.to_c # nil.to_c returns (0+0i)
x.to_d # nil.to_d returns 0.0
x.to_i # nil.to_i returns 0
x.to_f # nil.to_f returns 0.0
x.to_h # nil.to_h returns {}
x.to_r # nil.to_r returns (0/1)
x.to_s # nil.to_s returns ''
x.to_sym # nil.to_sym raises an error
x.intern # nil.intern raises an error
x.inspect # nil.inspect returns "nil"
x.hash # nil.hash returns an Integer
x.object_id # nil.object_id returns an Integer
x.__id__ # nil.object_id returns an Integer

# good - if the intention is not to call the method on nil
x&.to_a || fallback
x&.to_c || fallback
x&.to_d || fallback
x&.to_i || fallback
x&.to_f || fallback
x&.to_h || fallback
x&.to_r || fallback
x&.to_s || fallback
x&.to_sym || fallback
x&.intern || fallback
x&.inspect || fallback
x&.hash || fallback
x&.object_id || fallback
x&.__id__ || fallback

x&.to_s or fallback

Cop Safety Information:

  • As shown in the examples below, there are generally two possible ways to correct the offense, but this cop’s autocorrection always chooses the option that preserves the current behavior. While this does not change how the code behaves, that option is not necessarily the appropriate fix in every situation. For this reason, the autocorrection provided by this cop is considered unsafe.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

support_autocorrect?

::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 a 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

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #string_literals_frozen_by_default?, #target_satisfies_all_gem_version_requirements?

::RuboCop::Cop::AutocorrectLogic - Included

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Instance Method Summary

::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_gem_version

Returns a gems locked versions (i.e.
#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

#disable_offense, #disable_offense_at_end_of_line, #disable_offense_before_and_after, #disable_offense_with_eol_or_surround_comment, #eol_comment, #eol_comment_would_be_inside_literal?, #heredoc_range, #line_with_eol_comment_too_long?, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #string_continuation?, #surrounding_heredoc?, #surrounding_percent_array?

::RuboCop::Cop::IgnoredNode - Included

#ignore_node, #ignored_node?, #part_of_ignored_node?, #ignored_nodes

Constructor Details

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

Instance Method Details

#on_or(node)

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/useless_or.rb', line 87



def on_or(node)
  if truthy_return_value_method?(node.lhs)
    report_offense(node, node.lhs)
  elsif truthy_return_value_method?(node.rhs)
    parent = node.parent
    parent = parent.parent if parent&.begin_type?

    report_offense(parent, node.rhs) if parent&.or_type?
  end
end


  








  

    #report_offense(or_node, truthy_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/useless_or.rb', line 100



def report_offense(or_node, truthy_node)
  add_offense(
    or_node.loc.operator.join(or_node.rhs.source_range),
    message: format(MSG, lhs: truthy_node.source, rhs: or_node.rhs.source)
  ) do |corrector|
    corrector.replace(or_node, or_node.lhs.source)
  end
end


  








  

    #truthy_return_value_method?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/useless_or.rb', line 83



def_node_matcher :truthy_return_value_method?, <<~PATTERN
  (send _ %TRUTHY_RETURN_VALUE_METHODS)
PATTERN