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

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::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

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::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 78



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 91



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))
end


  








  

    #truthy_return_value_method?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/useless_or.rb', line 74



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