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Class: RuboCop::Cop::Style::RedundantFormat

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/style/redundant_format.rb

Overview

Checks for calls to Kernel#format or Kernel#sprintf that are redundant.

Calling format with only a single string or constant argument is redundant, as it can be replaced by the string or constant itself.

Also looks for format calls where the arguments are literals that can be inlined into a string easily. This applies to the %s, %d, %i, %u, and %f format specifiers.

Examples:

# bad
format('the quick brown fox jumps over the lazy dog.')
sprintf('the quick brown fox jumps over the lazy dog.')

# good
'the quick brown fox jumps over the lazy dog.'

# bad
format(MESSAGE)
sprintf(MESSAGE)

# good
MESSAGE

# bad
format('%s %s', 'foo', 'bar')
sprintf('%s %s', 'foo', 'bar')

# good
'foo bar'

Cop Safety Information:

  • This cop’s autocorrection is unsafe because string object returned by format and sprintf are never frozen. If format('string') is autocorrected to 'string', FrozenError may occur when calling a destructive method like String#<<. Consider using 'string'.dup instead of format('string'). Additionally, since the necessity of dup cannot be determined automatically, this autocorrection is inherently unsafe.

    # frozen_string_literal: true

format('template').frozen? # => false
'template'.frozen?         # => true

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, #heredoc_range, #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, #range_overlaps_offense?, #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

#all_fields_literal?(string, arguments) ⇒ Boolean (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 132


def all_fields_literal?(string, arguments)
  count = 0
  sequences = RuboCop::Cop::Utils::FormatString.new(string).format_sequences
  return false unless sequences.any?

  sequences.each do |sequence|
    next if sequence.percent?

    hash = arguments.detect(&:hash_type?)
    next unless (argument = find_argument(sequence, arguments, hash))
    next unless matching_argument?(sequence, argument)

    count += 1
  end

  sequences.size == count
end


  








  

    #argument_value(argument)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 219


def argument_value(argument)
  argument = argument.children.first if argument.begin_type?

  if argument.dsym_type?
    dsym_value(argument)
  elsif argument.hash_type?
    hash_value(argument)
  elsif rational_number?(argument)
    rational_value(argument)
  elsif complex_number?(argument)
    complex_value(argument)
  elsif argument.respond_to?(:value)
    argument.value
  else
    argument.source
  end
end


  








  

    #argument_values(arguments)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 215


def argument_values(arguments)
  arguments.map { |argument| argument_value(argument) }
end


  








  

    #complex_number?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 73


def_node_matcher :complex_number?, <<~PATTERN
  {complex (send int :+ complex) (begin complex) (begin (send int :+ complex))}
PATTERN


  








  

    #complex_value(complex_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 251


def complex_value(complex_node)
  Complex(complex_node.source)
end


  








  

    #detect_unnecessary_fields(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 109


def detect_unnecessary_fields(node)
  return unless node.first_argument&.str_type?

  string = node.first_argument.value
  arguments = node.arguments[1..]

  return unless string && arguments.any?
  return if splatted_arguments?(node)

  register_all_fields_literal(node, string, arguments)
end


  








  

    #dsym_value(dsym_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 237


def dsym_value(dsym_node)
  dsym_node.children.first.source
end


  








  

    #find_argument(sequence, arguments, hash)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 150


def find_argument(sequence, arguments, hash)
  if hash && (sequence.annotated? || sequence.template?)
    find_hash_value_node(hash, sequence.name.to_sym).first
  elsif sequence.arg_number
    arguments[sequence.arg_number.to_i - 1]
  else
    # If the specifier contains `*`, the following arguments will be used
    # to specify the width and can be ignored.
    (sequence.arity - 1).times { arguments.shift }
    arguments.shift
  end
end


  








  

    #find_hash_value_node(node, name)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 78


def_node_search  :find_hash_value_node, <<~PATTERN
  (pair (sym %1) $_)
PATTERN


  








  

    #float?(argument)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 191


def float?(argument)
  numeric?(argument) && Float(argument_value(argument), exception: false)
end


  








  

    #format_without_additional_args?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 63


def_node_matcher :format_without_additional_args?, <<~PATTERN
  (send {(const {nil? cbase} :Kernel) nil?} %RESTRICT_ON_SEND ${str dstr const})
PATTERN


  








  

    #hash_value(hash_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 241


def hash_value(hash_node)
  hash_node.each_pair.with_object({}) do |pair, hash|
    hash[pair.key.value] = argument_value(pair.value)
  end
end


  








  

    #integer?(argument)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 187


def integer?(argument)
  numeric?(argument) && Integer(argument_value(argument), exception: false)
end


  








  

    #matching_argument?(sequence, argument)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 163


def matching_argument?(sequence, argument)
  # Template specifiers don't give a type, any acceptable literal type is ok.
  return argument.type?(*ACCEPTABLE_LITERAL_TYPES) if sequence.template?

  # An argument matches a specifier if it can be easily converted
  # to that type.
  case sequence.type
  when 's'
    argument.type?(*ACCEPTABLE_LITERAL_TYPES)
  when 'd', 'i', 'u'
    integer?(argument)
  when 'f'
    float?(argument)
  else
    false
  end
end


  








  

    #message(node, prefer)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 105


def message(node, prefer)
  format(MSG, prefer: prefer, method_name: node.method_name)
end


  








  

    #numeric?(argument)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 181


def numeric?(argument)
  argument.type?(:numeric, :str) ||
    rational_number?(argument) ||
    complex_number?(argument)
end


  








  

    #on_send(node)  
  

  [ GitHub ]


  

  


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


def on_send(node)
  format_without_additional_args?(node) do |value|
    replacement = value.source

    add_offense(node, message: message(node, replacement)) do |corrector|
      corrector.replace(node, replacement)
    end
    return
  end

  detect_unnecessary_fields(node)
end


  








  

    #quote(string, node)   (private)
  



  

    


Add correct quotes to the formatted string, preferring retaining the existing
quotes if possible.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 197


def quote(string, node)
  str_node = node.first_argument
  start_delimiter = str_node.loc.begin.source
  end_delimiter = str_node.loc.end.source

  # If there is any interpolation, the delimiters need to be changed potentially
  if node.each_descendant(:dstr, :dsym).any?
    case start_delimiter
    when "'"
      start_delimiter = end_delimiter = '"'
    when /\A%q(.)/
      start_delimiter = "%Q#{Regexp.last_match[1]}"
    end
  end

  "#{start_delimiter}#{string}#{end_delimiter}"
end


  








  

    #rational_number?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 68


def_node_matcher :rational_number?, <<~PATTERN
  {rational (send int :/ rational) (begin rational) (begin (send int :/ rational))}
PATTERN


  








  

    #rational_value(rational_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 247


def rational_value(rational_node)
  rational_node.source.to_r
end


  








  

    #register_all_fields_literal(node, string, arguments)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 121


def register_all_fields_literal(node, string, arguments)
  return unless all_fields_literal?(string, arguments.dup)

  formatted_string = format(string, *argument_values(arguments))
  replacement = quote(formatted_string, node)

  add_offense(node, message: message(node, replacement)) do |corrector|
    corrector.replace(node, replacement)
  end
end


  








  

    #splatted_arguments?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_format.rb', line 83


def_node_matcher :splatted_arguments?, <<~PATTERN
  (send _ %RESTRICT_ON_SEND <{
    splat
    (hash <kwsplat ...>)
  } ...>)
PATTERN