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Class: RuboCop::Cop::Style::FrozenStringLiteralComment

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/frozen_string_literal_comment.rb

Overview

Helps you transition from mutable string literals to frozen string literals. It will add the # frozen_string_literal: true magic comment to the top of files to enable frozen string literals. Frozen string literals may be default in future Ruby. The comment will be added below a shebang and encoding comment. The frozen string literal comment is only valid in Ruby 2.3+.

Note that the cop will accept files where the comment exists but is set to false instead of true.

To require a blank line after this comment, please see Layout/EmptyLineAfterMagicComment cop.

Examples:

EnforcedStyle: always (default)

# The `always` style will always add the frozen string literal comment
# to a file, regardless of the Ruby version or if `freeze` or `<<` are
# called on a string literal.
# bad
module Bar
  # ...
end

# good
# frozen_string_literal: true

module Bar
  # ...
end

# good
# frozen_string_literal: false

module Bar
  # ...
end

EnforcedStyle: never

# The `never` will enforce that the frozen string literal comment does
# not exist in a file.
# bad
# frozen_string_literal: true

module Baz
  # ...
end

# good
module Baz
  # ...
end

EnforcedStyle: always_true

# The `always_true` style enforces that the frozen string literal
# comment is set to `true`. This is a stricter option than `always`
# and forces projects to use frozen string literals.
# bad
# frozen_string_literal: false

module Baz
  # ...
end

# bad
module Baz
  # ...
end

# good
# frozen_string_literal: true

module Bar
  # ...
end

Cop Safety Information:

  • This cop’s autocorrection is unsafe since any strings mutations will change from being accepted to raising FrozenError, as all strings will become frozen by default, and will need to be manually refactored.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

::RuboCop::Cop::FrozenStringLiteral - Included

FROZEN_STRING_LITERAL, FROZEN_STRING_LITERAL_ENABLED, FROZEN_STRING_LITERAL_TYPES_RUBY27

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

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::TargetRubyVersion - Extended

::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::RangeHelp - Included

#add_range, #column_offset_between,
#contents_range

A range containing only the contents of a literal with delimiters (e.g.

#directions,
#effective_column

Returns the column attribute of the range, except if the range is on the first line and there’s a byte order mark at the beginning of that line, in which case 1 is subtracted from the column value.

#final_pos, #move_pos, #move_pos_str, #range_between, #range_by_whole_lines, #range_with_comments, #range_with_comments_and_lines, #range_with_surrounding_comma, #range_with_surrounding_space, #source_range

::RuboCop::Cop::FrozenStringLiteral - 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

#disabled_offense(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 178

def disabled_offense(processed_source)
  frozen_string_literal_comment = frozen_string_literal_comment(processed_source)

  add_offense(frozen_string_literal_comment.pos, message: MSG_DISABLED) do |corrector|
    enable_comment(corrector)
  end
end

#enable_comment(corrector) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 190

def enable_comment(corrector)
  comment = frozen_string_literal_comment(processed_source)

  corrector.replace(line_range(comment.line), FROZEN_STRING_LITERAL_ENABLED)
end

#ensure_comment(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 120

def ensure_comment(processed_source)
  return if frozen_string_literal_comment_exists?

  missing_offense(processed_source)
end

#ensure_enabled_comment(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 126

def ensure_enabled_comment(processed_source)
  if frozen_string_literal_specified?
    return if frozen_string_literals_enabled?

    # The comment exists, but is not enabled.
    disabled_offense(processed_source)
  else # The comment doesn't exist at all.
    missing_true_offense(processed_source)
  end
end

#ensure_no_comment(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 114

def ensure_no_comment(processed_source)
  return unless frozen_string_literal_comment_exists?

  unnecessary_comment_offense(processed_source)
end

#following_comment (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 214

def following_comment
  "\n#{FROZEN_STRING_LITERAL_ENABLED}"
end

#frozen_string_literal_comment(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 152

def frozen_string_literal_comment(processed_source)
  processed_source.tokens.find do |token|
    token.text.start_with?(FROZEN_STRING_LITERAL)
  end
end

#insert_comment(corrector) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 196

def insert_comment(corrector)
  comment = last_special_comment(processed_source)

  if comment
    corrector.insert_after(line_range(comment.line), following_comment)
  else
    corrector.insert_before(processed_source.buffer.source_range, preceding_comment)
  end
end

#last_special_comment(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 137

def last_special_comment(processed_source)
  token_number = 0
  if processed_source.tokens[token_number].text.start_with?(SHEBANG)
    token = processed_source.tokens[token_number]
    token_number += 1
  end

  next_token = processed_source.tokens[token_number]
  if next_token&.text&.valid_encoding? && Encoding::ENCODING_PATTERN.match?(next_token.text)
    token = next_token
  end

  token
end

#line_range(line) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 206

def line_range(line)
  processed_source.buffer.line_range(line)
end

#missing_offense(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 158

def missing_offense(processed_source)
  range = source_range(processed_source.buffer, 0, 0)

  add_offense(range, message: MSG_MISSING) { |corrector| insert_comment(corrector) }
end

#missing_true_offense(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 164

def missing_true_offense(processed_source)
  range = source_range(processed_source.buffer, 0, 0)

  add_offense(range, message: MSG_MISSING_TRUE) { |corrector| insert_comment(corrector) }
end

#on_new_investigation

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 99

def on_new_investigation
  return if processed_source.tokens.empty?

  case style
  when :never
    ensure_no_comment(processed_source)
  when :always_true
    ensure_enabled_comment(processed_source)
  else
    ensure_comment(processed_source)
  end
end

#preceding_comment (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 210

def preceding_comment
  "#{FROZEN_STRING_LITERAL_ENABLED}\n"
end

#remove_comment(corrector, node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 186

def remove_comment(corrector, node)
  corrector.remove(range_with_surrounding_space(node.pos, side: :right))
end

#unnecessary_comment_offense(processed_source) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/frozen_string_literal_comment.rb', line 170

def unnecessary_comment_offense(processed_source)
  frozen_string_literal_comment = frozen_string_literal_comment(processed_source)

  add_offense(frozen_string_literal_comment.pos, message: MSG_UNNECESSARY) do |corrector|
    remove_comment(corrector, frozen_string_literal_comment)
  end
end