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Class: RuboCop::Cop::Style::RedundantFetchBlock

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/style/redundant_fetch_block.rb

Overview

Identifies places where fetch(key) { value } can be replaced by fetch(key, value).

In such cases fetch(key, value) method is faster than fetch(key) { value }.

Note
The block string 'value' in hash.fetch(:key) { 'value' } is detected when frozen string literal magic comment is enabled (i.e. # frozen_string_literal: true), but not when disabled.

Examples:

SafeForConstants: false (default)

# bad
hash.fetch(:key) { 5 }
hash.fetch(:key) { true }
hash.fetch(:key) { nil }
array.fetch(5) { :value }
ENV.fetch(:key) { 'value' }

# good
hash.fetch(:key, 5)
hash.fetch(:key, true)
hash.fetch(:key, nil)
array.fetch(5, :value)
ENV.fetch(:key, 'value')

SafeForConstants: true

# bad
ENV.fetch(:key) { VALUE }

# good
ENV.fetch(:key, VALUE)

Cop Safety Information:

  • This cop is unsafe because it cannot be guaranteed that the receiver does not have a different implementation of fetch.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::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::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::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 Attribute Details

#check_for_constant?Boolean (readonly, private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 111

def check_for_constant?
  cop_config['SafeForConstants']
end

#check_for_string?Boolean (readonly, private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 115

def check_for_string?
  frozen_string_literals_enabled?
end

Instance Method Details

#basic_literal?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 74

def basic_literal?(node)
  node&.basic_literal?
end

#build_bad_method(send, body) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 104

def build_bad_method(send, body)
  key = send.children[2].source
  block = body ? "{ #{body.source} }" : '{}'

  "fetch(#{key}) #{block}"
end

#build_good_method(send, body) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 97

def build_good_method(send, body)
  key = send.children[2].source
  default_value = body ? body.source : 'nil'

  "fetch(#{key}, #{default_value})"
end

#const_type?(node) ⇒ Boolean (private)

[ GitHub ]

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

def const_type?(node)
  node&.const_type?
end

#fetch_range(send, node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 93

def fetch_range(send, node)
  range_between(send.loc.selector.begin_pos, node.loc.end.end_pos)
end

#on_block(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 55

def on_block(node) # rubocop:disable InternalAffairs/NumblockHandler
  redundant_fetch_block_candidate?(node) do |send, body|
    return if should_not_check?(send, body)

    range = fetch_range(send, node)
    good = build_good_method(send, body)
    bad = build_bad_method(send, body)

    add_offense(range, message: format(MSG, good: good, bad: bad)) do |corrector|
      _, _, key = send.children
      default_value = body ? body.source : 'nil'

      corrector.replace(range, "fetch(#{key.source}, #{default_value})")
    end
  end
end

#rails_cache?(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 89

def_node_matcher :rails_cache?, <<~PATTERN
  (send (const _ :Rails) :cache)
PATTERN

#redundant_fetch_block_candidate?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 48

def_node_matcher :redundant_fetch_block_candidate?, <<~PATTERN
  (block
    $(call _ :fetch _)
    (args)
    ${nil? #basic_literal? #const_type?})
PATTERN

#should_not_check?(send, body) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_fetch_block.rb', line 82

def should_not_check?(send, body)
  (body&.const_type? && !check_for_constant?) ||
    (body&.str_type? && !check_for_string?) ||
    rails_cache?(send.receiver)
end