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Class: RuboCop::Cop::Style::HashTransformKeys

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::TargetRubyVersion, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
self, ::RuboCop::Cop::HashTransformMethod, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/hash_transform_keys.rb

Overview

Looks for uses of _.each_with_object({}) {…​}, \_.map {…​}.to_h, and Hash[\_.map {…​}] that are actually just transforming the keys of a hash, and tries to use a simpler & faster call to transform_keys instead. It should only be enabled on Ruby version 2.5 or newer. (transform_keys was added in Ruby 2.5.)

Examples:

# bad
{a: 1, b: 2}.each_with_object({}) { |(k, v), h| h[foo(k)] = v }
Hash[{a: 1, b: 2}.collect { |k, v| [foo(k), v] }]
{a: 1, b: 2}.map { |k, v| [k.to_s, v] }.to_h
{a: 1, b: 2}.to_h { |k, v| [k.to_s, v] }

# good
{a: 1, b: 2}.transform_keys { |k| foo(k) }
{a: 1, b: 2}.transform_keys { |k| k.to_s }

Cop Safety Information:

  • This cop is unsafe, as it can produce false positives if we are transforming an enumerable of key-value-like pairs that isn’t actually a hash, e.g.: [[k1, v1], [k2, v2], …​]

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::HashTransformMethod - Included

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.
.builtin?

Class Method Summary

::RuboCop::Cop::TargetRubyVersion - Extended

minimum_target_ruby_version, required_minimum_ruby_version, support_target_ruby_version?

::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

Cops (other than builtin) are encouraged to implement this.
.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, #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::HashTransformMethod - Included

#array_receiver?, #on_block, #on_csend, #on_send, #execute_correction, #extract_captures, #handle_possible_offense, #new_method_name, #on_bad_each_with_object, #on_bad_hash_brackets_map, #on_bad_map_to_h, #on_bad_to_h, #prepare_correction

::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, #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, #max_line_length,
#range_by_lines

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

#extract_captures(match) (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/hash_transform_keys.rb', line 84



def extract_captures(match)
  key_argname, key_body_expr, val_body_expr = *match
  Captures.new(key_argname, key_body_expr, val_body_expr)
end


  








  

    #new_method_name   (private)
  

  [ GitHub ]


  

  


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



def new_method_name
  'transform_keys'
end


  








  

    #on_bad_each_with_object(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/hash_transform_keys.rb', line 36



def_node_matcher :on_bad_each_with_object, <<~PATTERN
  (block
    (call !#array_receiver? :each_with_object (hash))
    (args
      (mlhs
        (arg $_)
        (arg _val))
      (arg _memo))
    (call (lvar _memo) :[]= $!`_memo $(lvar _val)))
PATTERN


  








  

    #on_bad_hash_brackets_map(node)  
  

  [ GitHub ]


  

  


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



def_node_matcher :on_bad_hash_brackets_map, <<~PATTERN
  (send
    (const _ :Hash)
    :[]
    (block
      (call !#array_receiver? {:map :collect})
      (args
        (arg $_)
        (arg _val))
      (array $_ $(lvar _val))))
PATTERN


  








  

    #on_bad_map_to_h(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/hash_transform_keys.rb', line 61



def_node_matcher :on_bad_map_to_h, <<~PATTERN
  (call
    (block
      (call !#array_receiver? {:map :collect})
      (args
        (arg $_)
        (arg _val))
      (array $_ $(lvar _val)))
    :to_h)
PATTERN


  








  

    #on_bad_to_h(node)  
  

  [ GitHub ]


  

  


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



def_node_matcher :on_bad_to_h, <<~PATTERN
  (block
    (call !#array_receiver? :to_h)
    (args
      (arg $_)
      (arg _val))
    (array $_ $(lvar _val)))
PATTERN