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Class: RuboCop::Cop::Style::HashConversion

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/hash_conversion.rb

Overview

Checks the usage of pre-2.1 Hash[args] method of converting enumerables and sequences of values to hashes.

Correction code from splat argument (Hash[*ary]) is not simply determined. For example, Hash[*ary] can be replaced with ary.each_slice(2).to_h but it will be complicated. So, AllowSplatArgument option is true by default to allow splat argument for simple code.

Examples:

# bad
Hash[ary]

# good
ary.to_h

# bad
Hash[key1, value1, key2, value2]

# good
{key1 => value1, key2 => value2}

AllowSplatArgument: true (default)

# good
Hash[*ary]

AllowSplatArgument: false

# bad
Hash[*ary]

Cop Safety Information:

  • This cop’s autocorrection is unsafe because ArgumentError occurs if the number of elements is odd:

    Hash[[[1, 2], [3]]] #=> {1=>2, 3=>nil}
    [[1, 2], [5]].to_h  #=> wrong array length at 1 (expected 2, was 1) (ArgumentError)

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

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::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

#allowed_splat_argument?Boolean (readonly, private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 138

def allowed_splat_argument?
  cop_config.fetch('AllowSplatArgument', true)
end

Instance Method Details

#args_to_hash(args) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 131

def args_to_hash(args)
  content = args.each_slice(2)
                .map { |arg1, arg2| "#{arg1.source} => #{arg2.source}" }
                .join(', ')
  "{#{content}}"
end

#hash_from_array?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 54

def_node_matcher :hash_from_array?, '(send (const {nil? cbase} :Hash) :[] ...)'

#multi_argument(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 118

def multi_argument(node)
  if node.arguments.count.odd?
    add_offense(node, message: MSG_LITERAL_MULTI_ARG)
  else
    add_offense(node, message: MSG_LITERAL_MULTI_ARG) do |corrector|
      corrector.replace(node, args_to_hash(node.arguments))

      parent = node.parent
      add_parentheses(parent, corrector) if parent&.send_type? && !parent.parenthesized?
    end
  end
end

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 56

def on_send(node)
  return unless hash_from_array?(node)

  # There are several cases:
  # If there is one argument:
  #   Hash[ary] => ary.to_h
  #   Hash[*ary] => don't suggest corrections
  # If there is 0 or 2+ arguments:
  #   Hash[a1, a2, a3, a4] => {a1 => a2, a3 => a4}
  #   ...but don't suggest correction if there is odd number of them (it is a bug)
  node.arguments.count == 1 ? single_argument(node) : multi_argument(node)
end

#register_offense_for_hash(node, hash_argument) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 94

def register_offense_for_hash(node, hash_argument)
  add_offense(node, message: MSG_LITERAL_HASH_ARG) do |corrector|
    corrector.replace(node, "{#{hash_argument.source}}")

    parent = node.parent
    add_parentheses(parent, corrector) if parent&.send_type? && !parent.parenthesized?
  end
end

#register_offense_for_zip_method(node, zip_method) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 103

def register_offense_for_zip_method(node, zip_method)
  add_offense(node, message: MSG_TO_H) do |corrector|
    if zip_method.parenthesized?
      corrector.insert_before(zip_method.loc.end, '[]')
    else
      corrector.insert_after(zip_method, '([])')
    end
  end
end

#requires_parens?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 113

def requires_parens?(node)
  (node.call_type? && node.arguments.any? && !node.parenthesized?) ||
    node.or_type? || node.and_type?
end

#single_argument(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 71

def single_argument(node)
  first_argument = node.first_argument
  if first_argument.hash_type?
    register_offense_for_hash(node, first_argument)
  elsif first_argument.splat_type?
    add_offense(node, message: MSG_SPLAT) unless allowed_splat_argument?
  elsif use_zip_method_without_argument?(first_argument)
    register_offense_for_zip_method(node, first_argument)
  else
    add_offense(node, message: MSG_TO_H) do |corrector|
      replacement = first_argument.source
      replacement = "(#{replacement})" if requires_parens?(first_argument)
      corrector.replace(node, "#{replacement}.to_h")
    end
  end
end

#use_zip_method_without_argument?(first_argument) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/hash_conversion.rb', line 88

def use_zip_method_without_argument?(first_argument)
  return false unless first_argument&.send_type?

  first_argument.method?(:zip) && first_argument.arguments.empty?
end