Class: RuboCop::Cop::Lint::RedundantTypeConversion

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Defined in:
lib/rubocop/cop/lint/redundant_type_conversion.rb

Overview

Checks for redundant uses of to_s, to_sym, to_i, to_f, to_d, to_r, to_c, to_a, to_h, and to_set.

When one of these methods is called on an object of the same type, that object is returned, making the call unnecessary. The cop detects conversion methods called on object literals, class constructors, class [] methods, and the Kernel methods String(), Integer(), Float(), BigDecimal(), Rational(), Complex(), and Array().

Specifically, these cases are detected for each conversion method:

  • to_s when called on a string literal, interpolated string, heredoc, or with String.new or String().
  • to_sym when called on a symbol literal or interpolated symbol.
  • to_i when called on an integer literal or with Integer().
  • to_f when called on a float literal or with Float().
  • to_d when called with BigDecimal().
  • to_r when called on a rational literal or with Rational().
  • to_c when called on a complex literal or with Complex().
  • to_a when called on an array literal, or with Array.new, Array() or Array[].
  • to_h when called on a hash literal, or with Hash.new, Hash() or Hash[].
  • to_set when called on Set.new or Set[].

In all cases, chaining one of the same to_* conversion methods listed above is redundant.

The cop can also register an offense for chaining conversion methods on methods that are expected to return a specific type regardless of receiver (eg. foo.inspect.to_s and foo.to_json.to_s).

Examples:

# bad
"text".to_s
:sym.to_sym
42.to_i
8.5.to_f
12r.to_r
1i.to_c
[].to_a
{}.to_h
Set.new.to_set

# good
"text"
:sym
42
8.5
12r
1i
[]
{}
Set.new

# bad
Integer(var).to_i

# good
Integer(var)

# good - chaining to a type constructor with exceptions suppressed
# in this case, `Integer()` could return `nil`
Integer(var, exception: false).to_i

# bad
BigDecimal(var).to_d

# good
BigDecimal(var)

# bad - chaining the same conversion
foo.to_s.to_s

# good
foo.to_s

# bad - chaining a conversion to a method that is expected to return the same type
foo.inspect.to_s
foo.to_json.to_s

# good
foo.inspect
foo.to_json

Constant Summary collapse

MSG = 
'Redundant `%<method>s` detected.'
TYPED_METHODS =

Methods that already are expected to return a given type, which makes a further conversion redundant.

{ to_s: %i[inspect to_json] }.freeze
CONVERSION_METHODS = 
Set[*LITERAL_NODE_TYPES.keys].freeze
RESTRICT_ON_SEND = 
CONVERSION_METHODS + [:to_d]

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source, #project_index

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, #always_autocorrect?, autocorrect_incompatible_with, badge, #begin_investigation, #callbacks_needed, callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #cop_config, cop_name, #cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #parser_engine, #ready, #relevant_file?, requires_gem, #string_literals_frozen_by_default?, support_autocorrect?, support_multiple_source?, #target_gem_version, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

cop_dir_for, #exclude_limit, read_limits

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#array_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 167

def_node_matcher :array_constructor?, <<~PATTERN
  {
    (send (const {cbase nil?} :Array) {:new :[]} ...)
    #type_constructor?(:Array)
  }
PATTERN

#bigdecimal_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 152

def_node_matcher :bigdecimal_constructor?, <<~PATTERN
  #type_constructor?(:BigDecimal)
PATTERN

#complex_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 162

def_node_matcher :complex_constructor?, <<~PATTERN
  #type_constructor?(:Complex)
PATTERN

#exception_false_keyword_argument?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 191

def_node_matcher :exception_false_keyword_argument?, <<~PATTERN
  (hash (pair (sym :exception) false))
PATTERN

#float_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 147

def_node_matcher :float_constructor?, <<~PATTERN
  #type_constructor?(:Float)
PATTERN

#hash_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 175

def_node_matcher :hash_constructor?, <<~PATTERN
  {
    (block (send (const {cbase nil?} :Hash) :new) ...)
    (send (const {cbase nil?} :Hash) {:new :[]} ...)
    (send {nil? (const {cbase nil?} :Kernel)} :Hash ...)
  }
PATTERN

#integer_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 142

def_node_matcher :integer_constructor?, <<~PATTERN
  #type_constructor?(:Integer)
PATTERN

#on_send(node) ⇒ Object Also known as: on_csend

rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 196

def on_send(node)
  return if node.arguments.any? || hash_or_set_with_block?(node)

  receiver = find_receiver(node)
  return unless literal_receiver?(node, receiver) ||
                constructor?(node, receiver) ||
                chained_conversion?(node, receiver) ||
                chained_to_typed_method?(node, receiver)

  message = format(MSG, method: node.method_name)

  add_offense(node.loc.selector, message: message) do |corrector|
    corrector.remove(node.loc.dot.join(node.loc.end || node.loc.selector))
  end
end

#rational_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 157

def_node_matcher :rational_constructor?, <<~PATTERN
  #type_constructor?(:Rational)
PATTERN

#set_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 184

def_node_matcher :set_constructor?, <<~PATTERN
  {
    (send (const {cbase nil?} :Set) {:new :[]} ...)
  }
PATTERN

#string_constructor?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 134

def_node_matcher :string_constructor?, <<~PATTERN
  {
    (send (const {cbase nil?} :String) :new ...)
    #type_constructor?(:String)
  }
PATTERN

#type_constructor?(node, type_symbol) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_type_conversion.rb', line 129

def_node_matcher :type_constructor?, <<~PATTERN
  (send {nil? (const {cbase nil?} :Kernel)} %1 ...)
PATTERN