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Class: RuboCop::Cop::Style::RedundantInterpolation

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:
self, ::RuboCop::Cop::PercentLiteral, ::RuboCop::Cop::RangeHelp, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/redundant_interpolation.rb

Overview

Checks for strings that are just an interpolated expression.

Examples:

# bad
"#{@var}"

# good
@var.to_s

# good if @var is already a String
@var

Cop Safety Information:

  • Autocorrection is unsafe because when calling a destructive method to string, the resulting string may have different behavior or raise FrozenError.

    x = 'a'
y = "#{x}"
y << 'b'   # return 'ab'
x          # return 'a'
y = x.to_s
y << 'b'   # return 'ab'
x          # return 'ab'

x = 'a'.freeze
y = "#{x}"
y << 'b'   # return 'ab'.
y = x.to_s
y << 'b'   # raise `FrozenError`.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

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::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::PercentLiteral - Included

#begin_source, #percent_literal?, #process, #type

::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::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

Class Method Details

.autocorrect_incompatible_with

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 45



def self.autocorrect_incompatible_with
  [Style::LineEndConcatenation]
end


  







Instance Method Details



  

    #autocorrect_other(corrector, embedded_node, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 122



def autocorrect_other(corrector, embedded_node, node)
  loc = node.loc
  embedded_loc = embedded_node.loc

  corrector.replace(loc.begin, '')
  corrector.replace(loc.end, '')
  corrector.replace(embedded_loc.begin, '(')
  corrector.replace(embedded_loc.end, ').to_s')
end


  








  

    #autocorrect_single_variable_interpolation(corrector, embedded_node, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 105



def autocorrect_single_variable_interpolation(corrector, embedded_node, node)
  embedded_var = embedded_node.children.first

  source = if require_parentheses?(embedded_var)
             receiver = range_between(
               embedded_var.source_range.begin_pos, embedded_var.loc.selector.end_pos
             )
             arguments = embedded_var.arguments.map(&:source).join(', ')

             "#{receiver.source}(#{arguments})"
           else
             embedded_var.source
           end

  corrector.replace(node, "#{source}.to_s")
end


  








  

    #autocorrect_variable_interpolation(corrector, embedded_node, node)   (private)
  

  [ GitHub ]


  

  


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



def autocorrect_variable_interpolation(corrector, embedded_node, node)
  replacement = "#{embedded_node.source}.to_s"

  corrector.replace(node, replacement)
end


  








  

    #embedded_in_percent_array?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 95



def embedded_in_percent_array?(node)
  node.parent&.array_type? && percent_literal?(node.parent)
end


  








  

    #implicit_concatenation?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 91



def implicit_concatenation?(node)
  node.parent&.dstr_type?
end


  








  

    #interpolation?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 83



def interpolation?(node)
  variable_interpolation?(node) || node.begin_type?
end


  








  

    #on_dstr(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 49



def on_dstr(node)
  return unless single_interpolation?(node)

  add_offense(node) do |corrector|
    embedded_node = node.children.first

    if variable_interpolation?(embedded_node)
      autocorrect_variable_interpolation(corrector, embedded_node, node)
    elsif single_variable_interpolation?(embedded_node)
      autocorrect_single_variable_interpolation(corrector, embedded_node, node)
    else
      autocorrect_other(corrector, embedded_node, node)
    end
  end
end


  








  

    #require_parentheses?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 132



def require_parentheses?(node)
  node.send_type? && !node.arguments.count.zero? && !node.parenthesized_call?
end


  








  

    #single_interpolation?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 67



def single_interpolation?(node)
  node.children.one? &&
    interpolation?(node.children.first) &&
    !implicit_concatenation?(node) &&
    !embedded_in_percent_array?(node)
end


  








  

    #single_variable_interpolation?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


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



def single_variable_interpolation?(node)
  return false unless node.children.one?

  first_child = node.children.first

  variable_interpolation?(first_child) ||
    (first_child.send_type? && !first_child.operator_method?)
end


  








  

    #variable_interpolation?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_interpolation.rb', line 87



def variable_interpolation?(node)
  node.variable? || node.reference?
end