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Class: RuboCop::Cop::Lint::RedundantRegexpQuantifiers

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::RangeHelp, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb

Overview

Checks for redundant quantifiers inside Regexp literals.

It is always allowed when interpolation is used in a regexp literal, because it’s unknown what kind of string will be expanded as a result:

/(?:a*#{interpolation})?/x

Examples:

# bad
/(?:x+)+/

# good
/(?:x)+/

# good
/(?:x+)/

# bad
/(?:x+)?/

# good
/(?:x)*/

# good
/(?:x*)/

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.

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 a 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

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #string_literals_frozen_by_default?, #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::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

Actually private methods.
#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, #range_overlaps_offense?, #string_continuation, #string_continuation?, #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

#character_set?(expr) ⇒ Boolean (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 83



def character_set?(expr)
  expr.is?(:character, :set)
end


  








  

    #each_redundantly_quantified_pair(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 61



def each_redundantly_quantified_pair(node)
  seen = Set.new
  node.parsed_tree&.each_expression do |(expr)|
    next if seen.include?(expr) || !redundant_group?(expr) || !mergeable_quantifier(expr)

    expr.each_expression do |(subexp)|
      seen << subexp
      break unless redundantly_quantifiable?(subexp)

      yield(expr, subexp) if mergeable_quantifier(subexp)
    end
  end
end


  








  

    #mergeable_quantifier(expr)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 87



def mergeable_quantifier(expr)
  # Merging reluctant or possessive quantifiers would be more complex,
  # and Ruby does not emit warnings for these cases.
  return unless expr.quantifier&.greedy?

  # normalize quantifiers, e.g. "{1,}" => "+"
  case expr.quantity
  when [0, -1]
    '*'
  when [0, 1]
    '?'
  when [1, -1]
    '+'
  end
end


  








  

    #merged_quantifier(exp1, exp2)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 103



def merged_quantifier(exp1, exp2)
  quantifier1 = mergeable_quantifier(exp1)
  quantifier2 = mergeable_quantifier(exp2)
  if quantifier1 == quantifier2
    # (?:a+)+ equals (?:a+) ; (?:a*)* equals (?:a*) ; # (?:a?)? equals (?:a?)
    quantifier1
  else
    # (?:a+)*, (?:a+)?, (?:a*)+, (?:a*)?, (?:a?)+, (?:a?)* - all equal (?:a*)
    '*'
  end
end


  








  

    #message(group, child, replacement)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 119



def message(group, child, replacement)
  format(
    MSG_REDUNDANT_QUANTIFIER,
    inner_quantifier: child.quantifier.to_s,
    outer_quantifier: group.quantifier.to_s,
    replacement: replacement
  )
end


  








  

    #on_regexp(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 42



def on_regexp(node)
  return if node.interpolation?

  each_redundantly_quantified_pair(node) do |group, child|
    replacement = merged_quantifier(group, child)
    add_offense(
      quantifier_range(group, child),
      message: message(group, child, replacement)
    ) do |corrector|
      # drop outer quantifier
      corrector.replace(group.loc.quantifier, '')
      # replace inner quantifier
      corrector.replace(child.loc.quantifier, replacement)
    end
  end
end


  








  

    #quantifier_range(group, child)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 115



def quantifier_range(group, child)
  range_between(child.loc.quantifier.begin_pos, group.loc.quantifier.end_pos)
end


  








  

    #redundant_group?(expr)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 75



def redundant_group?(expr)
  expr.is?(:passive, :group) && expr.count { |child| child.type != :free_space } == 1
end


  








  

    #redundantly_quantifiable?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/redundant_regexp_quantifiers.rb', line 79



def redundantly_quantifiable?(node)
  redundant_group?(node) || character_set?(node) || node.terminal?
end