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Class: RuboCop::Cop::Style::CombinableLoops

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

Overview

Checks for places where multiple consecutive loops over the same data can be combined into a single loop. It is very likely that combining them will make the code more efficient and more concise.

Note
 Autocorrection is not applied when the block variable names differ in separate loops, as it is impossible to determine which variable name should be prioritized.

Examples:

# bad
def method
  items.each do |item|
    do_something(item)
  end

  items.each do |item|
    do_something_else(item)
  end
end

# good
def method
  items.each do |item|
    do_something(item)
    do_something_else(item)
  end
end

# bad
def method
  for item in items do
    do_something(item)
  end

  for item in items do
    do_something_else(item)
  end
end

# good
def method
  for item in items do
    do_something(item)
    do_something_else(item)
  end
end

# good
def method
  each_slice(2) { |slice| do_something(slice) }
  each_slice(3) { |slice| do_something(slice) }
end

Cop Safety Information:

  • The cop is unsafe, because the first loop might modify state that the second loop depends on; these two aren’t combinable.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, 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.

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::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

#collection_looping_method?(node) ⇒ Boolean (private)

[ GitHub ] 

  


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



def collection_looping_method?(node)
  method_name = node.method_name
  method_name.start_with?('each') || method_name.end_with?('_each')
end


  








  

    #combine_with_left_sibling(corrector, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/combinable_loops.rb', line 112



def combine_with_left_sibling(corrector, node)
  corrector.remove(node.left_sibling.body.source_range.end.join(node.left_sibling.loc.end))
  corrector.remove(node.source_range.begin.join(node.body.source_range.begin))

  correct_end_of_block(corrector, node)
end


  








  

    #correct_end_of_block(corrector, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/combinable_loops.rb', line 119



def correct_end_of_block(corrector, node)
  return unless node.left_sibling.respond_to?(:braces?)
  return if node.right_sibling&.block_type? || node.right_sibling&.numblock_type?

  end_of_block = node.left_sibling.braces? ? '}' : ' end'
  corrector.remove(node.loc.end)
  corrector.insert_before(node.source_range.end, end_of_block)
end


  








  

    #on_block(node)  
    Also known as: #on_numblock
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/combinable_loops.rb', line 68



def on_block(node)
  return unless node.parent&.begin_type?
  return unless collection_looping_method?(node)
  return unless same_collection_looping_block?(node, node.left_sibling)
  return unless node.body && node.left_sibling.body

  add_offense(node) do |corrector|
    next unless node.arguments == node.left_sibling.arguments

    combine_with_left_sibling(corrector, node)
  end
end


  








  

    #on_for(node)  
  

  [ GitHub ]


  

  


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



def on_for(node)
  return unless node.parent&.begin_type?
  return unless same_collection_looping_for?(node, node.left_sibling)

  add_offense(node) do |corrector|
    combine_with_left_sibling(corrector, node)
  end
end


  








  

    #on_numblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/combinable_loops.rb', line 82



alias on_numblock on_block


  








  

    #same_collection_looping_block?(node, sibling)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/combinable_loops.rb', line 100



def same_collection_looping_block?(node, sibling)
  return false if sibling.nil? || (!sibling.block_type? && !sibling.numblock_type?)

  sibling.method?(node.method_name) &&
    sibling.receiver == node.receiver &&
    sibling.send_node.arguments == node.send_node.arguments
end


  








  

    #same_collection_looping_for?(node, sibling)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/combinable_loops.rb', line 108



def same_collection_looping_for?(node, sibling)
  sibling&.for_type? && node.collection == sibling.collection
end