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Class: RuboCop::Cop::Style::RedundantBegin

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/style/redundant_begin.rb

Overview

Checks for redundant begin blocks.

Currently it checks for code like this:

Examples:

# bad
def redundant
  begin
    ala
    bala
  rescue StandardError => e
    something
  end
end

# good
def preferred
  ala
  bala
rescue StandardError => e
  something
end

# bad
begin
  do_something
end

# good
do_something

# bad
# When using Ruby 2.5 or later.
do_something do
  begin
    something
  rescue => ex
    anything
  end
end

# good
# In Ruby 2.5 or later, you can omit {begin} in {do-end} block.
do_something do
  something
rescue => ex
  anything
end

# good
# Stabby lambdas don't support implicit {begin} in {do-end} blocks.
-> do
  begin
    foo
  rescue Bar
    baz
  end
end

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,
#arguments_range

A range containing the first to the last argument of a method call or method definition.
#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_gem_version

Returns a gems locked versions (i.e.
#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, #eol_comment, #eol_comment_would_be_inside_literal?, #heredoc_range, #line_with_eol_comment_too_long?, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #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

Class Method Details

.autocorrect_incompatible_with

[ GitHub ] 

  


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



def self.autocorrect_incompatible_with
  [Style::BlockDelimiters]
end


  







Instance Method Details



  

    #allowable_kwbegin?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


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



def allowable_kwbegin?(node)
  empty_begin?(node) ||
    begin_block_has_multiline_statements?(node) ||
    contain_rescue_or_ensure?(node) ||
    valid_context_using_only_begin?(node)
end


  








  

    #begin_block_has_multiline_statements?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 205



def begin_block_has_multiline_statements?(node)
  return false unless node.parent

  node.children.count >= 2
end


  








  

    #condition_range(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 197



def condition_range(node)
  range_between(node.loc.keyword.begin_pos, node.condition.source_range.end_pos)
end


  








  

    #contain_rescue_or_ensure?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 211



def contain_rescue_or_ensure?(node)
  first_child = node.children.first

  first_child.type?(:rescue, :ensure)
end


  








  

    #correct_modifier_form_after_multiline_begin_block(corrector, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 190



def correct_modifier_form_after_multiline_begin_block(corrector, node)
  condition_range = condition_range(node.parent)

  corrector.insert_after(node.children.first, " #{condition_range.source}")
  corrector.remove(range_by_whole_lines(condition_range, include_final_newline: true))
end


  








  

    #empty_begin?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 201



def empty_begin?(node)
  node.children.empty?
end


  








  

    #inspect_branches(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 228



def inspect_branches(node)
  node.branches.each do |branch|
    next unless branch&.kwbegin_type?
    next if branch.rescue_node || branch.ensure_node

    register_offense(branch)
  end
end


  








  

    #offensive_kwbegins(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 76



def_node_search :offensive_kwbegins, <<~PATTERN
  [(kwbegin ...) !#allowable_kwbegin?]
PATTERN


  








  

    #on_block(node)  
    Also known as: #on_numblock, #on_itblock
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 111



def on_block(node)
  return if target_ruby_version < 2.5
  return if node.send_node.lambda_literal?
  return if node.braces?
  return unless node.body&.kwbegin_type?

  register_offense(node.body)
end


  








  

    #on_case(node)  
    Also known as: #on_case_match
  

  [ GitHub ]


  

  


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



def on_case(node)
  inspect_branches(node)
end


  








  

    #on_case_match(node)  
  



  

    


Alias for #on_case.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 97



alias on_case_match on_case


  








  

    #on_def(node)  
    Also known as: #on_defs
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 80



def on_def(node)
  return unless node.body&.kwbegin_type?
  return if node.endless?

  register_offense(node.body)
end


  








  

    #on_defs(node)  
  



  

    


Alias for #on_def.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 86



alias on_defs on_def


  








  

    #on_if(node)  
  

  [ GitHub ]


  

  


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



def on_if(node)
  return if node.modifier_form?

  inspect_branches(node)
end


  








  

    #on_itblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 121



alias on_itblock on_block


  








  

    #on_kwbegin(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 123



def on_kwbegin(node)
  return unless (target_node = offensive_kwbegins(node).to_a.last)

  register_offense(target_node)
end


  








  

    #on_numblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 120



alias on_numblock on_block


  








  

    #on_until(node)  
  



  

    


Alias for #on_while.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 109



alias on_until on_while


  








  

    #on_while(node)  
    Also known as: #on_until
  

  [ GitHub ]


  

  


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



def on_while(node)
  return if node.modifier_form?

  body = node.body

  return unless body&.kwbegin_type?
  return if body.rescue_node || body.ensure_node

  register_offense(body)
end


  








  

    #register_offense(node)   (private)
  

  [ GitHub ]


  

  


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



def register_offense(node)
  offense_range = node.loc.begin

  add_offense(offense_range) do |corrector|
    if node.parent&.assignment?
      replace_begin_with_statement(corrector, offense_range, node)
    else
      remove_begin(corrector, offense_range, node)
    end

    if use_modifier_form_after_multiline_begin_block?(node)
      correct_modifier_form_after_multiline_begin_block(corrector, node)
    end
    corrector.remove(node.loc.end)
  end
end


  








  

    #remove_begin(corrector, offense_range, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 167



def remove_begin(corrector, offense_range, node)
  if node.parent.respond_to?(:endless?) && node.parent.endless?
    offense_range = range_with_surrounding_space(offense_range, newlines: true)
  end

  corrector.remove(offense_range)
end


  








  

    #replace_begin_with_statement(corrector, offense_range, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 155



def replace_begin_with_statement(corrector, offense_range, node)
  first_child = node.children.first

  source = first_child.source
  source = "(#{source})" if first_child.if_type? && first_child.modifier_form?

  corrector.replace(offense_range, source)
  corrector.remove(range_between(offense_range.end_pos, first_child.source_range.end_pos))

  restore_removed_comments(corrector, offense_range, node, first_child)
end


  








  

    #restore_removed_comments(corrector, offense_range, node, first_child)   (private)
  



  

    


Restore comments that occur between "begin" and "first_child".
These comments will be moved to above the assignment line.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 177



def restore_removed_comments(corrector, offense_range, node, first_child)
  comments_range = range_between(offense_range.end_pos, first_child.source_range.begin_pos)
  comments = comments_range.source

  corrector.insert_before(node.parent, comments) unless comments.blank?
end


  








  

    #use_modifier_form_after_multiline_begin_block?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 184



def use_modifier_form_after_multiline_begin_block?(node)
  return false unless (parent = node.parent)

  node.multiline? && parent.if_type? && parent.modifier_form?
end


  








  

    #valid_begin_assignment?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 224



def valid_begin_assignment?(node)
  node.parent&.assignment? && !node.children.one?
end


  








  

    #valid_context_using_only_begin?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_begin.rb', line 217



def valid_context_using_only_begin?(node)
  parent = node.parent

  valid_begin_assignment?(node) || parent&.post_condition_loop? ||
    parent&.send_type? || parent&.operator_keyword?
end