Class: RuboCop::Cop::Lint::UnreachableLoop

Inherits:
Base
  • Object
show all
Includes:
AllowedPattern
Defined in:
lib/rubocop/cop/lint/unreachable_loop.rb

Overview

Checks for loops that will have at most one iteration.

A loop that can never reach the second iteration is a possible error in the code. In rare cases where only one iteration (or at most one iteration) is intended behavior, the code should be refactored to use if conditionals.

Note
 Block methods that are used with Enumerables are considered to be loops.

AllowedPatterns can be used to match against the block receiver in order to allow code that would otherwise be registered as an offense (eg. times used not in an Enumerable context).

Examples:

# bad
while node
  do_something(node)
  node = node.parent
  break
end

# good
while node
  do_something(node)
  node = node.parent
end

# bad
def verify_list(head)
  item = head
  begin
    if verify(item)
      return true
    else
      return false
    end
  end while(item)
end

# good
def verify_list(head)
  item = head
  begin
    if verify(item)
      item = item.next
    else
      return false
    end
  end while(item)

  true
end

# bad
def find_something(items)
  items.each do |item|
    if something?(item)
      return item
    else
      raise NotFoundError
    end
  end
end

# good
def find_something(items)
  items.each do |item|
    if something?(item)
      return item
    end
  end
  raise NotFoundError
end

# bad
2.times { raise ArgumentError }

AllowedPatterns: ['(exactly|at_least|at_most)\(\d+\)\.times'] (default)


# good
exactly(2).times { raise StandardError }

Constant Summary collapse

MSG = 
'This loop will have at most one iteration.'
CONTINUE_KEYWORDS = 
%i[next redo].freeze

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #begin_investigation, callbacks_needed, #callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #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, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

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

#on_block(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unreachable_loop.rb', line 100

def on_block(node)
  check(node) if loop_method?(node)
end

#on_numblock(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unreachable_loop.rb', line 104

def on_numblock(node)
  check(node) if loop_method?(node)
end

#on_while(node) ⇒ Object Also known as: on_until, on_while_post, on_until_post, on_for 



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# File 'lib/rubocop/cop/lint/unreachable_loop.rb', line 92

def on_while(node)
  check(node)
end