Class: RuboCop::Cop::Style::ArrayFirstLast

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Defined in:
lib/rubocop/cop/style/array_first_last.rb

Overview

Identifies usages of ‘arr` and `arr` and suggests to change them to use `arr.first` and `arr.last` instead.

The cop is disabled by default due to safety concerns.

Examples:

# bad
arr[0]
arr[-1]

# good
arr.first
arr.last
arr[0] = 2
arr[0][-2]

Constant Summary collapse

MSG = 
'Use `%<preferred>s`.'
RESTRICT_ON_SEND = 
%i[[]].freeze

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, #always_autocorrect?, autocorrect_incompatible_with, badge, #begin_investigation, #callbacks_needed, callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #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, #parser_engine, #ready, #relevant_file?, requires_gem, #string_literals_frozen_by_default?, 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_send(node) ⇒ Object

rubocop:disable Metrics/AbcSize



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# File 'lib/rubocop/cop/style/array_first_last.rb', line 35

def on_send(node)
  return unless node.arguments.size == 1 && node.first_argument.int_type?

  value = node.first_argument.value
  return unless [0, -1].include?(value)

  node = innermost_braces_node(node)
  return if node.parent && brace_method?(node.parent)

  preferred = (value.zero? ? 'first' : 'last')
  add_offense(node.loc.selector, message: format(MSG, preferred: preferred)) do |corrector|
    corrector.replace(node.loc.selector, ".#{preferred}")
  end
end