Class: RuboCop::Cop::Performance::DeleteSuffix

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
RegexpMetacharacter
Defined in:
lib/rubocop/cop/performance/delete_suffix.rb

Overview

In Ruby 2.5, `String#delete_suffix` has been added.

This cop identifies places where `gsub(/suffixz/, '')` and `sub(/suffixz/, '')` can be replaced by `delete_suffix('suffix')`.

This cop has `SafeMultiline` configuration option that `true` by default because `suffix$` is unsafe as it will behave incompatible with `delete_suffix?` for receiver is multiline string.

The `delete_suffix('suffix')` method is faster than `gsub(/suffixz/, '')`.

Examples:


# bad
str.gsub(/suffix\z/, '')
str.gsub!(/suffix\z/, '')

str.sub(/suffix\z/, '')
str.sub!(/suffix\z/, '')

# good
str.delete_suffix('suffix')
str.delete_suffix!('suffix')

SafeMultiline: true (default)


# good
str.gsub(/suffix$/, '')
str.gsub!(/suffix$/, '')
str.sub(/suffix$/, '')
str.sub!(/suffix$/, '')

SafeMultiline: false


# bad
str.gsub(/suffix$/, '')
str.gsub!(/suffix$/, '')
str.sub(/suffix$/, '')
str.sub!(/suffix$/, '')

Constant Summary collapse

MSG = 
'Use `%<prefer>s` instead of `%<current>s`.'
RESTRICT_ON_SEND = 
%i[gsub gsub! sub sub!].freeze
PREFERRED_METHODS = 
{
  gsub: :delete_suffix,
  gsub!: :delete_suffix!,
  sub: :delete_suffix,
  sub!: :delete_suffix!
}.freeze

Instance Method Summary collapse

Instance Method Details

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/performance/delete_suffix.rb', line 67

def on_send(node)
  return unless (receiver, bad_method, regexp_str, replace_string = delete_suffix_candidate?(node))
  return unless replace_string.empty?

  good_method = PREFERRED_METHODS[bad_method]

  message = format(MSG, current: bad_method, prefer: good_method)

  add_offense(node.loc.selector, message: message) do |corrector|
    regexp_str = drop_end_metacharacter(regexp_str)
    regexp_str = interpret_string_escapes(regexp_str)
    string_literal = to_string_literal(regexp_str)

    new_code = "#{receiver.source}.#{good_method}(#{string_literal})"

    corrector.replace(node, new_code)
  end
end