123456789_123456789_123456789_123456789_123456789_

Class: RuboCop::Cop::Performance::DeletePrefix

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, TargetRubyVersion, AutoCorrector, Base
Instance Chain:
self, ::RuboCop::Cop::RegexpMetacharacter, Base
Inherits: Base
  • Object
Defined in: lib/rubocop/cop/performance/delete_prefix.rb

Overview

In Ruby 2.5, String#delete_prefix has been added.

This cop identifies places where gsub(/\Aprefix/, '') and sub(/\Aprefix/, '') can be replaced by delete_prefix('prefix').

This cop has SafeMultiline configuration option that true by default because ^prefix is unsafe as it will behave incompatible with delete_prefix for receiver is multiline string.

The delete_prefix('prefix') method is faster than gsub(/\Aprefix/, '').

Examples:

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

str.sub(/\Aprefix/, '')
str.sub!(/\Aprefix/, '')

# good
str.delete_prefix('prefix')
str.delete_prefix!('prefix')

SafeMultiline: true (default)

# good
str.gsub(/^prefix/, '')
str.gsub!(/^prefix/, '')
str.sub(/^prefix/, '')
str.sub!(/^prefix/, '')

SafeMultiline: false

# bad
str.gsub(/^prefix/, '')
str.gsub!(/^prefix/, '')
str.sub(/^prefix/, '')
str.sub!(/^prefix/, '')

Cop Safety Information:

  • This cop is unsafe because Pathname has sub but not delete_prefix.

Constant Summary

Instance Attribute Summary

::RuboCop::Cop::RegexpMetacharacter - Included

#safe_multiline?

Instance Method Summary

::RuboCop::Cop::RegexpMetacharacter - Included

#drop_end_metacharacter, #drop_start_metacharacter, #literal_at_end?, #literal_at_end_with_backslash_z?, #literal_at_end_with_dollar?, #literal_at_start?, #literal_at_start_with_backslash_a?, #literal_at_start_with_caret?

Instance Method Details

#on_csend(node)

Alias for #on_send.

[ GitHub ] 

  


# File 'lib/rubocop/cop/performance/delete_prefix.rb', line 90



alias on_csend on_send


  








  

    #on_send(node)  
    Also known as: #on_csend
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/performance/delete_prefix.rb', line 71



def on_send(node)
  return unless (receiver, bad_method, regexp_str, replace_string = delete_prefix_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_start_metacharacter(regexp_str)
    regexp_str = interpret_string_escapes(regexp_str)
    string_literal = to_string_literal(regexp_str)

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

    corrector.replace(node, new_code)
  end
end