Class: RuboCop::Cop::Performance::StringReplacement

Inherits:
Cop
  • Object
show all
Defined in:
lib/rubocop/cop/performance/string_replacement.rb

Overview

This cop identifies places where ‘gsub` can be replaced by `tr` or `delete`.

Examples:

@bad
'abc'.gsub('b', 'd')
'abc'.gsub('a', '')
'abc'.gsub(/a/, 'd')
'abc'.gsub!('a', 'd')

@good
'abc'.gsub(/.*/, 'a')
'abc'.gsub(/a+/, 'd')
'abc'.tr('b', 'd')
'a b c'.delete(' ')

Constant Summary collapse

MSG = 
'Use `%s` instead of `%s`.'.freeze
DETERMINISTIC_REGEX = 
/\A(?:#{LITERAL_REGEX})+\Z/
REGEXP_CONSTRUCTOR_METHODS = 
[:new, :compile].freeze
GSUB_METHODS = 
[:gsub, :gsub!].freeze
DETERMINISTIC_TYPES = 
[:regexp, :str, :send].freeze
DELETE = 
'delete'.freeze
TR = 
'tr'.freeze
BANG = 
'!'.freeze
SINGLE_QUOTE = 
"'".freeze

Constants included from Util

Util::ASGN_NODES, Util::BYTE_ORDER_MARK, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::OPERATOR_METHODS, Util::SHORTHAND_ASGN_NODES, Util::STRING_ESCAPES, Util::STRING_ESCAPE_REGEX

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods inherited from Cop

#add_offense, all, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, #cop_name, cop_name, cop_type, #correct, #debug?, #details, #display_cop_names?, #display_style_guide?, #excluded_file?, #extra_details?, inherited, #initialize, #join_force?, lint?, match?, non_rails, #parse, qualified_cop_name, #reference_url, #relevant_file?, #style_guide_url, #target_ruby_version

Methods included from Sexp

#s

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search_body

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

begins_its_line?, block_length, comment_line?, directions, double_quotes_acceptable?, double_quotes_required?, effective_column, ends_its_line?, first_part_of_call_chain, interpret_string_escapes, line_range, move_pos, numeric_range_size, on_node, operator?, parentheses?, parenthesized_call?, range_with_surrounding_comma, range_with_surrounding_space, source_range, strip_quotes, ternary_op?, to_string_literal, to_symbol_literal, within_node?

Methods included from PathUtil

absolute?, hidden?, issue_deprecation_warning, match_path?, relative_path

Constructor Details

This class inherits a constructor from RuboCop::Cop::Cop

Instance Method Details

#autocorrect(node) ⇒ Object 



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# File 'lib/rubocop/cop/performance/string_replacement.rb', line 59

def autocorrect(node)
  _string, method, first_param, second_param = *node
  first_source, = first_source(first_param)
  second_source, = *second_param

  if regex?(first_param)
    first_source = interpret_string_escapes(first_source)
  end

  replacement_method = replacement_method(method,
                                          first_source,
                                          second_source)

  lambda do |corrector|
    corrector.replace(node.loc.selector, replacement_method)
    unless first_param.str_type?
      corrector.replace(first_param.source_range,
                        to_string_literal(first_source))
    end

    if second_source.empty? && first_source.length == 1
      remove_second_param(corrector, node, first_param)
    end
  end
end

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/performance/string_replacement.rb', line 33

def on_send(node)
  _string, method, first_param, second_param = *node
  return unless GSUB_METHODS.include?(method)
  return unless string?(second_param)
  return unless DETERMINISTIC_TYPES.include?(first_param.type)

  first_source, options = first_source(first_param)
  second_source, = *second_param

  return if first_source.nil?

  if regex?(first_param)
    return unless first_source =~ DETERMINISTIC_REGEX
    return if options
    # This must be done after checking DETERMINISTIC_REGEX
    # Otherwise things like \s will trip us up
    first_source = interpret_string_escapes(first_source)
  end

  return if first_source.length != 1
  return unless second_source.length <= 1

  message = message(method, first_source, second_source)
  add_offense(node, range(node), message)
end