Class: RuboCop::Cop::Performance::UnfreezeString

Inherits:
Cop
  • Object
show all
Extended by:
TargetRubyVersion
Defined in:
lib/rubocop/cop/performance/unfreeze_string.rb

Overview

In Ruby 2.3 or later, use unary plus operator to unfreeze a string literal instead of `String#dup` and `String.new`. Unary plus operator is faster than `String#dup`.

Note: `String.new` (without operator) is not exactly the same as `+''`. These differ in encoding. `String.new.encoding` is always `ASCII-8BIT`. However, `(+'').encoding` is the same as script encoding(e.g. `UTF-8`). So, if you expect `ASCII-8BIT` encoding, disable this cop.

Examples:

# bad
''.dup
"something".dup
String.new
String.new('')
String.new('something')

# good
+'something'
+''

Constant Summary

MSG =
'Use unary plus to get an unfrozen string literal.'.freeze

Constants included from Util

Util::ASGN_NODES, Util::BYTE_ORDER_MARK, Util::CONDITIONAL_NODES, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::LOGICAL_OPERATOR_NODES, Util::MODIFIER_NODES, Util::OPERATOR_METHODS, Util::SHORTHAND_ASGN_NODES

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods included from TargetRubyVersion

minimum_target_ruby_version, support_target_ruby_version?

Methods inherited from Cop

#add_offense, all, autocorrect_incompatible_with, badge, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, #correct, department, #duplicate_location?, #excluded_file?, #find_location, #highlights, inherited, #initialize, #join_force?, lint?, match?, #message, #messages, non_rails, #parse, qualified_cop_name, #relevant_file?, #target_rails_version, #target_ruby_version

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search, #node_search_all, #node_search_body, #node_search_first

Methods included from AST::Sexp

#s

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?, comment_line?, double_quotes_required?, effective_column, ends_its_line?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, needs_escaping?, on_node, operator?, parentheses?, parenthesized_call?, precede?, range_between, range_by_whole_lines, range_with_surrounding_comma, range_with_surrounding_space, same_line?, source_range, strip_quotes, stripped_source_upto, symbol_without_quote?, to_string_literal, to_supported_styles, to_symbol_literal, within_node?

Methods included from PathUtil

absolute?, find_file_upwards, match_path?, pwd, relative_path, reset_pwd, smart_path

Constructor Details

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

Instance Method Details

#on_send(node) ⇒ Object



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# File 'lib/rubocop/cop/performance/unfreeze_string.rb', line 44

def on_send(node)
  add_offense(node) if dup_string?(node) || string_new?(node)
end