class RuboCop::Cop::Performance::UnfreezeString
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`). Therefore, auto-correction is unsafe. So, if you expect `ASCII-8BIT` encoding, disable this cop.
@example
# bad ''.dup "something".dup String.new String.new('') String.new('something') # good +'something' +''
Constants
- MSG
- RESTRICT_ON_SEND
Public Instance Methods
on_send(node)
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# File lib/rubocop/cop/performance/unfreeze_string.rb, line 44 def on_send(node) return unless dup_string?(node) || string_new?(node) add_offense(node) do |corrector| string_value = "+#{string_value(node)}" string_value = "(#{string_value})" if node.parent&.send_type? corrector.replace(node, string_value) end end
Private Instance Methods
string_value(node)
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# File lib/rubocop/cop/performance/unfreeze_string.rb, line 57 def string_value(node) if node.receiver.source == 'String' && node.method?(:new) node.arguments.empty? ? "''" : node.first_argument.source else node.receiver.source end end