Sha256: 0dc8ecaf79a8b75bf5c39754c569b576d3ca84c55609997612ec57019bbc83f8
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Contents
# frozen_string_literal: true module RuboCop module Cop module Performance # 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' # +'' class UnfreezeString < Base extend AutoCorrector MSG = 'Use unary plus to get an unfrozen string literal.' RESTRICT_ON_SEND = %i[dup new].freeze def_node_matcher :dup_string?, <<~PATTERN (send {str dstr} :dup) PATTERN def_node_matcher :string_new?, <<~PATTERN { (send (const nil? :String) :new {str dstr}) (send (const nil? :String) :new) } PATTERN 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 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 end end end end
Version data entries
2 entries across 2 versions & 1 rubygems
Version | Path |
---|---|
rubocop-performance-1.11.5 | lib/rubocop/cop/performance/unfreeze_string.rb |
rubocop-performance-1.11.4 | lib/rubocop/cop/performance/unfreeze_string.rb |