interpolation.rb

module I18n
  extend CurrentVendor

  # Implemented to support method call on translation keys
  INTERPOLATION_WITH_METHOD_PATTERN = Regexp.union(
    /%%/,
    /%\{(\w+)\}/,                               # matches placeholders like "%{foo}"
    /%<(\w+)>(.*?\d*\.?\d*[bBdiouxXeEfgGcps])/, # matches placeholders like "%<foo>.d"
    /%\{(\w+)\.(\w+)\}/ # matches placeholders like "%{foo.upcase}"
  )

  class << self
    def interpolate_hash(string, values)
      string.gsub(INTERPOLATION_WITH_METHOD_PATTERN) do |match|
        if match == '%%'
          '%'
        else
          key = (Regexp.last_match[1] || Regexp.last_match[2] || Regexp.last_match[4]).to_sym
          value = values.key?(key) ? values[key] : "%{#{key}}" #  raise(MissingInterpolationArgument.new(key, values, string))
          value = value.call(values) if value.respond_to?(:call)
          if Regexp.last_match[3]
            "%#{Regexp.last_match[3]}" % value
          else
            (Regexp.last_match[5] ? value.send(Regexp.last_match[5]) : value)
          end
        end
      end
    end

    # Точная копия translate, только с нужным backend-ом
    def vt(*args)
      options  = args.last.is_a?(Hash) ? args.pop.dup : {}
      key      = args.shift
      backend  = current_vendor.i18n
      locale   = options.delete(:locale) || config.locale
      handling = (options.delete(:throw) && :throw) || (options.delete(:raise) && :raise) # TODO deprecate :raise

      enforce_available_locales!(locale)
      raise I18n::ArgumentError if key.is_a?(String) && key.empty?

      result = catch(:exception) do
        if key.is_a?(Array)
          key.map { |k| backend.translate(locale, k, options) }
        else
          backend.translate(locale, key, options)
        end
      end
      result.is_a?(MissingTranslation) ? handle_exception(handling, result, locale, key, options) : result
    end
  end
end