build_path_regex

# File actionview/lib/action_view/template/resolver.rb, line 19
      def build_path_regex
        handlers = Template::Handlers.extensions.map { |x| Regexp.escape(x) }.join("|")
        formats = Template::Types.symbols.map { |x| Regexp.escape(x) }.join("|")
        locales = "[a-z]{2}(?:-[A-Z]{2})?"
        variants = "[^.]*"

        %{
          \A
          (?:(?<prefix>.*)/)?
          (?<partial>_)?
          (?<action>.*?)
          (?:\.(?<locale>#{locales}))??
          (?:\.(?<format>#{formats}))??
          (?:\+(?<variant>#{variants}))??
          (?:\.(?<handler>#{handlers}))?
          \z
        }
      end