build_host_url

# File actionpack/lib/action_dispatch/http/url.rb, line 105
          def build_host_url(host, port, protocol, options, path)
            if match = host.match(HOST_REGEXP)
              protocol ||= match[1] unless protocol == false
              host       = match[2]
              port       = match[3] unless options.key? :port
            end

            protocol = normalize_protocol protocol
            host     = normalize_host(host, options)

            result = protocol.dup

            if options[:user] && options[:password]
              result << "#{Rack::Utils.escape(options[:user])}:#{Rack::Utils.escape(options[:password])}@"
            end

            result << host
            normalize_port(port, protocol) { |normalized_port|
              result << ":#{normalized_port}"
            }

            result.concat path
          end