query builder helper for play

UriBuilder.scala

object UriBuilder {
  def base(base: String) = new UriBuilder(base, Vector.empty, Vector.empty)
}

case class UriBuilder(
    base: String, path: Vector[String], query: Vector[(String, String)]) {

  def path(segments: String*): UriBuilder =
    new UriBuilder(base, segments.toVector, Vector.empty)

  def query(values: (String, String)*): UriBuilder =
    copy(query = query ++ values.toVector)

  def queryOpt(values: (String, Option[String])*): UriBuilder =
    copy(query = query ++ values.toVector.collect{ case (k, Some(v)) => k -> v })

  def build(values: (String, String)*): String = {
    val qValues = values.toVector ++ query
    val lengthEstimate =
      base.length + path.foldLeft(0)((a, v) => a + v.length + 1) +
      qValues.foldLeft(0)((a, kv) => kv._1.length + kv._2.length + 2)
    val sb = new StringBuilder(lengthEstimate)
    sb.append(base)
    path.addString(sb, "/", "/", "")
    def toQueryParam(start: Char, p: (String, String)) =
      sb.append(start).append(p._1).append('=').append(p._2)
    qValues match {
      case head +: tail =>
        toQueryParam('?', head)
        tail.foreach(kv => toQueryParam('&', kv))
      case _ =>
    }
    sb.toString()
  }
}