upsert

RichMutableMap.scala

implicit class RichMutableMap[K, V](val m: scala.collection.mutable.Map[K, V]) extends AnyVal {
  def upsert(key: K, insertValue: => V, updateValue: => V => V = null): scala.collection.mutable.Map[K, V] = {
    if (m.contains(key) && updateValue != null)
      m.update(key, updateValue(m(key)))
    else
      m.update(key, insertValue)

    m
  }
}