第014讲：Scala中Map和HashMap源码剖析及代码实践(从1000个代码案例中学习人工智能和大数据实战)

第014讲：Scala中Map和HashMap源码剖析及代码实践

/**
 * A generic trait for immutable maps. Concrete classes have to provide
 * functionality for the abstract methods in `Map`:
 *
 * {
  {
  {
 *    def get(key: A): Option[B]
 *    def iterator: Iterator[(A, B)]
 *    def + [B1 >: B](kv: (A, B1)): Map[A, B1]
 *    def -(key: A): Map[A, B]
 * }}}
 *
 * @since 1
 */
trait Map[A, +B] extends Iterable[(A, B)]
//                    with GenMap[A, B]
                    with scala.collection.Map[A, B]
                    with MapLike[A, B, Map[A, B]] { self =>

  override def empty: Map[A, B] = Map.empty
  override def toMap[T, U](implicit ev: (A, B