Scala SetBuffer

问题描述

我正在尝试将我的项目从Scala 2.12更新到Scala 2.13。我看到Scala团队在收藏方面做了很多更改。

我在Scala 2.12中有一个类似这样的SetBuffer

object SetBuffer extends MutableSetFactory[SetBuffer] {
  override def empty[Elem] = new SetBuffer[Elem](Set.empty)

  def apply[Elem](initialSet: Iterable[Elem]): SetBuffer[Elem] =
    new SetBuffer[Elem](initialSet.toSet)

  override def newBuilder[Elem] = new SetBufferBuilder[Elem]()

  class SetBufferBuilder[Elem] extends mutable.GrowingBuilder[Elem,SetBuffer[Elem]](SetBuffer.empty) {
    override def result(): SetBuffer[Elem] =
      new SetBuffer[Elem](elems.getDelta)
  }
}

class SetBuffer[ElemType](initialSet: Set[ElemType])
  extends mutable.HashSet[ElemType]
    with mutable.SetLike[ElemType,SetBuffer[ElemType]]
    with GenericSetTemplate[ElemType,SetBuffer] {

  initialSet.map(+=)

  override def companion: SetBuffer.type = SetBuffer

  def getDeltaBuffer: SetBuffer[ElemType] = {
    SetBuffer[ElemType]((this -- initialSet).toSeq:_*)
  }

  def getDelta: immutable.Set[ElemType] = {
    val deltaElements = (this -- initialSet).toSeq
    immutable.Set[ElemType](deltaElements: _*)
  }

  def ++(that: Iterable[ElemType]): SetBuffer[ElemType] =
    SetBuffer(toIterable ++ that)

  def append(that: Iterable[ElemType]): Unit = this ++= that

  def ++=(that: Iterable[ElemType]): Unit = that.map(+=)
}

Scala 2.13删除了mutable.SetLike[ElemType,SetBuffer[ElemType]]和GenericSetTemplate[ElemType,SetBuffer]并最终定为mutable.HashSet。有没有一种方法可以重写class SetBuffer[ElemType](initialSet: Set[ElemType])中的代码，使其行为相同并具有相同的性能？

解决方法

我想到两个主意。

首先-您可以尝试使用似乎不是最终版本的https://www.scala-lang.org/api/current/scala/collection/mutable/LinkedHashSet.html。我不确定是否有可能，而且我没有搜索性能特征。

第二，您要继承而不是继承。包装HashSet实例，并将所有调用委托给它。不过，您必须实现许多接口才能实现相同的行为。

scala scala scala-collections