ConstArray.scala

package vector

import scala.reflect.ClassTag
import collection.{immutable,mutable}
import mutable.Cloneable

/** Const Interface for a Wrapped Array
 * An instance of this class is either a MutableArray or ImmutableArray
 */
sealed abstract class ConstArray[+A] protected (arr: Array[A])
  extends collection.AbstractSeq[A]
    with collection.IndexedSeq[A]
    with collection.IndexedSeqOps[A,ConstArray,ConstArray[A]] {
  export arr.{apply,length}
  
  def frozen(): ImmutableArray[A]
}

final class MutableArray[A] private (arr: Array[A])
  extends ConstArray[A](arr)
    with mutable.IndexedSeq[A]
    with mutable.IndexedSeqOps[A,MutableArray,MutableArray[A]] {
  export arr.update
  
  override def iterableFactory = collection.ClassTagSeqFactory.AnySeqDelegate(MutableArray)
  override def clone() = new MutableArray[A](arr.clone())
  
  def frozen() = ImmutableArray.freeze(arr)
}

object MutableArray extends collection.StrictOptimizedClassTagSeqFactory[MutableArray] {
  override def empty[A: ClassTag]: MutableArray[A] = new MutableArray[A](Array.empty)
  override def from[E: ClassTag](it: IterableOnce[E]): MutableArray[E] = new MutableArray[E](Array.from(it))
  override def newBuilder[A: ClassTag]: mutable.Builder[A, MutableArray[A]] = mutable.ArrayBuilder.make[A].mapResult(new MutableArray[A](_))
}

final class ImmutableArray[+A] private (arr: Array[A])
  extends ConstArray[A](arr)
    with immutable.IndexedSeq[A] {
  
  def this(xs: A*)(using ClassTag[A]) = this(Array[A](xs:_*))
  override def iterableFactory = collection.ClassTagSeqFactory.AnySeqDelegate(ImmutableArray)
  
  def frozen() = this
}

object ImmutableArray extends collection.StrictOptimizedClassTagSeqFactory[ImmutableArray] {
  def freeze[T](arr: Array[T]) = new ImmutableArray[T](arr.clone())
  override def empty[A: ClassTag]: ImmutableArray[A] = new ImmutableArray[A](Array.empty)
  override def from[E: ClassTag](it: IterableOnce[E]): ImmutableArray[E] = new ImmutableArray[E](Array.from(it))
  override def newBuilder[A: ClassTag]: mutable.Builder[A, ImmutableArray[A]] = mutable.ArrayBuilder.make[A].mapResult(new ImmutableArray[A](_))
}