added apply, unapplySeq and newBuilder to ArraySeq companion

Author: ghik

compat/src/main/scala-2.11_2.12/scala/collection/compat/immutable/ArraySeq.scala

@@ -58,7 +58,7 @@ abstract class ArraySeq[+T] extends AbstractSeq[T] with IndexedSeq[T] {
   /** Creates new builder for this collection ==> move to subclasses
    */
   override protected[this] def newBuilder: Builder[T, ArraySeq[T]] =
-    new WrappedArrayBuilder[T](elemTag).mapResult(w => ArraySeq.unsafeWrapArray(w.array))
+    ArraySeq.newBuilder[T](elemTag)
 
 }
 
@@ -69,6 +69,20 @@ object ArraySeq {
   private val EmptyArraySeq           = new ofRef[AnyRef](new Array[AnyRef](0))
   def empty[T <: AnyRef]: ArraySeq[T] = EmptyArraySeq.asInstanceOf[ArraySeq[T]]
 
+  def newBuilder[T](implicit elemTag: ClassTag[T]): Builder[T, ArraySeq[T]] =
+    new WrappedArrayBuilder[T](elemTag).mapResult(w => unsafeWrapArray(w.array))
+
+  def apply[T](elems: T*)(implicit elemTag: ClassTag[T]): ArraySeq[T] = {
+    if (elems.isEmpty) empty[T]
+    else {
+      val b = newBuilder[T]
+      b ++= elems
+      b.result()
+    }
+  }
+
+  def unapplySeq[T](seq: ArraySeq[T]): Some[Seq[T]] = Some(seq)
+
   /**
    * Wrap an existing `Array` into an `ArraySeq` of the proper primitive specialization type
    * without copying.