Mild refactor for reading

Author: som-snytt

library/src/scala/collection/immutable/HashSet.scala

@@ -606,48 +606,37 @@ private final class BitmapIndexedSetNode[A](
 
  if (element0 == element) {
  if (this.payloadArity == 2 && this.nodeArity == 0) {
- /*
- * Create new node with remaining pair. The new node will a) either become the new root
- * returned, or b) unwrapped and inlined during returning.
- */
+ // Create new node with remaining pair. The new node will a) either become the new root
+ // returned, or b) unwrapped and inlined during returning.
  val newDataMap = if (shift == 0) (dataMap ^ bitpos) else bitposFrom(maskFrom(elementHash, 0))
- if (index == 0)
- return new BitmapIndexedSetNode[A](newDataMap, 0, Array(getPayload(1)), Array(originalHashes(1)), size - 1, improve(originalHashes(1)))
- else
- return new BitmapIndexedSetNode[A](newDataMap, 0, Array(getPayload(0)), Array(originalHashes(0)), size - 1, improve(originalHashes(0)))
+ if (index == 0) new BitmapIndexedSetNode[A](newDataMap, 0, Array(getPayload(1)), Array(originalHashes(1)), size - 1, improve(originalHashes(1)))
+ else new BitmapIndexedSetNode[A](newDataMap, 0, Array(getPayload(0)), Array(originalHashes(0)), size - 1, improve(originalHashes(0)))
  }
- else return copyAndRemoveValue(bitpos, elementHash)
- } else return this
+ else copyAndRemoveValue(bitpos, elementHash)
+ }
+ else this
  }
-
- if ((nodeMap & bitpos) != 0) {
+ else if ((nodeMap & bitpos) != 0) {
  val index = indexFrom(nodeMap, mask, bitpos)
  val subNode = this.getNode(index)
-
  val subNodeNew = subNode.removed(element, originalHash, elementHash, shift + BitPartitionSize)
 
- if (subNodeNew eq subNode) return this
-
- // cache just in case subNodeNew is a hashCollision node, in which in which case a little arithmetic is avoided
- // in Vector#length
- val subNodeNewSize = subNodeNew.size
-
- if (subNodeNewSize == 1) {
- if (this.size == subNode.size) {
+ if (subNodeNew eq subNode) this
+ // if subNodeNew is a hashCollision node, size has cost in Vector#length
+ else subNodeNew.size match {
+ case 1 =>
  // subNode is the only child (no other data or node children of `this` exist)
  // escalate (singleton or empty) result
- return subNodeNew.asInstanceOf[BitmapIndexedSetNode[A]]
- } else {
+ if (this.size == subNode.size) subNodeNew.asInstanceOf[BitmapIndexedSetNode[A]]
  // inline value (move to front)
- return copyAndMigrateFromNodeToInline(bitpos, elementHash, subNode, subNodeNew)
- }
- } else if (subNodeNewSize > 1) {
- // modify current node (set replacement node)
- return copyAndSetNode(bitpos, subNode, subNodeNew)
+ else copyAndMigrateFromNodeToInline(bitpos, elementHash, subNode, subNodeNew)
+ case subNodeNewSize if subNodeNewSize > 1 =>
+  // modify current node (set replacement node)
+  copyAndSetNode(bitpos, subNode, subNodeNew)
+ case _ => this
  }
  }
-
- this
+ else this
  }
  /** Variant of `removed` which will perform mutation on only the top-level node (`this`), rather than return a new
  * node
@@ -1428,6 +1417,8 @@ private final class BitmapIndexedSetNode[A](
  override def hashCode(): Int =
  throw new UnsupportedOperationException("Trie nodes do not support hashing.")
 
+ override def toString: String = f"BitmapIndexedSetNode(size=$size, dataMap=$dataMap%x, nodeMap=$nodeMap%x)" // content=${scala.runtime.ScalaRunTime.stringOf(content)}
+
  override def copy(): BitmapIndexedSetNode[A] = {
  val contentClone = content.clone()
  val contentLength = contentClone.length
@@ -2077,7 +2068,7 @@ private[collection] final class HashSetBuilder[A] extends ReusableBuilder[A, Has
  ensureUnaliased()
  val h = elem.##
  val im = improve(h)
- update(rootNode, elem, h, im, 0)
+ update(rootNode, elem, originalHash = h, elementHash = im, shift = 0)
  this
  }