Method update

src/Map.js:273–336

(ownerID, shift, keyHash, key, value, didChangeSize, didAlter)

  }

  update(ownerID, shift, keyHash, key, value, didChangeSize, didAlter) {
    if (keyHash === undefined) {
      keyHash = hash(key);
    }
    const keyHashFrag = (shift === 0 ? keyHash : keyHash >>> shift) & MASK;
    const bit = 1 << keyHashFrag;
    const bitmap = this.bitmap;
    const exists = (bitmap & bit) !== 0;

    if (!exists && value === NOT_SET) {
      return this;
    }

    const idx = popCount(bitmap & (bit - 1));
    const nodes = this.nodes;
    const node = exists ? nodes[idx] : undefined;
    const newNode = updateNode(
      node,
      ownerID,
      shift + SHIFT,
      keyHash,
      key,
      value,
      didChangeSize,
      didAlter
    );

    if (newNode === node) {
      return this;
    }

    if (!exists && newNode && nodes.length >= MAX_BITMAP_INDEXED_SIZE) {
      return expandNodes(ownerID, nodes, bitmap, keyHashFrag, newNode);
    }

    if (
      exists &&
      !newNode &&
      nodes.length === 2 &&
      isLeafNode(nodes[idx ^ 1])
    ) {
      return nodes[idx ^ 1];
    }

    if (exists && newNode && nodes.length === 1 && isLeafNode(newNode)) {
      return newNode;
    }

    const isEditable = ownerID && ownerID === this.ownerID;
    const newBitmap = exists ? (newNode ? bitmap : bitmap ^ bit) : bitmap | bit;
    const newNodes = exists
      ? newNode
        ? setAt(nodes, idx, newNode, isEditable)
        : spliceOut(nodes, idx, isEditable)
      : spliceIn(nodes, idx, newNode, isEditable);

    if (isEditable) {
      this.bitmap = newBitmap;