Method modify

packages/effect/src/internal/hashMap/node.ts:192–243

(
    edit: number,
    shift: number,
    f: HashMap.UpdateFn<V>,
    hash: number,
    key: K,
    size: SizeRef
  )

  ) {}

  modify(
    edit: number,
    shift: number,
    f: HashMap.UpdateFn<V>,
    hash: number,
    key: K,
    size: SizeRef
  ): Node<K, V> {
    const mask = this.mask
    const children = this.children
    const frag = hashFragment(shift, hash)
    const bit = toBitmap(frag)
    const indx = fromBitmap(mask, bit)
    const exists = mask & bit
    const canEdit = canEditNode(this, edit)

    if (!exists) {
      const _newChild = new EmptyNode<K, V>().modify(edit, shift + SIZE, f, hash, key, size)
      if (!_newChild) return this
      return children.length >= MAX_INDEX_NODE ?
        expand(edit, frag, _newChild, mask, children) :
        new IndexedNode(edit, mask | bit, arraySpliceIn(canEdit, indx, _newChild, children))
    }

    const current = children[indx]!
    const child = current.modify(edit, shift + SIZE, f, hash, key, size)

    if (current === child) return this
    let bitmap = mask
    let newChildren
    if (isEmptyNode(child)) {
      // remove
      bitmap &= ~bit
      if (!bitmap) return new EmptyNode()
      if (children.length <= 2 && isLeafNode(children[indx ^ 1]!)) {
        return children[indx ^ 1]! // collapse
      }

      newChildren = arraySpliceOut(canEdit, indx, children)
    } else {
      // modify
      newChildren = arrayUpdate(canEdit, indx, child, children)
    }

    if (canEdit) {
      this.mask = bitmap
      this.children = newChildren
      return this
    }

    return new IndexedNode(edit, bitmap, newChildren)
  }
}

/** @internal */