Class BlockNode

frontend/lib/src/render-tree/BlockNode.ts:29–121

 * A container AppNode that holds children.
 */
export class BlockNode implements AppNode {
  public readonly children: AppNode[]

  public readonly deltaBlock: BlockProto

  public readonly scriptRunId: string

  public readonly fragmentId?: string

  public readonly deltaMsgReceivedAt?: number

  // The hash of the script that created this block.
  public readonly activeScriptHash: string

  public constructor(
    activeScriptHash: string,
    children?: AppNode[],
    deltaBlock?: BlockProto,
    scriptRunId?: string,
    fragmentId?: string,
    deltaMsgReceivedAt?: number
  ) {
    this.activeScriptHash = activeScriptHash
    this.children = children ?? []
    this.deltaBlock = deltaBlock ?? new BlockProto({})
    this.scriptRunId = scriptRunId ?? NO_SCRIPT_RUN_ID
    this.fragmentId = fragmentId
    this.deltaMsgReceivedAt = deltaMsgReceivedAt
  }

  /** True if this Block has no children. */
  public get isEmpty(): boolean {
    return this.children.length === 0
  }

  public replaceTransientNodeWithSelf(node: TransientNode): AppNode {
    if (node.scriptRunId !== this.scriptRunId) {
      // This TransientNode was not defined in this script run, so we return the block node
      // to replace everything
      return this
    }

    // It's essentially an empty transient node, so we return the block node
    if (node.transientNodes.length === 0) {
      return this
    }

    // At this point, we should clear the transient nodes that are stale
    const newTransientNodes = node.updateTransientNodes(
      element =>
        element.accept(new ClearStaleNodeVisitor(this.scriptRunId)) as
          | ElementNode
          | undefined
    )

    // The resulting transient node is empty, so we return this node
    if (newTransientNodes.length === 0) {
      return this