buildHydrationDiffNode() — react Function Reference

Source Code

packages/react-reconciler/src/ReactFiberHydrationContext.js lines 97–144

function buildHydrationDiffNode(
  fiber: Fiber,
  distanceFromLeaf: number,
): HydrationDiffNode {
  if (fiber.return === null) {
    // We're at the root.
    if (hydrationDiffRootDEV === null) {
      hydrationDiffRootDEV = {
        fiber: fiber,
        children: [],
        serverProps: undefined,
        serverTail: [],
        distanceFromLeaf: distanceFromLeaf,
      };
    } else if (hydrationDiffRootDEV.fiber !== fiber) {
      throw new Error(
        'Saw multiple hydration diff roots in a pass. This is a bug in React.',
      );
    } else if (hydrationDiffRootDEV.distanceFromLeaf > distanceFromLeaf) {
      hydrationDiffRootDEV.distanceFromLeaf = distanceFromLeaf;
    }
    return hydrationDiffRootDEV;
  }
  const siblings = buildHydrationDiffNode(
    fiber.return,
    distanceFromLeaf + 1,
  ).children;
  // The same node may already exist in the parent. Since we currently always render depth first
  // and rerender if we suspend or terminate early, if a shared ancestor was added we should still
  // be inside of that shared ancestor which means it was the last one to be added. If this changes
  // we may have to scan the whole set.
  if (siblings.length > 0 && siblings[siblings.length - 1].fiber === fiber) {
    const existing = siblings[siblings.length - 1];
    if (existing.distanceFromLeaf > distanceFromLeaf) {
      existing.distanceFromLeaf = distanceFromLeaf;
    }
    return existing;
  }
  const newNode: HydrationDiffNode = {
    fiber: fiber,
    children: [],
    serverProps: undefined,
    serverTail: [],
    distanceFromLeaf: distanceFromLeaf,
  };
  siblings.push(newNode);
  return newNode;
}