Add cloneMultiple method to the ShadowNode class

packages/react-native/ReactCommon/react/renderer/core/ShadowNode.cpp

@@ -368,6 +368,80 @@ ShadowNode::Unshared ShadowNode::cloneTree(
   return std::const_pointer_cast<ShadowNode>(childNode);
 }
 
+ShadowNode::Unshared ShadowNode::cloneMultipleRecursive(
+    const ShadowNode& shadowNode,
+    const std::unordered_set<const ShadowNodeFamily*>& families,
+    const std::unordered_map<const ShadowNodeFamily*, int>& childrenCount,
+    const std::function<Unshared(
+        const ShadowNode& oldShadowNode,
+        const std::optional<ShadowNode::ListOfShared>& newChildren)>& callback)
+    const {
+  const auto family = &shadowNode.getFamily();
+  auto children = shadowNode.getChildren();
+  auto count = childrenCount.at(family);
+  auto shouldUpdateChildren = false;
+  std::optional<ShadowNode::ListOfShared> newChildren;
+
+  for (int i = 0; count > 0 && i < children.size(); i++) {
+    const auto childFamily = &children[i]->getFamily();
+    if (childrenCount.contains(childFamily)) {
+      count--;
+      shouldUpdateChildren = true;
+      children[i] = cloneMultipleRecursive(
+          *children[i], families, childrenCount, callback);
+    }
+  }
+
+  if (shouldUpdateChildren) {
+    newChildren = std::move(children);
+  }
+
+  if (families.contains(family)) {
+    return callback(shadowNode, newChildren);
+  }
+
+  return shadowNode.clone(
+      {ShadowNodeFragment::propsPlaceholder(),
+       newChildren
+           ? std::make_shared<ShadowNode::ListOfShared>(std::move(*newChildren))
+           : ShadowNodeFragment::childrenPlaceholder()});
+}
+
+ShadowNode::Unshared ShadowNode::cloneMultiple(
+    const std::unordered_set<const ShadowNodeFamily*>& families,
+    const std::function<Unshared(
+        const ShadowNode& oldShadowNode,
+        const std::optional<ShadowNode::ListOfShared>& newChildren)>& callback)
+    const {
+  std::unordered_map<const ShadowNodeFamily*, int> childrenCount;
+
+  for (const auto& family : families) {
+    if (childrenCount.contains(family)) {
+      continue;
+    }
+
+    childrenCount[family] = 0;
+
+    auto ancestor = family;
+    while ((ancestor != nullptr) && ancestor != this->family_.get()) {
+      ancestor = ancestor->parent_.lock().get();
+      auto ancestorIt = childrenCount.find(ancestor);
+      if (ancestorIt != childrenCount.end()) {
+        ancestorIt->second++;
+        break;
+      }
+
+      childrenCount[ancestor] = 1;
+    }
+  }
+
+  if (childrenCount.empty()) {
+    return ShadowNode::Unshared{nullptr};
+  }
+
+  return cloneMultipleRecursive(*this, families, childrenCount, callback);
+}
+
 #pragma mark - DebugStringConvertible
 
 #if RN_DEBUG_STRING_CONVERTIBLE

packages/react-native/ReactCommon/react/renderer/core/ShadowNode.h

@@ -107,6 +107,20 @@ class ShadowNode : public Sealable,
       const std::function<Unshared(const ShadowNode& oldShadowNode)>& callback)
       const;
 
+  /*
+   * Clones the nodes (and the subtree containing all the nodes) by
+   * replacing the `oldShadowNode` for every `shadowNodeFamily` from `families`
+   * with a node that `callback` returns.
+   *
+   * Returns `nullptr` if the operation cannot be performed successfully.
+   */
+  Unshared cloneMultiple(
+      const std::unordered_set<const ShadowNodeFamily*>& families,
+      const std::function<Unshared(
+          const ShadowNode& oldShadowNode,
+          const std::optional<ShadowNode::ListOfShared>& newChildren)>&
+          callback) const;
+
 #pragma mark - Getters
 
   ComponentName getComponentName() const;
@@ -252,6 +266,15 @@ class ShadowNode : public Sealable,
       const ShadowNode& sourceShadowNode,
       const Props::Shared& props);
 
+  Unshared cloneMultipleRecursive(
+      const ShadowNode& shadowNode,
+      const std::unordered_set<const ShadowNodeFamily*>& families,
+      const std::unordered_map<const ShadowNodeFamily*, int>& childrenCount,
+      const std::function<Unshared(
+          const ShadowNode& oldShadowNode,
+          const std::optional<ShadowNode::ListOfShared>& newChildren)>&
+          callback) const;
+
  protected:
   /*
    * Traits associated with the particular `ShadowNode` class and an instance of