From ec5b1fd259403b613100286fe73a0592b8d57781 Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Tue, 17 Jul 2018 22:41:32 -0700
Subject: [PATCH] Fabric: Optimized ShadowNode::replaceChild() with
 `suggestedIndex` argument

Summary:
@public
In most cases callsite knows probable index of replacing child node, hence it makes sense to provide this info to `replaceChild` to illuminate O(n) search in most cases.

Reviewed By: mdvacca

Differential Revision: D8814809

fbshipit-source-id: 0edf82878a72260365e2757beb3886ad07c7464d
---
 .../fabric/components/view/ConcreteViewShadowNode.h    |  4 ++--
 .../components/view/yoga/YogaLayoutableShadowNode.cpp  |  4 ++--
 ReactCommon/fabric/core/layout/LayoutableShadowNode.h  |  2 +-
 ReactCommon/fabric/core/shadownode/ShadowNode.cpp      | 10 +++++++++-
 ReactCommon/fabric/core/shadownode/ShadowNode.h        |  2 +-
 5 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/ReactCommon/fabric/components/view/ConcreteViewShadowNode.h b/ReactCommon/fabric/components/view/ConcreteViewShadowNode.h
index eb79d9223..0bddc1a7e 100644
--- a/ReactCommon/fabric/components/view/ConcreteViewShadowNode.h
+++ b/ReactCommon/fabric/components/view/ConcreteViewShadowNode.h
@@ -108,11 +108,11 @@ public:
     }
   }
 
-  LayoutableShadowNode *cloneAndReplaceChild(LayoutableShadowNode *child) override {
+  LayoutableShadowNode *cloneAndReplaceChild(LayoutableShadowNode *child, int suggestedIndex = -1) override {
     ensureUnsealed();
     auto childShadowNode = static_cast<const ConcreteViewShadowNode *>(child);
     auto clonedChildShadowNode = std::static_pointer_cast<ConcreteViewShadowNode>(childShadowNode->clone());
-    ShadowNode::replaceChild(childShadowNode->shared_from_this(), clonedChildShadowNode);
+    ShadowNode::replaceChild(childShadowNode->shared_from_this(), clonedChildShadowNode, suggestedIndex);
     return clonedChildShadowNode.get();
   }
 
diff --git a/ReactCommon/fabric/components/view/yoga/YogaLayoutableShadowNode.cpp b/ReactCommon/fabric/components/view/yoga/YogaLayoutableShadowNode.cpp
index df6e9d353..ddfc55180 100644
--- a/ReactCommon/fabric/components/view/yoga/YogaLayoutableShadowNode.cpp
+++ b/ReactCommon/fabric/components/view/yoga/YogaLayoutableShadowNode.cpp
@@ -79,7 +79,7 @@ void YogaLayoutableShadowNode::appendChild(YogaLayoutableShadowNode *child) {
   auto childYogaNodeRawPtr = &child->yogaNode_;
 
   if (childYogaNodeRawPtr->getOwner() != nullptr) {
-    child = static_cast<YogaLayoutableShadowNode *>(cloneAndReplaceChild(child));
+    child = static_cast<YogaLayoutableShadowNode *>(cloneAndReplaceChild(child, yogaNode_.getChildren().size()));
     childYogaNodeRawPtr = &child->yogaNode_;
     assert(childYogaNodeRawPtr->getOwner() == nullptr);
   }
@@ -154,7 +154,7 @@ YGNode *YogaLayoutableShadowNode::yogaNodeCloneCallbackConnector(YGNode *oldYoga
   auto oldNode =
     static_cast<YogaLayoutableShadowNode *>(oldYogaNode->getContext());
   auto clonedNode =
-    static_cast<YogaLayoutableShadowNode *>(parentNode->cloneAndReplaceChild(oldNode));
+    static_cast<YogaLayoutableShadowNode *>(parentNode->cloneAndReplaceChild(oldNode, childIndex));
   return &clonedNode->yogaNode_;
 }
 
diff --git a/ReactCommon/fabric/core/layout/LayoutableShadowNode.h b/ReactCommon/fabric/core/layout/LayoutableShadowNode.h
index 5eb5e8b8b..febc222cf 100644
--- a/ReactCommon/fabric/core/layout/LayoutableShadowNode.h
+++ b/ReactCommon/fabric/core/layout/LayoutableShadowNode.h
@@ -91,7 +91,7 @@ protected:
    * In case layout algorithm needs to mutate this (probably sealed) node,
    * it has to clone and replace it in the hierarchy before to do so.
    */
-  virtual LayoutableShadowNode *cloneAndReplaceChild(LayoutableShadowNode *child) = 0;
+  virtual LayoutableShadowNode *cloneAndReplaceChild(LayoutableShadowNode *child, int suggestedIndex = -1) = 0;
 
   /*
    * Sets layout metrics for the shadow node.
diff --git a/ReactCommon/fabric/core/shadownode/ShadowNode.cpp b/ReactCommon/fabric/core/shadownode/ShadowNode.cpp
index 5013b1426..91adbc16b 100644
--- a/ReactCommon/fabric/core/shadownode/ShadowNode.cpp
+++ b/ReactCommon/fabric/core/shadownode/ShadowNode.cpp
@@ -110,10 +110,18 @@ void ShadowNode::appendChild(const SharedShadowNode &child) {
   nonConstChildren->push_back(child);
 }
 
-void ShadowNode::replaceChild(const SharedShadowNode &oldChild, const SharedShadowNode &newChild) {
+void ShadowNode::replaceChild(const SharedShadowNode &oldChild, const SharedShadowNode &newChild, int suggestedIndex) {
   ensureUnsealed();
 
   auto nonConstChildren = std::const_pointer_cast<SharedShadowNodeList>(children_);
+
+  if (suggestedIndex != -1 && suggestedIndex < nonConstChildren->size()) {
+    if (nonConstChildren->at(suggestedIndex) == oldChild) {
+      (*nonConstChildren)[suggestedIndex] = newChild;
+      return;
+    }
+  }
+
   std::replace(nonConstChildren->begin(), nonConstChildren->end(), oldChild, newChild);
 }
 
diff --git a/ReactCommon/fabric/core/shadownode/ShadowNode.h b/ReactCommon/fabric/core/shadownode/ShadowNode.h
index 1f220f50b..a7bc76d40 100644
--- a/ReactCommon/fabric/core/shadownode/ShadowNode.h
+++ b/ReactCommon/fabric/core/shadownode/ShadowNode.h
@@ -93,7 +93,7 @@ public:
 #pragma mark - Mutating Methods
 
   void appendChild(const SharedShadowNode &child);
-  void replaceChild(const SharedShadowNode &oldChild, const SharedShadowNode &newChild);
+  void replaceChild(const SharedShadowNode &oldChild, const SharedShadowNode &newChild, int suggestedIndex = -1);
   void clearSourceNode();
 
   /*