Use vector.empty() to check for emptyness

Summary:
Changelog: [Internal]

Using `empty()` vs `size() == 0` or `size() > 0`.
It is a more semantic way to check whether container is empty or not.

Reviewed By: JoshuaGross

Differential Revision: D21573183

fbshipit-source-id: b83283f687432a037941852114717a0f014e28db

React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.mm

@@ -519,7 +519,7 @@ static NSString *RCTRecursiveAccessibilityLabel(UIView *view)
 {
   auto const &accessibilityActions = _props->accessibilityActions;
 
-  if (accessibilityActions.size() == 0) {
+  if (accessibilityActions.empty()) {
     return nil;
   }
 

React/Fabric/Mounting/RCTComponentViewRegistry.mm

@@ -189,7 +189,7 @@ const NSInteger RCTComponentViewRegistryRecyclePoolMaxSize = 1024;
   RCTAssertMainQueue();
   auto &recycledViews = _recyclePool[componentHandle];
 
-  if (recycledViews.size() == 0) {
+  if (recycledViews.empty()) {
     return [self.componentViewFactory createComponentViewWithComponentHandle:componentHandle];
   }
 

React/Fabric/Mounting/RCTMountingManager.mm

@@ -274,7 +274,7 @@ static void RNPerformMountInstructions(
   auto surfaceId = transaction->getSurfaceId();
   auto &mutations = transaction->getMutations();
 
-  if (mutations.size() == 0) {
+  if (mutations.empty()) {
     return;
   }
 

React/Fabric/RCTSurfaceTouchHandler.mm

@@ -362,7 +362,7 @@ RCT_NOT_IMPLEMENTED(-(instancetype)initWithTarget : (id)target action : (SEL)act
 {
   [super reset];
 
-  if (_activeTouches.size() != 0) {
+  if (!_activeTouches.empty()) {
     std::vector<ActiveTouch> activeTouches;
     activeTouches.reserve(_activeTouches.size());
 

ReactCommon/fabric/components/image/ImageShadowNode.cpp

@@ -45,7 +45,7 @@ void ImageShadowNode::updateStateIfNeeded() {
 ImageSource ImageShadowNode::getImageSource() const {
   auto sources = getConcreteProps().sources;
 
-  if (sources.size() == 0) {
+  if (sources.empty()) {
     return {
         /* .type = */ ImageSource::Type::Invalid,
     };

ReactCommon/fabric/components/view/yoga/YogaLayoutableShadowNode.cpp

@@ -597,7 +597,7 @@ void YogaLayoutableShadowNode::ensureYogaChildrenOwnersConsistency() const {
   // The owner might be not equal to the `yogaNode_` though.
   auto &yogaChildren = yogaNode_.getChildren();
 
-  if (yogaChildren.size() > 0) {
+  if (!yogaChildren.empty()) {
     auto owner = yogaChildren.at(0)->getOwner();
     for (auto const &child : yogaChildren) {
       assert(child->getOwner() == owner);
@@ -617,7 +617,7 @@ void YogaLayoutableShadowNode::ensureYogaChildrenLookFine() const {
   for (auto const &yogaChild : yogaChildren) {
     assert(yogaChild->getContext());
     assert(yogaChild->getChildren().size() < 16384);
-    if (yogaChild->getChildren().size() > 0) {
+    if (!yogaChild->getChildren().empty()) {
       assert(!yogaChild->hasMeasureFunc());
     }
   }
@@ -635,7 +635,7 @@ void YogaLayoutableShadowNode::ensureYogaChildrenAlighment() const {
   auto &children = getChildren();
 
   if (getTraits().check(ShadowNodeTraits::Trait::LeafYogaNode)) {
-    assert(yogaChildren.size() == 0);
+    assert(yogaChildren.empty());
     return;
   }
 

ReactCommon/fabric/core/events/EventQueue.cpp

@@ -96,7 +96,7 @@ void EventQueue::flushStateUpdates() const {
   {
     std::lock_guard<std::mutex> lock(queueMutex_);
 
-    if (stateUpdateQueue_.size() == 0) {
+    if (stateUpdateQueue_.empty()) {
       return;
     }
 

ReactCommon/fabric/core/layout/LayoutableShadowNode.cpp

@@ -121,7 +121,7 @@ LayoutMetrics LayoutableShadowNode::getRelativeLayoutMetrics(
 
   auto ancestors = shadowNode.getFamily().getAncestors(ancestorShadowNode);
 
-  if (ancestors.size() == 0) {
+  if (ancestors.empty()) {
     return EmptyLayoutMetrics;
   }
 

ReactCommon/fabric/core/shadownode/ShadowNode.cpp

@@ -254,7 +254,7 @@ ShadowNode::Unshared ShadowNode::cloneTree(
         callback) const {
   auto ancestors = shadowNodeFamily.getAncestors(*this);
 
-  if (ancestors.size() == 0) {
+  if (ancestors.empty()) {
     return ShadowNode::Unshared{nullptr};
   }
 

ReactCommon/fabric/mounting/Differentiator.cpp

@@ -65,7 +65,7 @@ class TinyMap final {
 
   inline Iterator end() {
     // `back()` asserts on the vector being non-empty
-    if (vector_.size() == 0 || numErased_ == vector_.size()) {
+    if (vector_.empty() || numErased_ == vector_.size()) {
       return nullptr;
     }
 
@@ -112,7 +112,7 @@ class TinyMap final {
    */
   inline Iterator begin_() {
     // `front()` asserts on the vector being non-empty
-    if (vector_.size() == 0 || vector_.size() == numErased_) {
+    if (vector_.empty() || vector_.size() == numErased_) {
       return nullptr;
     }
 
@@ -125,9 +125,8 @@ class TinyMap final {
    * vector.
    */
   inline void cleanVector(bool forceClean = false) {
-    if ((numErased_ < (vector_.size() / 2) && !forceClean) ||
-        vector_.size() == 0 || numErased_ == 0 ||
-        numErased_ == erasedAtFront_) {
+    if ((numErased_ < (vector_.size() / 2) && !forceClean) || vector_.empty() ||
+        numErased_ == 0 || numErased_ == erasedAtFront_) {
       return;
     }
 
@@ -259,7 +258,7 @@ static void calculateShadowViewMutations(
     ShadowView const &parentShadowView,
     ShadowViewNodePair::List &&oldChildPairs,
     ShadowViewNodePair::List &&newChildPairs) {
-  if (oldChildPairs.size() == 0 && newChildPairs.size() == 0) {
+  if (oldChildPairs.empty() && newChildPairs.empty()) {
     return;
   }
 

ReactCommon/fabric/mounting/ShadowTree.cpp

@@ -41,7 +41,7 @@ static ShadowNode::Unshared progressState(ShadowNode const &shadowNode) {
   }
 
   auto newChildren = ShadowNode::ListOfShared{};
-  if (shadowNode.getChildren().size() > 0) {
+  if (!shadowNode.getChildren().empty()) {
     auto index = size_t{0};
     for (auto const &childNode : shadowNode.getChildren()) {
       auto newChildNode = progressState(*childNode);
@@ -170,7 +170,7 @@ static void updateMountedFlag(
     return;
   }
 
-  if (oldChildren.size() == 0 && newChildren.size() == 0) {
+  if (oldChildren.empty() && newChildren.empty()) {
     // Both lists are empty, nothing to do.
     return;
   }

ReactCommon/fabric/mounting/ShadowTreeRegistry.cpp

@@ -12,8 +12,7 @@ namespace react {
 
 ShadowTreeRegistry::~ShadowTreeRegistry() {
   assert(
-      registry_.size() == 0 &&
-      "Deallocation of non-empty `ShadowTreeRegistry`.");
+      registry_.empty() && "Deallocation of non-empty `ShadowTreeRegistry`.");
 }
 
 void ShadowTreeRegistry::add(std::unique_ptr<ShadowTree> &&shadowTree) const {

ReactCommon/fabric/scheduler/Scheduler.cpp

@@ -118,10 +118,10 @@ Scheduler::~Scheduler() {
       });
 
   assert(
-      surfaceIds.size() == 0 &&
+      surfaceIds.empty() &&
       "Scheduler was destroyed with outstanding Surfaces.");
 
-  if (surfaceIds.size() == 0) {
+  if (surfaceIds.empty()) {
     return;
   }
 
@@ -177,7 +177,7 @@ void Scheduler::renderTemplateToSurface(
     const std::string &uiTemplate) {
   SystraceSection s("Scheduler::renderTemplateToSurface");
   try {
-    if (uiTemplate.size() == 0) {
+    if (uiTemplate.empty()) {
       return;
     }
     NativeModuleRegistry nMR;

ReactCommon/fabric/uimanager/UIManager.cpp

@@ -153,7 +153,7 @@ ShadowNode::Shared UIManager::getNewestCloneOfShadowNode(
 
   auto ancestors = shadowNode.getFamily().getAncestors(*ancestorShadowNode);
 
-  if (ancestors.size() == 0) {
+  if (ancestors.empty()) {
     return nullptr;
   }