Fabric: Unifying usage of autos

Summary:
I was watching a classic magnificent talk about modern C++ by Herb Sutter and I was totally sold on double down on using `auto` in our codebase. Surprisingly, 95% of the code base already follows Herb's guidence; I just changed the last 5% to make it consistent.
All those changes must work *exactly* like it was before.
The talk: https://youtu.be/xnqTKD8uD64?t=28m25s

Reviewed By: mdvacca

Differential Revision: D9753301

fbshipit-source-id: 9629aa485a5d6e51806cc96306c297284d4f90b8

ReactCommon/fabric/attributedstring/AttributedString.cpp

@@ -40,7 +40,7 @@ const std::vector<Fragment> &AttributedString::getFragments() const {
 }
 
 std::string AttributedString::getString() const {
-  std::string string;
+  auto string = std::string {};
   for (const auto &fragment : fragments_) {
     string += fragment.string;
   }
@@ -50,7 +50,7 @@ std::string AttributedString::getString() const {
 #pragma mark - DebugStringConvertible
 
 SharedDebugStringConvertibleList AttributedString::getDebugChildren() const {
-  SharedDebugStringConvertibleList list = {};
+  auto list = SharedDebugStringConvertibleList {};
 
   for (auto &&fragment : fragments_) {
     auto propsList = fragment.textAttributes.DebugStringConvertible::getDebugProps();

ReactCommon/fabric/attributedstring/conversions.h

@@ -83,8 +83,8 @@ inline void fromDynamic(const folly::dynamic &value, FontVariant &result) {
 }
 
 inline std::string toString(const FontVariant &fontVariant) {
-  std::string result;
-  std::string separator = ", ";
+  auto result = std::string {};
+  auto separator = std::string {", "};
   if ((int)fontVariant & (int)FontVariant::SmallCaps) { result += "small-caps" + separator; }
   if ((int)fontVariant & (int)FontVariant::OldstyleNums) { result += "oldstyle-nums" + separator; }
   if ((int)fontVariant & (int)FontVariant::LiningNums) { result += "lining-nums" + separator; }

ReactCommon/fabric/components/image/ImageShadowNode.cpp

@@ -59,7 +59,7 @@ ImageSource ImageShadowNode::getImageSource() const {
   auto targetImageArea = size.width * size.height * scale * scale;
   auto bestFit = kFloatMax;
 
-  ImageSource bestSource;
+  auto bestSource = ImageSource {};
 
   for (const auto &source : sources) {
     auto sourceSize = source.size;

ReactCommon/fabric/components/root/RootProps.cpp

@@ -14,7 +14,7 @@ namespace facebook {
 namespace react {
 
 static YGStyle yogaStyleFromLayoutConstraints(const LayoutConstraints &layoutConstraints) {
-  YGStyle yogaStyle;
+  auto yogaStyle = YGStyle {};
   yogaStyle.minDimensions[YGDimensionWidth] =
     yogaStyleValueFromFloat(layoutConstraints.minimumSize.width);
   yogaStyle.minDimensions[YGDimensionHeight] =

ReactCommon/fabric/components/scrollview/ScrollViewProps.cpp

@@ -47,7 +47,7 @@ ScrollViewProps::ScrollViewProps(const ScrollViewProps &sourceProps, const RawPr
 #pragma mark - DebugStringConvertible
 
 SharedDebugStringConvertibleList ScrollViewProps::getDebugProps() const {
-  ScrollViewProps defaultScrollViewProps;
+  auto defaultScrollViewProps = ScrollViewProps {};
 
   return
     ViewProps::getDebugProps() +

ReactCommon/fabric/components/scrollview/ScrollViewShadowNode.cpp

@@ -19,7 +19,7 @@ const char ScrollViewComponentName[] = "ScrollView";
 void ScrollViewShadowNode::updateLocalData() {
   ensureUnsealed();
 
-  Rect contentBoundingRect;
+  auto contentBoundingRect = Rect {};
   for (const auto &childNode : getLayoutableChildNodes()) {
     contentBoundingRect.unionInPlace(childNode->getLayoutMetrics().frame);
   }

ReactCommon/fabric/components/text/basetext/BaseTextProps.cpp

@@ -16,7 +16,7 @@ namespace facebook {
 namespace react {
 
 static TextAttributes convertRawProp(const RawProps &rawProps, const TextAttributes defaultTextAttributes) {
-  TextAttributes textAttributes;
+  auto textAttributes = TextAttributes {};
 
   // Color
   textAttributes.foregroundColor = convertRawProp(rawProps, "color", defaultTextAttributes.foregroundColor);

ReactCommon/fabric/components/text/basetext/BaseTextShadowNode.cpp

@@ -20,13 +20,13 @@ AttributedString BaseTextShadowNode::getAttributedString(
   const TextAttributes &textAttributes,
   const SharedShadowNode &parentNode
 ) const {
-  AttributedString attributedString;
+  auto attributedString = AttributedString {};
 
   for (const auto &childNode : parentNode->getChildren()) {
     // RawShadowNode
     auto rawTextShadowNode = std::dynamic_pointer_cast<const RawTextShadowNode>(childNode);
     if (rawTextShadowNode) {
-      AttributedString::Fragment fragment;
+      auto fragment = AttributedString::Fragment {};
       fragment.string = rawTextShadowNode->getProps()->text;
       fragment.textAttributes = textAttributes;
       fragment.parentShadowNode = parentNode;
@@ -37,14 +37,14 @@ AttributedString BaseTextShadowNode::getAttributedString(
     // TextShadowNode
     auto textShadowNode = std::dynamic_pointer_cast<const TextShadowNode>(childNode);
     if (textShadowNode) {
-      TextAttributes localTextAttributes = textAttributes;
+      auto localTextAttributes = textAttributes;
       localTextAttributes.apply(textShadowNode->getProps()->textAttributes);
       attributedString.appendAttributedString(textShadowNode->getAttributedString(localTextAttributes, textShadowNode));
       continue;
     }
 
     // Any other kind of ShadowNode
-    AttributedString::Fragment fragment;
+    auto fragment = AttributedString::Fragment {};
     fragment.shadowNode = childNode;
     fragment.textAttributes = textAttributes;
     attributedString.appendFragment(fragment);

ReactCommon/fabric/components/text/paragraph/ParagraphProps.cpp

@@ -15,7 +15,7 @@ namespace facebook {
 namespace react {
 
 static ParagraphAttributes convertRawProp(const RawProps &rawProps, const ParagraphAttributes &defaultParagraphAttributes) {
-  ParagraphAttributes paragraphAttributes;
+  auto paragraphAttributes = ParagraphAttributes {};
 
   paragraphAttributes.maximumNumberOfLines = convertRawProp(rawProps, "numberOfLines", defaultParagraphAttributes.maximumNumberOfLines);
   paragraphAttributes.ellipsizeMode = convertRawProp(rawProps, "ellipsizeMode", defaultParagraphAttributes.ellipsizeMode);

ReactCommon/fabric/components/view/ConcreteViewShadowNode.h

@@ -116,7 +116,7 @@ class ConcreteViewShadowNode:
 #pragma mark - DebugStringConvertible
 
   SharedDebugStringConvertibleList getDebugProps() const override {
-    SharedDebugStringConvertibleList list = {};
+    auto list = SharedDebugStringConvertibleList {};
 
     auto basePropsList = ShadowNode::getDebugProps();
     std::move(basePropsList.begin(), basePropsList.end(), std::back_inserter(list));

ReactCommon/fabric/components/view/conversions.h

@@ -72,9 +72,8 @@ inline folly::Optional<Float> optionalFloatFromYogaValue(const YGValue &value, f
 }
 
 inline LayoutMetrics layoutMetricsFromYogaNode(YGNode &yogaNode) {
-  LayoutMetrics layoutMetrics;
-
-  YGLayout layout = yogaNode.getLayout();
+  auto layoutMetrics = LayoutMetrics {};
+  auto layout = yogaNode.getLayout();
 
   layoutMetrics.frame = Rect {
     Point {
@@ -227,7 +226,7 @@ inline void fromDynamic(const folly::dynamic &value, YGFloatOptional &result) {
 
 inline void fromDynamic(const folly::dynamic &value, Transform &result) {
   assert(value.isArray());
-  Transform transformMatrix;
+  auto transformMatrix = Transform {};
   for (const auto &tranformConfiguration : value) {
     assert(tranformConfiguration.isObject());
     auto pair = *tranformConfiguration.items().begin();
@@ -237,7 +236,7 @@ inline void fromDynamic(const folly::dynamic &value, Transform &result) {
     if (operation == "matrix") {
       assert(parameters.isArray());
       assert(parameters.size() == transformMatrix.matrix.size());
-      int i = 0;
+      auto i = 0;
       for (auto item : parameters) {
         transformMatrix.matrix[i++] = (Float)item.asDouble();
       }
@@ -407,10 +406,10 @@ inline std::string toString(const std::array<YGValue, YGEdgeCount> &value) {
     {"left", "top", "right", "bottom", "start", "end", "horizontal", "vertical", "all"}
   };
 
-  std::string result;
-  std::string separator = ", ";
+  auto result = std::string {};
+  auto separator = std::string {", "};
 
-  for (int i = 0; i < YGEdgeCount; i++) {
+  for (auto i = 0; i < YGEdgeCount; i++) {
     if (value[i].unit == YGUnitUndefined) {
       continue;
     }

ReactCommon/fabric/components/view/primitives.h

@@ -24,41 +24,40 @@ struct Transform {
   }};
 
   static Transform Identity() {
-    Transform transform;
-    return transform;
+    return {};
   }
 
   static Transform Perspective(const Float &perspective) {
-    Transform transform;
+    auto transform = Transform {};
     transform.matrix[11] = -1.0 / perspective;
     return transform;
   }
 
   static Transform Scale(const Float &factorX, const Float &factorY, const Float &factorZ) {
-    Transform transform;
+    auto transform = Transform {};
     transform.matrix[0] = factorX;
     transform.matrix[5] = factorY;
     transform.matrix[10] = factorZ;
     return transform;
   }
 
   static Transform Translate(const Float &x, const Float &y, const Float &z) {
-    Transform transform;
+    auto transform = Transform {};
     transform.matrix[12] = x;
     transform.matrix[13] = y;
     transform.matrix[14] = z;
     return transform;
   }
 
   static Transform Skew(const Float &x, const Float &y) {
-    Transform transform;
+    auto transform = Transform {};
     transform.matrix[4] = std::tan(x);
     transform.matrix[1] = std::tan(y);
     return transform;
   }
 
   static Transform RotateX(const Float &radians) {
-    Transform transform;
+    auto transform = Transform {};
     transform.matrix[5] = std::cos(radians);
     transform.matrix[6] = std::sin(radians);
     transform.matrix[9] = -std::sin(radians);
@@ -67,7 +66,7 @@ struct Transform {
   }
 
   static Transform RotateY(const Float &radians) {
-    Transform transform;
+    auto transform = Transform {};
     transform.matrix[0] = std::cos(radians);
     transform.matrix[2] = -std::sin(radians);
     transform.matrix[8] = std::sin(radians);
@@ -76,7 +75,7 @@ struct Transform {
   }
 
   static Transform RotateZ(const Float &radians) {
-    Transform transform;
+    auto transform = Transform {};
     transform.matrix[0] = std::cos(radians);
     transform.matrix[1] = std::sin(radians);
     transform.matrix[4] = -std::sin(radians);
@@ -85,15 +84,15 @@ struct Transform {
   }
 
   static Transform Rotate(const Float &x, const Float &y, const Float &z) {
-    Transform transform;
+    auto transform = Transform {};
     if (x != 0) { transform = transform * Transform::RotateX(x); }
     if (y != 0) { transform = transform * Transform::RotateY(y); }
     if (z != 0) { transform = transform * Transform::RotateZ(z); }
     return transform;
   }
 
   bool operator ==(const Transform& rhs) const {
-    for (int i = 0; i < 16; i++) {
+    for (auto i = 0; i < 16; i++) {
       if (matrix[i] != rhs.matrix[i]) {
         return false;
       }
@@ -110,15 +109,15 @@ struct Transform {
       return rhs;
     }
 
-    const Transform &lhs = *this;
-    Transform result;
+    const auto &lhs = *this;
+    auto result = Transform {};
 
-    Float lhs00 = lhs.matrix[0], lhs01 = lhs.matrix[1], lhs02 = lhs.matrix[2], lhs03 = lhs.matrix[3],
+    auto lhs00 = lhs.matrix[0], lhs01 = lhs.matrix[1], lhs02 = lhs.matrix[2], lhs03 = lhs.matrix[3],
     lhs10 = lhs.matrix[4], lhs11 = lhs.matrix[5], lhs12 = lhs.matrix[6], lhs13 = lhs.matrix[7],
     lhs20 = lhs.matrix[8], lhs21 = lhs.matrix[9], lhs22 = lhs.matrix[10], lhs23 = lhs.matrix[11],
     lhs30 = lhs.matrix[12], lhs31 = lhs.matrix[13], lhs32 = lhs.matrix[14], lhs33 = lhs.matrix[15];
 
-    Float rhs0 = rhs.matrix[0], rhs1 = rhs.matrix[1], rhs2 = rhs.matrix[2], rhs3 = rhs.matrix[3];
+    auto rhs0 = rhs.matrix[0], rhs1 = rhs.matrix[1], rhs2 = rhs.matrix[2], rhs3 = rhs.matrix[3];
     result.matrix[0] = rhs0 * lhs00 + rhs1 * lhs10 + rhs2 * lhs20 + rhs3 * lhs30;
     result.matrix[1] = rhs0 * lhs01 + rhs1 * lhs11 + rhs2 * lhs21 + rhs3 * lhs31;
     result.matrix[2] = rhs0 * lhs02 + rhs1 * lhs12 + rhs2 * lhs22 + rhs3 * lhs32;

ReactCommon/fabric/components/view/propsConversions.h

@@ -20,7 +20,7 @@ static inline std::array<YGValue, 2> convertRawProp(
   const std::array<YGValue, 2> &sourceValue,
   const std::array<YGValue, 2> &defaultValue
 ) {
-  std::array<YGValue, 2> dimentions = defaultValue;
+  auto dimentions = defaultValue;
   dimentions[YGDimensionWidth] = convertRawProp(rawProps, widthName, sourceValue[YGDimensionWidth], defaultValue[YGDimensionWidth]);
   dimentions[YGDimensionHeight] = convertRawProp(rawProps, heightName, sourceValue[YGDimensionHeight], defaultValue[YGDimensionWidth]);
   return dimentions;
@@ -33,7 +33,7 @@ static inline std::array<YGValue, YGEdgeCount> convertRawProp(
   const std::array<YGValue, YGEdgeCount> &sourceValue,
   const std::array<YGValue, YGEdgeCount> &defaultValue
 ) {
-  std::array<YGValue, YGEdgeCount> result = defaultValue;
+  auto result = defaultValue;
   result[YGEdgeLeft] = convertRawProp(rawProps, prefix + "Left" + suffix, sourceValue[YGEdgeLeft], defaultValue[YGEdgeLeft]);
   result[YGEdgeTop] = convertRawProp(rawProps, prefix + "Top" + suffix, sourceValue[YGEdgeTop], defaultValue[YGEdgeTop]);
   result[YGEdgeRight] = convertRawProp(rawProps, prefix + "Right" + suffix, sourceValue[YGEdgeRight], defaultValue[YGEdgeRight]);
@@ -51,7 +51,7 @@ static inline std::array<YGValue, YGEdgeCount> convertRawProp(
   const std::array<YGValue, YGEdgeCount> &sourceValue,
   const std::array<YGValue, YGEdgeCount> &defaultValue
 ) {
-  std::array<YGValue, YGEdgeCount> result = defaultValue;
+  auto result = defaultValue;
   result[YGEdgeLeft] = convertRawProp(rawProps, "left", sourceValue[YGEdgeLeft], defaultValue[YGEdgeLeft]);
   result[YGEdgeTop] = convertRawProp(rawProps, "top", sourceValue[YGEdgeTop], defaultValue[YGEdgeTop]);
   result[YGEdgeRight] = convertRawProp(rawProps, "right", sourceValue[YGEdgeRight], defaultValue[YGEdgeRight]);
@@ -62,7 +62,7 @@ static inline std::array<YGValue, YGEdgeCount> convertRawProp(
 }
 
 static inline YGStyle convertRawProp(const RawProps &rawProps, const YGStyle &sourceValue) {
-  YGStyle yogaStyle;
+  auto yogaStyle = YGStyle {};
   yogaStyle.direction = convertRawProp(rawProps, "direction", sourceValue.direction, yogaStyle.direction);
   yogaStyle.flexDirection = convertRawProp(rawProps, "flexDirection", sourceValue.flexDirection, yogaStyle.flexDirection);
   yogaStyle.justifyContent = convertRawProp(rawProps, "justifyContent", sourceValue.justifyContent, yogaStyle.justifyContent);

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

@@ -28,7 +28,7 @@ YogaStylableProps::YogaStylableProps(const YogaStylableProps &sourceProps, const
 #pragma mark - DebugStringConvertible
 
 SharedDebugStringConvertibleList YogaStylableProps::getDebugProps() const {
-  YGStyle defaultYogaStyle;
+  auto defaultYogaStyle = YGStyle {};
   return {
     debugStringConvertibleItem("direction", yogaStyle.direction, defaultYogaStyle.direction),
     debugStringConvertibleItem("flexDirection", yogaStyle.flexDirection, defaultYogaStyle.flexDirection),

ReactCommon/fabric/core/layout/LayoutableShadowNode.cpp

@@ -78,12 +78,12 @@ void LayoutableShadowNode::layout(LayoutContext layoutContext) {
     child->ensureUnsealed();
     child->setHasNewLayout(false);
 
-    const LayoutMetrics childLayoutMetrics = child->getLayoutMetrics();
+    const auto childLayoutMetrics = child->getLayoutMetrics();
     if (childLayoutMetrics.displayType == DisplayType::None) {
       continue;
     }
 
-    LayoutContext childLayoutContext = LayoutContext(layoutContext);
+    auto childLayoutContext = LayoutContext(layoutContext);
     childLayoutContext.absolutePosition += childLayoutMetrics.frame.origin;
 
     child->layout(layoutContext);
@@ -95,7 +95,7 @@ void LayoutableShadowNode::layoutChildren(LayoutContext layoutContext) {
 }
 
 SharedDebugStringConvertibleList LayoutableShadowNode::getDebugProps() const {
-  SharedDebugStringConvertibleList list = {};
+  auto list = SharedDebugStringConvertibleList {};
 
   if (getHasNewLayout()) {
     list.push_back(std::make_shared<DebugStringConvertibleItem>("hasNewLayout"));
@@ -105,8 +105,8 @@ SharedDebugStringConvertibleList LayoutableShadowNode::getDebugProps() const {
     list.push_back(std::make_shared<DebugStringConvertibleItem>("dirty"));
   }
 
-  LayoutMetrics layoutMetrics = getLayoutMetrics();
-  LayoutMetrics defaultLayoutMetrics = LayoutMetrics();
+  auto layoutMetrics = getLayoutMetrics();
+  auto defaultLayoutMetrics = LayoutMetrics();
 
   list.push_back(std::make_shared<DebugStringConvertibleItem>("frame", toString(layoutMetrics.frame)));
 

ReactCommon/fabric/core/shadownode/ShadowNode.cpp

@@ -154,7 +154,7 @@ std::string ShadowNode::getDebugValue() const {
 }
 
 SharedDebugStringConvertibleList ShadowNode::getDebugChildren() const {
-  SharedDebugStringConvertibleList debugChildren = {};
+  auto debugChildren = SharedDebugStringConvertibleList {};
 
   for (auto child : *children_) {
     auto debugChild = std::dynamic_pointer_cast<const DebugStringConvertible>(child);

ReactCommon/fabric/debug/DebugStringConvertible.cpp

@@ -56,13 +56,13 @@ std::string DebugStringConvertible::getDebugPropsDescription(DebugStringConverti
 }
 
 std::string DebugStringConvertible::getDebugDescription(DebugStringConvertibleOptions options, int depth) const {
-  std::string nameString = getDebugName();
-  std::string valueString = getDebugValue();
-  std::string childrenString = getDebugChildrenDescription(options, depth);
-  std::string propsString = getDebugPropsDescription(options, depth);
+  auto nameString = getDebugName();
+  auto valueString = getDebugValue();
+  auto childrenString = getDebugChildrenDescription(options, depth);
+  auto propsString = getDebugPropsDescription(options, depth);
 
-  std::string leading = options.format ? std::string(depth * 2, ' ') : "";
-  std::string trailing = options.format ? "\n" : "";
+  auto leading = options.format ? std::string(depth * 2, ' ') : std::string {""};
+  auto trailing = options.format ? std::string {"\n"} : std::string {""};
 
   return leading + "<" + nameString +
     (valueString.empty() ? "" : "=" + valueString) +

ReactCommon/fabric/debug/debugStringConvertibleUtils.h

@@ -45,7 +45,7 @@ inline SharedDebugStringConvertible debugStringConvertibleItem(std::string name,
 }
 
 inline SharedDebugStringConvertibleList operator+(const SharedDebugStringConvertibleList &lhs, const SharedDebugStringConvertibleList &rhs) {
-  SharedDebugStringConvertibleList result = {};
+  auto result = SharedDebugStringConvertibleList {};
   std::move(lhs.begin(), lhs.end(), std::back_inserter(result));
   std::move(rhs.begin(), rhs.end(), std::back_inserter(result));
   return result;