C++ style enums 8/N: Direction (#1392)

Summary:
X-link: https://github.com/facebook/react-native/pull/39483

Pull Request resolved: https://github.com/facebook/yoga/pull/1392

Moves internal usages of YGDirection to Direction.

bypass-github-export-checks

Changelog: [Internal]

Reviewed By: rshest

Differential Revision: D49335231

fbshipit-source-id: 459fe820c91be88734cebaa8655cd3f0afda83bf

tests/YGStyleAccessorsTest.cpp

@@ -82,10 +82,10 @@ namespace facebook::yoga {
 
 ACCESSOR_TEST(
     direction,
-    YGDirectionInherit,
-    YGDirectionLTR,
-    YGDirectionRTL,
-    YGDirectionInherit);
+    Direction::Inherit,
+    Direction::LTR,
+    Direction::RTL,
+    Direction::Inherit);
 
 ACCESSOR_TEST(
     flexDirection,

yoga/YGMacros.h

@@ -90,10 +90,11 @@
 
 #ifdef __cplusplus
 
-namespace facebook::yoga::enums {
+namespace facebook::yoga {
 
 template <typename T>
-constexpr int count(); // can't use `= delete` due to a defect in clang < 3.9
+constexpr int
+ordinalCount(); // can't use `= delete` due to a defect in clang < 3.9
 
 namespace detail {
 template <int... xs>
@@ -102,7 +103,7 @@ constexpr int n() {
 }
 } // namespace detail
 
-} // namespace facebook::yoga::enums
+} // namespace facebook::yoga
 #endif
 
 #define YG_ENUM_DECL(NAME, ...)                               \
@@ -110,16 +111,16 @@ constexpr int n() {
   YG_EXPORT const char* NAME##ToString(NAME);
 
 #ifdef __cplusplus
-#define YG_ENUM_SEQ_DECL(NAME, ...)  \
-  YG_ENUM_DECL(NAME, __VA_ARGS__)    \
-  YG_EXTERN_C_END                    \
-                                     \
-  namespace facebook::yoga::enums {  \
-  template <>                        \
-  constexpr int count<NAME>() {      \
-    return detail::n<__VA_ARGS__>(); \
-  }                                  \
-  }                                  \
+#define YG_ENUM_SEQ_DECL(NAME, ...)    \
+  YG_ENUM_DECL(NAME, __VA_ARGS__)      \
+  YG_EXTERN_C_END                      \
+                                       \
+  namespace facebook::yoga {           \
+  template <>                          \
+  constexpr int ordinalCount<NAME>() { \
+    return detail::n<__VA_ARGS__>();   \
+  }                                    \
+  }                                    \
   YG_EXTERN_C_BEGIN
 #else
 #define YG_ENUM_SEQ_DECL YG_ENUM_DECL

yoga/Yoga.cpp

@@ -429,10 +429,10 @@ void updateIndexedStyleProp(
 #define MSVC_HINT(PROP) decltype(Style{}.PROP())
 
 void YGNodeStyleSetDirection(const YGNodeRef node, const YGDirection value) {
-  updateStyle<MSVC_HINT(direction)>(node, &Style::direction, value);
+  updateStyle<MSVC_HINT(direction)>(node, &Style::direction, scopedEnum(value));
 }
 YGDirection YGNodeStyleGetDirection(const YGNodeConstRef node) {
-  return resolveRef(node)->getStyle().direction();
+  return unscopedEnum(resolveRef(node)->getStyle().direction());
 }
 
 void YGNodeStyleSetFlexDirection(
@@ -754,51 +754,82 @@ YGValue YGNodeStyleGetMaxHeight(const YGNodeConstRef node) {
   return resolveRef(node)->getStyle().maxDimensions()[YGDimensionHeight];
 }
 
-#define YG_NODE_LAYOUT_PROPERTY_IMPL(type, name, instanceName) \
-  type YGNodeLayoutGet##name(const YGNodeConstRef node) {      \
-    return resolveRef(node)->getLayout().instanceName;         \
+namespace {
+
+template <auto LayoutMember>
+float getResolvedLayoutProperty(
+    const YGNodeConstRef nodeRef,
+    const YGEdge edge) {
+  const auto node = resolveRef(nodeRef);
+  yoga::assertFatalWithNode(
+      node,
+      edge <= YGEdgeEnd,
+      "Cannot get layout properties of multi-edge shorthands");
+
+  if (edge == YGEdgeStart) {
+    if (node->getLayout().direction() == Direction::RTL) {
+      return (node->getLayout().*LayoutMember)[YGEdgeRight];
+    } else {
+      return (node->getLayout().*LayoutMember)[YGEdgeLeft];
+    }
   }
 
-#define YG_NODE_LAYOUT_RESOLVED_PROPERTY_IMPL(type, name, instanceName) \
-  type YGNodeLayoutGet##name(                                           \
-      const YGNodeConstRef nodeRef, const YGEdge edge) {                \
-    const auto node = resolveRef(nodeRef);                              \
-    yoga::assertFatalWithNode(                                          \
-        node,                                                           \
-        edge <= YGEdgeEnd,                                              \
-        "Cannot get layout properties of multi-edge shorthands");       \
-                                                                        \
-    if (edge == YGEdgeStart) {                                          \
-      if (node->getLayout().direction() == YGDirectionRTL) {            \
-        return node->getLayout().instanceName[YGEdgeRight];             \
-      } else {                                                          \
-        return node->getLayout().instanceName[YGEdgeLeft];              \
-      }                                                                 \
-    }                                                                   \
-                                                                        \
-    if (edge == YGEdgeEnd) {                                            \
-      if (node->getLayout().direction() == YGDirectionRTL) {            \
-        return node->getLayout().instanceName[YGEdgeLeft];              \
-      } else {                                                          \
-        return node->getLayout().instanceName[YGEdgeRight];             \
-      }                                                                 \
-    }                                                                   \
-                                                                        \
-    return node->getLayout().instanceName[edge];                        \
+  if (edge == YGEdgeEnd) {
+    if (node->getLayout().direction() == Direction::RTL) {
+      return (node->getLayout().*LayoutMember)[YGEdgeLeft];
+    } else {
+      return (node->getLayout().*LayoutMember)[YGEdgeRight];
+    }
   }
 
-YG_NODE_LAYOUT_PROPERTY_IMPL(float, Left, position[YGEdgeLeft])
-YG_NODE_LAYOUT_PROPERTY_IMPL(float, Top, position[YGEdgeTop])
-YG_NODE_LAYOUT_PROPERTY_IMPL(float, Right, position[YGEdgeRight])
-YG_NODE_LAYOUT_PROPERTY_IMPL(float, Bottom, position[YGEdgeBottom])
-YG_NODE_LAYOUT_PROPERTY_IMPL(float, Width, dimensions[YGDimensionWidth])
-YG_NODE_LAYOUT_PROPERTY_IMPL(float, Height, dimensions[YGDimensionHeight])
-YG_NODE_LAYOUT_PROPERTY_IMPL(YGDirection, Direction, direction())
-YG_NODE_LAYOUT_PROPERTY_IMPL(bool, HadOverflow, hadOverflow())
+  return (node->getLayout().*LayoutMember)[edge];
+}
 
-YG_NODE_LAYOUT_RESOLVED_PROPERTY_IMPL(float, Margin, margin)
-YG_NODE_LAYOUT_RESOLVED_PROPERTY_IMPL(float, Border, border)
-YG_NODE_LAYOUT_RESOLVED_PROPERTY_IMPL(float, Padding, padding)
+} // namespace
+
+float YGNodeLayoutGetLeft(const YGNodeConstRef node) {
+  return resolveRef(node)->getLayout().position[YGEdgeLeft];
+}
+
+float YGNodeLayoutGetTop(const YGNodeConstRef node) {
+  return resolveRef(node)->getLayout().position[YGEdgeTop];
+}
+
+float YGNodeLayoutGetRight(const YGNodeConstRef node) {
+  return resolveRef(node)->getLayout().position[YGEdgeRight];
+}
+
+float YGNodeLayoutGetBottom(const YGNodeConstRef node) {
+  return resolveRef(node)->getLayout().position[YGEdgeBottom];
+}
+
+float YGNodeLayoutGetWidth(const YGNodeConstRef node) {
+  return resolveRef(node)->getLayout().dimensions[YGDimensionWidth];
+}
+
+float YGNodeLayoutGetHeight(const YGNodeConstRef node) {
+  return resolveRef(node)->getLayout().dimensions[YGDimensionHeight];
+}
+
+YGDirection YGNodeLayoutGetDirection(const YGNodeConstRef node) {
+  return unscopedEnum(resolveRef(node)->getLayout().direction());
+}
+
+bool YGNodeLayoutGetHadOverflow(const YGNodeConstRef node) {
+  return resolveRef(node)->getLayout().hadOverflow();
+}
+
+float YGNodeLayoutGetMargin(YGNodeConstRef node, YGEdge edge) {
+  return getResolvedLayoutProperty<&LayoutResults::margin>(node, edge);
+}
+
+float YGNodeLayoutGetBorder(YGNodeConstRef node, YGEdge edge) {
+  return getResolvedLayoutProperty<&LayoutResults::border>(node, edge);
+}
+
+float YGNodeLayoutGetPadding(YGNodeConstRef node, YGEdge edge) {
+  return getResolvedLayoutProperty<&LayoutResults::padding>(node, edge);
+}
 
 #ifdef DEBUG
 void YGNodePrint(const YGNodeConstRef node, const YGPrintOptions options) {
@@ -926,5 +957,5 @@ void YGNodeCalculateLayout(
     const float ownerHeight,
     const YGDirection ownerDirection) {
   yoga::calculateLayout(
-      resolveRef(node), ownerWidth, ownerHeight, ownerDirection);
+      resolveRef(node), ownerWidth, ownerHeight, scopedEnum(ownerDirection));
 }

yoga/algorithm/CalculateLayout.cpp

@@ -38,7 +38,7 @@ bool calculateLayoutInternal(
     yoga::Node* const node,
     const float availableWidth,
     const float availableHeight,
-    const YGDirection ownerDirection,
+    const Direction ownerDirection,
     const MeasureMode widthMeasureMode,
     const MeasureMode heightMeasureMode,
     const float ownerWidth,
@@ -130,7 +130,7 @@ static void computeFlexBasisForChild(
     const float ownerWidth,
     const float ownerHeight,
     const MeasureMode heightMode,
-    const YGDirection direction,
+    const Direction direction,
     LayoutData& layoutMarkerData,
     const uint32_t depth,
     const uint32_t generationCount) {
@@ -321,7 +321,7 @@ static void layoutAbsoluteChild(
     const float width,
     const MeasureMode widthMode,
     const float height,
-    const YGDirection direction,
+    const Direction direction,
     LayoutData& layoutMarkerData,
     const uint32_t depth,
     const uint32_t generationCount) {
@@ -771,7 +771,7 @@ static float computeFlexBasisForChildren(
     const float availableInnerHeight,
     MeasureMode widthMeasureMode,
     MeasureMode heightMeasureMode,
-    YGDirection direction,
+    Direction direction,
     YGFlexDirection mainAxis,
     bool performLayout,
     LayoutData& layoutMarkerData,
@@ -812,7 +812,7 @@ static float computeFlexBasisForChildren(
     }
     if (performLayout) {
       // Set the initial position (relative to the owner).
-      const YGDirection childDirection = child->resolveDirection(direction);
+      const Direction childDirection = child->resolveDirection(direction);
       const float mainDim =
           isRow(mainAxis) ? availableInnerWidth : availableInnerHeight;
       const float crossDim =
@@ -1478,7 +1478,7 @@ static void calculateLayoutImpl(
     yoga::Node* const node,
     const float availableWidth,
     const float availableHeight,
-    const YGDirection ownerDirection,
+    const Direction ownerDirection,
     const MeasureMode widthMeasureMode,
     const MeasureMode heightMeasureMode,
     const float ownerWidth,
@@ -1506,7 +1506,7 @@ static void calculateLayoutImpl(
   (performLayout ? layoutMarkerData.layouts : layoutMarkerData.measures) += 1;
 
   // Set the resolved resolution in the node's layout.
-  const YGDirection direction = node->resolveDirection(ownerDirection);
+  const Direction direction = node->resolveDirection(ownerDirection);
   node->setLayoutDirection(direction);
 
   const YGFlexDirection flexRowDirection =
@@ -1515,8 +1515,8 @@ static void calculateLayoutImpl(
       resolveDirection(YGFlexDirectionColumn, direction);
 
   const YGEdge startEdge =
-      direction == YGDirectionLTR ? YGEdgeLeft : YGEdgeRight;
-  const YGEdge endEdge = direction == YGDirectionLTR ? YGEdgeRight : YGEdgeLeft;
+      direction == Direction::LTR ? YGEdgeLeft : YGEdgeRight;
+  const YGEdge endEdge = direction == Direction::LTR ? YGEdgeRight : YGEdgeLeft;
 
   const float marginRowLeading =
       node->getLeadingMargin(flexRowDirection, ownerWidth).unwrap();
@@ -2408,7 +2408,7 @@ bool calculateLayoutInternal(
     yoga::Node* const node,
     const float availableWidth,
     const float availableHeight,
-    const YGDirection ownerDirection,
+    const Direction ownerDirection,
     const MeasureMode widthMeasureMode,
     const MeasureMode heightMeasureMode,
     const float ownerWidth,
@@ -2668,7 +2668,7 @@ void calculateLayout(
     yoga::Node* const node,
     const float ownerWidth,
     const float ownerHeight,
-    const YGDirection ownerDirection) {
+    const Direction ownerDirection) {
   Event::publish<Event::LayoutPassStart>(node);
   LayoutData markerData = {};
 

yoga/algorithm/CalculateLayout.h

@@ -16,6 +16,6 @@ void calculateLayout(
     yoga::Node* const node,
     const float ownerWidth,
     const float ownerHeight,
-    const YGDirection ownerDirection);
+    const Direction ownerDirection);
 
 } // namespace facebook::yoga

yoga/algorithm/FlexDirection.h

@@ -25,8 +25,8 @@ inline bool isColumn(const YGFlexDirection flexDirection) {
 
 inline YGFlexDirection resolveDirection(
     const YGFlexDirection flexDirection,
-    const YGDirection direction) {
-  if (direction == YGDirectionRTL) {
+    const Direction direction) {
+  if (direction == Direction::RTL) {
     if (flexDirection == YGFlexDirectionRow) {
       return YGFlexDirectionRowReverse;
     } else if (flexDirection == YGFlexDirectionRowReverse) {
@@ -39,7 +39,7 @@ inline YGFlexDirection resolveDirection(
 
 inline YGFlexDirection resolveCrossDirection(
     const YGFlexDirection flexDirection,
-    const YGDirection direction) {
+    const Direction direction) {
   return isColumn(flexDirection)
       ? resolveDirection(YGFlexDirectionRow, direction)
       : YGFlexDirectionColumn;

yoga/algorithm/FlexLine.cpp

@@ -15,7 +15,7 @@ namespace facebook::yoga {
 
 FlexLine calculateFlexLine(
     yoga::Node* const node,
-    const YGDirection ownerDirection,
+    const Direction ownerDirection,
     const float mainAxisownerSize,
     const float availableInnerWidth,
     const float availableInnerMainDim,

yoga/algorithm/FlexLine.h

@@ -64,7 +64,7 @@ struct FlexLine {
 // computeFlexBasisForChildren function).
 FlexLine calculateFlexLine(
     yoga::Node* const node,
-    YGDirection ownerDirection,
+    Direction ownerDirection,
     float mainAxisownerSize,
     float availableInnerWidth,
     float availableInnerMainDim,

yoga/bits/NumericBitfield.h

@@ -10,8 +10,10 @@
 #include <bitset>
 #include <cstdint>
 #include <cstdio>
+#include <type_traits>
 
 #include <yoga/YGEnums.h>
+#include <yoga/enums/YogaEnums.h>
 
 namespace facebook::yoga::details {
 
@@ -28,11 +30,11 @@ constexpr uint32_t mask(uint8_t bitWidth, uint8_t index) {
 namespace facebook::yoga {
 
 // The number of bits necessary to represent enums defined with YG_ENUM_SEQ_DECL
-template <typename Enum>
+template <
+    typename Enum,
+    std::enable_if_t<(ordinalCount<Enum>() > 0), bool> = true>
 constexpr uint8_t minimumBitCount() {
-  static_assert(
-      enums::count<Enum>() > 0, "Enums must have at least one entries");
-  return details::log2ceilFn(enums::count<Enum>() - 1);
+  return details::log2ceilFn(ordinalCount<Enum>() - 1);
 }
 
 template <typename Enum>
@@ -41,12 +43,13 @@ constexpr Enum getEnumData(uint32_t flags, uint8_t index) {
       (flags & details::mask(minimumBitCount<Enum>(), index)) >> index);
 }
 
-template <typename Enum>
-void setEnumData(uint32_t& flags, uint8_t index, uint32_t newValue) {
+template <typename Enum, typename Value>
+void setEnumData(uint32_t& flags, uint8_t index, Value newValue) {
   flags =
       (flags &
        ~static_cast<uint32_t>(details::mask(minimumBitCount<Enum>(), index))) |
-      ((newValue << index) & (details::mask(minimumBitCount<Enum>(), index)));
+      ((static_cast<uint32_t>(newValue) << index) &
+       (details::mask(minimumBitCount<Enum>(), index)));
 }
 
 constexpr bool getBooleanData(uint32_t flags, uint8_t index) {

yoga/node/LayoutResults.h

@@ -10,6 +10,7 @@
 #include <array>
 
 #include <yoga/bits/NumericBitfield.h>
+#include <yoga/enums/Direction.h>
 #include <yoga/node/CachedMeasurement.h>
 #include <yoga/numeric/FloatOptional.h>
 
@@ -27,7 +28,7 @@ struct LayoutResults {
   std::array<float, 4> padding = {};
 
  private:
-  uint32_t direction_ : 2 = static_cast<uint32_t>(YGDirectionInherit) & 0x03;
+  Direction direction_ : bitCount<Direction>() = Direction::Inherit;
   bool hadOverflow_ : 1 = false;
 
  public:
@@ -37,7 +38,7 @@ struct LayoutResults {
   // Instead of recomputing the entire layout every single time, we cache some
   // information to break early when nothing changed
   uint32_t generationCount = 0;
-  YGDirection lastOwnerDirection = YGDirectionInherit;
+  Direction lastOwnerDirection = Direction::Inherit;
 
   uint32_t nextCachedMeasurementsIndex = 0;
   std::array<CachedMeasurement, MaxCachedMeasurements> cachedMeasurements = {};
@@ -45,12 +46,12 @@ struct LayoutResults {
 
   CachedMeasurement cachedLayout{};
 
-  YGDirection direction() const {
-    return static_cast<YGDirection>(direction_);
+  Direction direction() const {
+    return direction_;
   }
 
-  void setDirection(YGDirection direction) {
-    direction_ = static_cast<uint32_t>(direction) & 0x03;
+  void setDirection(Direction direction) {
+    direction_ = direction;
   }
 
   bool hadOverflow() const {

yoga/node/Node.cpp

@@ -296,7 +296,7 @@ void Node::removeChild(size_t index) {
   children_.erase(children_.begin() + static_cast<ptrdiff_t>(index));
 }
 
-void Node::setLayoutDirection(YGDirection direction) {
+void Node::setLayoutDirection(Direction direction) {
   layout_.setDirection(direction);
 }
 
@@ -318,7 +318,7 @@ void Node::setLayoutPadding(float padding, YGEdge edge) {
   layout_.padding[edge] = padding;
 }
 
-void Node::setLayoutLastOwnerDirection(YGDirection direction) {
+void Node::setLayoutLastOwnerDirection(Direction direction) {
   layout_.lastOwnerDirection = direction;
 }
 
@@ -369,14 +369,14 @@ FloatOptional Node::relativePosition(
 }
 
 void Node::setPosition(
-    const YGDirection direction,
+    const Direction direction,
     const float mainSize,
     const float crossSize,
     const float ownerWidth) {
   /* Root nodes should be always layouted as LTR, so we don't return negative
    * values. */
-  const YGDirection directionRespectingRoot =
-      owner_ != nullptr ? direction : YGDirectionLTR;
+  const Direction directionRespectingRoot =
+      owner_ != nullptr ? direction : Direction::LTR;
   const YGFlexDirection mainAxis =
       yoga::resolveDirection(style_.flexDirection(), directionRespectingRoot);
   const YGFlexDirection crossAxis =
@@ -447,10 +447,10 @@ void Node::resolveDimension() {
   }
 }
 
-YGDirection Node::resolveDirection(const YGDirection ownerDirection) {
-  if (style_.direction() == YGDirectionInherit) {
-    return ownerDirection > YGDirectionInherit ? ownerDirection
-                                               : YGDirectionLTR;
+Direction Node::resolveDirection(const Direction ownerDirection) {
+  if (style_.direction() == Direction::Inherit) {
+    return ownerDirection != Direction::Inherit ? ownerDirection
+                                                : Direction::LTR;
   } else {
     return style_.direction();
   }

yoga/node/Node.h

@@ -14,6 +14,7 @@
 #include <yoga/Yoga.h>
 
 #include <yoga/config/Config.h>
+#include <yoga/enums/Direction.h>
 #include <yoga/enums/Errata.h>
 #include <yoga/enums/MeasureMode.h>
 #include <yoga/enums/NodeType.h>
@@ -289,7 +290,7 @@ class YG_EXPORT Node : public ::YGNode {
   void setConfig(Config* config);
 
   void setDirty(bool isDirty);
-  void setLayoutLastOwnerDirection(YGDirection direction);
+  void setLayoutLastOwnerDirection(Direction direction);
   void setLayoutComputedFlexBasis(const FloatOptional computedFlexBasis);
   void setLayoutComputedFlexBasisGeneration(
       uint32_t computedFlexBasisGeneration);
@@ -298,13 +299,13 @@ class YG_EXPORT Node : public ::YGNode {
       YGDimension dimension);
   void setLayoutHadOverflow(bool hadOverflow);
   void setLayoutDimension(float dimensionValue, YGDimension dimension);
-  void setLayoutDirection(YGDirection direction);
+  void setLayoutDirection(Direction direction);
   void setLayoutMargin(float margin, YGEdge edge);
   void setLayoutBorder(float border, YGEdge edge);
   void setLayoutPadding(float padding, YGEdge edge);
   void setLayoutPosition(float position, YGEdge edge);
   void setPosition(
-      const YGDirection direction,
+      const Direction direction,
       const float mainSize,
       const float crossSize,
       const float ownerWidth);
@@ -315,7 +316,7 @@ class YG_EXPORT Node : public ::YGNode {
   YGValue marginTrailingValue(const YGFlexDirection axis) const;
   YGValue resolveFlexBasisPtr() const;
   void resolveDimension();
-  YGDirection resolveDirection(const YGDirection ownerDirection);
+  Direction resolveDirection(const Direction ownerDirection);
   void clearChildren();
   /// Replaces the occurrences of oldChild with newChild
   void replaceChild(Node* oldChild, Node* newChild);

yoga/style/Style.h

@@ -15,6 +15,7 @@
 #include <yoga/Yoga.h>
 
 #include <yoga/bits/NumericBitfield.h>
+#include <yoga/enums/Direction.h>
 #include <yoga/numeric/FloatOptional.h>
 #include <yoga/style/CompactValue.h>
 
@@ -22,7 +23,7 @@ namespace facebook::yoga {
 
 class YG_EXPORT Style {
   template <typename Enum>
-  using Values = std::array<CompactValue, enums::count<Enum>()>;
+  using Values = std::array<CompactValue, ordinalCount<Enum>()>;
 
  public:
   using Dimensions = Values<YGDimension>;
@@ -100,7 +101,7 @@ class YG_EXPORT Style {
  private:
   static constexpr uint8_t directionOffset = 0;
   static constexpr uint8_t flexdirectionOffset =
-      directionOffset + minimumBitCount<YGDirection>();
+      directionOffset + minimumBitCount<Direction>();
   static constexpr uint8_t justifyContentOffset =
       flexdirectionOffset + minimumBitCount<YGFlexDirection>();
   static constexpr uint8_t alignContentOffset =
@@ -139,10 +140,10 @@ class YG_EXPORT Style {
   // for library users needing a type
   using ValueRepr = std::remove_reference<decltype(margin_[0])>::type;
 
-  YGDirection direction() const {
-    return getEnumData<YGDirection>(flags, directionOffset);
+  Direction direction() const {
+    return getEnumData<Direction>(flags, directionOffset);
   }
-  BitfieldRef<YGDirection> direction() {
+  BitfieldRef<Direction> direction() {
     return {*this, directionOffset};
   }