C++ Cleanup 1/N: Reorganize YGStyle

Summary:
X-link: facebook/react-native#39171

## This diff

This diff adds a `style` directory for code related to storing and manipulating styles. `YGStyle`, which is not a public API, is renamed to `yoga::Style` and moved into this folder, alongside `CompactValue`. We will eventually add `ValuePool` alongside this for the next generation style representation.

## This stack

The organization of the C++ internals of Yoga are in need of attention.
1. Some of the C++ internals are namespaced, but others not.
2. Some of the namespaces include `detail`, but are meant to be used outside of the translation unit (FB Clang Tidy rules warn on any usage of these)
2. Most of the files are in a flat hierarchy, except for event tracing in its own folder
3. Some files and functions begin with YG, others don’t
4. Some functions are uppercase, others are not
5. Almost all of the interesting logic is in Yoga.cpp, and the file is too large to reason about
6. There are multiple grab bag files where folks put random functions they need in (Utils, BitUtils, Yoga-Internal.h)
7. There is no clear indication from file structure or type naming what is private vs not
8. Handles like `YGNodeRef` and `YGConfigRef` can be used to access internals just by importing headers

This stack does some much needed spring cleaning:
1. All non-public headers and C++ implementation details are in separate folders from the root level `yoga`. This will give us room to split up logic and add more files without too large a flat hierarchy
3. All private C++ internals are under the `facebook::yoga` namespace. Details namespaces are only ever used within the same header, as they are intended
4. Utils files are split
5. Most C++ internals drop the YG prefix
6. Most C++ internal function names are all lower camel case
7. We start to split up Yoga.cpp
8. Every header beginning with YG or at the top-level directory is public and C only, with the exception of Yoga-Internal.h which has non-public functions for bindings
9. It is not possible to use private APIs without static casting handles to internal classes

This will give us more leeway to continue splitting monolithic files, and consistent guidelines for style in new files as well.

These changes should not be breaking to any project using only public Yoga headers. This includes every usage of Yoga in fbsource except for RN Fabric which is currently tied to internals. This refactor should make that boundary clearer.

Changelog: [Internal]

Differential Revision: https://www.internalfb.com/diff/D48710084?entry_point=27

fbshipit-source-id: 0041268777ee6f371ab0714de95147cd8929083f

Yoga.podspec

@@ -35,7 +35,14 @@ Pod::Spec.new do |spec|
       '-std=c++17',
       '-fPIC'
   ]
-  spec.source_files = 'yoga/**/*.{h,cpp}'
-  spec.public_header_files = 'yoga/{Yoga,YGEnums,YGMacros,YGValue}.h'
+
   spec.swift_version = '5.1'
+  spec.source_files = 'yoga/**/*.{h,cpp}'
+  spec.header_mappings_dir = 'yoga'
+
+  public_header_files = 'yoga/{Yoga,YGEnums,YGMacros,YGValue}.h'
+  spec.public_header_files = public_header_files
+
+  all_header_files = 'yoga/**/*.h'
+  spec.private_header_files = Dir.glob(all_header_files) - Dir.glob(public_header_files)
 end

tests/CompactValueTest.cpp

@@ -7,11 +7,11 @@
 
 #define YOGA_COMPACT_VALUE_TEST
 
-#include <yoga/CompactValue.h>
+#include <yoga/style/CompactValue.h>
 #include <gtest/gtest.h>
 #include <cmath>
 
-using facebook::yoga::detail::CompactValue;
+using facebook::yoga::CompactValue;
 
 const auto tooSmall = nextafterf(CompactValue::LOWER_BOUND, -INFINITY);
 const auto tooLargePoints =

tests/YGStyleAccessorsTest.cpp

@@ -8,9 +8,8 @@
 #include <cstdint>
 #include <type_traits>
 #include <gtest/gtest.h>
-#include <yoga/YGEnums.h>
-#include <yoga/YGStyle.h>
-#include <yoga/YGValue.h>
+#include <yoga/Yoga.h>
+#include <yoga/style/Style.h>
 
 #define ACCESSOR_TESTS_1(NAME, X) \
   style.NAME() = X;               \
@@ -31,14 +30,14 @@
 #define ACCESSOR_TESTS_N(a, b, c, d, e, COUNT, ...) ACCESSOR_TESTS_##COUNT
 #define ACCESSOR_TESTS(...) ACCESSOR_TESTS_N(__VA_ARGS__, 5, 4, 3, 2, 1)
 
-#define INDEX_ACCESSOR_TESTS_1(NAME, IDX, X)                           \
-  {                                                                    \
-    auto style = YGStyle{};                                            \
-    style.NAME()[IDX] = X;                                             \
-    ASSERT_EQ(style.NAME()[IDX], X);                                   \
-    auto asArray = decltype(std::declval<const YGStyle&>().NAME()){X}; \
-    style.NAME() = asArray;                                            \
-    ASSERT_EQ(static_cast<decltype(asArray)>(style.NAME()), asArray);  \
+#define INDEX_ACCESSOR_TESTS_1(NAME, IDX, X)                          \
+  {                                                                   \
+    auto style = Style{};                                             \
+    style.NAME()[IDX] = X;                                            \
+    ASSERT_EQ(style.NAME()[IDX], X);                                  \
+    auto asArray = decltype(std::declval<const Style&>().NAME()){X};  \
+    style.NAME() = asArray;                                           \
+    ASSERT_EQ(static_cast<decltype(asArray)>(style.NAME()), asArray); \
   }
 
 #define INDEX_ACCESSOR_TESTS_2(NAME, IDX, X, Y) \
@@ -64,22 +63,20 @@
 
 // test macro for up to 5 values. If more are needed, extend the macros above.
 #define ACCESSOR_TEST(NAME, DEFAULT_VAL, ...)      \
-  TEST(YGStyle, style_##NAME##_access) {           \
-    auto style = YGStyle{};                        \
+  TEST(Style, style_##NAME##_access) {             \
+    auto style = Style{};                          \
     ASSERT_EQ(style.NAME(), DEFAULT_VAL);          \
     ACCESSOR_TESTS(__VA_ARGS__)(NAME, __VA_ARGS__) \
   }
 
 #define INDEX_ACCESSOR_TEST(NAME, DEFAULT_VAL, IDX, ...)      \
-  TEST(YGStyle, style_##NAME##_access) {                      \
-    ASSERT_EQ(YGStyle{}.NAME()[IDX], DEFAULT_VAL);            \
+  TEST(Style, style_##NAME##_access) {                        \
+    ASSERT_EQ(Style{}.NAME()[IDX], DEFAULT_VAL);              \
     INDEX_ACCESSOR_TESTS(__VA_ARGS__)(NAME, IDX, __VA_ARGS__) \
   }
 
 namespace facebook::yoga {
 
-using CompactValue = detail::CompactValue;
-
 // TODO: MSVC doesn't like the macros
 #ifndef _MSC_VER
 

yoga/Utils.h

@@ -8,8 +8,8 @@
 #pragma once
 
 #include "YGNode.h"
-#include "Yoga-internal.h"
-#include "CompactValue.h"
+#include <yoga/Yoga-internal.h>
+#include <yoga/style/CompactValue.h>
 
 // This struct is an helper model to hold the data for step 4 of flexbox algo,
 // which is collecting the flex items in a line.
@@ -56,8 +56,8 @@ struct YGCollectFlexItemsRowValues {
 
 bool YGValueEqual(const YGValue& a, const YGValue& b);
 inline bool YGValueEqual(
-    facebook::yoga::detail::CompactValue a,
-    facebook::yoga::detail::CompactValue b) {
+    facebook::yoga::CompactValue a,
+    facebook::yoga::CompactValue b) {
   return YGValueEqual((YGValue) a, (YGValue) b);
 }
 
@@ -115,7 +115,7 @@ inline YGFloatOptional YGResolveValue(
 }
 
 inline YGFloatOptional YGResolveValue(
-    facebook::yoga::detail::CompactValue value,
+    facebook::yoga::CompactValue value,
     float ownerSize) {
   return YGResolveValue((YGValue) value, ownerSize);
 }
@@ -140,7 +140,7 @@ inline YGFlexDirection YGResolveFlexDirection(
 }
 
 inline YGFloatOptional YGResolveValueMargin(
-    facebook::yoga::detail::CompactValue value,
+    facebook::yoga::CompactValue value,
     const float ownerSize) {
   return value.isAuto() ? YGFloatOptional{0} : YGResolveValue(value, ownerSize);
 }

yoga/YGConfig.h

@@ -9,8 +9,8 @@
 
 #include <yoga/Yoga.h>
 
-#include "BitUtils.h"
-#include "Yoga-internal.h"
+#include <yoga/BitUtils.h>
+#include <yoga/Yoga-internal.h>
 
 namespace facebook::yoga {
 

yoga/YGFloatOptional.h

@@ -9,7 +9,7 @@
 
 #include <cmath>
 #include <limits>
-#include "Yoga-internal.h"
+#include <yoga/Yoga-internal.h>
 
 struct YGFloatOptional {
 private:

yoga/YGLayout.h

@@ -7,9 +7,9 @@
 
 #pragma once
 
-#include "BitUtils.h"
-#include "YGFloatOptional.h"
-#include "Yoga-internal.h"
+#include <yoga/BitUtils.h>
+#include <yoga/YGFloatOptional.h>
+#include <yoga/Yoga-internal.h>
 
 struct YGLayout {
   std::array<float, 4> position = {};

yoga/YGNode.cpp

@@ -11,7 +11,8 @@
 #include "Utils.h"
 
 using namespace facebook;
-using facebook::yoga::detail::CompactValue;
+using namespace facebook::yoga;
+using facebook::yoga::CompactValue;
 
 YGNode::YGNode(const YGConfigRef config) : config_{config} {
   YGAssert(
@@ -53,7 +54,7 @@ void YGNode::print(void* printContext) {
 }
 
 CompactValue YGNode::computeEdgeValueForRow(
-    const YGStyle::Edges& edges,
+    const Style::Edges& edges,
     YGEdge rowEdge,
     YGEdge edge,
     CompactValue defaultValue) {
@@ -71,7 +72,7 @@ CompactValue YGNode::computeEdgeValueForRow(
 }
 
 CompactValue YGNode::computeEdgeValueForColumn(
-    const YGStyle::Edges& edges,
+    const Style::Edges& edges,
     YGEdge edge,
     CompactValue defaultValue) {
   if (!edges[edge].isUndefined()) {
@@ -86,7 +87,7 @@ CompactValue YGNode::computeEdgeValueForColumn(
 }
 
 CompactValue YGNode::computeRowGap(
-    const YGStyle::Gutters& gutters,
+    const Style::Gutters& gutters,
     CompactValue defaultValue) {
   if (!gutters[YGGutterRow].isUndefined()) {
     return gutters[YGGutterRow];
@@ -98,7 +99,7 @@ CompactValue YGNode::computeRowGap(
 }
 
 CompactValue YGNode::computeColumnGap(
-    const YGStyle::Gutters& gutters,
+    const Style::Gutters& gutters,
     CompactValue defaultValue) {
   if (!gutters[YGGutterColumn].isUndefined()) {
     return gutters[YGGutterColumn];
@@ -431,7 +432,7 @@ YGValue YGNode::resolveFlexBasisPtr() const {
 
 void YGNode::resolveDimension() {
   using namespace yoga;
-  const YGStyle& style = getStyle();
+  const Style& style = getStyle();
   for (auto dim : {YGDimensionWidth, YGDimensionHeight}) {
     if (!style.maxDimensions()[dim].isUndefined() &&
         YGValueEqual(style.maxDimensions()[dim], style.minDimensions()[dim])) {

yoga/YGNode.h

@@ -9,11 +9,12 @@
 
 #include <cstdint>
 #include <stdio.h>
-#include "CompactValue.h"
 #include "YGConfig.h"
 #include "YGLayout.h"
-#include "YGStyle.h"
-#include "Yoga-internal.h"
+#include <yoga/Yoga-internal.h>
+
+#include <yoga/style/CompactValue.h>
+#include <yoga/style/Style.h>
 
 YGConfigRef YGConfigGetDefault();
 
@@ -52,7 +53,7 @@ struct YOGA_EXPORT YGNode {
     PrintWithContextFn withContext;
   } print_ = {nullptr};
   YGDirtiedFunc dirtied_ = nullptr;
-  YGStyle style_ = {};
+  facebook::yoga::Style style_ = {};
   YGLayout layout_ = {};
   uint32_t lineIndex_ = 0;
   YGNodeRef owner_ = nullptr;
@@ -80,7 +81,7 @@ struct YOGA_EXPORT YGNode {
   // DO NOT CHANGE THE VISIBILITY OF THIS METHOD!
   YGNode& operator=(YGNode&&) = default;
 
-  using CompactValue = facebook::yoga::detail::CompactValue;
+  using CompactValue = facebook::yoga::CompactValue;
 
 public:
   YGNode() : YGNode{YGConfigGetDefault()} { flags_.hasNewLayout = true; }
@@ -123,9 +124,9 @@ struct YOGA_EXPORT YGNode {
   YGDirtiedFunc getDirtied() const { return dirtied_; }
 
   // For Performance reasons passing as reference.
-  YGStyle& getStyle() { return style_; }
+  facebook::yoga::Style& getStyle() { return style_; }
 
-  const YGStyle& getStyle() const { return style_; }
+  const facebook::yoga::Style& getStyle() const { return style_; }
 
   // For Performance reasons passing as reference.
   YGLayout& getLayout() { return layout_; }
@@ -178,22 +179,22 @@ struct YOGA_EXPORT YGNode {
   }
 
   static CompactValue computeEdgeValueForColumn(
-      const YGStyle::Edges& edges,
+      const facebook::yoga::Style::Edges& edges,
       YGEdge edge,
       CompactValue defaultValue);
 
   static CompactValue computeEdgeValueForRow(
-      const YGStyle::Edges& edges,
+      const facebook::yoga::Style::Edges& edges,
       YGEdge rowEdge,
       YGEdge edge,
       CompactValue defaultValue);
 
   static CompactValue computeRowGap(
-      const YGStyle::Gutters& gutters,
+      const facebook::yoga::Style::Gutters& gutters,
       CompactValue defaultValue);
 
   static CompactValue computeColumnGap(
-      const YGStyle::Gutters& gutters,
+      const facebook::yoga::Style::Gutters& gutters,
       CompactValue defaultValue);
 
   // Methods related to positions, margin, padding and border
@@ -273,7 +274,7 @@ struct YOGA_EXPORT YGNode {
 
   void setDirtiedFunc(YGDirtiedFunc dirtiedFunc) { dirtied_ = dirtiedFunc; }
 
-  void setStyle(const YGStyle& style) { style_ = style; }
+  void setStyle(const facebook::yoga::Style& style) { style_ = style; }
 
   void setLayout(const YGLayout& layout) { layout_ = layout; }
 

yoga/YGNodePrint.cpp

@@ -13,7 +13,7 @@
 
 #include "YGNodePrint.h"
 #include "YGNode.h"
-#include "Yoga-internal.h"
+#include <yoga/Yoga-internal.h>
 #include "Utils.h"
 
 namespace facebook::yoga {
@@ -25,7 +25,7 @@ static void indent(string& base, uint32_t level) {
   }
 }
 
-static bool areFourValuesEqual(const YGStyle::Edges& four) {
+static bool areFourValuesEqual(const Style::Edges& four) {
   return YGValueEqual(four[0], four[1]) && YGValueEqual(four[0], four[2]) &&
       YGValueEqual(four[0], four[3]);
 }
@@ -90,10 +90,10 @@ static void appendNumberIfNotZero(
 static void appendEdges(
     string& base,
     const string& key,
-    const YGStyle::Edges& edges) {
+    const Style::Edges& edges) {
   if (areFourValuesEqual(edges)) {
     auto edgeValue = YGNode::computeEdgeValueForColumn(
-        edges, YGEdgeLeft, detail::CompactValue::ofZero());
+        edges, YGEdgeLeft, CompactValue::ofZero());
     appendNumberIfNotZero(base, key, edgeValue);
   } else {
     for (int edge = YGEdgeLeft; edge != YGEdgeAll; ++edge) {
@@ -106,14 +106,14 @@ static void appendEdges(
 static void appendEdgeIfNotUndefined(
     string& base,
     const string& str,
-    const YGStyle::Edges& edges,
+    const Style::Edges& edges,
     const YGEdge edge) {
   // TODO: this doesn't take RTL / YGEdgeStart / YGEdgeEnd into account
   auto value = (edge == YGEdgeLeft || edge == YGEdgeRight)
       ? YGNode::computeEdgeValueForRow(
-            edges, edge, edge, detail::CompactValue::ofUndefined())
+            edges, edge, edge, CompactValue::ofUndefined())
       : YGNode::computeEdgeValueForColumn(
-            edges, edge, detail::CompactValue::ofUndefined());
+            edges, edge, CompactValue::ofUndefined());
   appendNumberIfNotUndefined(base, str, value);
 }
 
@@ -188,17 +188,15 @@ void YGNodeToString(
     appendEdges(str, "padding", style.padding());
     appendEdges(str, "border", style.border());
 
-    if (YGNode::computeColumnGap(
-            style.gap(), detail::CompactValue::ofUndefined()) !=
+    if (YGNode::computeColumnGap(style.gap(), CompactValue::ofUndefined()) !=
         YGNode::computeColumnGap(
-            YGNode().getStyle().gap(), detail::CompactValue::ofUndefined())) {
+            YGNode().getStyle().gap(), CompactValue::ofUndefined())) {
       appendNumberIfNotUndefined(
           str, "column-gap", style.gap()[YGGutterColumn]);
     }
-    if (YGNode::computeRowGap(
-            style.gap(), detail::CompactValue::ofUndefined()) !=
+    if (YGNode::computeRowGap(style.gap(), CompactValue::ofUndefined()) !=
         YGNode::computeRowGap(
-            YGNode().getStyle().gap(), detail::CompactValue::ofUndefined())) {
+            YGNode().getStyle().gap(), CompactValue::ofUndefined())) {
       appendNumberIfNotUndefined(str, "row-gap", style.gap()[YGGutterRow]);
     }
 

yoga/Yoga-internal.h

@@ -14,7 +14,7 @@
 
 #include <yoga/Yoga.h>
 
-#include "CompactValue.h"
+#include <yoga/style/CompactValue.h>
 
 using YGVector = std::vector<YGNodeRef>;