Add support for context-aware measure and baseline functions

Summary:
@public

Context-aware measure and baseline functions are an internal Yoga feature that will be used for Yoga’s JNI code.

It will be possible to specify a context when calculating layout, which will be passed on to baseline and measure functions. This will be a private feature.

Reviewed By: SidharthGuglani

Differential Revision: D14100509

fbshipit-source-id: acf4a030549b2e38d5ce0cd5dbe837864e5ffd81

tests/YGNodeCallbackTest.cpp

@@ -36,7 +36,36 @@ TEST(YGNode, measure_with_measure_fn) {
       });
 
   ASSERT_EQ(
-      n.measure(23, YGMeasureModeExactly, 24, YGMeasureModeAtMost),
+      n.measure(23, YGMeasureModeExactly, 24, YGMeasureModeAtMost, nullptr),
+      (YGSize{23, 12}));
+}
+
+TEST(YGNode, measure_with_context_measure_fn) {
+  auto n = YGNode{};
+  n.setMeasureFunc(
+      [](YGNode*, float, YGMeasureMode, float, YGMeasureMode, void* ctx) {
+        return *(YGSize*) ctx;
+      });
+
+  auto result = YGSize{123.4, -56.7};
+  ASSERT_EQ(
+      n.measure(0, YGMeasureModeUndefined, 0, YGMeasureModeUndefined, &result),
+      result);
+}
+
+TEST(YGNode, switching_measure_fn_types) {
+  auto n = YGNode{};
+  n.setMeasureFunc(
+      [](YGNode*, float, YGMeasureMode, float, YGMeasureMode, void*) {
+        return YGSize{};
+      });
+  n.setMeasureFunc(
+      [](YGNode*, float w, YGMeasureMode wm, float h, YGMeasureMode hm) {
+        return YGSize{w * wm, h / hm};
+      });
+
+  ASSERT_EQ(
+      n.measure(23, YGMeasureModeExactly, 24, YGMeasureModeAtMost, nullptr),
       (YGSize{23, 12}));
 }
 
@@ -50,6 +79,17 @@ TEST(YGNode, hasMeasureFunc_after_unset) {
   ASSERT_FALSE(n.hasMeasureFunc());
 }
 
+TEST(YGNode, hasMeasureFunc_after_unset_context) {
+  auto n = YGNode{};
+  n.setMeasureFunc(
+      [](YGNode*, float, YGMeasureMode, float, YGMeasureMode, void*) {
+        return YGSize{};
+      });
+
+  n.setMeasureFunc(nullptr);
+  ASSERT_FALSE(n.hasMeasureFunc());
+}
+
 TEST(YGNode, hasBaselineFunc_initial) {
   auto n = YGNode{};
   ASSERT_FALSE(n.hasBaselineFunc());
@@ -65,7 +105,17 @@ TEST(YGNode, baseline_with_baseline_fn) {
   auto n = YGNode{};
   n.setBaseLineFunc([](YGNode*, float w, float h) { return w + h; });
 
-  ASSERT_EQ(n.baseline(1.25f, 2.5f), 3.75f);
+  ASSERT_EQ(n.baseline(1.25f, 2.5f, nullptr), 3.75f);
+}
+
+TEST(YGNode, baseline_with_context_baseline_fn) {
+  auto n = YGNode{};
+  n.setBaseLineFunc([](YGNode*, float w, float h, void* ctx) {
+    return w + h + *(float*) ctx;
+  });
+
+  auto ctx = -10.0f;
+  ASSERT_EQ(n.baseline(1.25f, 2.5f, &ctx), -6.25f);
 }
 
 TEST(YGNode, hasBaselineFunc_after_unset) {
@@ -76,6 +126,21 @@ TEST(YGNode, hasBaselineFunc_after_unset) {
   ASSERT_FALSE(n.hasBaselineFunc());
 }
 
+TEST(YGNode, hasBaselineFunc_after_unset_context) {
+  auto n = YGNode{};
+  n.setBaseLineFunc([](YGNode*, float, float, void*) { return 0.0f; });
+
+  n.setMeasureFunc(nullptr);
+  ASSERT_FALSE(n.hasMeasureFunc());
+}
+
+TEST(YGNode, switching_baseline_fn_types) {
+  auto n = YGNode{};
+  n.setBaseLineFunc([](YGNode*, float, float, void*) { return 0.0f; });
+  n.setBaseLineFunc([](YGNode*, float, float) { return 1.0f; });
+  ASSERT_EQ(n.baseline(1, 2, nullptr), 1.0f);
+}
+
 void PrintTo(const YGSize& size, std::ostream* os) {
   *os << "YGSize{" << size.width << ", " << size.height << "}";
 }