Remove the usage of YGUndefined in the default values of Border in YGStyle

Summary: Remove the usage of YGUndefined in the default values of Border in YGStyle. In the getter of Border function, YGUndefined is used just to keep it logically consistent. The proper solution would be to change the api in `Yoga.h` to accept `YGFloatOptional`, but that would require to change lot of the code in client of this library. Will make a separate diff for that.

Reviewed By: emilsjolander

Differential Revision: D7195115

fbshipit-source-id: e635cf55ac94d8a90caef6cafce281579da2cbfc

yoga/Utils.cpp

@@ -49,3 +49,7 @@ bool YGFloatsEqual(const float a, const float b) {
   }
   return YGFloatIsUndefined(a) && YGFloatIsUndefined(b);
 }
+
+float YGFloatSanitize(const float& val) {
+  return YGFloatIsUndefined(val) ? 0 : val;
+}

yoga/Utils.h

@@ -86,6 +86,9 @@ bool YGFloatArrayEqual(
   return areEqual;
 }
 
+// This function returns 0 if YGFloatIsUndefined(val) is true and val otherwise
+float YGFloatSanitize(const float& val);
+
 YGFlexDirection YGFlexDirectionCross(
     const YGFlexDirection flexDirection,
     const YGDirection direction);

yoga/YGStyle.cpp

@@ -7,7 +7,7 @@
 
 #include "YGStyle.h"
 
-const YGValue kYGValueUndefined = {YGUndefined, YGUnitUndefined};
+const YGValue kYGValueUndefined = {0, YGUnitUndefined};
 
 const YGValue kYGValueAuto = {YGUndefined, YGUnitAuto};
 

yoga/Yoga.cpp

@@ -760,7 +760,35 @@ YG_NODE_STYLE_EDGE_PROPERTY_UNIT_IMPL(YGValue, Position, position, position);
 YG_NODE_STYLE_EDGE_PROPERTY_UNIT_IMPL(YGValue, Margin, margin, margin);
 YG_NODE_STYLE_EDGE_PROPERTY_UNIT_AUTO_IMPL(YGValue, Margin, margin);
 YG_NODE_STYLE_EDGE_PROPERTY_UNIT_IMPL(YGValue, Padding, padding, padding);
-YG_NODE_STYLE_EDGE_PROPERTY_IMPL(float, Border, border, border);
+
+// TODO: Change the API to accept YGFloatOptional.
+void YGNodeStyleSetBorder(
+    const YGNodeRef node,
+    const YGEdge edge,
+    const float border) {
+  YGValue value = {
+      .value = YGFloatSanitize(border),
+      .unit = YGFloatIsUndefined(border) ? YGUnitUndefined : YGUnitPoint,
+  };
+  if ((node->getStyle().border[edge].value != value.value &&
+       value.unit != YGUnitUndefined) ||
+      node->getStyle().border[edge].unit != value.unit) {
+    YGStyle style = node->getStyle();
+    style.border[edge] = value;
+    node->setStyle(style);
+    node->markDirtyAndPropogate();
+  }
+}
+
+float YGNodeStyleGetBorder(const YGNodeRef node, const YGEdge edge) {
+  if (node->getStyle().border[edge].unit == YGUnitUndefined) {
+    // TODO: Rather than returning YGUndefined, change the api to return
+    // YGFloatOptional.
+    return YGUndefined;
+  }
+
+  return node->getStyle().border[edge].value;
+}
 
 YG_NODE_STYLE_PROPERTY_UNIT_AUTO_IMPL(YGValue, Width, width, dimensions[YGDimensionWidth]);
 YG_NODE_STYLE_PROPERTY_UNIT_AUTO_IMPL(YGValue, Height, height, dimensions[YGDimensionHeight]);

yoga/Yoga.h

@@ -42,6 +42,11 @@ typedef struct YGValue {
   YGUnit unit;
 } YGValue;
 
+struct YGFloatOptional {
+  bool isUndefined;
+  float value;
+};
+
 extern const YGValue YGValueUndefined;
 extern const YGValue YGValueAuto;