Add constructor in YGLayout

Summary: Add default constructor in YGLayout and moved to separate file. This diff also addresses https://github.com/facebook/yoga/pull/700

Reviewed By: emilsjolander

Differential Revision: D7019653

fbshipit-source-id: 5a2655626db0915fcebe7d4517e2d0b2e2484460

yoga/YGLayout.h

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+#pragma once
+#include "Yoga-internal.h"
+
+struct YGLayout {
+  std::array<float, 4> position;
+  std::array<float, 2> dimensions;
+  std::array<float, 6> margin;
+  std::array<float, 6> border;
+  std::array<float, 6> padding;
+  YGDirection direction;
+
+  uint32_t computedFlexBasisGeneration;
+  float computedFlexBasis;
+  bool hadOverflow;
+
+  // Instead of recomputing the entire layout every single time, we
+  // cache some information to break early when nothing changed
+  uint32_t generationCount;
+  YGDirection lastParentDirection;
+
+  uint32_t nextCachedMeasurementsIndex;
+  std::array<YGCachedMeasurement, YG_MAX_CACHED_RESULT_COUNT>
+      cachedMeasurements;
+  std::array<float, 2> measuredDimensions;
+
+  YGCachedMeasurement cachedLayout;
+  bool didUseLegacyFlag;
+  bool doesLegacyStretchFlagAffectsLayout;
+
+  YGLayout();
+
+  bool operator==(YGLayout layout) const;
+  bool operator!=(YGLayout layout) const;
+};