[ASLayout] General Layout Cleanup (#2920)

* Remove duplicate import

* Move `ASLayoutController` related code out of CoreGraphics+ASConvenience

* Further cleanup

* Move private layout files to Privat/Layout

* Move ASLayoutElementStylePrivate into Private/Layout

* Further cleanup

* Move tvOS related files to tvOS folder

* Further cleanup

AsyncDisplayKit/Private/Layout/ASStackLayoutSpecUtilities.h

@@ -0,0 +1,129 @@
+//
+//  ASStackLayoutSpecUtilities.h
+//  AsyncDisplayKit
+//
+//  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.
+//
+
+#import "ASStackLayoutSpec.h"
+
+typedef struct {
+  ASStackLayoutDirection direction;
+  CGFloat spacing;
+  ASStackLayoutJustifyContent justifyContent;
+  ASStackLayoutAlignItems alignItems;
+} ASStackLayoutSpecStyle;
+
+inline CGFloat stackDimension(const ASStackLayoutDirection direction, const CGSize size)
+{
+  return (direction == ASStackLayoutDirectionVertical) ? size.height : size.width;
+}
+
+inline CGFloat crossDimension(const ASStackLayoutDirection direction, const CGSize size)
+{
+  return (direction == ASStackLayoutDirectionVertical) ? size.width : size.height;
+}
+
+inline BOOL compareCrossDimension(const ASStackLayoutDirection direction, const CGSize a, const CGSize b)
+{
+  return crossDimension(direction, a) < crossDimension(direction, b);
+}
+
+inline CGPoint directionPoint(const ASStackLayoutDirection direction, const CGFloat stack, const CGFloat cross)
+{
+  return (direction == ASStackLayoutDirectionVertical) ? CGPointMake(cross, stack) : CGPointMake(stack, cross);
+}
+
+inline CGSize directionSize(const ASStackLayoutDirection direction, const CGFloat stack, const CGFloat cross)
+{
+  return (direction == ASStackLayoutDirectionVertical) ? CGSizeMake(cross, stack) : CGSizeMake(stack, cross);
+}
+
+inline ASSizeRange directionSizeRange(const ASStackLayoutDirection direction,
+                                      const CGFloat stackMin,
+                                      const CGFloat stackMax,
+                                      const CGFloat crossMin,
+                                      const CGFloat crossMax)
+{
+  return {directionSize(direction, stackMin, crossMin), directionSize(direction, stackMax, crossMax)};
+}
+
+inline ASStackLayoutAlignItems alignment(ASStackLayoutAlignSelf childAlignment, ASStackLayoutAlignItems stackAlignment)
+{
+  switch (childAlignment) {
+    case ASStackLayoutAlignSelfCenter:
+      return ASStackLayoutAlignItemsCenter;
+    case ASStackLayoutAlignSelfEnd:
+      return ASStackLayoutAlignItemsEnd;
+    case ASStackLayoutAlignSelfStart:
+      return ASStackLayoutAlignItemsStart;
+    case ASStackLayoutAlignSelfStretch:
+      return ASStackLayoutAlignItemsStretch;
+    case ASStackLayoutAlignSelfAuto:
+    default:
+      return stackAlignment;
+  }
+}
+
+inline ASStackLayoutAlignItems alignment(ASHorizontalAlignment alignment, ASStackLayoutAlignItems defaultAlignment)
+{
+  switch (alignment) {
+    case ASHorizontalAlignmentLeft:
+      return ASStackLayoutAlignItemsStart;
+    case ASHorizontalAlignmentMiddle:
+      return ASStackLayoutAlignItemsCenter;
+    case ASHorizontalAlignmentRight:
+      return ASStackLayoutAlignItemsEnd;
+    case ASHorizontalAlignmentNone:
+    default:
+      return defaultAlignment;
+  }
+}
+
+inline ASStackLayoutAlignItems alignment(ASVerticalAlignment alignment, ASStackLayoutAlignItems defaultAlignment)
+{
+  switch (alignment) {
+    case ASVerticalAlignmentTop:
+      return ASStackLayoutAlignItemsStart;
+    case ASVerticalAlignmentCenter:
+      return ASStackLayoutAlignItemsCenter;
+    case ASVerticalAlignmentBottom:
+      return ASStackLayoutAlignItemsEnd;
+    case ASVerticalAlignmentNone:
+    default:
+      return defaultAlignment;
+  }
+}
+
+inline ASStackLayoutJustifyContent justifyContent(ASHorizontalAlignment alignment, ASStackLayoutJustifyContent defaultJustifyContent)
+{
+  switch (alignment) {
+    case ASHorizontalAlignmentLeft:
+      return ASStackLayoutJustifyContentStart;
+    case ASHorizontalAlignmentMiddle:
+      return ASStackLayoutJustifyContentCenter;
+    case ASHorizontalAlignmentRight:
+      return ASStackLayoutJustifyContentEnd;
+    case ASHorizontalAlignmentNone:
+    default:
+      return defaultJustifyContent;
+  }
+}
+
+inline ASStackLayoutJustifyContent justifyContent(ASVerticalAlignment alignment, ASStackLayoutJustifyContent defaultJustifyContent)
+{
+  switch (alignment) {
+    case ASVerticalAlignmentTop:
+      return ASStackLayoutJustifyContentStart;
+    case ASVerticalAlignmentCenter:
+      return ASStackLayoutJustifyContentCenter;
+    case ASVerticalAlignmentBottom:
+      return ASStackLayoutJustifyContentEnd;
+    case ASVerticalAlignmentNone:
+    default:
+      return defaultJustifyContent;
+  }
+}