moved baseline alignment to a layout spec.

AsyncDisplayKit/Private/ASStackTextPositionedLayout.h

@@ -0,0 +1,26 @@
+/*
+ *  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 "ASLayout.h"
+#import "ASDimension.h"
+#import "ASStackTextLayoutSpec.h"
+#import "ASStackPositionedLayout.h"
+
+struct ASStackTextPositionedLayout {
+    const std::vector<ASLayout *> sublayouts;
+    const CGFloat crossSize;
+    const CGFloat ascender;
+    const CGFloat descender;
+    
+    /** Given a positioned layout, computes each child position using baseline alignment. */
+    static ASStackTextPositionedLayout compute(const ASStackPositionedLayout &positionedLayout,
+                                               const ASStackTextLayoutSpecStyle &textStyle,
+                                               const ASSizeRange &constrainedSize);
+};