third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.h

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NGLayoutAlgorithm_h
#define NGLayoutAlgorithm_h

#include "core/CoreExport.h"
#include "wtf/Allocator.h"
#include "wtf/Noncopyable.h"

namespace blink {

class NGConstraintSpace;
class NGFragment;

// Base class for all LayoutNG algorithms.
class CORE_EXPORT NGLayoutAlgorithm {
  WTF_MAKE_NONCOPYABLE(NGLayoutAlgorithm);
  USING_FAST_MALLOC(NGLayoutAlgorithm);

 public:
  NGLayoutAlgorithm() {}

  // Actual layout function. Lays out the children and descendents within the
  // constraints given by the NGConstraintSpace. Returns a fragment with the
  // resulting layout information.
  // This function can not be const because for interruptible layout, we have
  // to be able to store state information.
  // Returns true when done; when this function returns false, it has to be
  // called again. The out parameter will only be set when this function
  // returns true. The same constraint space has to be passed each time.
  // TODO(layout-ng): Should we have a StartLayout function to avoid passing
  // the same space for each Layout iteration?
  virtual bool Layout(const NGConstraintSpace*, NGFragment**) = 0;
};

}  // namespace blink

#endif  // NGLayoutAlgorithm_h