third_party/WebKit/Source/core/animation/UnderlyingValueOwner.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 UnderlyingValueOwner_h
#define UnderlyingValueOwner_h

#include "core/animation/TypedInterpolationValue.h"
#include "wtf/Allocator.h"
#include "wtf/Noncopyable.h"
#include <memory>

namespace blink {

// Handles memory management of underlying InterpolationValues in applyStack()
// Ensures we perform copy on write if we are not the owner of an underlying
// InterpolationValue. This functions similar to a DataRef except on
// std::unique_ptr'd objects.
class UnderlyingValueOwner {
  WTF_MAKE_NONCOPYABLE(UnderlyingValueOwner);
  STACK_ALLOCATED();

 public:
  UnderlyingValueOwner()
      : m_type(nullptr), m_valueOwner(nullptr), m_value(nullptr) {}

  operator bool() const {
    DCHECK_EQ(static_cast<bool>(m_type), static_cast<bool>(m_value));
    return m_type;
  }

  const InterpolationType& type() const {
    DCHECK(m_type);
    return *m_type;
  }

  const InterpolationValue& value() const;

  void set(std::nullptr_t);
  void set(const InterpolationType&, const InterpolationValue&);
  void set(const InterpolationType&, InterpolationValue&&);
  void set(std::unique_ptr<TypedInterpolationValue>);
  void set(const TypedInterpolationValue*);

  InterpolationValue& mutableValue();

 private:
  const InterpolationType* m_type;
  InterpolationValue m_valueOwner;
  const InterpolationValue* m_value;
};

}  // namespace blink

#endif  // UnderlyingValueOwner_h