third_party/WebKit/Source/core/animation/UnderlyingValueOwner.cpp

// 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.

#include "core/animation/UnderlyingValueOwner.h"

#include <memory>

namespace blink {

struct NullValueWrapper {
  NullValueWrapper() : value(nullptr) {}
  const InterpolationValue value;
};

const InterpolationValue& UnderlyingValueOwner::value() const {
  DEFINE_STATIC_LOCAL(NullValueWrapper, nullValueWrapper, ());
  return *this ? *m_value : nullValueWrapper.value;
}

void UnderlyingValueOwner::set(std::nullptr_t) {
  m_type = nullptr;
  m_valueOwner.clear();
  m_value = nullptr;
}

void UnderlyingValueOwner::set(const InterpolationType& type,
                               const InterpolationValue& value) {
  DCHECK(value);
  m_type = &type;
  // By clearing m_valueOwner we will perform a copy before attempting to mutate
  // m_value, thus upholding the const contract for this instance of
  // interpolationValue.
  m_valueOwner.clear();
  m_value = &value;
}

void UnderlyingValueOwner::set(const InterpolationType& type,
                               InterpolationValue&& value) {
  DCHECK(value);
  m_type = &type;
  m_valueOwner = std::move(value);
  m_value = &m_valueOwner;
}

void UnderlyingValueOwner::set(std::unique_ptr<TypedInterpolationValue> value) {
  if (value)
    set(value->type(), std::move(value->mutableValue()));
  else
    set(nullptr);
}

void UnderlyingValueOwner::set(const TypedInterpolationValue* value) {
  if (value)
    set(value->type(), value->value());
  else
    set(nullptr);
}

InterpolationValue& UnderlyingValueOwner::mutableValue() {
  DCHECK(m_type && m_value);
  if (!m_valueOwner) {
    m_valueOwner = m_value->clone();
    m_value = &m_valueOwner;
  }
  return m_valueOwner;
}

}  // namespace blink