chromium/src/third_party/blink/renderer/platform/graphics/resource_id_traits.h

// Copyright 2021 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 THIRD_PARTY_BLINK_RENDERER_PLATFORM_GRAPHICS_RESOURCE_ID_TRAITS_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_GRAPHICS_RESOURCE_ID_TRAITS_H_

#include <limits>

#include "components/viz/common/resources/resource_id.h"
#include "third_party/blink/renderer/platform/wtf/cross_thread_copier.h"
#include "third_party/blink/renderer/platform/wtf/hash_functions.h"
#include "third_party/blink/renderer/platform/wtf/hash_traits.h"

namespace WTF {

template <>
struct WTF::CrossThreadCopier<viz::ResourceId>
    : public WTF::CrossThreadCopierPassThrough<viz::ResourceId> {};

template <>
struct HashTraits<viz::ResourceId> : GenericHashTraits<viz::ResourceId> {
  static const bool kEmptyValueIsZero = false;
  static viz::ResourceId EmptyValue() {
    return viz::ResourceId(std::numeric_limits<uint32_t>::max());
  }
  static void ConstructDeletedValue(viz::ResourceId& slot, bool) {
    slot = viz::ResourceId(std::numeric_limits<uint32_t>::max() - 1);
  }
  static bool IsDeletedValue(const viz::ResourceId& value) {
    return value.GetUnsafeValue() == std::numeric_limits<uint32_t>::max() - 1;
  }
};

}  // namespace WTF

namespace blink {

struct ResourceIdHash {
  STATIC_ONLY(ResourceIdHash);

  static bool Equal(const viz::ResourceId& a, const viz::ResourceId& b) {
    return a == b;
  }

  static uint32_t GetHash(const viz::ResourceId& id) {
    return WTF::HashInt(id.GetUnsafeValue());
  }

  static const bool safe_to_compare_to_empty_or_deleted = true;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_GRAPHICS_RESOURCE_ID_TRAITS_H_