src/dawn/wire/ObjectHandle.h

// Copyright 2022 The Dawn & Tint Authors
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#ifndef DAWN_WIRE_OBJECTHANDLE_H_
#define DAWN_WIRE_OBJECTHANDLE_H_

#include <cstddef>
#include <cstdint>

#include "dawn/common/HashUtils.h"
#include "dawn/wire/Wire.h"

namespace dawn::wire {

using ObjectId = uint32_t;
using ObjectGeneration = uint32_t;

// ObjectHandle identifies some WebGPU object in the wire.
// An ObjectHandle will never be reused, so can be used to uniquely identify an object forever.
struct ObjectHandle : public Handle {
    ObjectHandle();
    ObjectHandle(ObjectId objId, ObjectGeneration objGeneration);

    explicit ObjectHandle(const volatile ObjectHandle& rhs);
    ObjectHandle& operator=(const volatile ObjectHandle& rhs);

    ObjectHandle(const ObjectHandle& rhs);
    ObjectHandle& operator=(const ObjectHandle& rhs);

    // Allow direct conversion from the base Handle type.
    // NOLINTNEXTLINE(runtime/explicit)
    ObjectHandle(const Handle& rhs);

    // MSVC has a bug where it thinks the volatile copy assignment is a duplicate.
    // Workaround this by forwarding to a different function AssignFrom.
    template <typename T>
    ObjectHandle& operator=(const T& rhs) {
        return AssignFrom(rhs);
    }
    ObjectHandle& AssignFrom(const ObjectHandle& rhs);
    ObjectHandle& AssignFrom(const volatile ObjectHandle& rhs);

    bool IsValid() const;
};

}  // namespace dawn::wire

template <>
struct std::hash<dawn::wire::ObjectHandle> {
    size_t operator()(const dawn::wire::ObjectHandle& value) const {
        size_t hash = dawn::Hash(value.id);
        dawn::HashCombine(&hash, value.generation);
        return hash;
    }
};

#endif  // DAWN_WIRE_OBJECTHANDLE_H_