#pragma once

#include <cstdint>

#include "envoy/common/pure.h"

#include "absl/types/optional.h"

namespace Envoy {

/**

 * Interface for hashable types used in heterogeneous contexts (see, for example, usage in

 * FilterStateHashMethod).

 */

class Hashable {

public:

  /**

   * Request the 64-bit hash for this object.

   * @return absl::optional<uint64_t> the hash value, or absl::nullopt if a hash could not be

   * produced for this instance.

   */

  virtual absl::optional<uint64_t> hash() const PURE;

};

} // namespace Envoy