Program Listing for File nullable_pointer.hpp

            

            
/*
* SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

#ifndef HOLOSCAN_UTILS_CUDA_NULLABLE_POINTER_HPP
#define HOLOSCAN_UTILS_CUDA_NULLABLE_POINTER_HPP

#include <cstddef>

namespace holoscan {

template <typename T>
class Nullable {
 public:
  explicit Nullable(T value = 0) : value_(value) {}
  explicit Nullable(std::nullptr_t) : value_(0) {}
  operator T() const { return value_; }
  explicit operator bool() { return value_ != 0; }

  friend bool operator==(Nullable l, Nullable r) { return l.value_ == r.value_; }
  friend bool operator!=(Nullable l, Nullable r) { return !(l == r); }
  friend bool operator==(Nullable l, std::nullptr_t) { return l.value_ == 0; }
  friend bool operator==(std::nullptr_t, Nullable r) { return r.value_ == 0; }
  friend bool operator!=(Nullable l, std::nullptr_t) { return l.value_ != 0; }
  friend bool operator!=(std::nullptr_t, Nullable r) { return r.value_ != 0; }

  template <typename RESULT, RESULT func(T)>
  struct Deleter {
    typedef Nullable<T> pointer;
    void operator()(T value) const { func(value); }
  };

 private:
  T value_;
};

}  // namespace holoscan

#endif/* HOLOSCAN_UTILS_CUDA_NULLABLE_POINTER_HPP */