xrt_deleters.hpp

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// Copyright 2019-2022, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief Generic unique_ptr deleters for Monado types
 * @author Rylie Pavlik <rylie.pavlik@collabora.com>
 * @ingroup xrt_iface
 */
 
#pragma once
 
#include <memory>
 
namespace xrt {
 
/*!
 * Generic deleter functors for the variety of interface/object types in Monado.
 *
 * Use these with std::unique_ptr to make per-interface type aliases for unique ownership.
 * These are stateless deleters whose function pointer is statically specified as a template argument.
 */
namespace deleters {
        /*!
         * Deleter type for interfaces with destroy functions that take pointers to interface pointers (so they may be
         * zeroed).
         */
        template <typename T, void (*DeleterFn)(T **)> struct ptr_ptr_deleter
        {
                void
                operator()(T *obj) const noexcept
                {
                        if (obj == nullptr) {
                                return;
                        }
                        DeleterFn(&obj);
                }
        };
 
        /*!
         * Deleter type for interfaces with destroy functions that take just pointers.
         */
        template <typename T, void (*DeleterFn)(T *)> struct ptr_deleter
        {
                void
                operator()(T *obj) const noexcept
                {
                        if (obj == nullptr) {
                                return;
                        }
                        DeleterFn(obj);
                }
        };
 
        /*!
         * Deleter type for ref-counted interfaces with two-parameter `reference(dest, src)` functions.
         */
        template <typename T, void (*ReferenceFn)(T **, T *)> struct reference_deleter
        {
                void
                operator()(T *obj) const noexcept
                {
                        if (obj == nullptr) {
                                return;
                        }
                        ReferenceFn(&obj, nullptr);
                }
        };
} // namespace deleters
 
} // namespace xrt