xrt: Factor out deleters

src/xrt/include/xrt/xrt_deleters.hpp

@@ -0,0 +1,70 @@
+// Copyright 2019-2022, Collabora, Ltd.
+// SPDX-License-Identifier: BSL-1.0
+/*!
+ * @file
+ * @brief Generic unique_ptr deleters for Monado types
+ * @author Ryan Pavlik <ryan.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

src/xrt/include/xrt/xrt_device.hpp

@@ -1,4 +1,4 @@
-// Copyright 2019-2021, Collabora, Ltd.
+// Copyright 2019-2022, Collabora, Ltd.
 // SPDX-License-Identifier: BSL-1.0
 /*!
  * @file
@@ -10,25 +10,14 @@
 #pragma once
 
 #include "xrt_device.h"
+#include "xrt_deleters.hpp"
 
 #include <memory>
 
 namespace xrt {
 
-namespace deleters {
-	//! Deleter type for xrt_device
-	struct xrt_device_deleter
-	{
-		void
-		operator()(xrt_device *dev) const noexcept
-		{
-			xrt_device_destroy(&dev);
-		}
-	};
-
-} // namespace deleters
 
 //! Unique-ownership smart pointer for a @ref xrt_device implementation.
-using unique_xrt_device = std::unique_ptr<xrt_device, deleters::xrt_device_deleter>;
+using unique_xrt_device = std::unique_ptr<xrt_device, deleters::ptr_ptr_deleter<xrt_device, xrt_device_destroy>>;
 
 } // namespace xrt