output/Registry: replace output_plugins_for_each() with a container c…

…lass

src/CommandLine.cxx

@@ -173,8 +173,9 @@ static void version()
 #endif
 		   "\n\n"
 		   "Output plugins:\n");
-	audio_output_plugins_for_each(plugin)
-		fmt::print(" {}", plugin->name);
+	for (const auto &plugin : GetAllAudioOutputPlugins()) {
+		fmt::print(" {}", plugin.name);
+	}
 	fmt::print("\n"
 
 #ifdef ENABLE_ENCODER

src/output/Init.cxx

@@ -51,15 +51,15 @@ audio_output_detect()
 {
 	LogInfo(output_domain, "Attempt to detect audio output device");
 
-	audio_output_plugins_for_each(plugin) {
-		if (plugin->test_default_device == nullptr)
+	for (const auto &plugin : GetAllAudioOutputPlugins()) {
+		if (plugin.test_default_device == nullptr)
 			continue;
 
 		FmtInfo(output_domain,
 			"Attempting to detect a {:?} audio device",
-			plugin->name);
-		if (ao_plugin_test_default_device(plugin))
-			return plugin;
+			plugin.name);
+		if (ao_plugin_test_default_device(&plugin))
+			return &plugin;
 	}
 
 	throw std::runtime_error("Unable to detect an audio device");

src/output/Registry.cxx

@@ -92,9 +92,10 @@ constinit const AudioOutputPlugin *const audio_output_plugins[] = {
 const AudioOutputPlugin *
 GetAudioOutputPluginByName(const char *name) noexcept
 {
-	audio_output_plugins_for_each(plugin)
-		if (StringIsEqual(plugin->name, name))
-			return plugin;
+	for (const auto &plugin : GetAllAudioOutputPlugins()) {
+		if (StringIsEqual(plugin.name, name))
+			return &plugin;
+	}
 
 	return nullptr;
 }

src/output/Registry.hxx

@@ -1,20 +1,21 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 // Copyright The Music Player Daemon Project
 
-#ifndef MPD_OUTPUT_LIST_HXX
-#define MPD_OUTPUT_LIST_HXX
+#pragma once
+
+#include "util/DereferenceIterator.hxx"
+#include "util/TerminatedArray.hxx"
 
 struct AudioOutputPlugin;
 
 extern const AudioOutputPlugin *const audio_output_plugins[];
 
+static inline auto
+GetAllAudioOutputPlugins() noexcept
+{
+	return DereferenceContainerAdapter{TerminatedArray<const AudioOutputPlugin *const, nullptr>{audio_output_plugins}};
+}
+
 [[gnu::pure]]
 const AudioOutputPlugin *
 GetAudioOutputPluginByName(const char *name) noexcept;
-
-#define audio_output_plugins_for_each(plugin) \
-	for (const AudioOutputPlugin *plugin, \
-		*const*output_plugin_iterator = &audio_output_plugins[0]; \
-		(plugin = *output_plugin_iterator) != nullptr; ++output_plugin_iterator)
-
-#endif