output/Interface: convert to abstract class

Yet another C-style vtable replaced with C++.

src/output/plugins/OpenALOutputPlugin.cxx

@@ -20,7 +20,6 @@
 #include "config.h"
 #include "OpenALOutputPlugin.hxx"
 #include "../OutputAPI.hxx"
-#include "../Wrapper.hxx"
 #include "util/RuntimeError.hxx"
 
 #include <unistd.h>
@@ -33,14 +32,10 @@
 #include <OpenAL/alc.h>
 #endif
 
-class OpenALOutput {
-	friend struct AudioOutputWrapper<OpenALOutput>;
-
+class OpenALOutput final : AudioOutput {
 	/* should be enough for buffer size = 2048 */
 	static constexpr unsigned NUM_BUFFERS = 16;
 
-	AudioOutput base;
-
 	const char *device_name;
 	ALCdevice *device;
 	ALCcontext *context;
@@ -52,14 +47,18 @@ class OpenALOutput {
 
 	OpenALOutput(const ConfigBlock &block);
 
-	static OpenALOutput *Create(EventLoop &event_loop,
-				    const ConfigBlock &block);
+public:
+	static AudioOutput *Create(EventLoop &,
+				   const ConfigBlock &block) {
+		return new OpenALOutput(block);
+	}
 
-	void Open(AudioFormat &audio_format);
-	void Close();
+private:
+	void Open(AudioFormat &audio_format) override;
+	void Close() noexcept override;
 
 	gcc_pure
-	std::chrono::steady_clock::duration Delay() const noexcept {
+	std::chrono::steady_clock::duration Delay() const noexcept override {
 		return filled < NUM_BUFFERS || HasProcessed()
 			? std::chrono::steady_clock::duration::zero()
 			/* we don't know exactly how long we must wait
@@ -68,9 +67,9 @@ class OpenALOutput {
 			: std::chrono::milliseconds(50);
 	}
 
-	size_t Play(const void *chunk, size_t size);
+	size_t Play(const void *chunk, size_t size) override;
 
-	void Cancel();
+	void Cancel() noexcept override;
 
 private:
 	gcc_pure
@@ -138,7 +137,7 @@ OpenALOutput::SetupContext()
 }
 
 OpenALOutput::OpenALOutput(const ConfigBlock &block)
-	:base(openal_output_plugin),
+	:AudioOutput(0),
 	 device_name(block.GetBlockValue("device"))
 {
 	if (device_name == nullptr)
@@ -146,13 +145,7 @@ OpenALOutput::OpenALOutput(const ConfigBlock &block)
 					   ALC_DEFAULT_DEVICE_SPECIFIER);
 }
 
-inline OpenALOutput *
-OpenALOutput::Create(EventLoop &, const ConfigBlock &block)
-{
-	return new OpenALOutput(block);
-}
-
-inline void
+void
 OpenALOutput::Open(AudioFormat &audio_format)
 {
 	format = openal_audio_format(audio_format);
@@ -176,8 +169,8 @@ OpenALOutput::Open(AudioFormat &audio_format)
 	frequency = audio_format.sample_rate;
 }
 
-inline void
-OpenALOutput::Close()
+void
+OpenALOutput::Close() noexcept
 {
 	alcMakeContextCurrent(context);
 	alDeleteSources(1, &source);
@@ -186,7 +179,7 @@ OpenALOutput::Close()
 	alcCloseDevice(device);
 }
 
-inline size_t
+size_t
 OpenALOutput::Play(const void *chunk, size_t size)
 {
 	if (alcGetCurrentContext() != context)
@@ -214,8 +207,8 @@ OpenALOutput::Play(const void *chunk, size_t size)
 	return size;
 }
 
-inline void
-OpenALOutput::Cancel()
+void
+OpenALOutput::Cancel() noexcept
 {
 	filled = 0;
 	alcMakeContextCurrent(context);
@@ -226,22 +219,9 @@ OpenALOutput::Cancel()
 	filled = 0;
 }
 
-typedef AudioOutputWrapper<OpenALOutput> Wrapper;
-
 const struct AudioOutputPlugin openal_output_plugin = {
 	"openal",
 	nullptr,
-	&Wrapper::Init,
-	&Wrapper::Finish,
-	nullptr,
-	nullptr,
-	&Wrapper::Open,
-	&Wrapper::Close,
-	&Wrapper::Delay,
-	nullptr,
-	&Wrapper::Play,
-	nullptr,
-	&Wrapper::Cancel,
-	nullptr,
+	OpenALOutput::Create,
 	nullptr,
 };