mpd: add OutputIterator

src/mpdpp.cpp

@@ -31,62 +31,6 @@ MPD::Connection Mpd;
 
 namespace MPD {
 
-SongIterator::~SongIterator()
-{
-	if (m_connection)
-		finish();
-}
-
-void SongIterator::finish()
-{
-	// clean up
-	assert(m_connection);
-	mpd_response_finish(m_connection.get());
-	m_song = Song();
-	m_connection = nullptr;
-}
-
-Song &SongIterator::operator*() const
-{
-	assert(m_connection);
-	assert(!m_song.empty());
-	// we could make m_song a pointer to a Song and dereference here,
-	// but it's retarded as Song itself is essentially wrapper to
-	// std::shared_ptr. on the other hand, we need constness for the
-	// iterator to be able to play along with std::move_iterator.
-	return const_cast<Song &>(m_song);
-}
-
-Song *SongIterator::operator->() const
-{
-	return &**this;
-}
-
-SongIterator &SongIterator::operator++()
-{
-	assert(m_connection);
-	mpd_song *s = mpd_recv_song(m_connection.get());
-	if (s != nullptr)
-		m_song = Song(s);
-	else
-		finish();
-	return *this;
-}
-
-SongIterator SongIterator::operator++(int)
-{
-	SongIterator it(*this);
-	++*this;
-	return it;
-}
-
-SongIterator::SongIterator(std::shared_ptr<mpd_connection> conn)
-: m_connection(std::move(conn))
-{
-	// get the first element
-	++*this;
-}
-
 Connection::Connection() : m_connection(nullptr),
 				m_command_list_active(false),
 				m_idle(false),
@@ -354,7 +298,7 @@ SongIterator Connection::GetPlaylistChanges(unsigned version)
 	prechecksNoCommandsList();
 	mpd_send_queue_changes_meta(m_connection.get(), version);
 	checkErrors();
-	return SongIterator(m_connection);
+	return SongIterator(m_connection, mpd_recv_song);
 }
 
 Song Connection::GetCurrentSong()
@@ -381,7 +325,7 @@ SongIterator Connection::GetPlaylistContent(const std::string &path)
 {
 	prechecksNoCommandsList();
 	mpd_send_list_playlist_meta(m_connection.get(), path.c_str());
-	SongIterator result(m_connection);
+	SongIterator result(m_connection, mpd_recv_song);
 	checkErrors();
 	return result;
 }
@@ -390,7 +334,7 @@ SongIterator Connection::GetPlaylistContentNoInfo(const std::string &path)
 {
 	prechecksNoCommandsList();
 	mpd_send_list_playlist(m_connection.get(), path.c_str());
-	SongIterator result(m_connection);
+	SongIterator result(m_connection, mpd_recv_song);
 	checkErrors();
 	return result;
 }
@@ -720,7 +664,7 @@ SongIterator Connection::CommitSearchSongs()
 	prechecksNoCommandsList();
 	mpd_search_commit(m_connection.get());
 	checkErrors();
-	return SongIterator(m_connection);
+	return SongIterator(m_connection, mpd_recv_song);
 }
 
 void Connection::CommitSearchTags(StringConsumer f)
@@ -798,20 +742,15 @@ SongIterator Connection::GetSongs(const std::string &directory)
 	prechecksNoCommandsList();
 	mpd_send_list_meta(m_connection.get(), directory.c_str());
 	checkErrors();
-	return SongIterator(m_connection);
+	return SongIterator(m_connection, mpd_recv_song);
 }
 
-void Connection::GetOutputs(OutputConsumer f)
+OutputIterator Connection::GetOutputs()
 {
 	prechecksNoCommandsList();
 	mpd_send_outputs(m_connection.get());
-	while (mpd_output *output = mpd_recv_output(m_connection.get()))
-	{
-		f(Output(mpd_output_get_name(output), mpd_output_get_enabled(output)));
-		mpd_output_free(output);
-	}
-	mpd_response_finish(m_connection.get());
 	checkErrors();
+	return OutputIterator(m_connection, mpd_recv_output);
 }
 
 void Connection::EnableOutput(int id)

src/mpdpp.h

@@ -131,50 +131,144 @@ struct Item
 
 struct Output
 {
-	Output(const std::string &name_, bool enabled) : m_name(name_), m_enabled(enabled) { }
-	
-	const std::string &name() const { return m_name; }
-	bool isEnabled() const { return m_enabled; }
-	
+	Output() { }
+	Output(mpd_output *output) : m_output(output, mpd_output_free) { }
+
+	Output(const Output &rhs) : m_output(rhs.m_output) { }
+	Output(Output &&rhs) : m_output(std::move(rhs.m_output)) { }
+	Output &operator=(Output rhs)
+	{
+		m_output = std::move(rhs.m_output);
+		return *this;
+	}
+
+	bool operator==(const Output &rhs) const
+	{
+		if (empty() && rhs.empty())
+			return true;
+		else if (!empty() && !rhs.empty())
+			return id() == rhs.id()
+			    && std::strcmp(name(), rhs.name()) == 0
+			    && enabled() == rhs.enabled();
+		else
+			return false;
+	}
+	bool operator!=(const Output &rhs) const
+	{
+		return !(*this == rhs);
+	}
+
+	unsigned id() const
+	{
+		checkNonEmpty();
+		return mpd_output_get_id(m_output.get());
+	}
+	const char *name() const
+	{
+		checkNonEmpty();
+		return mpd_output_get_name(m_output.get());
+	}
+	bool enabled() const
+	{
+		checkNonEmpty();
+		return mpd_output_get_enabled(m_output.get());
+	}
+
+	bool empty() const { return m_output.get() == nullptr; }
+
 private:
-	std::string m_name;
-	bool m_enabled;
+	void checkNonEmpty() const
+	{
+		if (empty())
+			throw std::runtime_error("No associated mpd_output object");
+	}
+
+	std::shared_ptr<mpd_output> m_output;
 };
 
 typedef std::vector<Item> ItemList;
 typedef std::vector<std::string> StringList;
 typedef std::vector<Output> OutputList;
 
-struct SongIterator : std::iterator<std::forward_iterator_tag, Song>
+template <typename DestT, typename SourceT>
+struct Iterator : std::iterator<std::forward_iterator_tag, DestT>
 {
+	typedef SourceT *(*SourceFetcher)(mpd_connection *);
+
 	friend class Connection;
 
-	SongIterator() : m_connection(nullptr) { }
-	~SongIterator();
+	Iterator() : m_connection(nullptr), m_fetch_source(nullptr) { }
+	~Iterator()
+	{
+		if (m_connection)
+			finish();
+	}
 
-	void finish();
+	void finish()
+	{
+		// clean up
+		assert(m_connection);
+		mpd_response_finish(m_connection.get());
+		m_object = DestT();
+		m_connection = nullptr;
+	}
 
-	Song &operator*() const;
-	Song *operator->() const;
+	DestT &operator*() const
+	{
+		assert(m_connection);
+		if (m_object.empty())
+			throw std::runtime_error("empty object");
+		return const_cast<DestT &>(m_object);
+	}
+	DestT *operator->() const
+	{
+		return &**this;
+	}
 
-	SongIterator &operator++();
-	SongIterator operator++(int);
+	Iterator &operator++()
+	{
+		assert(m_connection);
+		assert(m_fetch_source != nullptr);
+		auto src = m_fetch_source(m_connection.get());
+		if (src != nullptr)
+			m_object = DestT(src);
+		else
+			finish();
+		return *this;
+	}
+	Iterator operator++(int)
+	{
+		Iterator it(*this);
+		++*this;
+		return it;
+	}
 
-	bool operator==(const SongIterator &rhs) {
+	bool operator==(const Iterator &rhs)
+	{
 		return m_connection == rhs.m_connection
-		    && m_song == rhs.m_song;
+		    && m_object == rhs.m_object;
 	}
-	bool operator!=(const SongIterator &rhs) {
+	bool operator!=(const Iterator &rhs)
+	{
 		return !(*this == rhs);
 	}
 
 private:
-	SongIterator(std::shared_ptr<mpd_connection> conn);
+	Iterator(std::shared_ptr<mpd_connection> conn, SourceFetcher fetch_source)
+	: m_connection(std::move(conn)), m_fetch_source(fetch_source)
+	{
+		// get the first element
+		++*this;
+	}
 
 	std::shared_ptr<mpd_connection> m_connection;
-	Song m_song;
+	SourceFetcher m_fetch_source;
+	DestT m_object;
 };
 
+typedef Iterator<Song, mpd_song> SongIterator;
+typedef Iterator<Output, mpd_output> OutputIterator;
+
 class Connection : private boost::noncopyable
 {
 	typedef std::function<void(Item)> ItemConsumer;
@@ -276,7 +370,7 @@ public:
 	SongIterator GetSongs(const std::string &directory);
 	void GetDirectories(const std::string &directory, StringConsumer f);
 	
-	void GetOutputs(OutputConsumer f);
+	OutputIterator GetOutputs();
 	void EnableOutput(int id);
 	void DisableOutput(int id);
 	

src/outputs.cpp

@@ -70,7 +70,7 @@ std::wstring Outputs::title()
 
 void Outputs::enterPressed()
 {
-	if (w.current().value().isEnabled())
+	if (w.current().value().enabled())
 	{
 		Mpd.DisableOutput(w.choice());
 		Statusbar::printf("Output \"%s\" disabled", w.current().value().name());
@@ -99,9 +99,11 @@ void Outputs::mouseButtonPressed(MEVENT me)
 void Outputs::FetchList()
 {
 	w.clear();
-	Mpd.GetOutputs([this](MPD::Output output) {
-		w.addItem(output, output.isEnabled());
-	});
+	for (MPD::OutputIterator out = Mpd.GetOutputs(), end; out != end; ++out)
+	{
+		bool enabled = out->enabled();
+		w.addItem(std::move(*out), enabled);
+	}
 	if (myScreen == this)
 		w.refresh();
 }

src/visualizer.cpp

@@ -458,12 +458,14 @@ void Visualizer::FindOutputID()
 	m_output_id = -1;
 	if (!Config.visualizer_output_name.empty())
 	{
-		size_t idx = 0;
-		Mpd.GetOutputs([this, &idx](MPD::Output output) {
-			if (output.name() == Config.visualizer_output_name)
-				m_output_id = idx;
-			++idx;
-		});
+		for (MPD::OutputIterator out = Mpd.GetOutputs(), end; out != end; ++out)
+		{
+			if (out->name() == Config.visualizer_output_name)
+			{
+				m_output_id = out->id();
+				break;
+			}
+		}
 		if (m_output_id == -1)
 			Statusbar::printf("There is no output named \"%s\"", Config.visualizer_output_name);
 	}