util/{Const,Writable}Buffer, ...: rename IsEmpty() to empty(), imitating STL

src/command/ClientCommands.cxx

@@ -58,7 +58,7 @@ handle_password(Client &client, Request args, Response &r)
 static TagMask
 ParseTagMask(Request request)
 {
-	if (request.IsEmpty())
+	if (request.empty())
 		throw ProtocolError(ACK_ERROR_ARG, "Not enough arguments");
 
 	TagMask result = TagMask::None();
@@ -77,14 +77,14 @@ ParseTagMask(Request request)
 CommandResult
 handle_tagtypes(Client &client, Request request, Response &r)
 {
-	if (request.IsEmpty()) {
+	if (request.empty()) {
 		tag_print_types(r);
 		return CommandResult::OK;
 	}
 
 	const char *cmd = request.shift();
 	if (StringIsEqual(cmd, "all")) {
-		if (!request.IsEmpty()) {
+		if (!request.empty()) {
 			r.Error(ACK_ERROR_ARG, "Too many arguments");
 			return CommandResult::ERROR;
 		}
@@ -92,7 +92,7 @@ handle_tagtypes(Client &client, Request request, Response &r)
 		client.tag_mask = TagMask::All();
 		return CommandResult::OK;
 	} else if (StringIsEqual(cmd, "clear")) {
-		if (!request.IsEmpty()) {
+		if (!request.empty()) {
 			r.Error(ACK_ERROR_ARG, "Too many arguments");
 			return CommandResult::ERROR;
 		}

src/command/DatabaseCommands.cxx

@@ -169,7 +169,7 @@ handle_count(Client &client, Request args, Response &r)
 	}
 
 	SongFilter filter;
-	if (!args.IsEmpty() && !filter.Parse(args, false)) {
+	if (!args.empty() && !filter.Parse(args, false)) {
 		r.Error(ACK_ERROR_ARG, "incorrect arguments");
 		return CommandResult::ERROR;
 	}
@@ -235,7 +235,7 @@ handle_list(Client &client, Request args, Response &r)
 		args.pop_back();
 	}
 
-	if (!args.IsEmpty()) {
+	if (!args.empty()) {
 		filter.reset(new SongFilter());
 		if (!filter->Parse(args, false)) {
 			r.Error(ACK_ERROR_ARG, "not able to parse args");

src/command/MessageCommands.cxx

@@ -76,7 +76,7 @@ handle_unsubscribe(Client &client, Request args, Response &r)
 CommandResult
 handle_channels(Client &client, gcc_unused Request args, Response &r)
 {
-	assert(args.IsEmpty());
+	assert(args.empty());
 
 	std::set<std::string> channels;
 	for (const auto &c : *client.GetInstance().client_list)
@@ -93,7 +93,7 @@ CommandResult
 handle_read_messages(Client &client,
 		     gcc_unused Request args, Response &r)
 {
-	assert(args.IsEmpty());
+	assert(args.empty());
 
 	while (!client.messages.empty()) {
 		const ClientMessage &msg = client.messages.front();

src/command/OtherCommands.cxx

@@ -284,7 +284,7 @@ handle_update(Client &client, Request args, Response &r, bool discard)
 	const char *path = "";
 
 	assert(args.size <= 1);
-	if (!args.IsEmpty()) {
+	if (!args.empty()) {
 		path = args.front();
 
 		if (*path == 0 || StringIsEqual(path, "/"))

src/command/OutputCommands.cxx

@@ -71,7 +71,7 @@ handle_toggleoutput(Client &client, Request args, Response &r)
 CommandResult
 handle_devices(Client &client, gcc_unused Request args, Response &r)
 {
-	assert(args.IsEmpty());
+	assert(args.empty());
 
 	printAudioDevices(r, client.GetPartition().outputs);
 	return CommandResult::OK;

src/command/PlayerCommands.cxx

@@ -95,7 +95,7 @@ handle_pause(Client &client, Request args, gcc_unused Response &r)
 {
 	auto &pc = client.GetPlayerControl();
 
-	if (!args.IsEmpty()) {
+	if (!args.empty()) {
 		bool pause_flag = args.ParseBool(0);
 		pc.LockSetPause(pause_flag);
 	} else

src/command/QueueCommands.cxx

@@ -242,7 +242,7 @@ handle_playlistinfo(Client &client, Request args, Response &r)
 CommandResult
 handle_playlistid(Client &client, Request args, Response &r)
 {
-	if (!args.IsEmpty()) {
+	if (!args.empty()) {
 		unsigned id = args.ParseUnsigned(0);
 		playlist_print_id(r, client.GetPlaylist(), id);
 	} else {