client: add tag_mask attribute

The "tagtypes" command now has several sub commands which can be used
to edit that mask.

src/client/Client.hxx

@@ -23,6 +23,7 @@
 #include "check.h"
 #include "ClientMessage.hxx"
 #include "command/CommandListBuilder.hxx"
+#include "tag/Mask.hxx"
 #include "event/FullyBufferedSocket.hxx"
 #include "event/TimeoutMonitor.hxx"
 #include "Compiler.h"
@@ -70,6 +71,11 @@ public:
 	/** idle flags that the client wants to receive */
 	unsigned idle_subscriptions;
 
+	/**
+	 * The tags this client is interested in.
+	 */
+	TagMask tag_mask = TagMask::All();
+
 	/**
 	 * A list of channel names this client is subscribed to.
 	 */

src/client/Response.cxx

@@ -23,6 +23,12 @@
 #include "util/FormatString.hxx"
 #include "util/AllocatedString.hxx"
 
+TagMask
+Response::GetTagMask() const
+{
+	return GetClient().tag_mask;
+}
+
 bool
 Response::Write(const void *data, size_t length)
 {

src/client/Response.hxx

@@ -22,11 +22,13 @@
 
 #include "check.h"
 #include "protocol/Ack.hxx"
+#include "Compiler.h"
 
 #include <stddef.h>
 #include <stdarg.h>
 
 class Client;
+class TagMask;
 
 class Response {
 	Client &client;
@@ -59,6 +61,13 @@ public:
 		return client;
 	}
 
+	/**
+	 * Accessor for Client::tag_mask.  Can be used if caller wants
+	 * to avoid including Client.hxx.
+	 */
+	gcc_pure
+	TagMask GetTagMask() const;
+
 	void SetCommand(const char *_command) {
 		command = _command;
 	}