command/queue: add range parameter to plchanges and plchangesposid

NEWS

@@ -5,6 +5,7 @@ ver 0.20 (not yet released)
   - report song duration with milliseconds precision
   - "sticker find" can match sticker values
   - drop the "file:///" prefix for absolute file paths
+  - add range parameter to command "plchanges" and "plchangesposid"
 * tags
   - ape, ogg: drop support for non-standard tag "album artist"
     affected filetypes: vorbis, flac, opus & all files with ape2 tags

doc/protocol.xml

@@ -1161,12 +1161,15 @@ OK
             <cmdsynopsis>
               <command>plchanges</command>
               <arg choice="req"><replaceable>VERSION</replaceable></arg>
+              <arg><replaceable>START:END</replaceable></arg>
             </cmdsynopsis>
           </term>
           <listitem>
             <para>
               Displays changed songs currently in the playlist since
-              <varname>VERSION</varname>.
+              <varname>VERSION</varname>.  Start and end positions may
+              be given to limit the output to changes in the given
+              range.
             </para>
             <para>
               To detect songs that were deleted at the end of the
@@ -1179,6 +1182,7 @@ OK
             <cmdsynopsis>
               <command>plchangesposid</command>
               <arg choice="req"><replaceable>VERSION</replaceable></arg>
+              <arg><replaceable>START:END</replaceable></arg>
             </cmdsynopsis>
           </term>
           <listitem>

src/PlaylistPrint.cxx

@@ -104,17 +104,21 @@ playlist_print_find(Response &r, Partition &partition,
 void
 playlist_print_changes_info(Response &r, Partition &partition,
 			    const playlist &playlist,
-			    uint32_t version)
+			    uint32_t version,
+			    unsigned start, unsigned end)
 {
-	queue_print_changes_info(r, partition, playlist.queue, version);
+	queue_print_changes_info(r, partition, playlist.queue, version,
+				 start, end);
 }
 
 void
 playlist_print_changes_position(Response &r,
 				const playlist &playlist,
-				uint32_t version)
+				uint32_t version,
+				unsigned start, unsigned end)
 {
-	queue_print_changes_position(r, playlist.queue, version);
+	queue_print_changes_position(r, playlist.queue, version,
+				     start, end);
 }
 
 #ifdef ENABLE_DATABASE

src/PlaylistPrint.hxx

@@ -79,7 +79,8 @@ playlist_print_find(Response &r, Partition &partition,
 void
 playlist_print_changes_info(Response &r, Partition &partition,
 			    const playlist &playlist,
-			    uint32_t version);
+			    uint32_t version,
+			    unsigned start, unsigned end);
 
 /**
  * Print changes since the specified playlist version, position only.
@@ -87,7 +88,8 @@ playlist_print_changes_info(Response &r, Partition &partition,
 void
 playlist_print_changes_position(Response &r,
 				const playlist &playlist,
-				uint32_t version);
+				uint32_t version,
+				unsigned start, unsigned end);
 
 /**
  * Send the stored playlist to the client.

src/command/AllCommands.cxx

@@ -148,8 +148,8 @@ static constexpr struct command commands[] = {
 	{ "playlistinfo", PERMISSION_READ, 0, 1, handle_playlistinfo },
 	{ "playlistmove", PERMISSION_CONTROL, 3, 3, handle_playlistmove },
 	{ "playlistsearch", PERMISSION_READ, 2, -1, handle_playlistsearch },
-	{ "plchanges", PERMISSION_READ, 1, 1, handle_plchanges },
-	{ "plchangesposid", PERMISSION_READ, 1, 1, handle_plchangesposid },
+	{ "plchanges", PERMISSION_READ, 1, 2, handle_plchanges },
+	{ "plchangesposid", PERMISSION_READ, 1, 2, handle_plchangesposid },
 	{ "previous", PERMISSION_CONTROL, 0, 0, handle_previous },
 	{ "prio", PERMISSION_CONTROL, 2, -1, handle_prio },
 	{ "prioid", PERMISSION_CONTROL, 2, -1, handle_prioid },

src/command/QueueCommands.cxx

@@ -251,8 +251,13 @@ handle_plchanges(Client &client, Request args, Response &r)
 	if (!ParseCommandArg32(r, version, args.front()))
 		return CommandResult::ERROR;
 
+	RangeArg range = RangeArg::All();
+	if (!args.ParseOptional(1, range, r))
+		return CommandResult::ERROR;
+
 	playlist_print_changes_info(r, client.partition,
-				    client.playlist, version);
+				    client.playlist, version,
+				    range.start, range.end);
 	return CommandResult::OK;
 }
 
@@ -263,7 +268,12 @@ handle_plchangesposid(Client &client, Request args, Response &r)
 	if (!ParseCommandArg32(r, version, args.front()))
 		return CommandResult::ERROR;
 
-	playlist_print_changes_position(r, client.playlist, version);
+	RangeArg range = RangeArg::All();
+	if (!args.ParseOptional(1, range, r))
+		return CommandResult::ERROR;
+
+	playlist_print_changes_position(r, client.playlist, version,
+					range.start, range.end);
 	return CommandResult::OK;
 }
 

src/queue/QueuePrint.cxx

@@ -71,19 +71,36 @@ queue_print_uris(Response &r, Partition &partition, const Queue &queue,
 
 void
 queue_print_changes_info(Response &r, Partition &partition, const Queue &queue,
-			 uint32_t version)
+			 uint32_t version,
+			 unsigned start, unsigned end)
 {
-	for (unsigned i = 0; i < queue.GetLength(); i++) {
+	assert(start <= end);
+
+	if (start >= queue.GetLength())
+		return;
+
+	if (end > queue.GetLength())
+		end = queue.GetLength();
+
+	for (unsigned i = start; i < end; i++)
 		if (queue.IsNewerAtPosition(i, version))
 			queue_print_song_info(r, partition, queue, i);
-	}
 }
 
 void
 queue_print_changes_position(Response &r, const Queue &queue,
-			     uint32_t version)
+			     uint32_t version,
+			     unsigned start, unsigned end)
 {
-	for (unsigned i = 0; i < queue.GetLength(); i++)
+	assert(start <= end);
+
+	if (start >= queue.GetLength())
+		return;
+
+	if (end > queue.GetLength())
+		end = queue.GetLength();
+
+	for (unsigned i = start; i < end; i++)
 		if (queue.IsNewerAtPosition(i, version))
 			r.Format("cpos: %i\nId: %i\n",
 				 i, queue.PositionToId(i));

src/queue/QueuePrint.hxx

@@ -42,11 +42,13 @@ queue_print_uris(Response &r, Partition &partition, const Queue &queue,
 
 void
 queue_print_changes_info(Response &r, Partition &partition, const Queue &queue,
-			 uint32_t version);
+			 uint32_t version,
+			 unsigned start, unsigned end);
 
 void
 queue_print_changes_position(Response &r, const Queue &queue,
-			     uint32_t version);
+			     uint32_t version,
+			     unsigned start, unsigned end);
 
 void
 queue_find(Response &response, Partition &partition, const Queue &queue,