command/queue: "playlistfind"/"playlistsearch" have a "window" parameter

NEWS

@@ -1,4 +1,6 @@
 ver 0.24 (not yet released)
+* protocol
+  - "playlistfind"/"playlistsearch" have a "window" parameter
 * player
   - add option "mixramp_analyzer" to scan MixRamp tags on-the-fly
 * tags

doc/protocol.rst

@@ -773,10 +773,15 @@ Whenever possible, ids should be used.
 
 .. _command_playlistfind:
 
-:command:`playlistfind {FILTER}`
+:command:`playlistfind {FILTER} [window {START:END}]`
     Search the queue for songs matching
     ``FILTER`` (see :ref:`Filters <filter_syntax>`).
 
+    ``window`` can be used to query only a portion of the real
+    response.  The parameter is two zero-based queue positions; a
+    start index (including) and an end index (excluding). The end
+    index can be omitted, which means the range is open-ended.
+
 .. _command_playlistid:
 
 :command:`playlistid {SONGID}`
@@ -794,7 +799,7 @@ Whenever possible, ids should be used.
 
 .. _command_playlistsearch:
 
-:command:`playlistsearch {FILTER}`
+:command:`playlistsearch {FILTER} [window {START:END}]`
     Search the queue for songs matching
     ``FILTER`` (see :ref:`Filters <filter_syntax>`).
     Parameters have the same meaning as for :ref:`find

src/command/QueueCommands.cxx

@@ -290,6 +290,14 @@ static CommandResult
 handle_playlist_match(Client &client, Request args, Response &r,
 		      bool fold_case)
 {
+	RangeArg window = RangeArg::All();
+	if (args.size >= 2 && StringIsEqual(args[args.size - 2], "window")) {
+		window = args.ParseRange(args.size - 1);
+
+		args.pop_back();
+		args.pop_back();
+	}
+
 	SongFilter filter;
 	try {
 		filter.Parse(args, fold_case);
@@ -302,6 +310,7 @@ handle_playlist_match(Client &client, Request args, Response &r,
 
 	QueueSelection selection;
 	selection.filter = &filter;
+	selection.window = window;
 
 	playlist_print_find(r, client.GetPlaylist(), selection);
 	return CommandResult::OK;