Allow range in listplaylist and listplaylistinfo

NEWS

@@ -12,6 +12,7 @@ ver 0.24 (not yet released)
   - stickers on playlists and some tag types
   - new command "stickernames"
   - new "search"/"find" filter "added-since"
+  - allow range in listplaylist and listplaylistinfo
 * database
   - attribute "added" shows when each song was added to the database
   - proxy: require MPD 0.21 or later

doc/protocol.rst

@@ -944,15 +944,17 @@ remote playlists (absolute URI with a supported scheme).
 
 .. _command_listplaylist:
 
-:command:`listplaylist {NAME}`
+:command:`listplaylist {NAME} [{START:END}]`
     Lists the songs in the playlist.  Playlist plugins are
-    supported.
+    supported. A range may be specified to list
+    only a part of the playlist. [#since_0_24]_
 
 .. _command_listplaylistinfo:
 
-:command:`listplaylistinfo {NAME}`
+:command:`listplaylistinfo {NAME} [{START:END}]`
     Lists the songs with metadata in the playlist.  Playlist
-    plugins are supported.
+    plugins are supported. A range may be specified to list
+    only a part of the playlist. [#since_0_24]_
 
 .. _command_listplaylists:
 

src/command/AllCommands.cxx

@@ -117,8 +117,8 @@ static constexpr struct command commands[] = {
 	{ "listneighbors", PERMISSION_READ, 0, 0, handle_listneighbors },
 #endif
 	{ "listpartitions", PERMISSION_READ, 0, 0, handle_listpartitions },
-	{ "listplaylist", PERMISSION_READ, 1, 1, handle_listplaylist },
-	{ "listplaylistinfo", PERMISSION_READ, 1, 1, handle_listplaylistinfo },
+	{ "listplaylist", PERMISSION_READ, 1, 2, handle_listplaylist },
+	{ "listplaylistinfo", PERMISSION_READ, 1, 2, handle_listplaylistinfo },
 	{ "listplaylists", PERMISSION_READ, 0, 0, handle_listplaylists },
 	{ "load", PERMISSION_ADD, 1, 3, handle_load },
 	{ "lsinfo", PERMISSION_READ, 0, 1, handle_lsinfo },

src/command/PlaylistCommands.cxx

@@ -125,8 +125,10 @@ handle_listplaylist(Client &client, Request args, Response &r)
 #endif
 					   );
 
+	RangeArg range = args.ParseOptional(1, RangeArg::All());
+
 	if (playlist_file_print(r, client.GetPartition(), SongLoader(client),
-				name, false))
+				name, range.start, range.end, false))
 		return CommandResult::OK;
 
 	throw PlaylistError::NoSuchList();
@@ -142,8 +144,10 @@ handle_listplaylistinfo(Client &client, Request args, Response &r)
 #endif
 					   );
 
+	RangeArg range = args.ParseOptional(1, RangeArg::All());
+
 	if (playlist_file_print(r, client.GetPartition(), SongLoader(client),
-				name, true))
+				name, range.start, range.end, true))
 		return CommandResult::OK;
 
 	throw PlaylistError::NoSuchList();

src/playlist/Print.cxx

@@ -18,14 +18,25 @@ static void
 playlist_provider_print(Response &r,
 			const SongLoader &loader,
 			const char *uri,
-			SongEnumerator &e, bool detail) noexcept
+			SongEnumerator &e,
+			unsigned start_index,
+			unsigned end_index,
+			bool detail) noexcept
 {
 	const auto base_uri = uri != nullptr
 		? PathTraitsUTF8::GetParent(uri)
 		: ".";
 
 	std::unique_ptr<DetachedSong> song;
-	while ((song = e.NextSong()) != nullptr) {
+
+	for (unsigned i = 0;
+	     i < end_index && (song = e.NextSong()) != nullptr;
+	     ++i) {
+		if (i < start_index) {
+			/* skip songs before the start index */
+			continue;
+		}
+
 		if (playlist_check_translate_song(*song, base_uri,
 						  loader) &&
 		    detail)
@@ -40,7 +51,10 @@ playlist_provider_print(Response &r,
 bool
 playlist_file_print(Response &r, Partition &partition,
 		    const SongLoader &loader,
-		    const LocatedUri &uri, bool detail)
+		    const LocatedUri &uri,
+		    unsigned start_index,
+		    unsigned end_index,
+		    bool detail)
 {
 	Mutex mutex;
 
@@ -56,6 +70,7 @@ playlist_file_print(Response &r, Partition &partition,
 	if (playlist == nullptr)
 		return false;
 
-	playlist_provider_print(r, loader, uri.canonical_uri, *playlist, detail);
+	playlist_provider_print(r, loader, uri.canonical_uri, *playlist,
+				start_index, end_index, detail);
 	return true;
 }

src/playlist/Print.hxx

@@ -18,6 +18,8 @@ struct Partition;
 bool
 playlist_file_print(Response &r, Partition &partition,
 		    const SongLoader &loader,
-		    const LocatedUri &uri, bool detail);
+		    const LocatedUri &uri,
+			unsigned start_index, unsigned end_index,
+			bool detail);
 
 #endif