Design: Update groups

Groups now use an index to manage their data.

Signed-off-by: Bryan Schumaker <bjschuma@gmail.com>

design.txt

@@ -35,6 +35,7 @@ Files:
 		album.db
 		artist.db
 		genre.db
+		groups.idx
 		library.db
 		track.db
 
@@ -106,7 +107,7 @@ Database:
 		Database::Database(filename);
 		void load();
 		void save();
-		void insert(T);
+		unsigned int insert(T);
 		void delete(unsigned int);
 		const unsigned int &size();
 		const T &operator[](unsigned int);
@@ -126,7 +127,7 @@ API:
 	Database.save();
 		Saves data to file.
 	Database.insert(T &);
-		Adds a new item to the db
+		Adds a new item to the db, returns the id of the item
 	Database.delete(unsigned int index);
 		Mark db[index] as invalid (quick deletion)
 	Database.size();
@@ -150,6 +151,7 @@ Index:
 		void save();
 		void insert(key, int);
 		void delete(key, int);
+		const set<string> &keys();
 		const set<int> &operator[](string);
 	};
 
@@ -172,6 +174,8 @@ API:
 		1) Remove int from the set of values associated with key
 		2) Do not delete key if set is empty
 		3) Index.save()
+	Index.keys();
+		Return a set of index keys
 	Index.operator[](string key);
 		Return the set associated with key
 
@@ -249,11 +253,11 @@ Track: /* This struct lies outside the library namespace */
 	};
 
 Databases:
-	Database<library :: Album>   album_db;
-	Database<library :: Artist>  artist_db;
-	Database<library :: Album>   genre_db;
-	Database<library :: Library> library_db;
-	Database<library :: Track>   track_db;
+	Database<library :: Album>   album_db(album.db);
+	Database<library :: Artist>  artist_db(artist.db);
+	Database<library :: Album>   genre_db(genre.db);
+	Database<library :: Library> library_db(library.db);
+	Database<library :: Track>   track_db(track.db);
 
 Updating algorithm:
 	set<pair<lib_id, track_path>> known_tracks;
@@ -265,7 +269,8 @@ Updating algorithm:
 	2) For each file in the scan directory, check if (lib_id, track_path)
 	   exists in the known_tracks map.
 	   2a) If the file is in the map, do nothing.
-	   2b) Else, add track to the library and to the library group
+	   2b) Else, add track to the library and to the "All Music" and
+	       "Library" and "Unplayed Tracks" groups
 	3) Save all databases
 
 	The taglib library should be used for finding artist, album, etc. tags
@@ -290,6 +295,37 @@ Updating algorithm:
 
 
 
+Groups: (lib/group.cpp)
+	Groups are going to be a new feature in Ocarina 6 and can compare
+	directly to Gmail-style labels.  Ocarina 6 will create dynamic groups
+	that cannot be deleted by the user based on library status.  Similar
+	to the library, groups should exist in their own namespace.
+
+Index:
+	Index group_idx(groups.idx)
+
+Default groups:
+	All music
+		All tracks are added to this group
+	Library
+	Banned Songs
+		These groups are mutually exclusive.  A track is either
+		in the Library or the Banned Songs group
+	Unplayed tracks
+		Tracks with a play count of 0
+
+- API
+	group :: list();
+		return group_idx.keys();
+	group :: get_tracks(name):
+		return group_idx[name]
+	group :: add(name, track_id)
+		group_idx.insert(name, track_id);
+	group :: del(name, track_id)
+		grou_idx.delete(name, track_id)
+
+
+
 Playlist: (lib/playlist.cpp)
 	A playlist is a simple list of songs that can be played either randomly
 	or in a user-defined order.  It would probably be best to use a linked
@@ -314,42 +350,6 @@ Playlist: (lib/playlist.cpp)
 
 
 
-Groups: (lib/group.cpp)
-	Groups are going to be a new feature in Ocarina 6 and can compare
-	directly to Gmail-style labels.  Ocarina 6 will create dynamic groups
-	that cannot be deleted by the user based on library status.
-
-	Default groups:
-		All music
-			All tracks are added to this group
-		Library
-		Banned Songs
-			These groups are mutually exclusive.  A track is either
-			in the Library or the Banned Songs group
-		Unplayed tracks
-			Tracks with a play count of 0
-
-
-- API
-	list_groups();
-		Return a list of group names
-	group_get_tracks(name):
-		Return a list of tracks that are in group "name"
-
-	Track.add_to_group(name);
-		Add a track to a group
-	Track.rm_from_group(name);
-		Remove a track from a group
-
-- Design TODO									<<<<<
-	- I need a way to loop over each track in the library to create
-	  dynamic groups.  Whole library iterator?
-	- A "Track" class with functions for accessing tags and with access
-	  to groups.  Perhaps make "Track" its own file, outside of the
-	  library and group code?
-
-
-
 Future work:
 	I want to set reasonable expectations for Ocarina 6 so that I don't
 	have to spend a large amount of time coding before releasing something