From eb3a62a5014e129da19f70b90c2b089301e08050 Mon Sep 17 00:00:00 2001
From: =?utf8?q?David=20=E2=80=98Bombe=E2=80=99=20Roden?=
 <bombe@pterodactylus.net>
Date: Thu, 19 Apr 2012 16:31:35 +0200
Subject: [PATCH] Add lazy group implementation and creator.

---
 .../demoscenemusic/data/DataManager.java           | 42 ++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java b/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
index b56634f..374bb6c 100644
--- a/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
+++ b/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
@@ -49,6 +49,7 @@ import net.pterodactylus.util.database.ValueFieldWhereClause;
 public class DataManager {
 
 	private final ObjectCreator<Artist> artistCreator = new ArtistCreator();
+	private final ObjectCreator<Group> groupCreator = new GroupCreator();
 
 	private final Database database;
 
@@ -250,4 +251,45 @@ public class DataManager {
 
 	}
 
+	private class LazyGroup extends DefaultGroup {
+
+		private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
+
+			@Override
+			public Void call() throws Exception {
+				if (!hasValue("artists")) {
+					value("artists", Collection.class).set(getArtistsByGroup(id()));
+				}
+				return null;
+			}
+
+		});
+
+		public LazyGroup(String id) {
+			super(id);
+		}
+
+		/**
+		 * {@inheritDoc}
+		 */
+		@Override
+		public Collection<Artist> artists() {
+			artistsMemoizer.get();
+			return super.artists();
+		}
+
+	}
+
+	private class GroupCreator implements ObjectCreator<Group> {
+
+		/**
+		 * {@inheritDoc}
+		 */
+		@Override
+		public Group createObject(ResultSet resultSet) throws SQLException {
+			return new LazyGroup(resultSet.getString("GROUPS.ID")).name(resultSet.getString("GROUPS.NAME")).url(resultSet.getString("GROUPS.URL"));
+		}
+
+	}
+
 }
-- 
2.7.4