Add interface for not-yet-created objects.

diff --git a/src/main/java/net/pterodactylus/sone/data/Shell.java b/src/main/java/net/pterodactylus/sone/data/Shell.java
new file mode 100644 (file)
index 0000000..9f1fc9b
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sone/data/Shell.java
@@ -0,0 +1,47 @@
+/*
+ * Sone - Shell.java - Copyright © 2010 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sone.data;
+
+/**
+ * Marker interface for classes that are only empty shells for objects that have
+ * not yet been retrieved from Freenet.
+ *
+ * @param <T>
+ *            The type of object that is shelled
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public interface Shell<T> {
+
+       /**
+        * Returns whether the shelled object can be unshelled now.
+        *
+        * @return {@code true} if {@link #getShelled()} can return the shelled
+        *         object, {@code false} otherwise
+        */
+       public boolean canUnshell();
+
+       /**
+        * Returns the object that is shelled. Returns {@code null} if the real
+        * object has not yet been retrieved.
+        *
+        * @return The shelled object, or {@code null} if the shelled object is not
+        *         retrieved yet
+        */
+       public T getShelled();
+
+}