Use a more generic Shell-aware cache.

[Sone.git] / src / main / java / net / pterodactylus / sone / data / ShellCache.java

diff --git a/src/main/java/net/pterodactylus/sone/data/ShellCache.java b/src/main/java/net/pterodactylus/sone/data/ShellCache.java
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+++ b/src/main/java/net/pterodactylus/sone/data/ShellCache.java
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+/*
+ * Sone - ShellCache.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;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * {@link Shell}-aware cache that will replace {@link Shell}s with the real
+ * objects but not the other way around.
+ *
+ * @param <T>
+ *            The type of the cached objects
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class ShellCache<T> {
+
+       /** The object cache. */
+       private final Map<String, T> cache = new HashMap<String, T>();
+
+       /**
+        * Stores the given object in this cache. If the given object is not a
+        * {@link Shell}, it is stored. If it is a {@link Shell} it is only stored
+        * if there is no object stored for the given ID.
+        *
+        * @param id
+        *            The ID of the object
+        * @param object
+        *            The object to store
+        */
+       public void put(String id, T object) {
+               if (!(object instanceof Shell<?>) || !cache.containsKey(id)) {
+                       cache.put(id, object);
+               }
+       }
+
+       /**
+        * Returns the post with the given ID.
+        *
+        * @param id
+        *            The ID of the post
+        * @return The post with the given ID, or {@code null} if there is no post
+        *         with the given ID
+        */
+       public T get(String id) {
+               return cache.get(id);
+       }
+
+}