2 * Sone - ShellCache.java - Copyright © 2010 David Roden
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, either version 3 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 package net.pterodactylus.sone.data;
20 import java.util.Collection;
21 import java.util.HashMap;
25 * {@link Shell}-aware cache that will replace {@link Shell}s with the real
26 * objects but not the other way around.
29 * The type of the cached objects
30 * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
32 public class ShellCache<T> {
34 /** The object cache. */
35 private final Map<String, T> objectCache = new HashMap<String, T>();
37 /** The shell cache. */
38 private final Map<String, Shell<T>> shellCache = new HashMap<String, Shell<T>>();
40 /** The shell creator. */
41 private final ShellCreator<T> shellCreator;
44 * Creates a new shell cache.
47 * The creator for new shells
49 public ShellCache(ShellCreator<T> shellCreator) {
50 this.shellCreator = shellCreator;
58 * Stores the given object in this cache. If the given object is not a
59 * {@link Shell}, it is stored. If it is a {@link Shell} it is only stored
60 * if there is no object stored for the given ID.
63 * The ID of the object
66 * @return The real object, or the shell if there is no real object yet
68 @SuppressWarnings("unchecked")
69 public T put(String id, T object) {
70 if (!(object instanceof Shell<?>)) {
71 objectCache.put(id, object);
72 shellCache.remove(id);
75 if (objectCache.containsKey(id)) {
76 return objectCache.get(id);
78 shellCache.put(id, (Shell<T>) object);
83 * Returns the post with the given ID.
87 * @return The post with the given ID, or {@code null} if there is no post
90 public T get(String id) {
91 if (!objectCache.containsKey(id)) {
92 Shell<T> shell = shellCreator.createShell(id);
93 shellCache.put(id, shell);
94 return shell.getShelled();
96 return objectCache.get(id);
100 * Returns all cached shells.
102 * @return All cached shells
104 public Collection<Shell<T>> getShells() {
105 return shellCache.values();