1 files changed, 114 insertions, 0 deletions
diff --git a/ridljar/com/sun/star/lib/uno/protocols/urp/Cache.java b/ridljar/com/sun/star/lib/uno/protocols/urp/Cache.java
new file mode 100644
index 000000000..26c2d449d
--- /dev/null
+++ b/ridljar/com/sun/star/lib/uno/protocols/urp/Cache.java
@@ -0,0 +1,114 @@
+/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+package com.sun.star.lib.uno.protocols.urp;
+
+import java.util.HashMap;
+
+/**
+ * An LRU cache for arbitrary objects.
+ *
+ * <p>This class is not synchronized, as any necessary synchronization will already
+ * take place in the client.</p>
+ */
+final class Cache {
+    /**
+     * Create a cache.
+     *
+     * @param size the maximum cache size, must be between 0, inclusive, and
+     * NOT_CACHED, exclusive.
+     */
+    public Cache(int size) {
+        maxSize = size;
+    }
+
+    public int add(boolean[] found, Object content) {
+        Entry e = map.get(content);
+        found[0] = e != null;
+        if (e == null) {
+            if (map.size() < maxSize) {
+                // There is still room for a new entry at the front:
+                e = new Entry(content, map.size(), null, first);
+                if (first == null) {
+                    last = e;
+                } else {
+                    first.prev = e;
+                }
+                first = e;
+            } else if (last != null) {
+                // Take last entry out and recycle as new front:
+                map.remove(last.content);
+                e = last;
+                e.content = content;
+                if (first != last) {
+                    // Reached only if maxSize > 1:
+                    last = last.prev;
+                    last.next = null;
+                    e.prev = null;
+                    e.next = first;
+                    first.prev = e;
+                    first = e;
+                }
+            } else {
+                // Reached iff maxSize == 0:
+                return NOT_CACHED;
+            }
+            map.put(content, e);
+        } else if (e != first) {
+            // Move to front (reached only if maxSize > 1):
+            e.prev.next = e.next;
+            if (e.next == null) {
+                last = e.prev;
+            } else {
+                e.next.prev = e.prev;
+            }
+            e.prev = null;
+            e.next = first;
+            first.prev = e;
+            first = e;
+        }
+        return e.index;
+    }
+
+    public static final int NOT_CACHED = 0xFFFF;
+
+    private static final class Entry {
+        public Entry(Object content, int index, Entry prev, Entry next) {
+            this.content = content;
+            this.index = index;
+            this.prev = prev;
+            this.next = next;
+        }
+
+        public Object content;
+        public int index;
+        public Entry prev;
+        public Entry next;
+    }
+
+    // first/last form a list of 0 to maxSize entries, most recently used first;
+    // map contains the same entries; each entry has a unique index in the range
+    // 0 to maxSize - 1
+    private final int maxSize;
+    private final HashMap<Object, Entry> map = new HashMap<Object, Entry>(); // from Object to Entry
+    private Entry first = null;
+    private Entry last = null;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */