--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/core/internal/jobs/StringPool.d	Tue Aug 12 02:34:21 2008 +0200
@@ -0,0 +1,75 @@
+/*******************************************************************************
+ * Copyright (c) 2005 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM - Initial API and implementation
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+module dwtx.core.internal.jobs.StringPool;
+
+import dwt.dwthelper.utils;
+import dwtx.dwtxhelper.Collection;
+
+/**
+ * A string pool is used for sharing strings in a way that eliminates duplicate
+ * equal strings.  A string pool instance can be maintained over a long period
+ * of time, or used as a temporary structure during a string sharing pass over
+ * a data structure.
+ * <p>
+ * This class is not intended to be subclassed by clients.
+ * </p>
+ *
+ * Note: This class is copied from dwtx.core.resources
+ *
+ * @since 3.1
+ */
+public final class StringPool {
+    private int savings;
+    private const HashMap map;
+
+    public this(){
+        map = new HashMap();
+    }
+
+    /**
+     * Adds a <code>String</code> to the pool.  Returns a <code>String</code>
+     * that is equal to the argument but that is unique within this pool.
+     * @param string The string to add to the pool
+     * @return A string that is equal to the argument.
+     */
+    public String add(String string) {
+        if (string is null)
+            return string;
+        Object result = map.get(string);
+        if (result !is null) {
+            if (stringcast(result) !is string)
+                savings += 44 + 2 * string.length;
+            return stringcast( result );
+        }
+        map.put(string, string);
+        return string;
+    }
+
+    /**
+     * Returns an estimate of the size in bytes that was saved by sharing strings in
+     * the pool.  In particular, this returns the size of all strings that were added to the
+     * pool after an equal string had already been added.  This value can be used
+     * to estimate the effectiveness of a string sharing operation, in order to
+     * determine if or when it should be performed again.
+     *
+     * In some cases this does not precisely represent the number of bytes that
+     * were saved.  For example, say the pool already contains string S1.  Now
+     * string S2, which is equal to S1 but not identical, is added to the pool five
+     * times. This method will return the size of string S2 multiplied by the
+     * number of times it was added, even though the actual savings in this case
+     * is only the size of a single copy of S2.
+     */
+    public int getSavedStringCount() {
+        return savings;
+    }
+}