VMString.java

/*
 * @(#) $(JCGO)/goclsp/vm/java/lang/VMString.java --
 * VM specific methods for Java "String" class.
 **
 * Project: JCGO (http://www.ivmaisoft.com/jcgo/)
 * Copyright (C) 2001-2008 Ivan Maidanski <ivmai@ivmaisoft.com>
 * All rights reserved.
 **
 * Class specification origin: GNU Classpath v0.93 vm/reference
 */

/*
 * This 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 2, or (at your option)
 * any later version.
 **
 * This software 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 (GPL) for more details.
 **
 * Linking this library statically or dynamically with other modules is
 * making a combined work based on this library. Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 **
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module. An independent module is a module which is not derived from
 * or based on this library. If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 */

package java.lang;

import java.lang.ref.WeakReference;

import java.util.HashMap;
import java.util.WeakHashMap;

final class VMString /* hard-coded class name */
{

 private static WeakHashMap internTable;

 private static HashMap internLiteralTable;

 private VMString() {}

 static synchronized String intern(String str)
 {
  WeakHashMap table;
  if ((table = internTable) == null)
  {
   String[] literals = getInitStrings0();
   int len = literals != null ? literals.length : 0;
   HashMap table2 = new HashMap(len / 3 + len + 1);
   for (int i = 0; i < len; i++)
   {
    String s = literals[i];
    if (s != null)
     table2.put(s, s);
   }
   internLiteralTable = table2;
   table = new WeakHashMap();
   internTable = table;
  }
  Object obj = table.get(str);
  if ((obj = obj != null ? ((WeakReference) obj).get() :
      internLiteralTable.get(str)) != null)
   return (String) obj;
  if (str == null) /* hack */
   throw new InternalError();
  table.put(str, new WeakReference(str));
  return str;
 }

 private static native
   String[] getInitStrings0(); /* JVM-core */ /* const data */
}