1 /*
2 * Copyright (c) 2001, Zoltan Farkas All Rights Reserved.
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * This library 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.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18
19 package net.sf.zel.instr;
20
21 import net.sf.zel.vm.*;
22
23 /**
24 * Takes a context key from the stack and puts
25 * the memory back in the stack
26 * if there is no memory a new memory will be allocated
27 * @author zoly
28 */
29 public final class ALSC extends Instruction
30 {
31 private static final long serialVersionUID = -7238322623988158309L;
32
33 private ALSC(){};
34
35 public void execute(ExecutionContext context) throws ZExecutionException
36 {
37 final Object ckey = context.stack.pop();
38 Object ctx = context.memContext.get(ckey);
39 if (ctx != null)
40 {
41 context.stack.push(ctx);
42 } else
43 {
44 ctx = context.newMem();
45 context.memContext.put(ckey, ctx);
46 context.stack.push(ctx);
47 }
48 context.ip++;
49 }
50 /**
51 * instance
52 */
53 public static final Instruction instance = new ALSC();
54 }