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.var;
20
21 import net.sf.zel.instr.*;
22 import net.sf.zel.vm.*;
23
24
25 public class NVL extends Instruction
26 {
27 private static final long serialVersionUID = -781612652169727505L;
28
29 private NVL(){};
30
31 public final void execute(ExecutionContext context) throws ZExecutionException
32 {
33 final Object defaultValue = context.popSyncStackVal();
34 final Object expression = context.popSyncStackVal();
35 context.stack.pop();
36 if (expression == null)
37 {
38 context.stack.push(defaultValue);
39 } else
40 {
41 context.stack.push(expression);
42 }
43 context.ip++;
44 }
45 /**
46 * instance
47 */
48 public static final Instruction instance = new NVL();
49 }