1 ////////////////////////////////////////////////////////////////////////////////
2 // MillScript: an Open Spice interpreter and batch website creation tool
3 // Copyright (C) 2001-2004 Open World Ltd
4 //
5 // This file is part of MillScript.
6 //
7 // MillScript is free software; you can redistribute it and/or modify it under
8 // the terms of the GNU General Public License as published by the Free
9 // Software Foundation; either version 2 of the License, or (at your option)
10 // any later version.
11 //
12 // MillScript is distributed in the hope that it will be useful, but WITHOUT
13 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 // more details.
16 //
17 // You should have received a copy of the GNU General Public License along with
18 // MillScript; if not, write to the Free Software Foundation, Inc., 59 Temple
19 // Place, Suite 330, Boston, MA 02111-1307 USA
20 ////////////////////////////////////////////////////////////////////////////////
21 package org.millscript.millscript.action;
22
23 import org.millscript.millscript.vm.Machine;
24
25 /**
26 * This class implements the action for a <code>none</code> expression. This
27 * action wraps another, ensuring that when performed it generates no results.
28 *
29 * @see org.millscript.millscript.expr.NoneExpr
30 * @see org.millscript.millscript.syntax.NoneSyntax
31 */
32 public final class NoneAction extends Action {
33
34 /**
35 * The action to ensure no results are returned from.
36 */
37 private Action cont;
38
39 /**
40 * Constructs a new <code>none</code> action to ensure the specified action
41 * returns no results.
42 *
43 * @param c the action to ensure returns no results
44 */
45 public NoneAction( final Action c ) {
46 cont = c;
47 }
48
49 /**
50 * @see org.millscript.millscript.action.Action#action(org.millscript.millscript.vm.Machine)
51 */
52 @Override
53 public void action( final Machine mc ) {
54 // Get the current number of results on the stack
55 int n = mc.getCount();
56 // Perform the wrapped action
57 cont.act( mc );
58 // Reset the number of results on the stack to the previous value
59 mc.setCount( n );
60 }
61
62 }