01: /*
02: * Jatha - a Common LISP-compatible LISP library in Java.
03: * Copyright (C) 1997-2005 Micheal Scott Hewett
04: *
05: * This library is free software; you can redistribute it and/or
06: * modify it under the terms of the GNU Lesser General Public
07: * License as published by the Free Software Foundation; either
08: * version 2.1 of the License, or (at your option) any later version.
09: *
10: * This library is distributed in the hope that it will be useful,
11: * but WITHOUT ANY WARRANTY; without even the implied warranty of
12: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13: * Lesser General Public License for more details.
14: *
15: * You should have received a copy of the GNU Lesser General Public
16: * License along with this library; if not, write to the Free Software
17: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18: *
19: *
20: * For further information, please contact Micheal Hewett at
21: * hewett@cs.stanford.edu
22: *
23: */
24:
25: package org.jatha.machine;
26:
27: import org.jatha.Jatha;
28:
29: // @date Sat Feb 1 22:18:53 1997
30: /**
31: * opNIL pushes the constant NIL onto the S register and pops the C register.
32: * Modifes S register.
33: * @see SECDMachine
34: * @author Micheal S. Hewett hewett@cs.stanford.edu
35: */
36: class opNIL extends SECDop {
37: /**
38: * It calls <tt>SECDop()</tt> with the machine argument
39: * and the label of this instruction.
40: * @see SECDMachine
41: */
42: public opNIL(Jatha lisp) {
43: super (lisp, "CONST_NIL");
44: }
45:
46: public void Execute(SECDMachine machine) {
47: machine.S.push(f_lisp.NIL);
48: machine.C.pop();
49: }
50: }
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