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.compile;
26:
27: import org.jatha.Jatha;
28: import org.jatha.dynatype.*;
29: import org.jatha.machine.*;
30:
31: public class EvalPrimitive extends LispPrimitive {
32: public EvalPrimitive(Jatha lisp) {
33: super (lisp, "EVAL", 1, 2);
34: }
35:
36: /**
37: * Input is a LISP expr to be evaluated.
38: * We compile it, push it's code on the
39: * stack, and execute it in the same environment.
40: */
41: public void Execute(SECDMachine machine) throws CompilerException {
42: LispValue expr = machine.S.pop();
43: LispValue code = f_lisp.COMPILER.compile(expr, f_lisp.NIL,
44: f_lisp.NIL);
45:
46: machine.C.pop(); // Pop the EVAL command
47:
48: // Push the new code on the stack.
49: machine.C.assign(code.append(machine.C.value()));
50: }
51: }
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