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
22 import java.util.List;
23 import net.sf.zel.instr.Instruction;
24 import net.sf.zel.nr.OperableDouble;
25 import net.sf.zel.nr.OperableNumber;
26 import net.sf.zel.vm.ExecutionContext;
27 import net.sf.zel.vm.ZExecutionException;
28
29
30 public final class SUM extends Instruction
31 {
32
33 /**
34 * instance
35 */
36 public static final Instruction instance = new SUM();
37
38 private static final long serialVersionUID = -2294409140735487983L;
39
40 private SUM(){};
41
42 /**
43 * RSUM instruction microcode
44 * @param context ExecutionContext
45 * @throws ZExecutionException
46 */
47 public void execute(final ExecutionContext context) throws ZExecutionException
48 {
49 final MatchIterator iterator = new MatchIterator((String) context.popSyncStackVal());
50 context.stack.pop();
51 Adder stuff = new Adder();
52 iterator.iterate(stuff, context.memContext);
53 context.stack.push(stuff.getSum());
54 context.ip++;
55 }
56
57 private static final class Adder implements MatchIterator.DoStuff
58 {
59
60 /**
61 * summ variable
62 */
63 private transient double sum = 0;
64 /**
65 * count variable
66 */
67 private transient double cnt = 0;
68
69 public OperableDouble getSum()
70 {
71 if (cnt == 0)
72 {
73 return null;
74 } else
75 {
76 return new OperableDouble(sum);
77 }
78 }
79
80 public void execute(Object obj, List context)
81 {
82 if (obj instanceof OperableNumber)
83 {
84 sum += ((Number) obj).doubleValue();
85 cnt++;
86 }
87 }
88 }
89 }