01: /*
02: * ============================================================================
03: * GNU Lesser General Public License
04: * ============================================================================
05: *
06: * JasperReports - Free Java report-generating library.
07: * Copyright (C) 2001-2006 JasperSoft Corporation http://www.jaspersoft.com
08: *
09: * This library is free software; you can redistribute it and/or
10: * modify it under the terms of the GNU Lesser General Public
11: * License as published by the Free Software Foundation; either
12: * version 2.1 of the License, or (at your option) any later version.
13: *
14: * This library is distributed in the hope that it will be useful,
15: * but WITHOUT ANY WARRANTY; without even the implied warranty of
16: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17: * Lesser General Public License for more details.
18: *
19: * You should have received a copy of the GNU Lesser General Public
20: * License along with this library; if not, write to the Free Software
21: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
22: *
23: * JasperSoft Corporation
24: * 303 Second Street, Suite 450 North
25: * San Francisco, CA 94107
26: * http://www.jaspersoft.com
27: */
28: package net.sf.jasperreports.engine.util;
29:
30: import java.util.LinkedList;
31:
32: /**
33: * Thread local stack utility class.
34: *
35: * @author Lucian Chirita (lucianc@users.sourceforge.net)
36: * @version $Id: ThreadLocalStack.java 1253 2006-05-15 08:12:34Z lucianc $
37: */
38: public class ThreadLocalStack {
39: private final ThreadLocal threadStack;
40:
41: public ThreadLocalStack() {
42: threadStack = new ThreadLocal();
43: }
44:
45: public void push(Object o) {
46: LinkedList stack = (LinkedList) threadStack.get();
47: if (stack == null) {
48: stack = new LinkedList();
49: threadStack.set(stack);
50: }
51: stack.addFirst(o);
52: }
53:
54: public Object top() {
55: Object o = null;
56: LinkedList stack = (LinkedList) threadStack.get();
57: if (stack != null && !stack.isEmpty()) {
58: o = stack.getFirst();
59: }
60: return o;
61: }
62:
63: public Object pop() {
64: Object o = null;
65: LinkedList stack = (LinkedList) threadStack.get();
66: if (stack != null) {
67: o = stack.removeFirst();
68: }
69: return o;
70: }
71:
72: public boolean empty() {
73: LinkedList stack = (LinkedList) threadStack.get();
74: return stack == null || stack.isEmpty();
75: }
76: }
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