1 /*
2 * Copyright (c) 2001-2017, 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 * Additionally licensed with:
19 *
20 * Licensed under the Apache License, Version 2.0 (the "License");
21 * you may not use this file except in compliance with the License.
22 * You may obtain a copy of the License at
23 *
24 * http://www.apache.org/licenses/LICENSE-2.0
25 *
26 * Unless required by applicable law or agreed to in writing, software
27 * distributed under the License is distributed on an "AS IS" BASIS,
28 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
29 * See the License for the specific language governing permissions and
30 * limitations under the License.
31 */
32 package org.spf4j.ds;
33
34 import javax.annotation.Nullable;
35 import javax.annotation.ParametersAreNonnullByDefault;
36
37 /**
38 * /**
39 * A simple stack implementation that does not support null elements.
40 * @author Zoltan Farkas
41 * @param <T>
42 */
43 @ParametersAreNonnullByDefault
44 public final class SimpleStack<T> extends SimpleStackNullSupport<T> {
45
46 public SimpleStack(final int size) {
47 super(size);
48 }
49
50 public SimpleStack() {
51 }
52
53 /**
54 * take a look at the top of stack
55 * returns null if there is no element.
56 * @return Object
57 */
58 @Nullable
59 @Override
60 public T peek() {
61 if (top > 0) {
62 return elems[top - 1];
63 } else {
64 return null;
65 }
66 }
67
68 @Nullable
69 public T peekAndPush(final T o) {
70 int t = top + 1;
71 ensureCapacity(t);
72 elems[top] = o;
73 T result;
74 if (top >= 0) {
75 result = elems[top - 1];
76 } else {
77 result = null;
78 }
79 top = t;
80 return result;
81 }
82
83 @Nullable
84 public T pollLast() {
85 if (size() <= 0) {
86 return null;
87 } else {
88 return pop();
89 }
90 }
91
92 @Override
93 public boolean remove(final Object o) {
94 for (int i = 0, l = top; i < l; i++) {
95 if (o.equals(elems[i])) {
96 fastRemove(i);
97 return true;
98 }
99 }
100 return false;
101 }
102
103 /**
104 * Not implemented, can be overwritten.
105 */
106 @Override
107 public int indexOf(final Object o) {
108 for (int i = 0, l = top; i < l; i++) {
109 if (o.equals(elems[i])) {
110 return i;
111 }
112 }
113 return -1;
114 }
115
116 /**
117 * Not implemented, can be overwritten.
118 */
119 @Override
120 public int lastIndexOf(final Object o) {
121 for (int i = size() - 1; i >= 0; i--) {
122 if (o.equals(elems[i])) {
123 return i;
124 }
125 }
126 return -1;
127 }
128
129 @Override
130 public boolean contains(final Object o) {
131 for (int i = 0; i < top; i++) {
132 if (elems[i].equals(o)) {
133 return true;
134 }
135 }
136 return false;
137 }
138
139
140 public void pushNull() {
141 throw new UnsupportedOperationException();
142 }
143
144
145 }