Sat, 07 Nov 2020 10:30:02 +0800
Added tag mips-jdk8u275-b01 for changeset eb6ee6a5f2fe
1 /*
2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
26 package com.sun.tools.javac.util;
28 import java.util.AbstractQueue;
29 import java.util.Collection;
30 import java.util.Iterator;
31 import java.util.NoSuchElementException;
33 /** A class for constructing lists by appending elements. Modelled after
34 * java.lang.StringBuffer.
35 *
36 * <p><b>This is NOT part of any supported API.
37 * If you write code that depends on this, you do so at your own risk.
38 * This code and its internal interfaces are subject to change or
39 * deletion without notice.</b>
40 */
41 public class ListBuffer<A> extends AbstractQueue<A> {
43 public static <T> ListBuffer<T> of(T x) {
44 ListBuffer<T> lb = new ListBuffer<T>();
45 lb.add(x);
46 return lb;
47 }
49 /** The list of elements of this buffer.
50 */
51 private List<A> elems;
53 /** A pointer pointing to the last element of 'elems' containing data,
54 * or null if the list is empty.
55 */
56 private List<A> last;
58 /** The number of element in this buffer.
59 */
60 private int count;
62 /** Has a list been created from this buffer yet?
63 */
64 private boolean shared;
66 /** Create a new initially empty list buffer.
67 */
68 public ListBuffer() {
69 clear();
70 }
72 public final void clear() {
73 this.elems = List.nil();
74 this.last = null;
75 count = 0;
76 shared = false;
77 }
79 /** Return the number of elements in this buffer.
80 */
81 public int length() {
82 return count;
83 }
84 public int size() {
85 return count;
86 }
88 /** Is buffer empty?
89 */
90 public boolean isEmpty() {
91 return count == 0;
92 }
94 /** Is buffer not empty?
95 */
96 public boolean nonEmpty() {
97 return count != 0;
98 }
100 /** Copy list and sets last.
101 */
102 private void copy() {
103 if (elems.nonEmpty()) {
104 List<A> orig = elems;
106 elems = last = List.<A>of(orig.head);
108 while ((orig = orig.tail).nonEmpty()) {
109 last.tail = List.<A>of(orig.head);
110 last = last.tail;
111 }
112 }
113 }
115 /** Prepend an element to buffer.
116 */
117 public ListBuffer<A> prepend(A x) {
118 elems = elems.prepend(x);
119 if (last == null) last = elems;
120 count++;
121 return this;
122 }
124 /** Append an element to buffer.
125 */
126 public ListBuffer<A> append(A x) {
127 x.getClass(); // null check
128 if (shared) copy();
129 List<A> newLast = List.<A>of(x);
130 if (last != null) {
131 last.tail = newLast;
132 last = newLast;
133 } else {
134 elems = last = newLast;
135 }
136 count++;
137 return this;
138 }
140 /** Append all elements in a list to buffer.
141 */
142 public ListBuffer<A> appendList(List<A> xs) {
143 while (xs.nonEmpty()) {
144 append(xs.head);
145 xs = xs.tail;
146 }
147 return this;
148 }
150 /** Append all elements in a list to buffer.
151 */
152 public ListBuffer<A> appendList(ListBuffer<A> xs) {
153 return appendList(xs.toList());
154 }
156 /** Append all elements in an array to buffer.
157 */
158 public ListBuffer<A> appendArray(A[] xs) {
159 for (int i = 0; i < xs.length; i++) {
160 append(xs[i]);
161 }
162 return this;
163 }
165 /** Convert buffer to a list of all its elements.
166 */
167 public List<A> toList() {
168 shared = true;
169 return elems;
170 }
172 /** Does the list contain the specified element?
173 */
174 public boolean contains(Object x) {
175 return elems.contains(x);
176 }
178 /** Convert buffer to an array
179 */
180 public <T> T[] toArray(T[] vec) {
181 return elems.toArray(vec);
182 }
183 public Object[] toArray() {
184 return toArray(new Object[size()]);
185 }
187 /** The first element in this buffer.
188 */
189 public A first() {
190 return elems.head;
191 }
193 /** Return first element in this buffer and remove
194 */
195 public A next() {
196 A x = elems.head;
197 if (!elems.isEmpty()) {
198 elems = elems.tail;
199 if (elems.isEmpty()) last = null;
200 count--;
201 }
202 return x;
203 }
205 /** An enumeration of all elements in this buffer.
206 */
207 public Iterator<A> iterator() {
208 return new Iterator<A>() {
209 List<A> elems = ListBuffer.this.elems;
210 public boolean hasNext() {
211 return !elems.isEmpty();
212 }
213 public A next() {
214 if (elems.isEmpty())
215 throw new NoSuchElementException();
216 A elem = elems.head;
217 elems = elems.tail;
218 return elem;
219 }
220 public void remove() {
221 throw new UnsupportedOperationException();
222 }
223 };
224 }
226 public boolean add(A a) {
227 append(a);
228 return true;
229 }
231 public boolean remove(Object o) {
232 throw new UnsupportedOperationException();
233 }
235 public boolean containsAll(Collection<?> c) {
236 for (Object x: c) {
237 if (!contains(x))
238 return false;
239 }
240 return true;
241 }
243 public boolean addAll(Collection<? extends A> c) {
244 for (A a: c)
245 append(a);
246 return true;
247 }
249 public boolean removeAll(Collection<?> c) {
250 throw new UnsupportedOperationException();
251 }
253 public boolean retainAll(Collection<?> c) {
254 throw new UnsupportedOperationException();
255 }
257 public boolean offer(A a) {
258 append(a);
259 return true;
260 }
262 public A poll() {
263 return next();
264 }
266 public A peek() {
267 return first();
268 }
270 public A last() {
271 return last != null ? last.head : null;
272 }
273 }