1 | /* |
2 | * Copyright 1999-2006 Sun Microsystems, Inc. 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. Sun designates this |
8 | * particular file as subject to the "Classpath" exception as provided |
9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
23 | * have any questions. |
24 | */ |
25 | |
26 | package com.sun.tools.javac.util; |
27 | |
28 | import java.util.Collection; |
29 | import java.util.Iterator; |
30 | import java.util.NoSuchElementException; |
31 | |
32 | /** A class for constructing lists by appending elements. Modelled after |
33 | * java.lang.StringBuffer. |
34 | * |
35 | * <p><b>This is NOT part of any API supported by Sun Microsystems. If |
36 | * you write code that depends on this, you do so at your own risk. |
37 | * This code and its internal interfaces are subject to change or |
38 | * deletion without notice.</b> |
39 | */ |
40 | public class ListBuffer<A> implements Collection<A> { |
41 | |
42 | public static <T> ListBuffer<T> lb() { |
43 | return new ListBuffer<T>(); |
44 | } |
45 | |
46 | /** The list of elements of this buffer. |
47 | */ |
48 | public List<A> elems; |
49 | |
50 | /** A pointer pointing to the last, sentinel element of `elems'. |
51 | */ |
52 | public List<A> last; |
53 | |
54 | /** The number of element in this buffer. |
55 | */ |
56 | public int count; |
57 | |
58 | /** Has a list been created from this buffer yet? |
59 | */ |
60 | public boolean shared; |
61 | |
62 | /** Create a new initially empty list buffer. |
63 | */ |
64 | public ListBuffer() { |
65 | clear(); |
66 | } |
67 | |
68 | public final void clear() { |
69 | this.elems = new List<A>(null,null); |
70 | this.last = this.elems; |
71 | count = 0; |
72 | shared = false; |
73 | } |
74 | |
75 | /** Return the number of elements in this buffer. |
76 | */ |
77 | public int length() { |
78 | return count; |
79 | } |
80 | public int size() { |
81 | return count; |
82 | } |
83 | |
84 | /** Is buffer empty? |
85 | */ |
86 | public boolean isEmpty() { |
87 | return count == 0; |
88 | } |
89 | |
90 | /** Is buffer not empty? |
91 | */ |
92 | public boolean nonEmpty() { |
93 | return count != 0; |
94 | } |
95 | |
96 | /** Copy list and sets last. |
97 | */ |
98 | private void copy() { |
99 | List<A> p = elems = new List<A>(elems.head, elems.tail); |
100 | while (true) { |
101 | List<A> tail = p.tail; |
102 | if (tail == null) break; |
103 | tail = new List<A>(tail.head, tail.tail); |
104 | p.setTail(tail); |
105 | p = tail; |
106 | } |
107 | last = p; |
108 | shared = false; |
109 | } |
110 | |
111 | /** Prepend an element to buffer. |
112 | */ |
113 | public ListBuffer<A> prepend(A x) { |
114 | elems = elems.prepend(x); |
115 | count++; |
116 | return this; |
117 | } |
118 | |
119 | /** Append an element to buffer. |
120 | */ |
121 | public ListBuffer<A> append(A x) { |
122 | if (shared) copy(); |
123 | last.head = x; |
124 | last.setTail(new List<A>(null,null)); |
125 | last = last.tail; |
126 | count++; |
127 | return this; |
128 | } |
129 | |
130 | /** Append all elements in a list to buffer. |
131 | */ |
132 | public ListBuffer<A> appendList(List<A> xs) { |
133 | while (xs.nonEmpty()) { |
134 | append(xs.head); |
135 | xs = xs.tail; |
136 | } |
137 | return this; |
138 | } |
139 | |
140 | /** Append all elements in a list to buffer. |
141 | */ |
142 | public ListBuffer<A> appendList(ListBuffer<A> xs) { |
143 | return appendList(xs.toList()); |
144 | } |
145 | |
146 | /** Append all elements in an array to buffer. |
147 | */ |
148 | public ListBuffer<A> appendArray(A[] xs) { |
149 | for (int i = 0; i < xs.length; i++) { |
150 | append(xs[i]); |
151 | } |
152 | return this; |
153 | } |
154 | |
155 | /** Convert buffer to a list of all its elements. |
156 | */ |
157 | public List<A> toList() { |
158 | shared = true; |
159 | return elems; |
160 | } |
161 | |
162 | /** Does the list contain the specified element? |
163 | */ |
164 | public boolean contains(Object x) { |
165 | return elems.contains(x); |
166 | } |
167 | |
168 | /** Convert buffer to an array |
169 | */ |
170 | public <T> T[] toArray(T[] vec) { |
171 | return elems.toArray(vec); |
172 | } |
173 | public Object[] toArray() { |
174 | return toArray(new Object[size()]); |
175 | } |
176 | |
177 | /** The first element in this buffer. |
178 | */ |
179 | public A first() { |
180 | return elems.head; |
181 | } |
182 | |
183 | /** Remove the first element in this buffer. |
184 | */ |
185 | public void remove() { |
186 | if (elems != last) { |
187 | elems = elems.tail; |
188 | count--; |
189 | } |
190 | } |
191 | |
192 | /** Return first element in this buffer and remove |
193 | */ |
194 | public A next() { |
195 | A x = elems.head; |
196 | remove(); |
197 | return x; |
198 | } |
199 | |
200 | /** An enumeration of all elements in this buffer. |
201 | */ |
202 | public Iterator<A> iterator() { |
203 | return new Iterator<A>() { |
204 | List<A> elems = ListBuffer.this.elems; |
205 | public boolean hasNext() { |
206 | return elems != last; |
207 | } |
208 | public A next() { |
209 | if (elems == last) |
210 | throw new NoSuchElementException(); |
211 | A elem = elems.head; |
212 | elems = elems.tail; |
213 | return elem; |
214 | } |
215 | public void remove() { |
216 | throw new UnsupportedOperationException(); |
217 | } |
218 | }; |
219 | } |
220 | |
221 | public boolean add(A a) { |
222 | throw new UnsupportedOperationException(); |
223 | } |
224 | public boolean remove(Object o) { |
225 | throw new UnsupportedOperationException(); |
226 | } |
227 | public boolean containsAll(Collection<?> c) { |
228 | throw new UnsupportedOperationException(); |
229 | } |
230 | public boolean addAll(Collection<? extends A> c) { |
231 | throw new UnsupportedOperationException(); |
232 | } |
233 | public boolean removeAll(Collection<?> c) { |
234 | throw new UnsupportedOperationException(); |
235 | } |
236 | public boolean retainAll(Collection<?> c) { |
237 | throw new UnsupportedOperationException(); |
238 | } |
239 | } |