| 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 | } |