| 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.lang.reflect.Array; |
| 29 | import java.util.ArrayList; |
| 30 | import java.util.Collection; |
| 31 | import java.util.Collections; |
| 32 | import java.util.Iterator; |
| 33 | import java.util.AbstractCollection; |
| 34 | import java.util.ListIterator; |
| 35 | import java.util.NoSuchElementException; |
| 36 | |
| 37 | /** A class for generic linked lists. Links are supposed to be |
| 38 | * immutable, the only exception being the incremental construction of |
| 39 | * lists via ListBuffers. List is the main container class in |
| 40 | * GJC. Most data structures and algorthms in GJC use lists rather |
| 41 | * than arrays. |
| 42 | * |
| 43 | * <p>Lists are always trailed by a sentinel element, whose head and tail |
| 44 | * are both null. |
| 45 | * |
| 46 | * <p><b>This is NOT part of any API supported by Sun Microsystems. If |
| 47 | * you write code that depends on this, you do so at your own risk. |
| 48 | * This code and its internal interfaces are subject to change or |
| 49 | * deletion without notice.</b> |
| 50 | */ |
| 51 | public class List<A> extends AbstractCollection<A> implements java.util.List<A> { |
| 52 | |
| 53 | /** The first element of the list, supposed to be immutable. |
| 54 | */ |
| 55 | public A head; |
| 56 | |
| 57 | /** The remainder of the list except for its first element, supposed |
| 58 | * to be immutable. |
| 59 | */ |
| 60 | //@Deprecated |
| 61 | public List<A> tail; |
| 62 | |
| 63 | /** Construct a list given its head and tail. |
| 64 | */ |
| 65 | List(A head, List<A> tail) { |
| 66 | this.tail = tail; |
| 67 | this.head = head; |
| 68 | } |
| 69 | |
| 70 | /** Construct an empty list. |
| 71 | */ |
| 72 | @SuppressWarnings("unchecked") |
| 73 | public static <A> List<A> nil() { |
| 74 | return EMPTY_LIST; |
| 75 | } |
| 76 | private static List EMPTY_LIST = new List<Object>(null,null) { |
| 77 | public List<Object> setTail(List<Object> tail) { |
| 78 | throw new UnsupportedOperationException(); |
| 79 | } |
| 80 | public boolean isEmpty() { |
| 81 | return true; |
| 82 | } |
| 83 | }; |
| 84 | |
| 85 | /** Construct a list consisting of given element. |
| 86 | */ |
| 87 | public static <A> List<A> of(A x1) { |
| 88 | return new List<A>(x1, List.<A>nil()); |
| 89 | } |
| 90 | |
| 91 | /** Construct a list consisting of given elements. |
| 92 | */ |
| 93 | public static <A> List<A> of(A x1, A x2) { |
| 94 | return new List<A>(x1, of(x2)); |
| 95 | } |
| 96 | |
| 97 | /** Construct a list consisting of given elements. |
| 98 | */ |
| 99 | public static <A> List<A> of(A x1, A x2, A x3) { |
| 100 | return new List<A>(x1, of(x2, x3)); |
| 101 | } |
| 102 | |
| 103 | /** Construct a list consisting of given elements. |
| 104 | */ |
| 105 | public static <A> List<A> of(A x1, A x2, A x3, A... rest) { |
| 106 | return new List<A>(x1, new List<A>(x2, new List<A>(x3, from(rest)))); |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * Construct a list consisting all elements of given array. |
| 111 | * @param array an array; if {@code null} return an empty list |
| 112 | */ |
| 113 | public static <A> List<A> from(A[] array) { |
| 114 | List<A> xs = nil(); |
| 115 | if (array != null) |
| 116 | for (int i = array.length - 1; i >= 0; i--) |
| 117 | xs = new List<A>(array[i], xs); |
| 118 | return xs; |
| 119 | } |
| 120 | |
| 121 | /** Construct a list consisting of a given number of identical elements. |
| 122 | * @param len The number of elements in the list. |
| 123 | * @param init The value of each element. |
| 124 | */ |
| 125 | @Deprecated |
| 126 | public static <A> List<A> fill(int len, A init) { |
| 127 | List<A> l = nil(); |
| 128 | for (int i = 0; i < len; i++) l = new List<A>(init, l); |
| 129 | return l; |
| 130 | } |
| 131 | |
| 132 | /** Does list have no elements? |
| 133 | */ |
| 134 | @Override |
| 135 | public boolean isEmpty() { |
| 136 | return tail == null; |
| 137 | } |
| 138 | |
| 139 | /** Does list have elements? |
| 140 | */ |
| 141 | //@Deprecated |
| 142 | public boolean nonEmpty() { |
| 143 | return tail != null; |
| 144 | } |
| 145 | |
| 146 | /** Return the number of elements in this list. |
| 147 | */ |
| 148 | //@Deprecated |
| 149 | public int length() { |
| 150 | List<A> l = this; |
| 151 | int len = 0; |
| 152 | while (l.tail != null) { |
| 153 | l = l.tail; |
| 154 | len++; |
| 155 | } |
| 156 | return len; |
| 157 | } |
| 158 | @Override |
| 159 | public int size() { |
| 160 | return length(); |
| 161 | } |
| 162 | |
| 163 | public List<A> setTail(List<A> tail) { |
| 164 | this.tail = tail; |
| 165 | return tail; |
| 166 | } |
| 167 | |
| 168 | /** Prepend given element to front of list, forming and returning |
| 169 | * a new list. |
| 170 | */ |
| 171 | public List<A> prepend(A x) { |
| 172 | return new List<A>(x, this); |
| 173 | } |
| 174 | |
| 175 | /** Prepend given list of elements to front of list, forming and returning |
| 176 | * a new list. |
| 177 | */ |
| 178 | public List<A> prependList(List<A> xs) { |
| 179 | if (this.isEmpty()) return xs; |
| 180 | if (xs.isEmpty()) return this; |
| 181 | if (xs.tail.isEmpty()) return prepend(xs.head); |
| 182 | // return this.prependList(xs.tail).prepend(xs.head); |
| 183 | List<A> result = this; |
| 184 | List<A> rev = xs.reverse(); |
| 185 | assert rev != xs; |
| 186 | // since xs.reverse() returned a new list, we can reuse the |
| 187 | // individual List objects, instead of allocating new ones. |
| 188 | while (rev.nonEmpty()) { |
| 189 | List<A> h = rev; |
| 190 | rev = rev.tail; |
| 191 | h.setTail(result); |
| 192 | result = h; |
| 193 | } |
| 194 | return result; |
| 195 | } |
| 196 | |
| 197 | /** Reverse list. |
| 198 | * If the list is empty or a singleton, then the same list is returned. |
| 199 | * Otherwise a new list is formed. |
| 200 | */ |
| 201 | public List<A> reverse() { |
| 202 | // if it is empty or a singleton, return itself |
| 203 | if (isEmpty() || tail.isEmpty()) |
| 204 | return this; |
| 205 | |
| 206 | List<A> rev = nil(); |
| 207 | for (List<A> l = this; l.nonEmpty(); l = l.tail) |
| 208 | rev = new List<A>(l.head, rev); |
| 209 | return rev; |
| 210 | } |
| 211 | |
| 212 | /** Append given element at length, forming and returning |
| 213 | * a new list. |
| 214 | */ |
| 215 | public List<A> append(A x) { |
| 216 | return of(x).prependList(this); |
| 217 | } |
| 218 | |
| 219 | /** Append given list at length, forming and returning |
| 220 | * a new list. |
| 221 | */ |
| 222 | public List<A> appendList(List<A> x) { |
| 223 | return x.prependList(this); |
| 224 | } |
| 225 | |
| 226 | /** |
| 227 | * Append given list buffer at length, forming and returning a new |
| 228 | * list. |
| 229 | */ |
| 230 | public List<A> appendList(ListBuffer<A> x) { |
| 231 | return appendList(x.toList()); |
| 232 | } |
| 233 | |
| 234 | /** Copy successive elements of this list into given vector until |
| 235 | * list is exhausted or end of vector is reached. |
| 236 | */ |
| 237 | @Override @SuppressWarnings("unchecked") |
| 238 | public <T> T[] toArray(T[] vec) { |
| 239 | int i = 0; |
| 240 | List<A> l = this; |
| 241 | Object[] dest = vec; |
| 242 | while (l.nonEmpty() && i < vec.length) { |
| 243 | dest[i] = l.head; |
| 244 | l = l.tail; |
| 245 | i++; |
| 246 | } |
| 247 | if (l.isEmpty()) { |
| 248 | if (i < vec.length) |
| 249 | vec[i] = null; |
| 250 | return vec; |
| 251 | } |
| 252 | |
| 253 | vec = (T[])Array.newInstance(vec.getClass().getComponentType(), size()); |
| 254 | return toArray(vec); |
| 255 | } |
| 256 | |
| 257 | public Object[] toArray() { |
| 258 | return toArray(new Object[size()]); |
| 259 | } |
| 260 | |
| 261 | /** Form a string listing all elements with given separator character. |
| 262 | */ |
| 263 | public String toString(String sep) { |
| 264 | if (isEmpty()) { |
| 265 | return ""; |
| 266 | } else { |
| 267 | StringBuffer buf = new StringBuffer(); |
| 268 | buf.append(head); |
| 269 | for (List<A> l = tail; l.nonEmpty(); l = l.tail) { |
| 270 | buf.append(sep); |
| 271 | buf.append(l.head); |
| 272 | } |
| 273 | return buf.toString(); |
| 274 | } |
| 275 | } |
| 276 | |
| 277 | /** Form a string listing all elements with comma as the separator character. |
| 278 | */ |
| 279 | @Override |
| 280 | public String toString() { |
| 281 | return toString(","); |
| 282 | } |
| 283 | |
| 284 | /** Compute a hash code, overrides Object |
| 285 | * @see java.util.List#hashCode |
| 286 | */ |
| 287 | @Override |
| 288 | public int hashCode() { |
| 289 | List<A> l = this; |
| 290 | int h = 1; |
| 291 | while (l.tail != null) { |
| 292 | h = h * 31 + (l.head == null ? 0 : l.head.hashCode()); |
| 293 | l = l.tail; |
| 294 | } |
| 295 | return h; |
| 296 | } |
| 297 | |
| 298 | /** Is this list the same as other list? |
| 299 | * @see java.util.List#equals |
| 300 | */ |
| 301 | @Override |
| 302 | public boolean equals(Object other) { |
| 303 | if (other instanceof List<?>) |
| 304 | return equals(this, (List<?>)other); |
| 305 | if (other instanceof java.util.List<?>) { |
| 306 | List<A> t = this; |
| 307 | Iterator<?> oIter = ((java.util.List<?>) other).iterator(); |
| 308 | while (t.tail != null && oIter.hasNext()) { |
| 309 | Object o = oIter.next(); |
| 310 | if ( !(t.head == null ? o == null : t.head.equals(o))) |
| 311 | return false; |
| 312 | t = t.tail; |
| 313 | } |
| 314 | return (t.isEmpty() && !oIter.hasNext()); |
| 315 | } |
| 316 | return false; |
| 317 | } |
| 318 | |
| 319 | /** Are the two lists the same? |
| 320 | */ |
| 321 | public static boolean equals(List xs, List ys) { |
| 322 | while (xs.tail != null && ys.tail != null) { |
| 323 | if (xs.head == null) { |
| 324 | if (ys.head != null) return false; |
| 325 | } else { |
| 326 | if (!xs.head.equals(ys.head)) return false; |
| 327 | } |
| 328 | xs = xs.tail; |
| 329 | ys = ys.tail; |
| 330 | } |
| 331 | return xs.tail == null && ys.tail == null; |
| 332 | } |
| 333 | |
| 334 | /** Does the list contain the specified element? |
| 335 | */ |
| 336 | @Override |
| 337 | public boolean contains(Object x) { |
| 338 | List<A> l = this; |
| 339 | while (l.tail != null) { |
| 340 | if (x == null) { |
| 341 | if (l.head == null) return true; |
| 342 | } else { |
| 343 | if (l.head.equals(x)) return true; |
| 344 | } |
| 345 | l = l.tail; |
| 346 | } |
| 347 | return false; |
| 348 | } |
| 349 | |
| 350 | /** The last element in the list, if any, or null. |
| 351 | */ |
| 352 | public A last() { |
| 353 | A last = null; |
| 354 | List<A> t = this; |
| 355 | while (t.tail != null) { |
| 356 | last = t.head; |
| 357 | t = t.tail; |
| 358 | } |
| 359 | return last; |
| 360 | } |
| 361 | |
| 362 | @SuppressWarnings("unchecked") |
| 363 | public static <T> List<T> convert(Class<T> klass, List<?> list) { |
| 364 | if (list == null) |
| 365 | return null; |
| 366 | for (Object o : list) |
| 367 | klass.cast(o); |
| 368 | return (List<T>)list; |
| 369 | } |
| 370 | |
| 371 | private static Iterator EMPTYITERATOR = new Iterator() { |
| 372 | public boolean hasNext() { |
| 373 | return false; |
| 374 | } |
| 375 | public Object next() { |
| 376 | throw new java.util.NoSuchElementException(); |
| 377 | } |
| 378 | public void remove() { |
| 379 | throw new UnsupportedOperationException(); |
| 380 | } |
| 381 | }; |
| 382 | |
| 383 | @SuppressWarnings("unchecked") |
| 384 | private static <A> Iterator<A> emptyIterator() { |
| 385 | return EMPTYITERATOR; |
| 386 | } |
| 387 | |
| 388 | @Override |
| 389 | public Iterator<A> iterator() { |
| 390 | if (tail == null) |
| 391 | return emptyIterator(); |
| 392 | return new Iterator<A>() { |
| 393 | List<A> elems = List.this; |
| 394 | public boolean hasNext() { |
| 395 | return elems.tail != null; |
| 396 | } |
| 397 | public A next() { |
| 398 | if (elems.tail == null) |
| 399 | throw new NoSuchElementException(); |
| 400 | A result = elems.head; |
| 401 | elems = elems.tail; |
| 402 | return result; |
| 403 | } |
| 404 | public void remove() { |
| 405 | throw new UnsupportedOperationException(); |
| 406 | } |
| 407 | }; |
| 408 | } |
| 409 | |
| 410 | public A get(int index) { |
| 411 | if (index < 0) |
| 412 | throw new IndexOutOfBoundsException(String.valueOf(index)); |
| 413 | |
| 414 | List<A> l = this; |
| 415 | for (int i = index; i-- > 0 && !l.isEmpty(); l = l.tail) |
| 416 | ; |
| 417 | |
| 418 | if (l.isEmpty()) |
| 419 | throw new IndexOutOfBoundsException("Index: " + index + ", " + |
| 420 | "Size: " + size()); |
| 421 | return l.head; |
| 422 | } |
| 423 | |
| 424 | public boolean addAll(int index, Collection<? extends A> c) { |
| 425 | if (c.isEmpty()) |
| 426 | return false; |
| 427 | throw new UnsupportedOperationException(); |
| 428 | } |
| 429 | |
| 430 | public A set(int index, A element) { |
| 431 | throw new UnsupportedOperationException(); |
| 432 | } |
| 433 | |
| 434 | public void add(int index, A element) { |
| 435 | throw new UnsupportedOperationException(); |
| 436 | } |
| 437 | |
| 438 | public A remove(int index) { |
| 439 | throw new UnsupportedOperationException(); |
| 440 | } |
| 441 | |
| 442 | public int indexOf(Object o) { |
| 443 | int i = 0; |
| 444 | for (List<A> l = this; l.tail != null; l = l.tail, i++) { |
| 445 | if (l.head == null ? o == null : l.head.equals(o)) |
| 446 | return i; |
| 447 | } |
| 448 | return -1; |
| 449 | } |
| 450 | |
| 451 | public int lastIndexOf(Object o) { |
| 452 | int last = -1; |
| 453 | int i = 0; |
| 454 | for (List<A> l = this; l.tail != null; l = l.tail, i++) { |
| 455 | if (l.head == null ? o == null : l.head.equals(o)) |
| 456 | last = i; |
| 457 | } |
| 458 | return last; |
| 459 | } |
| 460 | |
| 461 | public ListIterator<A> listIterator() { |
| 462 | return Collections.unmodifiableList(new ArrayList<A>(this)).listIterator(); |
| 463 | } |
| 464 | |
| 465 | public ListIterator<A> listIterator(int index) { |
| 466 | return Collections.unmodifiableList(new ArrayList<A>(this)).listIterator(index); |
| 467 | } |
| 468 | |
| 469 | public java.util.List<A> subList(int fromIndex, int toIndex) { |
| 470 | if (fromIndex < 0 || toIndex > size() || fromIndex > toIndex) |
| 471 | throw new IllegalArgumentException(); |
| 472 | |
| 473 | ArrayList<A> a = new ArrayList<A>(toIndex - fromIndex); |
| 474 | int i = 0; |
| 475 | for (List<A> l = this; l.tail != null; l = l.tail, i++) { |
| 476 | if (i == toIndex) |
| 477 | break; |
| 478 | if (i >= fromIndex) |
| 479 | a.add(l.head); |
| 480 | } |
| 481 | |
| 482 | return Collections.unmodifiableList(a); |
| 483 | } |
| 484 | } |