DocTreeScanner.java revision 3193:3b3bea483542
1/* 2 * Copyright (c) 2011, 2015, 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 */ 25 26package com.sun.source.util; 27 28import com.sun.source.doctree.*; 29import com.sun.tools.javac.tree.DCTree.DCIndex; 30 31 32/** 33 * A TreeVisitor that visits all the child tree nodes. 34 * To visit nodes of a particular type, just override the 35 * corresponding visitXYZ method. 36 * Inside your method, call super.visitXYZ to visit descendant 37 * nodes. 38 * 39 * <p>The default implementation of the visitXYZ methods will determine 40 * a result as follows: 41 * <ul> 42 * <li>If the node being visited has no children, the result will be {@code null}. 43 * <li>If the node being visited has one child, the result will be the 44 * result of calling {@code scan} on that child. The child may be a simple node 45 * or itself a list of nodes. 46 * <li> If the node being visited has more than one child, the result will 47 * be determined by calling {@code scan} each child in turn, and then combining the 48 * result of each scan after the first with the cumulative result 49 * so far, as determined by the {@link #reduce} method. Each child may be either 50 * a simple node of a list of nodes. The default behavior of the {@code reduce} 51 * method is such that the result of the visitXYZ method will be the result of 52 * the last child scanned. 53 * </ul> 54 * 55 * <p>Here is an example to count the number of erroneous nodes in a tree: 56 * <pre> 57 * class CountErrors extends DocTreeScanner<Integer,Void> { 58 * {@literal @}Override 59 * public Integer visitErroneous(ErroneousTree node, Void p) { 60 * return 1; 61 * } 62 * {@literal @}Override 63 * public Integer reduce(Integer r1, Integer r2) { 64 * return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2); 65 * } 66 * } 67 * </pre> 68 * 69 * @since 1.8 70 */ 71public class DocTreeScanner<R,P> implements DocTreeVisitor<R,P> { 72 73 /** 74 * Scans a single node. 75 * @param node the node to be scanned 76 * @param p a parameter value passed to the visit method 77 * @return the result value from the visit method 78 */ 79 public R scan(DocTree node, P p) { 80 return (node == null) ? null : node.accept(this, p); 81 } 82 83 private R scanAndReduce(DocTree node, P p, R r) { 84 return reduce(scan(node, p), r); 85 } 86 87 /** 88 * Scans a sequence of nodes. 89 * @param nodes the nodes to be scanned 90 * @param p a parameter value to be passed to the visit method for each node 91 * @return the combined return value from the visit methods. 92 * The values are combined using the {@link #reduce reduce} method. 93 */ 94 public R scan(Iterable<? extends DocTree> nodes, P p) { 95 R r = null; 96 if (nodes != null) { 97 boolean first = true; 98 for (DocTree node : nodes) { 99 r = (first ? scan(node, p) : scanAndReduce(node, p, r)); 100 first = false; 101 } 102 } 103 return r; 104 } 105 106 private R scanAndReduce(Iterable<? extends DocTree> nodes, P p, R r) { 107 return reduce(scan(nodes, p), r); 108 } 109 110 /** 111 * Reduces two results into a combined result. 112 * The default implementation is to return the first parameter. 113 * The general contract of the method is that it may take any action whatsoever. 114 * @param r1 the first of the values to be combined 115 * @param r2 the second of the values to be combined 116 * @return the result of combining the two parameters 117 */ 118 public R reduce(R r1, R r2) { 119 return r1; 120 } 121 122 123/* *************************************************************************** 124 * Visitor methods 125 ****************************************************************************/ 126 127 /** 128 * {@inheritDoc} This implementation returns {@code null}. 129 * 130 * @param node {@inheritDoc} 131 * @param p {@inheritDoc} 132 * @return the result of scanning 133 */ 134 @Override 135 public R visitAttribute(AttributeTree node, P p) { 136 return null; 137 } 138 139 /** 140 * {@inheritDoc} This implementation scans the children in left to right order. 141 * 142 * @param node {@inheritDoc} 143 * @param p {@inheritDoc} 144 * @return the result of scanning 145 */ 146 @Override 147 public R visitAuthor(AuthorTree node, P p) { 148 return scan(node.getName(), p); 149 } 150 151 /** 152 * {@inheritDoc} This implementation returns {@code null}. 153 * 154 * @param node {@inheritDoc} 155 * @param p {@inheritDoc} 156 * @return the result of scanning 157 */ 158 @Override 159 public R visitComment(CommentTree node, P p) { 160 return null; 161 } 162 163 /** 164 * {@inheritDoc} This implementation scans the children in left to right order. 165 * 166 * @param node {@inheritDoc} 167 * @param p {@inheritDoc} 168 * @return the result of scanning 169 */ 170 @Override 171 public R visitDeprecated(DeprecatedTree node, P p) { 172 return scan(node.getBody(), p); 173 } 174 175 /** 176 * {@inheritDoc} This implementation scans the children in left to right order. 177 * 178 * @param node {@inheritDoc} 179 * @param p {@inheritDoc} 180 * @return the result of scanning 181 */ 182 @Override 183 public R visitDocComment(DocCommentTree node, P p) { 184 R r = scan(node.getFirstSentence(), p); 185 r = scanAndReduce(node.getBody(), p, r); 186 r = scanAndReduce(node.getBlockTags(), p, r); 187 return r; 188 } 189 190 /** 191 * {@inheritDoc} This implementation returns {@code null}. 192 * 193 * @param node {@inheritDoc} 194 * @param p {@inheritDoc} 195 * @return the result of scanning 196 */ 197 @Override 198 public R visitDocRoot(DocRootTree node, P p) { 199 return null; 200 } 201 202 /** 203 * {@inheritDoc} This implementation returns {@code null}. 204 * 205 * @param node {@inheritDoc} 206 * @param p {@inheritDoc} 207 * @return the result of scanning 208 */ 209 @Override 210 public R visitEndElement(EndElementTree node, P p) { 211 return null; 212 } 213 214 /** 215 * {@inheritDoc} This implementation returns {@code null}. 216 * 217 * @param node {@inheritDoc} 218 * @param p {@inheritDoc} 219 * @return the result of scanning 220 */ 221 @Override 222 public R visitEntity(EntityTree node, P p) { 223 return null; 224 } 225 226 /** 227 * {@inheritDoc} This implementation returns {@code null}. 228 * 229 * @param node {@inheritDoc} 230 * @param p {@inheritDoc} 231 * @return the result of scanning 232 */ 233 @Override 234 public R visitErroneous(ErroneousTree node, P p) { 235 return null; 236 } 237 238 /** 239 * {@inheritDoc} This implementation returns {@code null}. 240 * 241 * @param node {@inheritDoc} 242 * @param p {@inheritDoc} 243 * @return the result of scanning 244 */ 245 @Override 246 public R visitIdentifier(IdentifierTree node, P p) { 247 return null; 248 } 249 250 /** 251 * {@inheritDoc} This implementation returns {@code null}. 252 * 253 * @param node {@inheritDoc} 254 * @param p {@inheritDoc} 255 * @return the result of scanning 256 */ 257 @Override 258 public R visitIndex(IndexTree node, P p) { 259 R r = scan(node.getSearchTerm(), p); 260 r = scanAndReduce(node.getDescription(), p, r); 261 return r; 262 } 263 264 /** 265 * {@inheritDoc} This implementation returns {@code null}. 266 * 267 * @param node {@inheritDoc} 268 * @param p {@inheritDoc} 269 * @return the result of scanning 270 */ 271 @Override 272 public R visitInheritDoc(InheritDocTree node, P p) { 273 return null; 274 } 275 276 /** 277 * {@inheritDoc} This implementation scans the children in left to right order. 278 * 279 * @param node {@inheritDoc} 280 * @param p {@inheritDoc} 281 * @return the result of scanning 282 */ 283 @Override 284 public R visitLink(LinkTree node, P p) { 285 R r = scan(node.getReference(), p); 286 r = scanAndReduce(node.getLabel(), p, r); 287 return r; 288 } 289 290 /** 291 * {@inheritDoc} This implementation returns {@code null}. 292 * 293 * @param node {@inheritDoc} 294 * @param p {@inheritDoc} 295 * @return the result of scanning 296 */ 297 @Override 298 public R visitLiteral(LiteralTree node, P p) { 299 return null; 300 } 301 302 /** 303 * {@inheritDoc} This implementation scans the children in left to right order. 304 * 305 * @param node {@inheritDoc} 306 * @param p {@inheritDoc} 307 * @return the result of scanning 308 */ 309 @Override 310 public R visitParam(ParamTree node, P p) { 311 R r = scan(node.getName(), p); 312 r = scanAndReduce(node.getDescription(), p, r); 313 return r; 314 } 315 316 /** 317 * {@inheritDoc} This implementation returns {@code null}. 318 * 319 * @param node {@inheritDoc} 320 * @param p {@inheritDoc} 321 * @return the result of scanning 322 */ 323 @Override 324 public R visitReference(ReferenceTree node, P p) { 325 return null; 326 } 327 328 /** 329 * {@inheritDoc} This implementation scans the children in left to right order. 330 * 331 * @param node {@inheritDoc} 332 * @param p {@inheritDoc} 333 * @return the result of scanning 334 */ 335 @Override 336 public R visitReturn(ReturnTree node, P p) { 337 return scan(node.getDescription(), p); 338 } 339 340 /** 341 * {@inheritDoc} This implementation scans the children in left to right order. 342 * 343 * @param node {@inheritDoc} 344 * @param p {@inheritDoc} 345 * @return the result of scanning 346 */ 347 @Override 348 public R visitSee(SeeTree node, P p) { 349 return scan(node.getReference(), p); 350 } 351 352 /** 353 * {@inheritDoc} This implementation scans the children in left to right order. 354 * 355 * @param node {@inheritDoc} 356 * @param p {@inheritDoc} 357 * @return the result of scanning 358 */ 359 @Override 360 public R visitSerial(SerialTree node, P p) { 361 return scan(node.getDescription(), p); 362 } 363 364 /** 365 * {@inheritDoc} This implementation scans the children in left to right order. 366 * 367 * @param node {@inheritDoc} 368 * @param p {@inheritDoc} 369 * @return the result of scanning 370 */ 371 @Override 372 public R visitSerialData(SerialDataTree node, P p) { 373 return scan(node.getDescription(), p); 374 } 375 376 /** 377 * {@inheritDoc} This implementation scans the children in left to right order. 378 * 379 * @param node {@inheritDoc} 380 * @param p {@inheritDoc} 381 * @return the result of scanning 382 */ 383 @Override 384 public R visitSerialField(SerialFieldTree node, P p) { 385 R r = scan(node.getName(), p); 386 r = scanAndReduce(node.getType(), p, r); 387 r = scanAndReduce(node.getDescription(), p, r); 388 return r; 389 } 390 391 /** 392 * {@inheritDoc} This implementation scans the children in left to right order. 393 * 394 * @param node {@inheritDoc} 395 * @param p {@inheritDoc} 396 * @return the result of scanning 397 */ 398 @Override 399 public R visitSince(SinceTree node, P p) { 400 return scan(node.getBody(), p); 401 } 402 403 /** 404 * {@inheritDoc} This implementation scans the children in left to right order. 405 * 406 * @param node {@inheritDoc} 407 * @param p {@inheritDoc} 408 * @return the result of scanning 409 */ 410 @Override 411 public R visitStartElement(StartElementTree node, P p) { 412 return scan(node.getAttributes(), p); 413 } 414 415 /** 416 * {@inheritDoc} This implementation returns {@code null}. 417 * 418 * @param node {@inheritDoc} 419 * @param p {@inheritDoc} 420 * @return the result of scanning 421 */ 422 @Override 423 public R visitText(TextTree node, P p) { 424 return null; 425 } 426 427 /** 428 * {@inheritDoc} This implementation scans the children in left to right order. 429 * 430 * @param node {@inheritDoc} 431 * @param p {@inheritDoc} 432 * @return the result of scanning 433 */ 434 @Override 435 public R visitThrows(ThrowsTree node, P p) { 436 R r = scan(node.getExceptionName(), p); 437 r = scanAndReduce(node.getDescription(), p, r); 438 return r; 439 } 440 441 /** 442 * {@inheritDoc} This implementation scans the children in left to right order. 443 * 444 * @param node {@inheritDoc} 445 * @param p {@inheritDoc} 446 * @return the result of scanning 447 */ 448 @Override 449 public R visitUnknownBlockTag(UnknownBlockTagTree node, P p) { 450 return scan(node.getContent(), p); 451 } 452 453 /** 454 * {@inheritDoc} This implementation scans the children in left to right order. 455 * 456 * @param node {@inheritDoc} 457 * @param p {@inheritDoc} 458 * @return the result of scanning 459 */ 460 @Override 461 public R visitUnknownInlineTag(UnknownInlineTagTree node, P p) { 462 return scan(node.getContent(), p); 463 } 464 465 /** 466 * {@inheritDoc} This implementation scans the children in left to right order. 467 * 468 * @param node {@inheritDoc} 469 * @param p {@inheritDoc} 470 * @return the result of scanning 471 */ 472 @Override 473 public R visitValue(ValueTree node, P p) { 474 return scan(node.getReference(), p); 475 } 476 477 /** 478 * {@inheritDoc} This implementation scans the children in left to right order. 479 * 480 * @param node {@inheritDoc} 481 * @param p {@inheritDoc} 482 * @return the result of scanning 483 */ 484 @Override 485 public R visitVersion(VersionTree node, P p) { 486 return scan(node.getBody(), p); 487 } 488 489 /** 490 * {@inheritDoc} This implementation returns {@code null}. 491 * 492 * @param node {@inheritDoc} 493 * @param p {@inheritDoc} 494 * @return the result of scanning 495 */ 496 @Override 497 public R visitOther(DocTree node, P p) { 498 return null; 499 } 500 501} 502