1 /*
   2  * Copyright (c) 2011, 2017, 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 
  26 package com.sun.source.util;
  27 
  28 import com.sun.source.doctree.*;
  29 
  30 
  31 /**
  32  * A TreeVisitor that visits all the child tree nodes.
  33  * To visit nodes of a particular type, just override the
  34  * corresponding visitXYZ method.
  35  * Inside your method, call super.visitXYZ to visit descendant
  36  * nodes.
  37  *
  38  * <p>The default implementation of the visitXYZ methods will determine
  39  * a result as follows:
  40  * <ul>
  41  * <li>If the node being visited has no children, the result will be {@code null}.
  42  * <li>If the node being visited has one child, the result will be the
  43  * result of calling {@code scan} on that child. The child may be a simple node
  44  * or itself a list of nodes.
  45  * <li> If the node being visited has more than one child, the result will
  46  * be determined by calling {@code scan} each child in turn, and then combining the
  47  * result of each scan after the first with the cumulative result
  48  * so far, as determined by the {@link #reduce} method. Each child may be either
  49  * a simple node of a list of nodes. The default behavior of the {@code reduce}
  50  * method is such that the result of the visitXYZ method will be the result of
  51  * the last child scanned.
  52  * </ul>
  53  *
  54  * <p>Here is an example to count the number of erroneous nodes in a tree:
  55  * <pre>
  56  *   class CountErrors extends DocTreeScanner&lt;Integer,Void&gt; {
  57  *      {@literal @}Override
  58  *      public Integer visitErroneous(ErroneousTree node, Void p) {
  59  *          return 1;
  60  *      }
  61  *      {@literal @}Override
  62  *      public Integer reduce(Integer r1, Integer r2) {
  63  *          return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2);
  64  *      }
  65  *   }
  66  * </pre>
  67  *
  68  * @since 1.8
  69  */
  70 public class DocTreeScanner<R,P> implements DocTreeVisitor<R,P> {
  71 
  72     /**
  73      * Scans a single node.
  74      * @param node the node to be scanned
  75      * @param p a parameter value passed to the visit method
  76      * @return the result value from the visit method
  77      */
  78     public R scan(DocTree node, P p) {
  79         return (node == null) ? null : node.accept(this, p);
  80     }
  81 
  82     private R scanAndReduce(DocTree node, P p, R r) {
  83         return reduce(scan(node, p), r);
  84     }
  85 
  86     /**
  87      * Scans a sequence of nodes.
  88      * @param nodes the nodes to be scanned
  89      * @param p a parameter value to be passed to the visit method for each node
  90      * @return the combined return value from the visit methods.
  91      *      The values are combined using the {@link #reduce reduce} method.
  92      */
  93     public R scan(Iterable<? extends DocTree> nodes, P p) {
  94         R r = null;
  95         if (nodes != null) {
  96             boolean first = true;
  97             for (DocTree node : nodes) {
  98                 r = (first ? scan(node, p) : scanAndReduce(node, p, r));
  99                 first = false;
 100             }
 101         }
 102         return r;
 103     }
 104 
 105     private R scanAndReduce(Iterable<? extends DocTree> nodes, P p, R r) {
 106         return reduce(scan(nodes, p), r);
 107     }
 108 
 109     /**
 110      * Reduces two results into a combined result.
 111      * The default implementation is to return the first parameter.
 112      * The general contract of the method is that it may take any action whatsoever.
 113      * @param r1 the first of the values to be combined
 114      * @param r2 the second of the values to be combined
 115      * @return the result of combining the two parameters
 116      */
 117     public R reduce(R r1, R r2) {
 118         return r1;
 119     }
 120 
 121 
 122 /* ***************************************************************************
 123  * Visitor methods
 124  ****************************************************************************/
 125 
 126     /**
 127      * {@inheritDoc} This implementation returns {@code null}.
 128      *
 129      * @param node  {@inheritDoc}
 130      * @param p  {@inheritDoc}
 131      * @return the result of scanning
 132      */
 133     @Override
 134     public R visitAttribute(AttributeTree node, P p) {
 135         return null;
 136     }
 137 
 138     /**
 139      * {@inheritDoc} This implementation scans the children in left to right order.
 140      *
 141      * @param node  {@inheritDoc}
 142      * @param p  {@inheritDoc}
 143      * @return the result of scanning
 144      */
 145     @Override
 146     public R visitAuthor(AuthorTree node, P p) {
 147         return scan(node.getName(), p);
 148     }
 149 
 150     /**
 151      * {@inheritDoc} This implementation returns {@code null}.
 152      *
 153      * @param node  {@inheritDoc}
 154      * @param p  {@inheritDoc}
 155      * @return the result of scanning
 156      */
 157     @Override
 158     public R visitComment(CommentTree node, P p) {
 159         return null;
 160     }
 161 
 162     /**
 163      * {@inheritDoc} This implementation scans the children in left to right order.
 164      *
 165      * @param node  {@inheritDoc}
 166      * @param p  {@inheritDoc}
 167      * @return the result of scanning
 168      */
 169     @Override
 170     public R visitDeprecated(DeprecatedTree node, P p) {
 171         return scan(node.getBody(), p);
 172     }
 173 
 174     /**
 175      * {@inheritDoc} This implementation scans the children in left to right order.
 176      *
 177      * @param node  {@inheritDoc}
 178      * @param p  {@inheritDoc}
 179      * @return the result of scanning
 180      */
 181     @Override
 182     public R visitDocComment(DocCommentTree node, P p) {
 183         R r = scan(node.getFirstSentence(), p);
 184         r = scanAndReduce(node.getBody(), p, r);
 185         r = scanAndReduce(node.getBlockTags(), p, r);
 186         return r;
 187     }
 188 
 189     /**
 190      * {@inheritDoc} This implementation returns {@code null}.
 191      *
 192      * @param node  {@inheritDoc}
 193      * @param p  {@inheritDoc}
 194      * @return the result of scanning
 195      */
 196     @Override
 197     public R visitDocRoot(DocRootTree node, P p) {
 198         return null;
 199     }
 200 
 201     /**
 202      * {@inheritDoc} This implementation returns {@code null}.
 203      *
 204      * @param node  {@inheritDoc}
 205      * @param p  {@inheritDoc}
 206      * @return the result of scanning
 207      */
 208     @Override
 209     public R visitDocType(DocTypeTree node, P p) {
 210         return null;
 211     }
 212 
 213     /**
 214      * {@inheritDoc} This implementation returns {@code null}.
 215      *
 216      * @param node  {@inheritDoc}
 217      * @param p  {@inheritDoc}
 218      * @return the result of scanning
 219      */
 220     @Override
 221     public R visitEndElement(EndElementTree node, P p) {
 222         return null;
 223     }
 224 
 225     /**
 226      * {@inheritDoc} This implementation returns {@code null}.
 227      *
 228      * @param node  {@inheritDoc}
 229      * @param p  {@inheritDoc}
 230      * @return the result of scanning
 231      */
 232     @Override
 233     public R visitEntity(EntityTree node, P p) {
 234         return null;
 235     }
 236 
 237     /**
 238      * {@inheritDoc} This implementation returns {@code null}.
 239      *
 240      * @param node  {@inheritDoc}
 241      * @param p  {@inheritDoc}
 242      * @return the result of scanning
 243      */
 244     @Override
 245     public R visitErroneous(ErroneousTree node, P p) {
 246         return null;
 247     }
 248 
 249     /**
 250      * {@inheritDoc} This implementation scans the children in left to right order.
 251      *
 252      * @param node  {@inheritDoc}
 253      * @param p  {@inheritDoc}
 254      * @return the result of scanning
 255      */
 256     @Override
 257     public R visitHidden(HiddenTree node, P p) {
 258         return scan(node.getBody(), p);
 259     }
 260 
 261     /**
 262      * {@inheritDoc} This implementation returns {@code null}.
 263      *
 264      * @param node  {@inheritDoc}
 265      * @param p  {@inheritDoc}
 266      * @return the result of scanning
 267      */
 268     @Override
 269     public R visitIdentifier(IdentifierTree node, P p) {
 270         return null;
 271     }
 272 
 273     /**
 274      * {@inheritDoc} This implementation returns {@code null}.
 275      *
 276      * @param node  {@inheritDoc}
 277      * @param p  {@inheritDoc}
 278      * @return the result of scanning
 279      */
 280     @Override
 281     public R visitIndex(IndexTree node, P p) {
 282         R r = scan(node.getSearchTerm(), p);
 283         r = scanAndReduce(node.getDescription(), p, r);
 284         return r;
 285     }
 286 
 287     /**
 288      * {@inheritDoc} This implementation returns {@code null}.
 289      *
 290      * @param node  {@inheritDoc}
 291      * @param p  {@inheritDoc}
 292      * @return the result of scanning
 293      */
 294     @Override
 295     public R visitInheritDoc(InheritDocTree node, P p) {
 296         return null;
 297     }
 298 
 299     /**
 300      * {@inheritDoc} This implementation scans the children in left to right order.
 301      *
 302      * @param node  {@inheritDoc}
 303      * @param p  {@inheritDoc}
 304      * @return the result of scanning
 305      */
 306     @Override
 307     public R visitLink(LinkTree node, P p) {
 308         R r = scan(node.getReference(), p);
 309         r = scanAndReduce(node.getLabel(), p, r);
 310         return r;
 311     }
 312 
 313     /**
 314      * {@inheritDoc} This implementation returns {@code null}.
 315      *
 316      * @param node  {@inheritDoc}
 317      * @param p  {@inheritDoc}
 318      * @return the result of scanning
 319      */
 320     @Override
 321     public R visitLiteral(LiteralTree node, P p) {
 322         return null;
 323     }
 324 
 325     /**
 326      * {@inheritDoc} This implementation scans the children in left to right order.
 327      *
 328      * @param node  {@inheritDoc}
 329      * @param p  {@inheritDoc}
 330      * @return the result of scanning
 331      */
 332     @Override
 333     public R visitParam(ParamTree node, P p) {
 334         R r = scan(node.getName(), p);
 335         r = scanAndReduce(node.getDescription(), p, r);
 336         return r;
 337     }
 338 
 339     /**
 340      * {@inheritDoc} This implementation scans the children in left to right order.
 341      *
 342      * @param node  {@inheritDoc}
 343      * @param p  {@inheritDoc}
 344      * @return the result of scanning
 345      */
 346     @Override
 347     public R visitProvides(ProvidesTree node, P p) {
 348         R r = scan(node.getServiceType(), p);
 349         r = scanAndReduce(node.getDescription(), p, r);
 350         return r;
 351     }
 352 
 353     /**
 354      * {@inheritDoc} This implementation returns {@code null}.
 355      *
 356      * @param node  {@inheritDoc}
 357      * @param p  {@inheritDoc}
 358      * @return the result of scanning
 359      */
 360     @Override
 361     public R visitReference(ReferenceTree node, P p) {
 362         return null;
 363     }
 364 
 365     /**
 366      * {@inheritDoc} This implementation scans the children in left to right order.
 367      *
 368      * @param node  {@inheritDoc}
 369      * @param p  {@inheritDoc}
 370      * @return the result of scanning
 371      */
 372     @Override
 373     public R visitReturn(ReturnTree node, P p) {
 374         return scan(node.getDescription(), p);
 375     }
 376 
 377     /**
 378      * {@inheritDoc} This implementation scans the children in left to right order.
 379      *
 380      * @param node  {@inheritDoc}
 381      * @param p  {@inheritDoc}
 382      * @return the result of scanning
 383      */
 384     @Override
 385     public R visitSee(SeeTree node, P p) {
 386         return scan(node.getReference(), p);
 387     }
 388 
 389     /**
 390      * {@inheritDoc} This implementation scans the children in left to right order.
 391      *
 392      * @param node  {@inheritDoc}
 393      * @param p  {@inheritDoc}
 394      * @return the result of scanning
 395      */
 396     @Override
 397     public R visitSerial(SerialTree node, P p) {
 398         return scan(node.getDescription(), p);
 399     }
 400 
 401     /**
 402      * {@inheritDoc} This implementation scans the children in left to right order.
 403      *
 404      * @param node  {@inheritDoc}
 405      * @param p  {@inheritDoc}
 406      * @return the result of scanning
 407      */
 408     @Override
 409     public R visitSerialData(SerialDataTree node, P p) {
 410         return scan(node.getDescription(), p);
 411     }
 412 
 413     /**
 414      * {@inheritDoc} This implementation scans the children in left to right order.
 415      *
 416      * @param node  {@inheritDoc}
 417      * @param p  {@inheritDoc}
 418      * @return the result of scanning
 419      */
 420     @Override
 421     public R visitSerialField(SerialFieldTree node, P p) {
 422         R r = scan(node.getName(), p);
 423         r = scanAndReduce(node.getType(), p, r);
 424         r = scanAndReduce(node.getDescription(), p, r);
 425         return r;
 426     }
 427 
 428     /**
 429      * {@inheritDoc} This implementation scans the children in left to right order.
 430      *
 431      * @param node  {@inheritDoc}
 432      * @param p  {@inheritDoc}
 433      * @return the result of scanning
 434      */
 435     @Override
 436     public R visitSince(SinceTree node, P p) {
 437         return scan(node.getBody(), p);
 438     }
 439 
 440     /**
 441      * {@inheritDoc} This implementation scans the children in left to right order.
 442      *
 443      * @param node  {@inheritDoc}
 444      * @param p  {@inheritDoc}
 445      * @return the result of scanning
 446      */
 447     @Override
 448     public R visitStartElement(StartElementTree node, P p) {
 449         return scan(node.getAttributes(), p);
 450     }
 451 
 452     /**
 453      * {@inheritDoc} This implementation scans the children in left to right order.
 454      *
 455      * @param node  {@inheritDoc}
 456      * @param p  {@inheritDoc}
 457      * @return the result of scanning
 458      * @since 10
 459      */
 460     @Override
 461     public R visitSummary(SummaryTree node, P p) {
 462         R r = scan(node.getSummary(), p);
 463         return r;
 464     }
 465 
 466     /**
 467      * {@inheritDoc} This implementation returns {@code null}.
 468      *
 469      * @param node  {@inheritDoc}
 470      * @param p  {@inheritDoc}
 471      * @return the result of scanning
 472      * @since 12
 473      */
 474     @Override
 475     public R visitSystemProperty(SystemPropertyTree node, P p) {
 476         return null;
 477     }
 478 
 479     /**
 480      * {@inheritDoc} This implementation returns {@code null}.
 481      *
 482      * @param node  {@inheritDoc}
 483      * @param p  {@inheritDoc}
 484      * @return the result of scanning
 485      */
 486     @Override
 487     public R visitText(TextTree node, P p) {
 488         return null;
 489     }
 490 
 491     /**
 492      * {@inheritDoc} This implementation scans the children in left to right order.
 493      *
 494      * @param node  {@inheritDoc}
 495      * @param p  {@inheritDoc}
 496      * @return the result of scanning
 497      */
 498     @Override
 499     public R visitThrows(ThrowsTree node, P p) {
 500         R r = scan(node.getExceptionName(), p);
 501         r = scanAndReduce(node.getDescription(), p, r);
 502         return r;
 503     }
 504 
 505     /**
 506      * {@inheritDoc} This implementation scans the children in left to right order.
 507      *
 508      * @param node  {@inheritDoc}
 509      * @param p  {@inheritDoc}
 510      * @return the result of scanning
 511      */
 512     @Override
 513     public R visitUnknownBlockTag(UnknownBlockTagTree node, P p) {
 514         return scan(node.getContent(), p);
 515     }
 516 
 517     /**
 518      * {@inheritDoc} This implementation scans the children in left to right order.
 519      *
 520      * @param node  {@inheritDoc}
 521      * @param p  {@inheritDoc}
 522      * @return the result of scanning
 523      */
 524     @Override
 525     public R visitUnknownInlineTag(UnknownInlineTagTree node, P p) {
 526         return scan(node.getContent(), p);
 527     }
 528 
 529     /**
 530      * {@inheritDoc} This implementation scans the children in left to right order.
 531      *
 532      * @param node  {@inheritDoc}
 533      * @param p  {@inheritDoc}
 534      * @return the result of scanning
 535      */
 536     @Override
 537     public R visitUses(UsesTree node, P p) {
 538         R r = scan(node.getServiceType(), p);
 539         r = scanAndReduce(node.getDescription(), p, r);
 540         return r;
 541     }
 542 
 543     /**
 544      * {@inheritDoc} This implementation scans the children in left to right order.
 545      *
 546      * @param node  {@inheritDoc}
 547      * @param p  {@inheritDoc}
 548      * @return the result of scanning
 549      */
 550     @Override
 551     public R visitValue(ValueTree node, P p) {
 552         return scan(node.getReference(), p);
 553     }
 554 
 555     /**
 556      * {@inheritDoc} This implementation scans the children in left to right order.
 557      *
 558      * @param node  {@inheritDoc}
 559      * @param p  {@inheritDoc}
 560      * @return the result of scanning
 561      */
 562     @Override
 563     public R visitVersion(VersionTree node, P p) {
 564         return scan(node.getBody(), p);
 565     }
 566 
 567     /**
 568      * {@inheritDoc} This implementation returns {@code null}.
 569      *
 570      * @param node  {@inheritDoc}
 571      * @param p  {@inheritDoc}
 572      * @return the result of scanning
 573      */
 574     @Override
 575     public R visitOther(DocTree node, P p) {
 576         return null;
 577     }
 578 
 579 }