001// License: GPL. For details, see LICENSE file. 002package org.openstreetmap.josm.io; 003 004import static org.openstreetmap.josm.tools.I18n.tr; 005import static org.openstreetmap.josm.tools.I18n.trn; 006 007import java.io.IOException; 008import java.io.InputStream; 009import java.net.HttpURLConnection; 010import java.util.ArrayList; 011import java.util.Collection; 012import java.util.Collections; 013import java.util.HashSet; 014import java.util.Iterator; 015import java.util.LinkedHashSet; 016import java.util.List; 017import java.util.Set; 018import java.util.concurrent.Callable; 019import java.util.concurrent.CompletionService; 020import java.util.concurrent.ExecutionException; 021import java.util.concurrent.ExecutorCompletionService; 022import java.util.concurrent.ExecutorService; 023import java.util.concurrent.Executors; 024import java.util.concurrent.Future; 025 026import org.openstreetmap.josm.Main; 027import org.openstreetmap.josm.data.osm.DataSet; 028import org.openstreetmap.josm.data.osm.DataSetMerger; 029import org.openstreetmap.josm.data.osm.Node; 030import org.openstreetmap.josm.data.osm.OsmPrimitive; 031import org.openstreetmap.josm.data.osm.OsmPrimitiveType; 032import org.openstreetmap.josm.data.osm.PrimitiveId; 033import org.openstreetmap.josm.data.osm.Relation; 034import org.openstreetmap.josm.data.osm.RelationMember; 035import org.openstreetmap.josm.data.osm.SimplePrimitiveId; 036import org.openstreetmap.josm.data.osm.Way; 037import org.openstreetmap.josm.gui.preferences.server.OverpassServerPreference; 038import org.openstreetmap.josm.gui.progress.NullProgressMonitor; 039import org.openstreetmap.josm.gui.progress.ProgressMonitor; 040import org.openstreetmap.josm.tools.Utils; 041 042/** 043 * Retrieves a set of {@link OsmPrimitive}s from an OSM server using the so called 044 * Multi Fetch API. 045 * 046 * Usage: 047 * <pre> 048 * MultiFetchServerObjectReader reader = MultiFetchServerObjectReader() 049 * .append(2345,2334,4444) 050 * .append(new Node(72343)); 051 * reader.parseOsm(); 052 * if (!reader.getMissingPrimitives().isEmpty()) { 053 * Main.info("There are missing primitives: " + reader.getMissingPrimitives()); 054 * } 055 * if (!reader.getSkippedWays().isEmpty()) { 056 * Main.info("There are skipped ways: " + reader.getMissingPrimitives()); 057 * } 058 * </pre> 059 */ 060public class MultiFetchServerObjectReader extends OsmServerReader { 061 /** 062 * the max. number of primitives retrieved in one step. Assuming IDs with 7 digits, 063 * this leads to a max. request URL of ~ 1600 Bytes ((7 digits + 1 Separator) * 200), 064 * which should be safe according to the 065 * <a href="http://www.boutell.com/newfaq/misc/urllength.html">WWW FAQ</a>. 066 */ 067 private static final int MAX_IDS_PER_REQUEST = 200; 068 069 private final Set<Long> nodes; 070 private final Set<Long> ways; 071 private final Set<Long> relations; 072 private Set<PrimitiveId> missingPrimitives; 073 private final DataSet outputDataSet; 074 075 /** 076 * Constructs a {@code MultiFetchServerObjectReader}. 077 */ 078 protected MultiFetchServerObjectReader() { 079 nodes = new LinkedHashSet<>(); 080 ways = new LinkedHashSet<>(); 081 relations = new LinkedHashSet<>(); 082 this.outputDataSet = new DataSet(); 083 this.missingPrimitives = new LinkedHashSet<>(); 084 } 085 086 /** 087 * Creates a new instance of {@link MultiFetchServerObjectReader} or {@link MultiFetchOverpassObjectReader} 088 * depending on the {@link OverpassServerPreference#useForMultiFetch preference}. 089 * 090 * @return a new instance 091 * @since 9241 092 */ 093 public static MultiFetchServerObjectReader create() { 094 return create(OverpassServerPreference.useForMultiFetch()); 095 } 096 097 /** 098 * Creates a new instance of {@link MultiFetchServerObjectReader} or {@link MultiFetchOverpassObjectReader} 099 * depending on the {@code fromMirror} parameter. 100 * 101 * @param fromMirror {@code false} for {@link MultiFetchServerObjectReader}, {@code true} for {@link MultiFetchOverpassObjectReader} 102 * @return a new instance 103 * @since 9241 104 */ 105 static MultiFetchServerObjectReader create(final boolean fromMirror) { 106 if (fromMirror) { 107 return new MultiFetchOverpassObjectReader(); 108 } else { 109 return new MultiFetchServerObjectReader(); 110 } 111 } 112 113 /** 114 * Remembers an {@link OsmPrimitive}'s id. The id will 115 * later be fetched as part of a Multi Get request. 116 * 117 * Ignore the id if it represents a new primitives. 118 * 119 * @param id the id 120 */ 121 protected void remember(PrimitiveId id) { 122 if (id.isNew()) return; 123 switch(id.getType()) { 124 case NODE: nodes.add(id.getUniqueId()); break; 125 case WAY: ways.add(id.getUniqueId()); break; 126 case RELATION: relations.add(id.getUniqueId()); break; 127 default: throw new AssertionError(); 128 } 129 } 130 131 /** 132 * appends a {@link OsmPrimitive} id to the list of ids which will be fetched from the server. 133 * 134 * @param ds the {@link DataSet} to which the primitive belongs 135 * @param id the primitive id 136 * @param type The primitive type. Must be one of {@link OsmPrimitiveType#NODE NODE}, {@link OsmPrimitiveType#WAY WAY}, 137 * {@link OsmPrimitiveType#RELATION RELATION} 138 * @return this 139 */ 140 public MultiFetchServerObjectReader append(DataSet ds, long id, OsmPrimitiveType type) { 141 OsmPrimitive p = ds.getPrimitiveById(id, type); 142 switch(type) { 143 case NODE: 144 return appendNode((Node) p); 145 case WAY: 146 return appendWay((Way) p); 147 case RELATION: 148 return appendRelation((Relation) p); 149 default: 150 return this; 151 } 152 } 153 154 /** 155 * appends a {@link Node} id to the list of ids which will be fetched from the server. 156 * 157 * @param node the node (ignored, if null) 158 * @return this 159 */ 160 public MultiFetchServerObjectReader appendNode(Node node) { 161 if (node == null) return this; 162 remember(node.getPrimitiveId()); 163 return this; 164 } 165 166 /** 167 * appends a {@link Way} id and the list of ids of nodes the way refers to the list of ids which will be fetched from the server. 168 * 169 * @param way the way (ignored, if null) 170 * @return this 171 */ 172 public MultiFetchServerObjectReader appendWay(Way way) { 173 if (way == null) return this; 174 if (way.isNew()) return this; 175 for (Node node: !recursesDown() ? way.getNodes() : Collections.<Node>emptyList()) { 176 if (!node.isNew()) { 177 remember(node.getPrimitiveId()); 178 } 179 } 180 remember(way.getPrimitiveId()); 181 return this; 182 } 183 184 /** 185 * appends a {@link Relation} id to the list of ids which will be fetched from the server. 186 * 187 * @param relation the relation (ignored, if null) 188 * @return this 189 */ 190 protected MultiFetchServerObjectReader appendRelation(Relation relation) { 191 if (relation == null) return this; 192 if (relation.isNew()) return this; 193 remember(relation.getPrimitiveId()); 194 for (RelationMember member : !recursesDown() ? relation.getMembers() : Collections.<RelationMember>emptyList()) { 195 if (OsmPrimitiveType.from(member.getMember()).equals(OsmPrimitiveType.RELATION)) { 196 // avoid infinite recursion in case of cyclic dependencies in relations 197 // 198 if (relations.contains(member.getMember().getId())) { 199 continue; 200 } 201 } 202 if (!member.getMember().isIncomplete()) { 203 append(member.getMember()); 204 } 205 } 206 return this; 207 } 208 209 /** 210 * appends an {@link OsmPrimitive} to the list of ids which will be fetched from the server. 211 * @param primitive the primitive 212 * @return this 213 */ 214 public MultiFetchServerObjectReader append(OsmPrimitive primitive) { 215 if (primitive != null) { 216 switch (OsmPrimitiveType.from(primitive)) { 217 case NODE: return appendNode((Node) primitive); 218 case WAY: return appendWay((Way) primitive); 219 case RELATION: return appendRelation((Relation) primitive); 220 default: break; 221 } 222 } 223 return this; 224 } 225 226 /** 227 * appends a list of {@link OsmPrimitive} to the list of ids which will be fetched from the server. 228 * 229 * @param primitives the list of primitives (ignored, if null) 230 * @return this 231 * 232 * @see #append(OsmPrimitive) 233 */ 234 public MultiFetchServerObjectReader append(Collection<? extends OsmPrimitive> primitives) { 235 if (primitives == null) return this; 236 for (OsmPrimitive primitive : primitives) { 237 append(primitive); 238 } 239 return this; 240 } 241 242 /** 243 * extracts a subset of max {@link #MAX_IDS_PER_REQUEST} ids from <code>ids</code> and 244 * replies the subset. The extracted subset is removed from <code>ids</code>. 245 * 246 * @param ids a set of ids 247 * @return the subset of ids 248 */ 249 protected Set<Long> extractIdPackage(Set<Long> ids) { 250 Set<Long> pkg = new HashSet<>(); 251 if (ids.isEmpty()) 252 return pkg; 253 if (ids.size() > MAX_IDS_PER_REQUEST) { 254 Iterator<Long> it = ids.iterator(); 255 for (int i = 0; i < MAX_IDS_PER_REQUEST; i++) { 256 pkg.add(it.next()); 257 } 258 ids.removeAll(pkg); 259 } else { 260 pkg.addAll(ids); 261 ids.clear(); 262 } 263 return pkg; 264 } 265 266 /** 267 * builds the Multi Get request string for a set of ids and a given {@link OsmPrimitiveType}. 268 * 269 * @param type The primitive type. Must be one of {@link OsmPrimitiveType#NODE NODE}, {@link OsmPrimitiveType#WAY WAY}, 270 * {@link OsmPrimitiveType#RELATION RELATION} 271 * @param idPackage the package of ids 272 * @return the request string 273 */ 274 protected String buildRequestString(final OsmPrimitiveType type, Set<Long> idPackage) { 275 return type.getAPIName() + "s?" + type.getAPIName() + "s=" + Utils.join(",", idPackage); 276 } 277 278 protected void rememberNodesOfIncompleteWaysToLoad(DataSet from) { 279 for (Way w: from.getWays()) { 280 if (w.hasIncompleteNodes()) { 281 for (Node n: w.getNodes()) { 282 if (n.isIncomplete()) { 283 nodes.add(n.getId()); 284 } 285 } 286 } 287 } 288 } 289 290 /** 291 * merges the dataset <code>from</code> to {@link #outputDataSet}. 292 * 293 * @param from the other dataset 294 */ 295 protected void merge(DataSet from) { 296 final DataSetMerger visitor = new DataSetMerger(outputDataSet, from); 297 visitor.merge(); 298 } 299 300 /** 301 * fetches a set of ids of a given {@link OsmPrimitiveType} from the server 302 * 303 * @param ids the set of ids 304 * @param type The primitive type. Must be one of {@link OsmPrimitiveType#NODE NODE}, {@link OsmPrimitiveType#WAY WAY}, 305 * {@link OsmPrimitiveType#RELATION RELATION} 306 * @param progressMonitor progress monitor 307 * @throws OsmTransferException if an error occurs while communicating with the API server 308 */ 309 protected void fetchPrimitives(Set<Long> ids, OsmPrimitiveType type, ProgressMonitor progressMonitor) throws OsmTransferException { 310 String msg; 311 final String baseUrl = getBaseUrl(); 312 switch (type) { 313 // CHECKSTYLE.OFF: SingleSpaceSeparator 314 case NODE: msg = tr("Fetching a package of nodes from ''{0}''", baseUrl); break; 315 case WAY: msg = tr("Fetching a package of ways from ''{0}''", baseUrl); break; 316 case RELATION: msg = tr("Fetching a package of relations from ''{0}''", baseUrl); break; 317 // CHECKSTYLE.ON: SingleSpaceSeparator 318 default: throw new AssertionError(); 319 } 320 progressMonitor.setTicksCount(ids.size()); 321 progressMonitor.setTicks(0); 322 // The complete set containing all primitives to fetch 323 Set<Long> toFetch = new HashSet<>(ids); 324 // Build a list of fetchers that will download smaller sets containing only MAX_IDS_PER_REQUEST (200) primitives each. 325 // we will run up to MAX_DOWNLOAD_THREADS concurrent fetchers. 326 int threadsNumber = Main.pref.getInteger("osm.download.threads", OsmApi.MAX_DOWNLOAD_THREADS); 327 threadsNumber = Math.min(Math.max(threadsNumber, 1), OsmApi.MAX_DOWNLOAD_THREADS); 328 final ExecutorService exec = Executors.newFixedThreadPool( 329 threadsNumber, Utils.newThreadFactory(getClass() + "-%d", Thread.NORM_PRIORITY)); 330 CompletionService<FetchResult> ecs = new ExecutorCompletionService<>(exec); 331 List<Future<FetchResult>> jobs = new ArrayList<>(); 332 while (!toFetch.isEmpty()) { 333 jobs.add(ecs.submit(new Fetcher(type, extractIdPackage(toFetch), progressMonitor))); 334 } 335 // Run the fetchers 336 for (int i = 0; i < jobs.size() && !isCanceled(); i++) { 337 progressMonitor.subTask(msg + "... " + progressMonitor.getTicks() + '/' + progressMonitor.getTicksCount()); 338 try { 339 FetchResult result = ecs.take().get(); 340 if (result.missingPrimitives != null) { 341 missingPrimitives.addAll(result.missingPrimitives); 342 } 343 if (result.dataSet != null && !isCanceled()) { 344 rememberNodesOfIncompleteWaysToLoad(result.dataSet); 345 merge(result.dataSet); 346 } 347 } catch (InterruptedException | ExecutionException e) { 348 Main.error(e); 349 } 350 } 351 exec.shutdown(); 352 // Cancel requests if the user chose to 353 if (isCanceled()) { 354 for (Future<FetchResult> job : jobs) { 355 job.cancel(true); 356 } 357 } 358 } 359 360 /** 361 * invokes one or more Multi Gets to fetch the {@link OsmPrimitive}s and replies 362 * the dataset of retrieved primitives. Note that the dataset includes non visible primitives too! 363 * In contrast to a simple Get for a node, a way, or a relation, a Multi Get always replies 364 * the latest version of the primitive (if any), even if the primitive is not visible (i.e. if 365 * visible==false). 366 * 367 * Invoke {@link #getMissingPrimitives()} to get a list of primitives which have not been 368 * found on the server (the server response code was 404) 369 * 370 * @return the parsed data 371 * @throws OsmTransferException if an error occurs while communicating with the API server 372 * @see #getMissingPrimitives() 373 * 374 */ 375 @Override 376 public DataSet parseOsm(ProgressMonitor progressMonitor) throws OsmTransferException { 377 int n = nodes.size() + ways.size() + relations.size(); 378 progressMonitor.beginTask(trn("Downloading {0} object from ''{1}''", 379 "Downloading {0} objects from ''{1}''", n, n, OsmApi.getOsmApi().getBaseUrl())); 380 try { 381 missingPrimitives = new HashSet<>(); 382 if (isCanceled()) return null; 383 fetchPrimitives(ways, OsmPrimitiveType.WAY, progressMonitor); 384 if (isCanceled()) return null; 385 fetchPrimitives(nodes, OsmPrimitiveType.NODE, progressMonitor); 386 if (isCanceled()) return null; 387 fetchPrimitives(relations, OsmPrimitiveType.RELATION, progressMonitor); 388 if (outputDataSet != null) { 389 outputDataSet.deleteInvisible(); 390 } 391 return outputDataSet; 392 } finally { 393 progressMonitor.finishTask(); 394 } 395 } 396 397 /** 398 * replies the set of ids of all primitives for which a fetch request to the 399 * server was submitted but which are not available from the server (the server 400 * replied a return code of 404) 401 * 402 * @return the set of ids of missing primitives 403 */ 404 public Set<PrimitiveId> getMissingPrimitives() { 405 return missingPrimitives; 406 } 407 408 /** 409 * Whether this reader fetches nodes when loading ways, or members when loading relations. 410 * 411 * @return {@code true} if the reader recurses down 412 */ 413 protected boolean recursesDown() { 414 return false; 415 } 416 417 /** 418 * The class holding the results given by {@link Fetcher}. 419 * It is only a wrapper of the resulting {@link DataSet} and the collection of {@link PrimitiveId} that could not have been loaded. 420 */ 421 protected static class FetchResult { 422 423 /** 424 * The resulting data set 425 */ 426 public final DataSet dataSet; 427 428 /** 429 * The collection of primitive ids that could not have been loaded 430 */ 431 public final Set<PrimitiveId> missingPrimitives; 432 433 /** 434 * Constructs a {@code FetchResult} 435 * @param dataSet The resulting data set 436 * @param missingPrimitives The collection of primitive ids that could not have been loaded 437 */ 438 public FetchResult(DataSet dataSet, Set<PrimitiveId> missingPrimitives) { 439 this.dataSet = dataSet; 440 this.missingPrimitives = missingPrimitives; 441 } 442 } 443 444 /** 445 * The class that actually download data from OSM API. 446 * Several instances of this class are used by {@link MultiFetchServerObjectReader} (one per set of primitives to fetch). 447 * The inheritance of {@link OsmServerReader} is only explained by the need to have a distinct OSM connection by {@code Fetcher} instance. 448 * @see FetchResult 449 */ 450 protected class Fetcher extends OsmServerReader implements Callable<FetchResult> { 451 452 private final Set<Long> pkg; 453 private final OsmPrimitiveType type; 454 private final ProgressMonitor progressMonitor; 455 456 /** 457 * Constructs a {@code Fetcher} 458 * @param type The primitive type. Must be one of {@link OsmPrimitiveType#NODE NODE}, {@link OsmPrimitiveType#WAY WAY}, 459 * {@link OsmPrimitiveType#RELATION RELATION} 460 * @param idsPackage The set of primitives ids to fetch 461 * @param progressMonitor The progress monitor 462 */ 463 public Fetcher(OsmPrimitiveType type, Set<Long> idsPackage, ProgressMonitor progressMonitor) { 464 this.pkg = idsPackage; 465 this.type = type; 466 this.progressMonitor = progressMonitor; 467 } 468 469 @Override 470 public DataSet parseOsm(ProgressMonitor progressMonitor) throws OsmTransferException { 471 // This method is implemented because of the OsmServerReader inheritance, but not used, 472 // as the main target of this class is the call() method. 473 return fetch(progressMonitor).dataSet; 474 } 475 476 @Override 477 public FetchResult call() throws Exception { 478 return fetch(progressMonitor); 479 } 480 481 /** 482 * fetches the requested primitives and updates the specified progress monitor. 483 * @param progressMonitor the progress monitor 484 * @return the {@link FetchResult} of this operation 485 * @throws OsmTransferException if an error occurs while communicating with the API server 486 */ 487 protected FetchResult fetch(ProgressMonitor progressMonitor) throws OsmTransferException { 488 try { 489 return multiGetIdPackage(type, pkg, progressMonitor); 490 } catch (OsmApiException e) { 491 if (e.getResponseCode() == HttpURLConnection.HTTP_NOT_FOUND) { 492 Main.info(tr("Server replied with response code 404, retrying with an individual request for each object.")); 493 return singleGetIdPackage(type, pkg, progressMonitor); 494 } else { 495 throw e; 496 } 497 } 498 } 499 500 @Override 501 protected String getBaseUrl() { 502 return MultiFetchServerObjectReader.this.getBaseUrl(); 503 } 504 505 /** 506 * invokes a Multi Get for a set of ids and a given {@link OsmPrimitiveType}. 507 * The retrieved primitives are merged to {@link #outputDataSet}. 508 * 509 * @param type The primitive type. Must be one of {@link OsmPrimitiveType#NODE NODE}, {@link OsmPrimitiveType#WAY WAY}, 510 * {@link OsmPrimitiveType#RELATION RELATION} 511 * @param pkg the package of ids 512 * @param progressMonitor progress monitor 513 * @return the {@link FetchResult} of this operation 514 * @throws OsmTransferException if an error occurs while communicating with the API server 515 */ 516 protected FetchResult multiGetIdPackage(OsmPrimitiveType type, Set<Long> pkg, ProgressMonitor progressMonitor) 517 throws OsmTransferException { 518 String request = buildRequestString(type, pkg); 519 FetchResult result = null; 520 try (InputStream in = getInputStream(request, NullProgressMonitor.INSTANCE)) { 521 if (in == null) return null; 522 progressMonitor.subTask(tr("Downloading OSM data...")); 523 try { 524 result = new FetchResult(OsmReader.parseDataSet(in, progressMonitor.createSubTaskMonitor(pkg.size(), false)), null); 525 } catch (IllegalDataException e) { 526 throw new OsmTransferException(e); 527 } 528 } catch (IOException ex) { 529 Main.warn(ex); 530 } 531 return result; 532 } 533 534 /** 535 * invokes a Multi Get for a single id and a given {@link OsmPrimitiveType}. 536 * The retrieved primitive is merged to {@link #outputDataSet}. 537 * 538 * @param type The primitive type. Must be one of {@link OsmPrimitiveType#NODE NODE}, {@link OsmPrimitiveType#WAY WAY}, 539 * {@link OsmPrimitiveType#RELATION RELATION} 540 * @param id the id 541 * @param progressMonitor progress monitor 542 * @return the {@link DataSet} resulting of this operation 543 * @throws OsmTransferException if an error occurs while communicating with the API server 544 */ 545 protected DataSet singleGetId(OsmPrimitiveType type, long id, ProgressMonitor progressMonitor) throws OsmTransferException { 546 String request = buildRequestString(type, Collections.singleton(id)); 547 DataSet result = null; 548 try (InputStream in = getInputStream(request, NullProgressMonitor.INSTANCE)) { 549 if (in == null) return null; 550 progressMonitor.subTask(tr("Downloading OSM data...")); 551 try { 552 result = OsmReader.parseDataSet(in, progressMonitor.createSubTaskMonitor(1, false)); 553 } catch (IllegalDataException e) { 554 throw new OsmTransferException(e); 555 } 556 } catch (IOException ex) { 557 Main.warn(ex); 558 } 559 return result; 560 } 561 562 /** 563 * invokes a sequence of Multi Gets for individual ids in a set of ids and a given {@link OsmPrimitiveType}. 564 * The retrieved primitives are merged to {@link #outputDataSet}. 565 * 566 * This method is used if one of the ids in pkg doesn't exist (the server replies with return code 404). 567 * If the set is fetched with this method it is possible to find out which of the ids doesn't exist. 568 * Unfortunately, the server does not provide an error header or an error body for a 404 reply. 569 * 570 * @param type The primitive type. Must be one of {@link OsmPrimitiveType#NODE NODE}, {@link OsmPrimitiveType#WAY WAY}, 571 * {@link OsmPrimitiveType#RELATION RELATION} 572 * @param pkg the set of ids 573 * @param progressMonitor progress monitor 574 * @return the {@link FetchResult} of this operation 575 * @throws OsmTransferException if an error occurs while communicating with the API server 576 */ 577 protected FetchResult singleGetIdPackage(OsmPrimitiveType type, Set<Long> pkg, ProgressMonitor progressMonitor) 578 throws OsmTransferException { 579 FetchResult result = new FetchResult(new DataSet(), new HashSet<PrimitiveId>()); 580 String baseUrl = OsmApi.getOsmApi().getBaseUrl(); 581 for (long id : pkg) { 582 try { 583 String msg; 584 switch (type) { 585 // CHECKSTYLE.OFF: SingleSpaceSeparator 586 case NODE: msg = tr("Fetching node with id {0} from ''{1}''", id, baseUrl); break; 587 case WAY: msg = tr("Fetching way with id {0} from ''{1}''", id, baseUrl); break; 588 case RELATION: msg = tr("Fetching relation with id {0} from ''{1}''", id, baseUrl); break; 589 // CHECKSTYLE.ON: SingleSpaceSeparator 590 default: throw new AssertionError(); 591 } 592 progressMonitor.setCustomText(msg); 593 result.dataSet.mergeFrom(singleGetId(type, id, progressMonitor)); 594 } catch (OsmApiException e) { 595 if (e.getResponseCode() == HttpURLConnection.HTTP_NOT_FOUND) { 596 Main.info(tr("Server replied with response code 404 for id {0}. Skipping.", Long.toString(id))); 597 result.missingPrimitives.add(new SimplePrimitiveId(id, type)); 598 } else { 599 throw e; 600 } 601 } 602 } 603 return result; 604 } 605 } 606}