1 /*
2 * Copyright (C) 2010, Google Inc. and others
3 *
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Distribution License v. 1.0 which is available at
6 * https://www.eclipse.org/org/documents/edl-v10.php.
7 *
8 * SPDX-License-Identifier: BSD-3-Clause
9 */
10
11 package org.eclipse.jgit.lib;
12
13 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_CORE_SECTION;
14 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_BARE;
15 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_WORKTREE;
16 import static org.eclipse.jgit.lib.Constants.DOT_GIT;
17 import static org.eclipse.jgit.lib.Constants.GIT_ALTERNATE_OBJECT_DIRECTORIES_KEY;
18 import static org.eclipse.jgit.lib.Constants.GIT_CEILING_DIRECTORIES_KEY;
19 import static org.eclipse.jgit.lib.Constants.GIT_DIR_KEY;
20 import static org.eclipse.jgit.lib.Constants.GIT_INDEX_FILE_KEY;
21 import static org.eclipse.jgit.lib.Constants.GIT_OBJECT_DIRECTORY_KEY;
22 import static org.eclipse.jgit.lib.Constants.GIT_WORK_TREE_KEY;
23
24 import java.io.File;
25 import java.io.IOException;
26 import java.text.MessageFormat;
27 import java.util.Collection;
28 import java.util.LinkedList;
29 import java.util.List;
30
31 import org.eclipse.jgit.annotations.NonNull;
32 import org.eclipse.jgit.api.errors.InvalidRefNameException;
33 import org.eclipse.jgit.errors.ConfigInvalidException;
34 import org.eclipse.jgit.errors.RepositoryNotFoundException;
35 import org.eclipse.jgit.internal.JGitText;
36 import org.eclipse.jgit.internal.storage.file.FileRepository;
37 import org.eclipse.jgit.lib.RepositoryCache.FileKey;
38 import org.eclipse.jgit.storage.file.FileBasedConfig;
39 import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
40 import org.eclipse.jgit.util.FS;
41 import org.eclipse.jgit.util.IO;
42 import org.eclipse.jgit.util.RawParseUtils;
43 import org.eclipse.jgit.util.StringUtils;
44 import org.eclipse.jgit.util.SystemReader;
45
46 /**
47 * Base builder to customize repository construction.
48 * <p>
49 * Repository implementations may subclass this builder in order to add custom
50 * repository detection methods.
51 *
52 * @param <B>
53 * type of the repository builder.
54 * @param <R>
55 * type of the repository that is constructed.
56 * @see RepositoryBuilder
57 * @see FileRepositoryBuilder
58 */
59 public class BaseRepositoryBuilder<B extends BaseRepositoryBuilder, R extends Repository> {
60 private static boolean isSymRef(byte[] ref) {
61 if (ref.length < 9)
62 return false;
63 return /**/ref[0] == 'g' //
64 && ref[1] == 'i' //
65 && ref[2] == 't' //
66 && ref[3] == 'd' //
67 && ref[4] == 'i' //
68 && ref[5] == 'r' //
69 && ref[6] == ':' //
70 && ref[7] == ' ';
71 }
72
73 private static File getSymRef(File workTree, File dotGit, FS fs)
74 throws IOException {
75 byte[] content = IO.readFully(dotGit);
76 if (!isSymRef(content)) {
77 throw new IOException(MessageFormat.format(
78 JGitText.get().invalidGitdirRef, dotGit.getAbsolutePath()));
79 }
80
81 int pathStart = 8;
82 int lineEnd = RawParseUtils.nextLF(content, pathStart);
83 while (content[lineEnd - 1] == '\n' ||
84 (content[lineEnd - 1] == '\r'
85 && SystemReader.getInstance().isWindows())) {
86 lineEnd--;
87 }
88 if (lineEnd == pathStart) {
89 throw new IOException(MessageFormat.format(
90 JGitText.get().invalidGitdirRef, dotGit.getAbsolutePath()));
91 }
92
93 String gitdirPath = RawParseUtils.decode(content, pathStart, lineEnd);
94 File gitdirFile = fs.resolve(workTree, gitdirPath);
95 if (gitdirFile.isAbsolute()) {
96 return gitdirFile;
97 }
98 return new File(workTree, gitdirPath).getCanonicalFile();
99 }
100
101 private FS fs;
102
103 private File gitDir;
104
105 private File objectDirectory;
106
107 private List<File> alternateObjectDirectories;
108
109 private File indexFile;
110
111 private File workTree;
112
113 private String initialBranch = Constants.MASTER;
114
115 /** Directories limiting the search for a Git repository. */
116 private List<File> ceilingDirectories;
117
118 /** True only if the caller wants to force bare behavior. */
119 private boolean bare;
120
121 /** True if the caller requires the repository to exist. */
122 private boolean mustExist;
123
124 /** Configuration file of target repository, lazily loaded if required. */
125 private Config config;
126
127 /**
128 * Set the file system abstraction needed by this repository.
129 *
130 * @param fs
131 * the abstraction.
132 * @return {@code this} (for chaining calls).
133 */
134 public B setFS(FS fs) {
135 this.fs = fs;
136 return self();
137 }
138
139 /**
140 * Get the file system abstraction, or null if not set.
141 *
142 * @return the file system abstraction, or null if not set.
143 */
144 public FS getFS() {
145 return fs;
146 }
147
148 /**
149 * Set the Git directory storing the repository metadata.
150 * <p>
151 * The meta directory stores the objects, references, and meta files like
152 * {@code MERGE_HEAD}, or the index file. If {@code null} the path is
153 * assumed to be {@code workTree/.git}.
154 *
155 * @param gitDir
156 * {@code GIT_DIR}, the repository meta directory.
157 * @return {@code this} (for chaining calls).
158 */
159 public B setGitDir(File gitDir) {
160 this.gitDir = gitDir;
161 this.config = null;
162 return self();
163 }
164
165 /**
166 * Get the meta data directory; null if not set.
167 *
168 * @return the meta data directory; null if not set.
169 */
170 public File getGitDir() {
171 return gitDir;
172 }
173
174 /**
175 * Set the directory storing the repository's objects.
176 *
177 * @param objectDirectory
178 * {@code GIT_OBJECT_DIRECTORY}, the directory where the
179 * repository's object files are stored.
180 * @return {@code this} (for chaining calls).
181 */
182 public B setObjectDirectory(File objectDirectory) {
183 this.objectDirectory = objectDirectory;
184 return self();
185 }
186
187 /**
188 * Get the object directory; null if not set.
189 *
190 * @return the object directory; null if not set.
191 */
192 public File getObjectDirectory() {
193 return objectDirectory;
194 }
195
196 /**
197 * Add an alternate object directory to the search list.
198 * <p>
199 * This setting handles one alternate directory at a time, and is provided
200 * to support {@code GIT_ALTERNATE_OBJECT_DIRECTORIES}.
201 *
202 * @param other
203 * another objects directory to search after the standard one.
204 * @return {@code this} (for chaining calls).
205 */
206 public B addAlternateObjectDirectory(File other) {
207 if (other != null) {
208 if (alternateObjectDirectories == null)
209 alternateObjectDirectories = new LinkedList<>();
210 alternateObjectDirectories.add(other);
211 }
212 return self();
213 }
214
215 /**
216 * Add alternate object directories to the search list.
217 * <p>
218 * This setting handles several alternate directories at once, and is
219 * provided to support {@code GIT_ALTERNATE_OBJECT_DIRECTORIES}.
220 *
221 * @param inList
222 * other object directories to search after the standard one. The
223 * collection's contents is copied to an internal list.
224 * @return {@code this} (for chaining calls).
225 */
226 public B addAlternateObjectDirectories(Collection<File> inList) {
227 if (inList != null) {
228 for (File path : inList)
229 addAlternateObjectDirectory(path);
230 }
231 return self();
232 }
233
234 /**
235 * Add alternate object directories to the search list.
236 * <p>
237 * This setting handles several alternate directories at once, and is
238 * provided to support {@code GIT_ALTERNATE_OBJECT_DIRECTORIES}.
239 *
240 * @param inList
241 * other object directories to search after the standard one. The
242 * array's contents is copied to an internal list.
243 * @return {@code this} (for chaining calls).
244 */
245 public B addAlternateObjectDirectories(File[] inList) {
246 if (inList != null) {
247 for (File path : inList)
248 addAlternateObjectDirectory(path);
249 }
250 return self();
251 }
252
253 /**
254 * Get ordered array of alternate directories; null if non were set.
255 *
256 * @return ordered array of alternate directories; null if non were set.
257 */
258 public File[] getAlternateObjectDirectories() {
259 final List<File> alts = alternateObjectDirectories;
260 if (alts == null)
261 return null;
262 return alts.toArray(new File[0]);
263 }
264
265 /**
266 * Force the repository to be treated as bare (have no working directory).
267 * <p>
268 * If bare the working directory aspects of the repository won't be
269 * configured, and will not be accessible.
270 *
271 * @return {@code this} (for chaining calls).
272 */
273 public B setBare() {
274 setIndexFile(null);
275 setWorkTree(null);
276 bare = true;
277 return self();
278 }
279
280 /**
281 * Whether this repository was forced bare by {@link #setBare()}.
282 *
283 * @return true if this repository was forced bare by {@link #setBare()}.
284 */
285 public boolean isBare() {
286 return bare;
287 }
288
289 /**
290 * Require the repository to exist before it can be opened.
291 *
292 * @param mustExist
293 * true if it must exist; false if it can be missing and created
294 * after being built.
295 * @return {@code this} (for chaining calls).
296 */
297 public B setMustExist(boolean mustExist) {
298 this.mustExist = mustExist;
299 return self();
300 }
301
302 /**
303 * Whether the repository must exist before being opened.
304 *
305 * @return true if the repository must exist before being opened.
306 */
307 public boolean isMustExist() {
308 return mustExist;
309 }
310
311 /**
312 * Set the top level directory of the working files.
313 *
314 * @param workTree
315 * {@code GIT_WORK_TREE}, the working directory of the checkout.
316 * @return {@code this} (for chaining calls).
317 */
318 public B setWorkTree(File workTree) {
319 this.workTree = workTree;
320 return self();
321 }
322
323 /**
324 * Get the work tree directory, or null if not set.
325 *
326 * @return the work tree directory, or null if not set.
327 */
328 public File getWorkTree() {
329 return workTree;
330 }
331
332 /**
333 * Set the local index file that is caching checked out file status.
334 * <p>
335 * The location of the index file tracking the status information for each
336 * checked out file in {@code workTree}. This may be null to assume the
337 * default {@code gitDiir/index}.
338 *
339 * @param indexFile
340 * {@code GIT_INDEX_FILE}, the index file location.
341 * @return {@code this} (for chaining calls).
342 */
343 public B setIndexFile(File indexFile) {
344 this.indexFile = indexFile;
345 return self();
346 }
347
348 /**
349 * Get the index file location, or null if not set.
350 *
351 * @return the index file location, or null if not set.
352 */
353 public File getIndexFile() {
354 return indexFile;
355 }
356
357 /**
358 * Set the initial branch of the new repository. If not specified
359 * ({@code null} or empty), fall back to the default name (currently
360 * master).
361 *
362 * @param branch
363 * initial branch name of the new repository. If {@code null} or
364 * empty the configured default branch will be used.
365 * @return {@code this}
366 * @throws InvalidRefNameException
367 * if the branch name is not valid
368 *
369 * @since 5.11
370 */
371 public B setInitialBranch(String branch) throws InvalidRefNameException {
372 if (StringUtils.isEmptyOrNull(branch)) {
373 this.initialBranch = Constants.MASTER;
374 } else {
375 if (!Repository.isValidRefName(Constants.R_HEADS + branch)) {
376 throw new InvalidRefNameException(MessageFormat
377 .format(JGitText.get().branchNameInvalid, branch));
378 }
379 this.initialBranch = branch;
380 }
381 return self();
382 }
383
384 /**
385 * Get the initial branch of the new repository.
386 *
387 * @return the initial branch of the new repository.
388 * @since 5.11
389 */
390 public @NonNull String getInitialBranch() {
391 return initialBranch;
392 }
393
394 /**
395 * Read standard Git environment variables and configure from those.
396 * <p>
397 * This method tries to read the standard Git environment variables, such as
398 * {@code GIT_DIR} and {@code GIT_WORK_TREE} to configure this builder
399 * instance. If an environment variable is set, it overrides the value
400 * already set in this builder.
401 *
402 * @return {@code this} (for chaining calls).
403 */
404 public B readEnvironment() {
405 return readEnvironment(SystemReader.getInstance());
406 }
407
408 /**
409 * Read standard Git environment variables and configure from those.
410 * <p>
411 * This method tries to read the standard Git environment variables, such as
412 * {@code GIT_DIR} and {@code GIT_WORK_TREE} to configure this builder
413 * instance. If a property is already set in the builder, the environment
414 * variable is not used.
415 *
416 * @param sr
417 * the SystemReader abstraction to access the environment.
418 * @return {@code this} (for chaining calls).
419 */
420 public B readEnvironment(SystemReader sr) {
421 if (getGitDir() == null) {
422 String val = sr.getenv(GIT_DIR_KEY);
423 if (val != null)
424 setGitDir(new File(val));
425 }
426
427 if (getObjectDirectory() == null) {
428 String val = sr.getenv(GIT_OBJECT_DIRECTORY_KEY);
429 if (val != null)
430 setObjectDirectory(new File(val));
431 }
432
433 if (getAlternateObjectDirectories() == null) {
434 String val = sr.getenv(GIT_ALTERNATE_OBJECT_DIRECTORIES_KEY);
435 if (val != null) {
436 for (String path : val.split(File.pathSeparator))
437 addAlternateObjectDirectory(new File(path));
438 }
439 }
440
441 if (getWorkTree() == null) {
442 String val = sr.getenv(GIT_WORK_TREE_KEY);
443 if (val != null)
444 setWorkTree(new File(val));
445 }
446
447 if (getIndexFile() == null) {
448 String val = sr.getenv(GIT_INDEX_FILE_KEY);
449 if (val != null)
450 setIndexFile(new File(val));
451 }
452
453 if (ceilingDirectories == null) {
454 String val = sr.getenv(GIT_CEILING_DIRECTORIES_KEY);
455 if (val != null) {
456 for (String path : val.split(File.pathSeparator))
457 addCeilingDirectory(new File(path));
458 }
459 }
460
461 return self();
462 }
463
464 /**
465 * Add a ceiling directory to the search limit list.
466 * <p>
467 * This setting handles one ceiling directory at a time, and is provided to
468 * support {@code GIT_CEILING_DIRECTORIES}.
469 *
470 * @param root
471 * a path to stop searching at; its parent will not be searched.
472 * @return {@code this} (for chaining calls).
473 */
474 public B addCeilingDirectory(File root) {
475 if (root != null) {
476 if (ceilingDirectories == null)
477 ceilingDirectories = new LinkedList<>();
478 ceilingDirectories.add(root);
479 }
480 return self();
481 }
482
483 /**
484 * Add ceiling directories to the search list.
485 * <p>
486 * This setting handles several ceiling directories at once, and is provided
487 * to support {@code GIT_CEILING_DIRECTORIES}.
488 *
489 * @param inList
490 * directory paths to stop searching at. The collection's
491 * contents is copied to an internal list.
492 * @return {@code this} (for chaining calls).
493 */
494 public B addCeilingDirectories(Collection<File> inList) {
495 if (inList != null) {
496 for (File path : inList)
497 addCeilingDirectory(path);
498 }
499 return self();
500 }
501
502 /**
503 * Add ceiling directories to the search list.
504 * <p>
505 * This setting handles several ceiling directories at once, and is provided
506 * to support {@code GIT_CEILING_DIRECTORIES}.
507 *
508 * @param inList
509 * directory paths to stop searching at. The array's contents is
510 * copied to an internal list.
511 * @return {@code this} (for chaining calls).
512 */
513 public B addCeilingDirectories(File[] inList) {
514 if (inList != null) {
515 for (File path : inList)
516 addCeilingDirectory(path);
517 }
518 return self();
519 }
520
521 /**
522 * Configure {@code GIT_DIR} by searching up the file system.
523 * <p>
524 * Starts from the current working directory of the JVM and scans up through
525 * the directory tree until a Git repository is found. Success can be
526 * determined by checking for {@code getGitDir() != null}.
527 * <p>
528 * The search can be limited to specific spaces of the local filesystem by
529 * {@link #addCeilingDirectory(File)}, or inheriting the list through a
530 * prior call to {@link #readEnvironment()}.
531 *
532 * @return {@code this} (for chaining calls).
533 */
534 public B findGitDir() {
535 if (getGitDir() == null)
536 findGitDir(new File("").getAbsoluteFile()); //$NON-NLS-1$
537 return self();
538 }
539
540 /**
541 * Configure {@code GIT_DIR} by searching up the file system.
542 * <p>
543 * Starts from the supplied directory path and scans up through the parent
544 * directory tree until a Git repository is found. Success can be determined
545 * by checking for {@code getGitDir() != null}.
546 * <p>
547 * The search can be limited to specific spaces of the local filesystem by
548 * {@link #addCeilingDirectory(File)}, or inheriting the list through a
549 * prior call to {@link #readEnvironment()}.
550 *
551 * @param current
552 * directory to begin searching in.
553 * @return {@code this} (for chaining calls).
554 */
555 public B findGitDir(File current) {
556 if (getGitDir() == null) {
557 FS tryFS = safeFS();
558 while (current != null) {
559 File dir = new File(current, DOT_GIT);
560 if (FileKey.isGitRepository(dir, tryFS)) {
561 setGitDir(dir);
562 break;
563 } else if (dir.isFile()) {
564 try {
565 setGitDir(getSymRef(current, dir, tryFS));
566 break;
567 } catch (IOException ignored) {
568 // Continue searching if gitdir ref isn't found
569 }
570 } else if (FileKey.isGitRepository(current, tryFS)) {
571 setGitDir(current);
572 break;
573 }
574
575 current = current.getParentFile();
576 if (current != null && ceilingDirectories != null
577 && ceilingDirectories.contains(current))
578 break;
579 }
580 }
581 return self();
582 }
583
584 /**
585 * Guess and populate all parameters not already defined.
586 * <p>
587 * If an option was not set, the setup method will try to default the option
588 * based on other options. If insufficient information is available, an
589 * exception is thrown to the caller.
590 *
591 * @return {@code this}
592 * @throws java.lang.IllegalArgumentException
593 * insufficient parameters were set, or some parameters are
594 * incompatible with one another.
595 * @throws java.io.IOException
596 * the repository could not be accessed to configure the rest of
597 * the builder's parameters.
598 */
599 public B setup() throws IllegalArgumentException, IOException {
600 requireGitDirOrWorkTree();
601 setupGitDir();
602 setupWorkTree();
603 setupInternals();
604 return self();
605 }
606
607 /**
608 * Create a repository matching the configuration in this builder.
609 * <p>
610 * If an option was not set, the build method will try to default the option
611 * based on other options. If insufficient information is available, an
612 * exception is thrown to the caller.
613 *
614 * @return a repository matching this configuration. The caller is
615 * responsible to close the repository instance when it is no longer
616 * needed.
617 * @throws java.lang.IllegalArgumentException
618 * insufficient parameters were set.
619 * @throws java.io.IOException
620 * the repository could not be accessed to configure the rest of
621 * the builder's parameters.
622 */
623 @SuppressWarnings({ "unchecked", "resource" })
624 public R build() throws IOException {
625 R repo = (R) new FileRepository(setup());
626 if (isMustExist() && !repo.getObjectDatabase().exists())
627 throw new RepositoryNotFoundException(getGitDir());
628 return repo;
629 }
630
631 /**
632 * Require either {@code gitDir} or {@code workTree} to be set.
633 */
634 protected void requireGitDirOrWorkTree() {
635 if (getGitDir() == null && getWorkTree() == null)
636 throw new IllegalArgumentException(
637 JGitText.get().eitherGitDirOrWorkTreeRequired);
638 }
639
640 /**
641 * Perform standard gitDir initialization.
642 *
643 * @throws java.io.IOException
644 * the repository could not be accessed
645 */
646 protected void setupGitDir() throws IOException {
647 // No gitDir? Try to assume its under the workTree or a ref to another
648 // location
649 if (getGitDir() == null && getWorkTree() != null) {
650 File dotGit = new File(getWorkTree(), DOT_GIT);
651 if (!dotGit.isFile())
652 setGitDir(dotGit);
653 else
654 setGitDir(getSymRef(getWorkTree(), dotGit, safeFS()));
655 }
656 }
657
658 /**
659 * Perform standard work-tree initialization.
660 * <p>
661 * This is a method typically invoked inside of {@link #setup()}, near the
662 * end after the repository has been identified and its configuration is
663 * available for inspection.
664 *
665 * @throws java.io.IOException
666 * the repository configuration could not be read.
667 */
668 protected void setupWorkTree() throws IOException {
669 if (getFS() == null)
670 setFS(FS.DETECTED);
671
672 // If we aren't bare, we should have a work tree.
673 //
674 if (!isBare() && getWorkTree() == null)
675 setWorkTree(guessWorkTreeOrFail());
676
677 if (!isBare()) {
678 // If after guessing we're still not bare, we must have
679 // a metadata directory to hold the repository. Assume
680 // its at the work tree.
681 //
682 if (getGitDir() == null)
683 setGitDir(getWorkTree().getParentFile());
684 if (getIndexFile() == null)
685 setIndexFile(new File(getGitDir(), "index")); //$NON-NLS-1$
686 }
687 }
688
689 /**
690 * Configure the internal implementation details of the repository.
691 *
692 * @throws java.io.IOException
693 * the repository could not be accessed
694 */
695 protected void setupInternals() throws IOException {
696 if (getObjectDirectory() == null && getGitDir() != null)
697 setObjectDirectory(safeFS().resolve(getGitDir(), Constants.OBJECTS));
698 }
699
700 /**
701 * Get the cached repository configuration, loading if not yet available.
702 *
703 * @return the configuration of the repository.
704 * @throws java.io.IOException
705 * the configuration is not available, or is badly formed.
706 */
707 protected Config getConfig() throws IOException {
708 if (config == null)
709 config = loadConfig();
710 return config;
711 }
712
713 /**
714 * Parse and load the repository specific configuration.
715 * <p>
716 * The default implementation reads {@code gitDir/config}, or returns an
717 * empty configuration if gitDir was not set.
718 *
719 * @return the repository's configuration.
720 * @throws java.io.IOException
721 * the configuration is not available.
722 */
723 protected Config loadConfig() throws IOException {
724 if (getGitDir() != null) {
725 // We only want the repository's configuration file, and not
726 // the user file, as these parameters must be unique to this
727 // repository and not inherited from other files.
728 //
729 File path = safeFS().resolve(getGitDir(), Constants.CONFIG);
730 FileBasedConfig cfg = new FileBasedConfig(path, safeFS());
731 try {
732 cfg.load();
733 } catch (ConfigInvalidException err) {
734 throw new IllegalArgumentException(MessageFormat.format(
735 JGitText.get().repositoryConfigFileInvalid, path
736 .getAbsolutePath(), err.getMessage()));
737 }
738 return cfg;
739 }
740 return new Config();
741 }
742
743 private File guessWorkTreeOrFail() throws IOException {
744 final Config cfg = getConfig();
745
746 // If set, core.worktree wins.
747 //
748 String path = cfg.getString(CONFIG_CORE_SECTION, null,
749 CONFIG_KEY_WORKTREE);
750 if (path != null)
751 return safeFS().resolve(getGitDir(), path).getCanonicalFile();
752
753 // If core.bare is set, honor its value. Assume workTree is
754 // the parent directory of the repository.
755 //
756 if (cfg.getString(CONFIG_CORE_SECTION, null, CONFIG_KEY_BARE) != null) {
757 if (cfg.getBoolean(CONFIG_CORE_SECTION, CONFIG_KEY_BARE, true)) {
758 setBare();
759 return null;
760 }
761 return getGitDir().getParentFile();
762 }
763
764 if (getGitDir().getName().equals(DOT_GIT)) {
765 // No value for the "bare" flag, but gitDir is named ".git",
766 // use the parent of the directory
767 //
768 return getGitDir().getParentFile();
769 }
770
771 // We have to assume we are bare.
772 //
773 setBare();
774 return null;
775 }
776
777 /**
778 * Get the configured FS, or {@link FS#DETECTED}.
779 *
780 * @return the configured FS, or {@link FS#DETECTED}.
781 */
782 protected FS safeFS() {
783 return getFS() != null ? getFS() : FS.DETECTED;
784 }
785
786 /**
787 * Get this object
788 *
789 * @return {@code this}
790 */
791 @SuppressWarnings("unchecked")
792 protected final B self() {
793 return (B) this;
794 }
795 }