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comparison dwtx/jface/text/link/LinkedModeModel.d @ 129:eb30df5ca28b

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Added JFace Text sources
author Frank Benoit <benoit@tionex.de>
date Sat, 23 Aug 2008 19:10:48 +0200
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1 /*******************************************************************************
2 * Copyright (c) 2000, 2008 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/
13 module dwtx.jface.text.link.LinkedModeModel;
14
15 import dwt.dwthelper.utils;
16
17 import java.util.ArrayList;
18 import java.util.Arrays;
19 import java.util.HashSet;
20 import java.util.Iterator;
21 import java.util.List;
22 import java.util.Map;
23 import java.util.Set;
24
25 import dwtx.core.runtime.Assert;
26 import dwtx.jface.text.BadLocationException;
27 import dwtx.jface.text.BadPositionCategoryException;
28 import dwtx.jface.text.DocumentEvent;
29 import dwtx.jface.text.IDocument;
30 import dwtx.jface.text.IDocumentExtension;
31 import dwtx.jface.text.IDocumentListener;
32 import dwtx.jface.text.IPositionUpdater;
33 import dwtx.jface.text.Position;
34 import dwtx.jface.text.IDocumentExtension.IReplace;
35 import dwtx.text.edits.MalformedTreeException;
36 import dwtx.text.edits.TextEdit;
37
38
39 /**
40 * The model for linked mode, umbrellas several
41 * {@link LinkedPositionGroup}s. Once installed, the model
42 * propagates any changes to a position to all its siblings in the same position
43 * group.
44 * <p>
45 * Setting up a model consists of first adding
46 * <code>LinkedPositionGroup</code>s to it, and then installing the
47 * model by either calling {@link #forceInstall()} or
48 * {@link #tryInstall()}. After installing the model, it becomes
49 * <em>sealed</em> and no more groups may be added.
50 * </p>
51 * <p>
52 * If a document change occurs that would modify more than one position
53 * group or that would invalidate the disjointness requirement of the positions,
54 * the model is torn down and all positions are deleted. The same happens
55 * upon calling {@link #exit(int)}.
56 * </p>
57 * <h4>Nesting</h4>
58 * <p>
59 * A <code>LinkedModeModel</code> may be nested into another model. This
60 * happens when installing a model the positions of which all fit into a
61 * single position in a parent model that has previously been installed on
62 * the same document(s).
63 * </p>
64 * <p>
65 * Clients may instantiate instances of this class.
66 * </p>
67 *
68 * @since 3.0
69 * @noextend This class is not intended to be subclassed by clients.
70 */
71 public class LinkedModeModel {
72
73 /**
74 * Checks whether there is already a model installed on <code>document</code>.
75 *
76 * @param document the <code>IDocument</code> of interest
77 * @return <code>true</code> if there is an existing model, <code>false</code>
78 * otherwise
79 */
80 public static bool hasInstalledModel(IDocument document) {
81 // if there is a manager, there also is a model
82 return LinkedModeManager.hasManager(document);
83 }
84
85 /**
86 * Checks whether there is already a linked mode model installed on any of
87 * the <code>documents</code>.
88 *
89 * @param documents the <code>IDocument</code>s of interest
90 * @return <code>true</code> if there is an existing model, <code>false</code>
91 * otherwise
92 */
93 public static bool hasInstalledModel(IDocument[] documents) {
94 // if there is a manager, there also is a model
95 return LinkedModeManager.hasManager(documents);
96 }
97
98 /**
99 * Cancels any linked mode model on the specified document. If there is no
100 * model, nothing happens.
101 *
102 * @param document the document whose <code>LinkedModeModel</code> should
103 * be canceled
104 */
105 public static void closeAllModels(IDocument document) {
106 LinkedModeManager.cancelManager(document);
107 }
108
109 /**
110 * Returns the model currently active on <code>document</code> at
111 * <code>offset</code>, or <code>null</code> if there is none.
112 *
113 * @param document the document for which the caller asks for a
114 * model
115 * @param offset the offset into <code>document</code>, as there may be
116 * several models on a document
117 * @return the model currently active on <code>document</code>, or
118 * <code>null</code>
119 */
120 public static LinkedModeModel getModel(IDocument document, int offset) {
121 if (!hasInstalledModel(document))
122 return null;
123
124 LinkedModeManager mgr= LinkedModeManager.getLinkedManager(new IDocument[] {document}, false);
125 if (mgr !is null)
126 return mgr.getTopEnvironment();
127 return null;
128 }
129
130 /**
131 * Encapsulates the edition triggered by a change to a linking position. Can
132 * be applied to a document as a whole.
133 */
134 private class Replace : IReplace {
135
136 /** The edition to apply on a document. */
137 private TextEdit fEdit;
138
139 /**
140 * Creates a new instance.
141 *
142 * @param edit the edition to apply to a document.
143 */
144 public Replace(TextEdit edit) {
145 fEdit= edit;
146 }
147
148 /*
149 * @see dwtx.jface.text.IDocumentExtension.IReplace#perform(dwtx.jface.text.IDocument, dwtx.jface.text.IDocumentListener)
150 */
151 public void perform(IDocument document, IDocumentListener owner) throws RuntimeException, MalformedTreeException {
152 document.removeDocumentListener(owner);
153 fIsChanging= true;
154 try {
155 fEdit.apply(document, TextEdit.UPDATE_REGIONS | TextEdit.CREATE_UNDO);
156 } catch (BadLocationException e) {
157 /* XXX: perform should really throw a BadLocationException
158 * see https://bugs.eclipse.org/bugs/show_bug.cgi?id=52950
159 */
160 throw new RuntimeException(e);
161 } finally {
162 document.addDocumentListener(owner);
163 fIsChanging= false;
164 }
165 }
166
167 }
168
169 /**
170 * The document listener triggering the linked updating of positions
171 * managed by this model.
172 */
173 private class DocumentListener : IDocumentListener {
174
175 private bool fExit= false;
176
177 /**
178 * Checks whether <code>event</code> occurs within any of the positions
179 * managed by this model. If not, the linked mode is left.
180 *
181 * @param event {@inheritDoc}
182 */
183 public void documentAboutToBeChanged(DocumentEvent event) {
184 // don't react on changes executed by the parent model
185 if (fParentEnvironment !is null && fParentEnvironment.isChanging())
186 return;
187
188 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
189 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
190 if (!group.isLegalEvent(event)) {
191 fExit= true;
192 return;
193 }
194 }
195 }
196
197 /**
198 * Propagates a change to a linked position to all its sibling positions.
199 *
200 * @param event {@inheritDoc}
201 */
202 public void documentChanged(DocumentEvent event) {
203 if (fExit) {
204 LinkedModeModel.this.exit(ILinkedModeListener.EXTERNAL_MODIFICATION);
205 return;
206 }
207 fExit= false;
208
209 // don't react on changes executed by the parent model
210 if (fParentEnvironment !is null && fParentEnvironment.isChanging())
211 return;
212
213 // collect all results
214 Map result= null;
215 for (Iterator it= fGroups.iterator(); it.hasNext();) {
216 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
217
218 Map map= group.handleEvent(event);
219 if (result !is null && map !is null) {
220 // exit if more than one position was changed
221 LinkedModeModel.this.exit(ILinkedModeListener.EXTERNAL_MODIFICATION);
222 return;
223 }
224 if (map !is null)
225 result= map;
226 }
227
228 if (result !is null) {
229 // edit all documents
230 for (Iterator it2= result.keySet().iterator(); it2.hasNext(); ) {
231 IDocument doc= (IDocument) it2.next();
232 TextEdit edit= (TextEdit) result.get(doc);
233 Replace replace= new Replace(edit);
234
235 // apply the edition, either as post notification replace
236 // on the calling document or directly on any other
237 // document
238 if (doc is event.getDocument()) {
239 if (doc instanceof IDocumentExtension) {
240 ((IDocumentExtension) doc).registerPostNotificationReplace(this, replace);
241 } else {
242 // ignore - there is no way we can log from JFace text...
243 }
244 } else {
245 replace.perform(doc, this);
246 }
247 }
248 }
249 }
250
251 }
252
253 /** The set of linked position groups. */
254 private final List fGroups= new ArrayList();
255 /** The set of documents spanned by this group. */
256 private final Set fDocuments= new HashSet();
257 /** The position updater for linked positions. */
258 private final IPositionUpdater fUpdater= new InclusivePositionUpdater(getCategory());
259 /** The document listener on the documents affected by this model. */
260 private final DocumentListener fDocumentListener= new DocumentListener();
261 /** The parent model for a hierarchical set up, or <code>null</code>. */
262 private LinkedModeModel fParentEnvironment;
263 /**
264 * The position in <code>fParentEnvironment</code> that includes all
265 * positions in this object, or <code>null</code> if there is no parent
266 * model.
267 */
268 private LinkedPosition fParentPosition= null;
269 /**
270 * A model is sealed once it has children - no more positions can be
271 * added.
272 */
273 private bool fIsSealed= false;
274 /** <code>true</code> when this model is changing documents. */
275 private bool fIsChanging= false;
276 /** The linked listeners. */
277 private final List fListeners= new ArrayList();
278 /** Flag telling whether we have exited: */
279 private bool fIsActive= true;
280 /**
281 * The sequence of document positions as we are going to iterate through
282 * them.
283 */
284 private List fPositionSequence= new ArrayList();
285
286 /**
287 * Whether we are in the process of editing documents (set by <code>Replace</code>,
288 * read by <code>DocumentListener</code>.
289 *
290 * @return <code>true</code> if we are in the process of editing a
291 * document, <code>false</code> otherwise
292 */
293 private bool isChanging() {
294 return fIsChanging || fParentEnvironment !is null && fParentEnvironment.isChanging();
295 }
296
297 /**
298 * Throws a <code>BadLocationException</code> if <code>group</code>
299 * conflicts with this model's groups.
300 *
301 * @param group the group being checked
302 * @throws BadLocationException if <code>group</code> conflicts with this
303 * model's groups
304 */
305 private void enforceDisjoint(LinkedPositionGroup group) throws BadLocationException {
306 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
307 LinkedPositionGroup g= (LinkedPositionGroup) it.next();
308 g.enforceDisjoint(group);
309 }
310 }
311
312 /**
313 * Causes this model to exit. Called either if an illegal document change
314 * is detected, or by the UI.
315 *
316 * @param flags the exit flags as defined in {@link ILinkedModeListener}
317 */
318 public void exit(int flags) {
319 if (!fIsActive)
320 return;
321
322 fIsActive= false;
323
324 for (Iterator it= fDocuments.iterator(); it.hasNext(); ) {
325 IDocument doc= (IDocument) it.next();
326 try {
327 doc.removePositionCategory(getCategory());
328 } catch (BadPositionCategoryException e) {
329 // won't happen
330 Assert.isTrue(false);
331 }
332 doc.removePositionUpdater(fUpdater);
333 doc.removeDocumentListener(fDocumentListener);
334 }
335
336 fDocuments.clear();
337 fGroups.clear();
338
339 List listeners= new ArrayList(fListeners);
340 fListeners.clear();
341 for (Iterator it= listeners.iterator(); it.hasNext(); ) {
342 ILinkedModeListener listener= (ILinkedModeListener) it.next();
343 listener.left(this, flags);
344 }
345
346
347 if (fParentEnvironment !is null)
348 fParentEnvironment.resume(flags);
349 }
350
351 /**
352 * Causes this model to stop forwarding updates. The positions are not
353 * unregistered however, which will only happen when <code>exit</code>
354 * is called, or after the next document change.
355 *
356 * @param flags the exit flags as defined in {@link ILinkedModeListener}
357 * @since 3.1
358 */
359 public void stopForwarding(int flags) {
360 fDocumentListener.fExit= true;
361 }
362
363 /**
364 * Puts <code>document</code> into the set of managed documents. This
365 * involves registering the document listener and adding our position
366 * category.
367 *
368 * @param document the new document
369 */
370 private void manageDocument(IDocument document) {
371 if (!fDocuments.contains(document)) {
372 fDocuments.add(document);
373 document.addPositionCategory(getCategory());
374 document.addPositionUpdater(fUpdater);
375 document.addDocumentListener(fDocumentListener);
376 }
377
378 }
379
380 /**
381 * Returns the position category used by this model.
382 *
383 * @return the position category used by this model
384 */
385 private String getCategory() {
386 return toString();
387 }
388
389 /**
390 * Adds a position group to this <code>LinkedModeModel</code>. This
391 * method may not be called if the model has been installed. Also, if
392 * a UI has been set up for this model, it may not pick up groups
393 * added afterwards.
394 * <p>
395 * If the positions in <code>group</code> conflict with any other group in
396 * this model, a <code>BadLocationException</code> is thrown. Also,
397 * if this model is nested inside another one, all positions in all
398 * groups of the child model have to reside within a single position in the
399 * parent model, otherwise a <code>BadLocationException</code> is thrown.
400 * </p>
401 * <p>
402 * If <code>group</code> already exists, nothing happens.
403 * </p>
404 *
405 * @param group the group to be added to this model
406 * @throws BadLocationException if the group conflicts with the other groups
407 * in this model or violates the nesting requirements.
408 * @throws IllegalStateException if the method is called when the
409 * model is already sealed
410 */
411 public void addGroup(LinkedPositionGroup group) throws BadLocationException {
412 if (group is null)
413 throw new IllegalArgumentException("group may not be null"); //$NON-NLS-1$
414 if (fIsSealed)
415 throw new IllegalStateException("model is already installed"); //$NON-NLS-1$
416 if (fGroups.contains(group))
417 // nothing happens
418 return;
419
420 enforceDisjoint(group);
421 group.seal();
422 fGroups.add(group);
423 }
424
425 /**
426 * Creates a new model.
427 * @since 3.1
428 */
429 public LinkedModeModel() {
430 }
431
432 /**
433 * Installs this model, which includes registering as document
434 * listener on all involved documents and storing global information about
435 * this model. Any conflicting model already present will be
436 * closed.
437 * <p>
438 * If an exception is thrown, the installation failed and
439 * the model is unusable.
440 * </p>
441 *
442 * @throws BadLocationException if some of the positions of this model
443 * were not valid positions on their respective documents
444 */
445 public void forceInstall() throws BadLocationException {
446 if (!install(true))
447 Assert.isTrue(false);
448 }
449
450 /**
451 * Installs this model, which includes registering as document
452 * listener on all involved documents and storing global information about
453 * this model. If there is another model installed on the
454 * document(s) targeted by the receiver that conflicts with it, installation
455 * may fail.
456 * <p>
457 * The return value states whether installation was
458 * successful; if not, the model is not installed and will not work.
459 * </p>
460 *
461 * @return <code>true</code> if installation was successful,
462 * <code>false</code> otherwise
463 * @throws BadLocationException if some of the positions of this model
464 * were not valid positions on their respective documents
465 */
466 public bool tryInstall() throws BadLocationException {
467 return install(false);
468 }
469
470 /**
471 * Installs this model, which includes registering as document
472 * listener on all involved documents and storing global information about
473 * this model. The return value states whether installation was
474 * successful; if not, the model is not installed and will not work.
475 * The return value can only then become <code>false</code> if
476 * <code>force</code> was set to <code>false</code> as well.
477 *
478 * @param force if <code>true</code>, any other model that cannot
479 * coexist with this one is canceled; if <code>false</code>,
480 * install will fail when conflicts occur and return false
481 * @return <code>true</code> if installation was successful,
482 * <code>false</code> otherwise
483 * @throws BadLocationException if some of the positions of this model
484 * were not valid positions on their respective documents
485 */
486 private bool install(bool force) throws BadLocationException {
487 if (fIsSealed)
488 throw new IllegalStateException("model is already installed"); //$NON-NLS-1$
489 enforceNotEmpty();
490
491 IDocument[] documents= getDocuments();
492 LinkedModeManager manager= LinkedModeManager.getLinkedManager(documents, force);
493 // if we force creation, we require a valid manager
494 Assert.isTrue(!(force && manager is null));
495 if (manager is null)
496 return false;
497
498 if (!manager.nestEnvironment(this, force))
499 if (force)
500 Assert.isTrue(false);
501 else
502 return false;
503
504 // we set up successfully. After this point, exit has to be called to
505 // remove registered listeners...
506 fIsSealed= true;
507 if (fParentEnvironment !is null)
508 fParentEnvironment.suspend();
509
510 // register positions
511 try {
512 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
513 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
514 group.register(this);
515 }
516 return true;
517 } catch (BadLocationException e){
518 // if we fail to add, make sure to release all listeners again
519 exit(ILinkedModeListener.NONE);
520 throw e;
521 }
522 }
523
524 /**
525 * Asserts that there is at least one linked position in this linked mode
526 * model, throws an IllegalStateException otherwise.
527 */
528 private void enforceNotEmpty() {
529 bool hasPosition= false;
530 for (Iterator it= fGroups.iterator(); it.hasNext(); )
531 if (!((LinkedPositionGroup) it.next()).isEmpty()) {
532 hasPosition= true;
533 break;
534 }
535 if (!hasPosition)
536 throw new IllegalStateException("must specify at least one linked position"); //$NON-NLS-1$
537
538 }
539
540 /**
541 * Collects all the documents that contained positions are set upon.
542 * @return the set of documents affected by this model
543 */
544 private IDocument[] getDocuments() {
545 Set docs= new HashSet();
546 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
547 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
548 docs.addAll(Arrays.asList(group.getDocuments()));
549 }
550 return (IDocument[]) docs.toArray(new IDocument[docs.size()]);
551 }
552
553 /**
554 * Returns whether the receiver can be nested into the given <code>parent</code>
555 * model. If yes, the parent model and its position that the receiver
556 * fits in are remembered.
557 *
558 * @param parent the parent model candidate
559 * @return <code>true</code> if the receiver can be nested into <code>parent</code>, <code>false</code> otherwise
560 */
561 bool canNestInto(LinkedModeModel parent) {
562 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
563 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
564 if (!enforceNestability(group, parent)) {
565 fParentPosition= null;
566 return false;
567 }
568 }
569
570 Assert.isNotNull(fParentPosition);
571 fParentEnvironment= parent;
572 return true;
573 }
574
575 /**
576 * Called by nested models when a group is added to them. All
577 * positions in all groups of a nested model have to fit inside a
578 * single position in the parent model.
579 *
580 * @param group the group of the nested model to be adopted.
581 * @param model the model to check against
582 * @return <code>false</code> if it failed to enforce nestability
583 */
584 private bool enforceNestability(LinkedPositionGroup group, LinkedModeModel model) {
585 Assert.isNotNull(model);
586 Assert.isNotNull(group);
587
588 try {
589 for (Iterator it= model.fGroups.iterator(); it.hasNext(); ) {
590 LinkedPositionGroup pg= (LinkedPositionGroup) it.next();
591 LinkedPosition pos;
592 pos= pg.adopt(group);
593 if (pos !is null && fParentPosition !is null && fParentPosition !is pos)
594 return false; // group does not fit into one parent position, which is illegal
595 else if (fParentPosition is null && pos !is null)
596 fParentPosition= pos;
597 }
598 } catch (BadLocationException e) {
599 return false;
600 }
601
602 // group must fit into exactly one of the parent's positions
603 return fParentPosition !is null;
604 }
605
606 /**
607 * Returns whether this model is nested.
608 *
609 * <p>
610 * This method is part of the private protocol between
611 * <code>LinkedModeUI</code> and <code>LinkedModeModel</code>.
612 * </p>
613 *
614 * @return <code>true</code> if this model is nested,
615 * <code>false</code> otherwise
616 */
617 public bool isNested() {
618 return fParentEnvironment !is null;
619 }
620
621 /**
622 * Returns the positions in this model that have a tab stop, in the
623 * order they were added.
624 *
625 * <p>
626 * This method is part of the private protocol between
627 * <code>LinkedModeUI</code> and <code>LinkedModeModel</code>.
628 * </p>
629 *
630 * @return the positions in this model that have a tab stop, in the
631 * order they were added
632 */
633 public List getTabStopSequence() {
634 return fPositionSequence;
635 }
636
637 /**
638 * Adds <code>listener</code> to the set of listeners that are informed
639 * upon state changes.
640 *
641 * @param listener the new listener
642 */
643 public void addLinkingListener(ILinkedModeListener listener) {
644 Assert.isNotNull(listener);
645 if (!fListeners.contains(listener))
646 fListeners.add(listener);
647 }
648
649 /**
650 * Removes <code>listener</code> from the set of listeners that are
651 * informed upon state changes.
652 *
653 * @param listener the new listener
654 */
655 public void removeLinkingListener(ILinkedModeListener listener) {
656 fListeners.remove(listener);
657 }
658
659 /**
660 * Finds the position in this model that is closest after
661 * <code>toFind</code>. <code>toFind</code> needs not be a position in
662 * this model and serves merely as an offset.
663 *
664 * <p>
665 * This method part of the private protocol between
666 * <code>LinkedModeUI</code> and <code>LinkedModeModel</code>.
667 * </p>
668 *
669 * @param toFind the position to search from
670 * @return the closest position in the same document as <code>toFind</code>
671 * after the offset of <code>toFind</code>, or <code>null</code>
672 */
673 public LinkedPosition findPosition(LinkedPosition toFind) {
674 LinkedPosition position= null;
675 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
676 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
677 position= group.getPosition(toFind);
678 if (position !is null)
679 break;
680 }
681 return position;
682 }
683
684 /**
685 * Registers a <code>LinkedPosition</code> with this model. Called
686 * by <code>PositionGroup</code>.
687 *
688 * @param position the position to register
689 * @throws BadLocationException if the position cannot be added to its
690 * document
691 */
692 void register(LinkedPosition position) throws BadLocationException {
693 Assert.isNotNull(position);
694
695 IDocument document= position.getDocument();
696 manageDocument(document);
697 try {
698 document.addPosition(getCategory(), position);
699 } catch (BadPositionCategoryException e) {
700 // won't happen as the category has been added by manageDocument()
701 Assert.isTrue(false);
702 }
703 int seqNr= position.getSequenceNumber();
704 if (seqNr !is LinkedPositionGroup.NO_STOP) {
705 fPositionSequence.add(position);
706 }
707 }
708
709 /**
710 * Suspends this model.
711 */
712 private void suspend() {
713 List l= new ArrayList(fListeners);
714 for (Iterator it= l.iterator(); it.hasNext(); ) {
715 ILinkedModeListener listener= (ILinkedModeListener) it.next();
716 listener.suspend(this);
717 }
718 }
719
720 /**
721 * Resumes this model. <code>flags</code> can be <code>NONE</code>
722 * or <code>SELECT</code>.
723 *
724 * @param flags <code>NONE</code> or <code>SELECT</code>
725 */
726 private void resume(int flags) {
727 List l= new ArrayList(fListeners);
728 for (Iterator it= l.iterator(); it.hasNext(); ) {
729 ILinkedModeListener listener= (ILinkedModeListener) it.next();
730 listener.resume(this, flags);
731 }
732 }
733
734 /**
735 * Returns whether an offset is contained by any position in this
736 * model.
737 *
738 * @param offset the offset to check
739 * @return <code>true</code> if <code>offset</code> is included by any
740 * position (see {@link LinkedPosition#includes(int)}) in this
741 * model, <code>false</code> otherwise
742 */
743 public bool anyPositionContains(int offset) {
744 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
745 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
746 if (group.contains(offset))
747 // take the first hit - exclusion is guaranteed by enforcing
748 // disjointness when adding positions
749 return true;
750 }
751 return false;
752 }
753
754 /**
755 * Returns the linked position group that contains <code>position</code>,
756 * or <code>null</code> if <code>position</code> is not contained in any
757 * group within this model. Group containment is tested by calling
758 * <code>group.contains(position)</code> for every <code>group</code> in
759 * this model.
760 *
761 * <p>
762 * This method part of the private protocol between
763 * <code>LinkedModeUI</code> and <code>LinkedModeModel</code>.
764 * </p>
765 *
766 * @param position the position the group of which is requested
767 * @return the first group in this model for which
768 * <code>group.contains(position)</code> returns <code>true</code>,
769 * or <code>null</code> if no group contains <code>position</code>
770 */
771 public LinkedPositionGroup getGroupForPosition(Position position) {
772 for (Iterator it= fGroups.iterator(); it.hasNext(); ) {
773 LinkedPositionGroup group= (LinkedPositionGroup) it.next();
774 if (group.contains(position))
775 return group;
776 }
777 return null;
778 }
779 }