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comparison org.eclipse.core.databinding/src/org/eclipse/core/databinding/validation/MultiValidator.d @ 78:0a55d2d5a946

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Added file for databinding
author Frank Benoit <benoit@tionex.de>
date Tue, 14 Apr 2009 11:35:29 +0200
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76:f05e6e8b2f2d 78:0a55d2d5a946
1 /*******************************************************************************
2 * Copyright (c) 2008 Matthew Hall 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 * Matthew Hall - initial API and implementation (bug 218269)
10 * Boris Bokowski - bug 218269
11 ******************************************************************************/
12
13 module org.eclipse.core.databinding.validation.MultiValidator;
14
15 import java.lang.all;
16
17 import java.util.ArrayList;
18 import java.util.Arrays;
19
20 import org.eclipse.core.databinding.ValidationStatusProvider;
21 import org.eclipse.core.databinding.observable.ChangeEvent;
22 import org.eclipse.core.databinding.observable.IChangeListener;
23 import org.eclipse.core.databinding.observable.IObservable;
24 import org.eclipse.core.databinding.observable.ObservableTracker;
25 import org.eclipse.core.databinding.observable.Observables;
26 import org.eclipse.core.databinding.observable.Realm;
27 import org.eclipse.core.databinding.observable.list.IListChangeListener;
28 import org.eclipse.core.databinding.observable.list.IObservableList;
29 import org.eclipse.core.databinding.observable.list.ListChangeEvent;
30 import org.eclipse.core.databinding.observable.list.ListDiffVisitor;
31 import org.eclipse.core.databinding.observable.list.WritableList;
32 import org.eclipse.core.databinding.observable.map.IObservableMap;
33 import org.eclipse.core.databinding.observable.set.IObservableSet;
34 import org.eclipse.core.databinding.observable.value.IObservableValue;
35 import org.eclipse.core.databinding.observable.value.WritableValue;
36 import org.eclipse.core.internal.databinding.observable.ValidatedObservableList;
37 import org.eclipse.core.internal.databinding.observable.ValidatedObservableMap;
38 import org.eclipse.core.internal.databinding.observable.ValidatedObservableSet;
39 import org.eclipse.core.internal.databinding.observable.ValidatedObservableValue;
40 import org.eclipse.core.runtime.Assert;
41 import org.eclipse.core.runtime.IStatus;
42
43 /**
44 * A validator for cross-constraints between observables.
45 *
46 * <p>
47 * Some practical examples of cross-constraints:
48 * <ul>
49 * <li>A start date cannot be later than an end date
50 * <li>A list of percentages should add up to 100%
51 * </ul>
52 * <p>
53 * Example: require two integer fields to contain either both even or both odd
54 * numbers.
55 *
56 * <pre>
57 * DataBindingContext dbc = new DataBindingContext();
58 *
59 * IObservableValue target0 = SWTObservables.observeText(text0, SWT.Modify);
60 * IObservableValue target1 = SWTObservables.observeText(text1, SWT.Modify);
61 *
62 * // Binding in two stages (from target to middle, then from middle to model)
63 * // simplifies the validation logic. Using the middle observables saves
64 * // the trouble of converting the target values cast(Strings) to the model type
65 * // (integers) manually during validation.
66 * final IObservableValue middle0 = new WritableValue(null, Integer.TYPE);
67 * final IObservableValue middle1 = new WritableValue(null, Integer.TYPE);
68 * dbc.bind(target0, middle0, null, null);
69 * dbc.bind(target1, middle1, null, null);
70 *
71 * // Create the multi-validator
72 * MultiValidator validator = new class() MultiValidator {
73 * protected IStatus validate() {
74 * // Calculate the validation status
75 * Integer value0 = cast(Integer) middle0.getValue();
76 * Integer value1 = cast(Integer) middle1.getValue();
77 * if (Math.abs(value0.intValue()) % 2 !is Math.abs(value1.intValue()) % 2)
78 * return ValidationStatus
79 * .error(&quot;Values must be both even or both odd&quot;);
80 * return ValidationStatus.ok();
81 * }
82 * };
83 * dbc.addValidationStatusProvider(validator);
84 *
85 * // Bind the middle observables to the model observables.
86 * IObservableValue model0 = new WritableValue(new Integer(2), Integer.TYPE);
87 * IObservableValue model1 = new WritableValue(new Integer(4), Integer.TYPE);
88 * dbc.bind(middle0, model0, null, null);
89 * dbc.bind(middle1, model1, null, null);
90 * </pre>
91 *
92 * <p>
93 * MultiValidator can also prevent invalid data from being copied to model. This
94 * is done by wrapping each target observable in a validated observable, and
95 * then binding the validated observable to the model.
96 *
97 * <pre>
98 *
99 * ...
100 *
101 * // Validated observables do not change value until the validator passes.
102 * IObservableValue validated0 = validator.observeValidatedValue(middle0);
103 * IObservableValue validated1 = validator.observeValidatedValue(middle1);
104 * IObservableValue model0 = new WritableValue(new Integer(2), Integer.TYPE);
105 * IObservableValue model1 = new WritableValue(new Integer(4), Integer.TYPE);
106 * // Bind to the validated value, not the middle/target
107 * dbc.bind(validated0, model0, null, null);
108 * dbc.bind(validated1, model1, null, null);
109 * </pre>
110 *
111 * Note: No guarantee is made as to the order of updates when multiple validated
112 * observables change value at once (i.e. multiple updates pending when the
113 * status becomes valid). Therefore the model may be in an invalid state after
114 * the first but before the last pending update.
115 *
116 * @since 1.1
117 */
118 public abstract class MultiValidator : ValidationStatusProvider {
119 private Realm realm;
120 private IObservableValue validationStatus;
121 private IObservableValue unmodifiableValidationStatus;
122 private WritableList targets;
123 private IObservableList unmodifiableTargets;
124 private IObservableList models;
125
126 IListChangeListener targetsListener = new class() IListChangeListener {
127 public void handleListChange(ListChangeEvent event) {
128 event.diff.accept(new class() ListDiffVisitor {
129 public void handleAdd(int index, Object element) {
130 (cast(IObservable) element)
131 .addChangeListener(dependencyListener);
132 }
133
134 public void handleRemove(int index, Object element) {
135 (cast(IObservable) element)
136 .removeChangeListener(dependencyListener);
137 }
138 });
139 }
140 };
141
142 private IChangeListener dependencyListener = new class() IChangeListener {
143 public void handleChange(ChangeEvent event) {
144 revalidate();
145 }
146 };
147
148 /**
149 * Constructs a MultiValidator on the default realm.
150 */
151 public this() {
152 this(Realm.getDefault());
153 }
154
155 /**
156 * Constructs a MultiValidator on the given realm.
157 *
158 * @param realm
159 * the realm on which validation takes place.
160 */
161 public this(Realm realm) {
162 Assert.isNotNull(realm, "Realm cannot be null"); //$NON-NLS-1$
163 this.realm = realm;
164
165 validationStatus = new WritableValue(realm, ValidationStatus.ok(),
166 IStatus.classinfo);
167
168 targets = new WritableList(realm, new ArrayList(), IObservable.classinfo);
169 targets.addListChangeListener(targetsListener);
170 unmodifiableTargets = Observables.unmodifiableObservableList(targets);
171
172 models = Observables.emptyObservableList(realm);
173 }
174
175 private void checkObservable(IObservable target) {
176 Assert.isNotNull(target, "Target observable cannot be null"); //$NON-NLS-1$
177 Assert
178 .isTrue(realm.equals(target.getRealm()),
179 "Target observable must be in the same realm as MultiValidator"); //$NON-NLS-1$
180 }
181
182 /**
183 * Returns an {@link IObservableValue} whose value is always the current
184 * validation status of this MultiValidator. The returned observable is in
185 * the same realm as this MultiValidator.
186 *
187 * @return an {@link IObservableValue} whose value is always the current
188 * validation status of this MultiValidator.
189 */
190 public IObservableValue getValidationStatus() {
191 if (unmodifiableValidationStatus is null) {
192 revalidate();
193 unmodifiableValidationStatus = Observables
194 .unmodifiableObservableValue(validationStatus);
195 }
196 return unmodifiableValidationStatus;
197 }
198
199 private void revalidate() {
200 final IObservable[] dependencies = ObservableTracker.runAndMonitor(
201 new class() Runnable {
202 public void run() {
203 try {
204 IStatus status = validate();
205 if (status is null)
206 status = ValidationStatus.ok();
207 validationStatus.setValue(status);
208 } catch (RuntimeException e) {
209 // Usually an NPE as dependencies are
210 // init'ed
211 validationStatus.setValue(ValidationStatus.error(e
212 .getMessage(), e));
213 }
214 }
215 }, null, null);
216 ObservableTracker.runAndIgnore(new class() Runnable {
217 public void run() {
218 targets.clear();
219 targets.addAll(Arrays.asList(dependencies));
220 }
221 });
222 }
223
224 /**
225 * Return the current validation status.
226 * <p>
227 * Note: To ensure that the validation status is kept current, all
228 * dependencies used to calculate status should be accessed through
229 * {@link IObservable} instances. Each dependency observable must be in the
230 * same realm as the MultiValidator.
231 *
232 * @return the current validation status.
233 */
234 protected abstract IStatus validate();
235
236 /**
237 * Returns a wrapper {@link IObservableValue} which stays in sync with the
238 * given target observable only when the validation status is valid.
239 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
240 * {@link IStatus#WARNING WARNING} severity are considered valid.
241 * <p>
242 * The wrapper behaves as follows with respect to the validation status:
243 * <ul>
244 * <li>While valid, the wrapper stays in sync with its target observable.
245 * <li>While invalid, the wrapper's value is the target observable's last
246 * valid value. If the target changes value, a stale event is fired
247 * signaling that a change is pending.
248 * <li>When status changes from invalid to valid, the wrapper takes the
249 * value of the target observable, and synchronization resumes.
250 * </ul>
251 *
252 * @param target
253 * the target observable being wrapped. Must be in the same realm
254 * as the MultiValidator.
255 * @return an IObservableValue which stays in sync with the given target
256 * observable only with the validation status is valid.
257 */
258 public IObservableValue observeValidatedValue(IObservableValue target) {
259 checkObservable(target);
260 return new ValidatedObservableValue(target, getValidationStatus());
261 }
262
263 /**
264 * Returns a wrapper {@link IObservableList} which stays in sync with the
265 * given target observable only when the validation status is valid.
266 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
267 * {@link IStatus#WARNING WARNING} severity are considered valid.
268 * <p>
269 * The wrapper behaves as follows with respect to the validation status:
270 * <ul>
271 * <li>While valid, the wrapper stays in sync with its target observable.
272 * <li>While invalid, the wrapper's elements are the target observable's
273 * last valid elements. If the target changes elements, a stale event is
274 * fired signaling that a change is pending.
275 * <li>When status changes from invalid to valid, the wrapper takes the
276 * elements of the target observable, and synchronization resumes.
277 * </ul>
278 *
279 * @param target
280 * the target observable being wrapped. Must be in the same realm
281 * as the MultiValidator.
282 * @return an IObservableValue which stays in sync with the given target
283 * observable only with the validation status is valid.
284 */
285 public IObservableList observeValidatedList(IObservableList target) {
286 checkObservable(target);
287 return new ValidatedObservableList(target, getValidationStatus());
288 }
289
290 /**
291 * Returns a wrapper {@link IObservableSet} which stays in sync with the
292 * given target observable only when the validation status is valid.
293 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
294 * {@link IStatus#WARNING WARNING} severity are considered valid.
295 * <p>
296 * The wrapper behaves as follows with respect to the validation status:
297 * <ul>
298 * <li>While valid, the wrapper stays in sync with its target observable.
299 * <li>While invalid, the wrapper's elements are the target observable's
300 * last valid elements. If the target changes elements, a stale event is
301 * fired signaling that a change is pending.
302 * <li>When status changes from invalid to valid, the wrapper takes the
303 * elements of the target observable, and synchronization resumes.
304 * </ul>
305 *
306 * @param target
307 * the target observable being wrapped. Must be in the same realm
308 * as the MultiValidator.
309 * @return an IObservableValue which stays in sync with the given target
310 * observable only with the validation status is valid.
311 */
312 public IObservableSet observeValidatedSet(IObservableSet target) {
313 checkObservable(target);
314 return new ValidatedObservableSet(target, getValidationStatus());
315 }
316
317 /**
318 * Returns a wrapper {@link IObservableMap} which stays in sync with the
319 * given target observable only when the validation status is valid.
320 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
321 * {@link IStatus#WARNING WARNING} severity are considered valid.
322 * <p>
323 * The wrapper behaves as follows with respect to the validation status:
324 * <ul>
325 * <li>While valid, the wrapper stays in sync with its target observable.
326 * <li>While invalid, the wrapper's entries are the target observable's
327 * last valid entries. If the target changes entries, a stale event is fired
328 * signaling that a change is pending.
329 * <li>When status changes from invalid to valid, the wrapper takes the
330 * entries of the target observable, and synchronization resumes.
331 * </ul>
332 *
333 * @param target
334 * the target observable being wrapped. Must be in the same realm
335 * as the MultiValidator.
336 * @return an IObservableValue which stays in sync with the given target
337 * observable only with the validation status is valid.
338 */
339 public IObservableMap observeValidatedMap(IObservableMap target) {
340 checkObservable(target);
341 return new ValidatedObservableMap(target, getValidationStatus());
342 }
343
344 public IObservableList getTargets() {
345 return unmodifiableTargets;
346 }
347
348 public IObservableList getModels() {
349 return models;
350 }
351
352 public void dispose() {
353 targets.clear(); // Remove listeners from dependencies
354
355 unmodifiableValidationStatus.dispose();
356 validationStatus.dispose();
357 unmodifiableTargets.dispose();
358 targets.dispose();
359 models.dispose();
360
361 realm = null;
362 validationStatus = null;
363 unmodifiableValidationStatus = null;
364 targets = null;
365 unmodifiableTargets = null;
366 models = null;
367
368 super.dispose();
369 }
370
371 }