observer.js 11 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286
  1. /**
  2. * @license
  3. * Copyright 2021 Google Inc.
  4. *
  5. * Permission is hereby granted, free of charge, to any person obtaining a copy
  6. * of this software and associated documentation files (the "Software"), to deal
  7. * in the Software without restriction, including without limitation the rights
  8. * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  9. * copies of the Software, and to permit persons to whom the Software is
  10. * furnished to do so, subject to the following conditions:
  11. *
  12. * The above copyright notice and this permission notice shall be included in
  13. * all copies or substantial portions of the Software.
  14. *
  15. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16. * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17. * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18. * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19. * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20. * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21. * THE SOFTWARE.
  22. */
  23. import { __assign, __extends, __read, __spreadArray, __values } from "tslib";
  24. /**
  25. * Mixin to add `MDCObserver` functionality to an optional base class.
  26. *
  27. * @deprecated Prefer MDCObserverFoundation for stricter closure compliance.
  28. * @template C Optional base class constructor type.
  29. * @param baseClass - Optional base class.
  30. * @return A class that extends the optional base class with `MDCObserver`
  31. * functionality.
  32. */
  33. export function mdcObserver(baseClass) {
  34. if (baseClass === void 0) { baseClass = /** @class */ (function () {
  35. function class_1() {
  36. }
  37. return class_1;
  38. }()); }
  39. // Mixin classes cannot use private members and Symbol() cannot be used in 3P
  40. // for IE11.
  41. var unobserveMap = new WeakMap();
  42. return /** @class */ (function (_super) {
  43. __extends(MDCObserver, _super);
  44. function MDCObserver() {
  45. return _super !== null && _super.apply(this, arguments) || this;
  46. }
  47. MDCObserver.prototype.observe = function (target, observers) {
  48. var e_1, _a;
  49. var _this = this;
  50. var cleanup = [];
  51. try {
  52. for (var _b = __values(Object.keys(observers)), _c = _b.next(); !_c.done; _c = _b.next()) {
  53. var property = _c.value;
  54. var observer = observers[property].bind(this);
  55. cleanup.push(observeProperty(target, property, observer));
  56. }
  57. }
  58. catch (e_1_1) { e_1 = { error: e_1_1 }; }
  59. finally {
  60. try {
  61. if (_c && !_c.done && (_a = _b.return)) _a.call(_b);
  62. }
  63. finally { if (e_1) throw e_1.error; }
  64. }
  65. var unobserve = function () {
  66. var e_2, _a;
  67. try {
  68. for (var cleanup_1 = __values(cleanup), cleanup_1_1 = cleanup_1.next(); !cleanup_1_1.done; cleanup_1_1 = cleanup_1.next()) {
  69. var cleanupFn = cleanup_1_1.value;
  70. cleanupFn();
  71. }
  72. }
  73. catch (e_2_1) { e_2 = { error: e_2_1 }; }
  74. finally {
  75. try {
  76. if (cleanup_1_1 && !cleanup_1_1.done && (_a = cleanup_1.return)) _a.call(cleanup_1);
  77. }
  78. finally { if (e_2) throw e_2.error; }
  79. }
  80. var unobserves = unobserveMap.get(_this) || [];
  81. var index = unobserves.indexOf(unobserve);
  82. if (index > -1) {
  83. unobserves.splice(index, 1);
  84. }
  85. };
  86. var unobserves = unobserveMap.get(this);
  87. if (!unobserves) {
  88. unobserves = [];
  89. unobserveMap.set(this, unobserves);
  90. }
  91. unobserves.push(unobserve);
  92. return unobserve;
  93. };
  94. MDCObserver.prototype.setObserversEnabled = function (target, enabled) {
  95. setObserversEnabled(target, enabled);
  96. };
  97. MDCObserver.prototype.unobserve = function () {
  98. var e_3, _a;
  99. // Iterate over a copy since unobserve() will remove themselves from the
  100. // array
  101. var unobserves = unobserveMap.get(this) || [];
  102. try {
  103. for (var _b = __values(__spreadArray([], __read(unobserves))), _c = _b.next(); !_c.done; _c = _b.next()) {
  104. var unobserve = _c.value;
  105. unobserve();
  106. }
  107. }
  108. catch (e_3_1) { e_3 = { error: e_3_1 }; }
  109. finally {
  110. try {
  111. if (_c && !_c.done && (_a = _b.return)) _a.call(_b);
  112. }
  113. finally { if (e_3) throw e_3.error; }
  114. }
  115. };
  116. return MDCObserver;
  117. }(baseClass));
  118. }
  119. /**
  120. * Observe a target's property for changes. When a property changes, the
  121. * provided `Observer` function will be invoked with the properties current and
  122. * previous values.
  123. *
  124. * The returned cleanup function will stop listening to changes for the
  125. * provided `Observer`.
  126. *
  127. * @template T The observed target type.
  128. * @template K The observed property.
  129. * @param target - The target to observe.
  130. * @param property - The property of the target to observe.
  131. * @param observer - An observer function to invoke each time the property
  132. * changes.
  133. * @return A cleanup function that will stop observing changes for the provided
  134. * `Observer`.
  135. */
  136. export function observeProperty(target, property, observer) {
  137. var targetObservers = installObserver(target, property);
  138. var observers = targetObservers.getObservers(property);
  139. observers.push(observer);
  140. return function () {
  141. observers.splice(observers.indexOf(observer), 1);
  142. };
  143. }
  144. /**
  145. * A Map of all `TargetObservers` that have been installed.
  146. */
  147. var allTargetObservers = new WeakMap();
  148. /**
  149. * Installs a `TargetObservers` for the provided target (if not already
  150. * installed), and replaces the given property with a getter and setter that
  151. * will respond to changes and call `TargetObservers`.
  152. *
  153. * Subsequent calls to `installObserver()` with the same target and property
  154. * will not override the property's previously installed getter/setter.
  155. *
  156. * @template T The observed target type.
  157. * @template K The observed property to create a getter/setter for.
  158. * @param target - The target to observe.
  159. * @param property - The property to create a getter/setter for, if needed.
  160. * @return The installed `TargetObservers` for the provided target.
  161. */
  162. function installObserver(target, property) {
  163. var observersMap = new Map();
  164. if (!allTargetObservers.has(target)) {
  165. allTargetObservers.set(target, {
  166. isEnabled: true,
  167. getObservers: function (key) {
  168. var observers = observersMap.get(key) || [];
  169. if (!observersMap.has(key)) {
  170. observersMap.set(key, observers);
  171. }
  172. return observers;
  173. },
  174. installedProperties: new Set()
  175. });
  176. }
  177. var targetObservers = allTargetObservers.get(target);
  178. if (targetObservers.installedProperties.has(property)) {
  179. // The getter/setter has already been replaced for this property
  180. return targetObservers;
  181. }
  182. // Retrieve (or create if it's a plain property) the original descriptor from
  183. // the target...
  184. var descriptor = getDescriptor(target, property) || {
  185. configurable: true,
  186. enumerable: true,
  187. value: target[property],
  188. writable: true
  189. };
  190. // ...and create a copy that will be used for the observer.
  191. var observedDescriptor = __assign({}, descriptor);
  192. var descGet = descriptor.get, descSet = descriptor.set;
  193. if ('value' in descriptor) {
  194. // The descriptor is a simple value (not a getter/setter).
  195. // For our observer descriptor that we copied, delete the value/writable
  196. // properties, since they are incompatible with the get/set properties
  197. // for descriptors.
  198. delete observedDescriptor.value;
  199. delete observedDescriptor.writable;
  200. // Set up a simple getter...
  201. var value_1 = descriptor.value;
  202. descGet = function () { return value_1; };
  203. // ...and setter (if the original property was writable).
  204. if (descriptor.writable) {
  205. descSet = function (newValue) {
  206. value_1 = newValue;
  207. };
  208. }
  209. }
  210. if (descGet) {
  211. observedDescriptor.get = function () {
  212. // `this as T` needed for closure conformance
  213. // tslint:disable-next-line:no-unnecessary-type-assertion
  214. return descGet.call(this);
  215. };
  216. }
  217. if (descSet) {
  218. observedDescriptor.set = function (newValue) {
  219. var e_4, _a;
  220. // `thus as T` needed for closure conformance
  221. // tslint:disable-next-line:no-unnecessary-type-assertion
  222. var previous = descGet ? descGet.call(this) : newValue;
  223. // tslint:disable-next-line:no-unnecessary-type-assertion
  224. descSet.call(this, newValue);
  225. if (targetObservers.isEnabled && (!descGet || newValue !== previous)) {
  226. try {
  227. for (var _b = __values(targetObservers.getObservers(property)), _c = _b.next(); !_c.done; _c = _b.next()) {
  228. var observer = _c.value;
  229. observer(newValue, previous);
  230. }
  231. }
  232. catch (e_4_1) { e_4 = { error: e_4_1 }; }
  233. finally {
  234. try {
  235. if (_c && !_c.done && (_a = _b.return)) _a.call(_b);
  236. }
  237. finally { if (e_4) throw e_4.error; }
  238. }
  239. }
  240. };
  241. }
  242. targetObservers.installedProperties.add(property);
  243. Object.defineProperty(target, property, observedDescriptor);
  244. return targetObservers;
  245. }
  246. /**
  247. * Retrieves the descriptor for a property from the provided target. This
  248. * function will walk up the target's prototype chain to search for the
  249. * descriptor.
  250. *
  251. * @template T The target type.
  252. * @template K The property type.
  253. * @param target - The target to retrieve a descriptor from.
  254. * @param property - The name of the property to retrieve a descriptor for.
  255. * @return the descriptor, or undefined if it does not exist. Keep in mind that
  256. * plain properties may not have a descriptor defined.
  257. */
  258. export function getDescriptor(target, property) {
  259. var descriptorTarget = target;
  260. var descriptor;
  261. while (descriptorTarget) {
  262. descriptor = Object.getOwnPropertyDescriptor(descriptorTarget, property);
  263. if (descriptor) {
  264. break;
  265. }
  266. // Walk up the instance's prototype chain in case the property is declared
  267. // on a superclass.
  268. descriptorTarget = Object.getPrototypeOf(descriptorTarget);
  269. }
  270. return descriptor;
  271. }
  272. /**
  273. * Enables or disables all observers for a provided target. Changes to observed
  274. * properties will not call any observers when disabled.
  275. *
  276. * @template T The observed target type.
  277. * @param target - The target to enable or disable observers for.
  278. * @param enabled - True to enable or false to disable observers.
  279. */
  280. export function setObserversEnabled(target, enabled) {
  281. var targetObservers = allTargetObservers.get(target);
  282. if (targetObservers) {
  283. targetObservers.isEnabled = enabled;
  284. }
  285. }
  286. //# sourceMappingURL=observer.js.map