256 lines
10 KiB
JavaScript
256 lines
10 KiB
JavaScript
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/**
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* @license
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* Copyright 2021 Google Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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import { __extends, __read, __spreadArray, __values } from "tslib";
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import { getDescriptor } from './observer';
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/**
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* Mixin to add `MDCObserver` functionality to an optional base class.
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*
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* @deprecated Prefer MDCObserverFoundation for stricter closure compliance.
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* @template C Optional base class constructor type.
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* @param baseClass - Optional base class.
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* @return A class that extends the optional base class with `MDCObserver`
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* functionality.
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*/
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export function mdcObserver(baseClass) {
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var _a, _b;
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if (baseClass === void 0) { baseClass = /** @class */ (function () {
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function class_1() {
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}
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return class_1;
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}()); }
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var unobserves = Symbol();
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return _b = /** @class */ (function (_super) {
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__extends(MDCObserver, _super);
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function MDCObserver() {
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var _this = _super !== null && _super.apply(this, arguments) || this;
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_this[_a] = [];
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return _this;
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}
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MDCObserver.prototype.observe = function (target, observers) {
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var e_1, _b;
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var _this = this;
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var cleanup = [];
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try {
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for (var _c = __values(Object.keys(observers)), _d = _c.next(); !_d.done; _d = _c.next()) {
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var property = _d.value;
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var observer = observers[property].bind(this);
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cleanup.push(observeProperty(target, property, observer));
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}
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}
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catch (e_1_1) { e_1 = { error: e_1_1 }; }
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finally {
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try {
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if (_d && !_d.done && (_b = _c.return)) _b.call(_c);
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}
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finally { if (e_1) throw e_1.error; }
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}
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var unobserve = function () {
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var e_2, _b;
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try {
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for (var cleanup_1 = __values(cleanup), cleanup_1_1 = cleanup_1.next(); !cleanup_1_1.done; cleanup_1_1 = cleanup_1.next()) {
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var cleanupFn = cleanup_1_1.value;
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cleanupFn();
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}
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}
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catch (e_2_1) { e_2 = { error: e_2_1 }; }
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finally {
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try {
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if (cleanup_1_1 && !cleanup_1_1.done && (_b = cleanup_1.return)) _b.call(cleanup_1);
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}
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finally { if (e_2) throw e_2.error; }
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}
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var index = _this[unobserves].indexOf(unobserve);
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if (index > -1) {
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_this[unobserves].splice(index, 1);
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}
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};
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this[unobserves].push(unobserve);
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return unobserve;
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};
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MDCObserver.prototype.setObserversEnabled = function (target, enabled) {
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setObserversEnabled(target, enabled);
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};
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MDCObserver.prototype.unobserve = function () {
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var e_3, _b;
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try {
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// Iterate over a copy since unobserve() will remove themselves from the
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// array
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for (var _c = __values(__spreadArray([], __read(this[unobserves]))), _d = _c.next(); !_d.done; _d = _c.next()) {
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var unobserve = _d.value;
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unobserve();
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}
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}
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catch (e_3_1) { e_3 = { error: e_3_1 }; }
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finally {
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try {
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if (_d && !_d.done && (_b = _c.return)) _b.call(_c);
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}
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finally { if (e_3) throw e_3.error; }
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}
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};
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return MDCObserver;
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}(baseClass)),
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_a = unobserves,
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_b;
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}
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var isTargetObservers = Symbol();
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var isEnabled = Symbol();
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var getObservers = Symbol();
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/**
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* Observe a target's property for changes. When a property changes, the
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* provided `Observer` function will be invoked with the properties current and
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* previous values.
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*
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* The returned cleanup function will stop listening to changes for the
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* provided `Observer`.
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*
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* @template T The observed target type.
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* @template K The observed property.
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* @param target - The target to observe.
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* @param property - The property of the target to observe.
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* @param observer - An observer function to invoke each time the property
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* changes.
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* @return A cleanup function that will stop observing changes for the provided
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* `Observer`.
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*/
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export function observeProperty(target, property, observer) {
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var observerPrototype = installObserver(target);
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var observers = observerPrototype[getObservers](property);
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observers.push(observer);
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return function () {
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observers.splice(observers.indexOf(observer), 1);
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};
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}
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/**
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* Installs a `TargetObservers` for the provided target (if not already
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* installed).
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*
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* A target's `TargetObservers` is installed as a Proxy on the target's
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* prototype.
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*
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* @template T The observed target type.
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* @param target - The target to observe.
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* @return The installed `TargetObservers` for the provided target.
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*/
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function installObserver(target) {
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var e_4, _a, e_5, _b;
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var prototype = Object.getPrototypeOf(target);
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if (prototype[isTargetObservers]) {
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return prototype;
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}
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// Proxy prototypes will not trap plain properties (not a getter/setter) that
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// are already defined. They only work on new plain properties.
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// We can work around this by deleting the properties, installing the Proxy,
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// then re-setting the properties.
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var existingKeyValues = new Map();
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var keys = Object.getOwnPropertyNames(target);
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try {
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for (var keys_1 = __values(keys), keys_1_1 = keys_1.next(); !keys_1_1.done; keys_1_1 = keys_1.next()) {
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var key = keys_1_1.value;
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var descriptor = getDescriptor(target, key);
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if (descriptor && descriptor.writable) {
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existingKeyValues.set(key, descriptor.value);
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delete target[key];
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}
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}
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}
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catch (e_4_1) { e_4 = { error: e_4_1 }; }
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finally {
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try {
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if (keys_1_1 && !keys_1_1.done && (_a = keys_1.return)) _a.call(keys_1);
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}
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finally { if (e_4) throw e_4.error; }
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}
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var proxy = new Proxy(Object.create(prototype), {
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get: function (target, key, receiver) {
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return Reflect.get(target, key, receiver);
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},
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set: function (target, key, newValue, receiver) {
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var e_6, _a;
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var isTargetObserversKey = key === isTargetObservers ||
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key === isEnabled || key === getObservers;
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var previous = Reflect.get(target, key, receiver);
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// Do not use receiver when setting the target's key. We do not want
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// to change whatever the target's inherent receiver is.
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Reflect.set(target, key, newValue);
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if (!isTargetObserversKey && proxy[isEnabled] &&
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newValue !== previous) {
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try {
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for (var _b = __values(proxy[getObservers](key)), _c = _b.next(); !_c.done; _c = _b.next()) {
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var observer = _c.value;
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observer(newValue, previous);
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}
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}
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catch (e_6_1) { e_6 = { error: e_6_1 }; }
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finally {
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try {
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if (_c && !_c.done && (_a = _b.return)) _a.call(_b);
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}
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finally { if (e_6) throw e_6.error; }
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}
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}
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return true;
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}
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});
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proxy[isTargetObservers] = true;
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proxy[isEnabled] = true;
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var observersMap = new Map();
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proxy[getObservers] = function (key) {
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var observers = observersMap.get(key) || [];
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if (!observersMap.has(key)) {
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observersMap.set(key, observers);
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}
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return observers;
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};
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Object.setPrototypeOf(target, proxy);
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try {
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// Re-set plain pre-existing properties so that the Proxy can trap them
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for (var _c = __values(existingKeyValues.entries()), _d = _c.next(); !_d.done; _d = _c.next()) {
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var _e = __read(_d.value, 2), key = _e[0], value = _e[1];
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target[key] = value;
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}
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}
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catch (e_5_1) { e_5 = { error: e_5_1 }; }
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finally {
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try {
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if (_d && !_d.done && (_b = _c.return)) _b.call(_c);
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}
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finally { if (e_5) throw e_5.error; }
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}
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return proxy;
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}
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/**
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* Enables or disables all observers for a provided target. Changes to observed
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* properties will not call any observers when disabled.
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*
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* @template T The observed target type.
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* @param target - The target to enable or disable observers for.
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* @param enabled - True to enable or false to disable observers.
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*/
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export function setObserversEnabled(target, enabled) {
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var prototype = Object.getPrototypeOf(target);
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if (prototype[isTargetObservers]) {
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prototype[isEnabled] = enabled;
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}
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}
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//# sourceMappingURL=observer-proxy.js.map
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