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https://github.com/odoo/owl.git
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Géry Debongnie
b2db7f21ed
Promises are kind of special, and do not behave like usual javascript values. For this issue, the problem is that when the observer tries to observe a promise value, the code will crash with an error like this: Uncaught TypeError: Method Promise.prototype.then called on incompatible receiver [object Object] Also, note that it does not make much sense to proxify promise methods anyway, since they are not (supposed) to be modified. So, with this commit, we simply consider that promises should be treated like a primitive value: simply ignored when determining if it should be proxified Note that I actually believe that putting promises in a useState is not a good idea in general. closes #677
100 lines
2.5 KiB
TypeScript
100 lines
2.5 KiB
TypeScript
/**
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* Owl Observer
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*
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* This code contains the logic that allows Owl to observe and react to state
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* changes.
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*
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* This is a Observer class that can observe any JS values. The way it works
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* can be summarized thusly:
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* - primitive values are not observed at all
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* - Objects and arrays are observed by replacing them with a Proxy
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* - each object/array metadata are tracked in a weakmap, and keep a revision
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* number
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*
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* Note that this code is loosely inspired by Vue.
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*/
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//------------------------------------------------------------------------------
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// Observer
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//------------------------------------------------------------------------------
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export class Observer {
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rev: number = 1;
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allowMutations: boolean = true;
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weakMap: WeakMap<any, any> = new WeakMap();
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notifyCB() {}
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observe<T>(value: T, parent?: any): T {
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if (
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value === null ||
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typeof value !== "object" ||
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value instanceof Date ||
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value instanceof Promise
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) {
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// fun fact: typeof null === 'object'
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return value;
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}
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let metadata = this.weakMap.get(value) || this._observe(value, parent);
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return metadata.proxy;
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}
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revNumber(value): number {
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const metadata = this.weakMap.get(value);
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return metadata ? metadata.rev : 0;
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}
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_observe(value, parent) {
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var self = this;
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const proxy = new Proxy(value, {
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get(target, k) {
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const targetValue = target[k];
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return self.observe(targetValue, value);
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},
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set(target, key: string, newVal): boolean {
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const value = target[key];
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if (newVal !== value) {
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if (!self.allowMutations) {
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throw new Error(
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`Observed state cannot be changed here! (key: "${key}", val: "${newVal}")`
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);
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}
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self._updateRevNumber(target);
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target[key] = newVal;
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self.notifyCB();
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}
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return true;
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},
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deleteProperty(target, key) {
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if (key in target) {
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delete target[key];
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self._updateRevNumber(target);
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self.notifyCB();
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}
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return true;
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},
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});
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const metadata = {
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value,
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proxy,
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rev: this.rev,
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parent,
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};
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this.weakMap.set(value, metadata);
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this.weakMap.set(metadata.proxy, metadata);
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return metadata;
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}
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_updateRevNumber(target: any) {
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this.rev++;
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let metadata = this.weakMap.get(target);
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let parent = target;
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do {
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metadata = this.weakMap.get(parent);
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metadata.rev++;
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} while ((parent = metadata.parent) && parent !== target);
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}
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}
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