85 lines
2.2 KiB
TypeScript
85 lines
2.2 KiB
TypeScript
import {Promise, PromiseWrapper} from 'angular2/src/facade/async';
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import {isBlank, isPresent, isPromise, CONST} from 'angular2/src/facade/lang';
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import {Pipe, PipeFactory, WrappedValue} from './pipe';
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import {ChangeDetectorRef} from '../change_detector_ref';
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/**
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* Implements async bindings to Promise.
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*
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* # Example
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*
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* In this example we bind the description promise to the DOM.
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* The async pipe will convert a promise to the value with which it is resolved. It will also
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* request a change detection check when the promise is resolved.
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*
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* ```
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* @Component({
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* selector: "task-cmp",
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* changeDetection: ON_PUSH
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* })
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* @View({
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* template: "Task Description {{ description | async }}"
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* })
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* class Task {
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* description:Promise<string>;
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* }
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*
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* ```
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*/
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export class PromisePipe implements Pipe {
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_latestValue: Object = null;
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_latestReturnedValue: Object = null;
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_sourcePromise: Promise<any>;
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constructor(public _ref: ChangeDetectorRef) {}
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supports(promise: any): boolean { return isPromise(promise); }
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onDestroy(): void {
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if (isPresent(this._sourcePromise)) {
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this._latestValue = null;
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this._latestReturnedValue = null;
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this._sourcePromise = null;
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}
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}
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transform(promise: Promise<any>, args: List<any> = null): any {
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if (isBlank(this._sourcePromise)) {
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this._sourcePromise = promise;
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promise.then((val) => {
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if (this._sourcePromise === promise) {
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this._updateLatestValue(val);
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}
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});
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return null;
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}
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if (promise !== this._sourcePromise) {
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this._sourcePromise = null;
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return this.transform(promise);
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}
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if (this._latestValue === this._latestReturnedValue) {
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return this._latestReturnedValue;
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} else {
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this._latestReturnedValue = this._latestValue;
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return WrappedValue.wrap(this._latestValue);
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}
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}
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_updateLatestValue(value: Object) {
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this._latestValue = value;
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this._ref.requestCheck();
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}
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}
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/**
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* Provides a factory for [PromisePipe].
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*/
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@CONST()
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export class PromisePipeFactory implements PipeFactory {
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supports(promise: any): boolean { return isPromise(promise); }
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create(cdRef: ChangeDetectorRef): Pipe { return new PromisePipe(cdRef); }
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}
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