9105005192
Refactor and simplifiy RxJS usage in the router package in order to reduce its size and increase performance. PR Close #40290
55 lines
2.4 KiB
TypeScript
55 lines
2.4 KiB
TypeScript
/**
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* @license
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* Copyright Google LLC All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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import {combineLatest, Observable, OperatorFunction} from 'rxjs';
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import {filter, map, scan, startWith, switchMap, take} from 'rxjs/operators';
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import {UrlTree} from '../url_tree';
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import {isUrlTree} from '../utils/type_guards';
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const INITIAL_VALUE = Symbol('INITIAL_VALUE');
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declare type INTERIM_VALUES = typeof INITIAL_VALUE | boolean | UrlTree;
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export function prioritizedGuardValue():
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OperatorFunction<Observable<boolean|UrlTree>[], boolean|UrlTree> {
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return switchMap(obs => {
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return combineLatest(obs.map(o => o.pipe(take(1), startWith(INITIAL_VALUE as INTERIM_VALUES))))
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.pipe(
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scan(
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(acc: INTERIM_VALUES, list: INTERIM_VALUES[]) => {
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let isPending = false;
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return list.reduce((innerAcc, val, i: number) => {
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if (innerAcc !== INITIAL_VALUE) return innerAcc;
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// Toggle pending flag if any values haven't been set yet
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if (val === INITIAL_VALUE) isPending = true;
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// Any other return values are only valid if we haven't yet hit a pending
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// call. This guarantees that in the case of a guard at the bottom of the
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// tree that returns a redirect, we will wait for the higher priority
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// guard at the top to finish before performing the redirect.
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if (!isPending) {
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// Early return when we hit a `false` value as that should always
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// cancel navigation
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if (val === false) return val;
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if (i === list.length - 1 || isUrlTree(val)) {
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return val;
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}
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}
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return innerAcc;
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}, acc);
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},
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INITIAL_VALUE),
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filter(item => item !== INITIAL_VALUE),
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map(item => isUrlTree(item) ? item : item === true), //
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take(1)) as Observable<boolean|UrlTree>;
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});
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}
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