Jason Aden
fdfedceeec
* If all guards return `true`, operator returns `true` * `false` and `UrlTree` are now both valid returns from a guard * Both these values wait for higher priority guards to resolve * Highest priority `false` or `UrlTree` value will be returned PR Close #26478
53 lines
2.1 KiB
TypeScript
53 lines
2.1 KiB
TypeScript
/**
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* @license
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* Copyright Google Inc. 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 {Observable, OperatorFunction, combineLatest} from 'rxjs';
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import {filter, scan, startWith, switchMap, take} from 'rxjs/operators';
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import {UrlTree} from '../url_tree';
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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(
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...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 call.
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// This guarantees that in the case of a guard at the bottom of the tree that
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// returns a redirect, we will wait for the higher priority guard at the top to
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// 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 cancel
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// navigation
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if (val === false) return val;
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if (i === list.length - 1 || val instanceof UrlTree) {
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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), take(1)) as Observable<boolean|UrlTree>;
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});
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}
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