feat(router): add prioritizedGuardValue operator optimization and allowing UrlTree return from guard (#26478)

* 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
This commit is contained in:
Jason Aden
2018-10-15 10:52:49 -07:00
committed by Misko Hevery
parent 9e5d440a0b
commit fdfedceeec
3 changed files with 235 additions and 0 deletions

View File

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