refactor: use delay instead of switchMap

Author: crisbeto

src/cdk/rxjs/rx-operators.ts

@@ -22,6 +22,7 @@ import {startWith as startWithOperator} from 'rxjs/operator/startWith';
 import {debounceTime as debounceTimeOperator} from 'rxjs/operator/debounceTime';
 import {auditTime as auditTimeOperator} from 'rxjs/operator/auditTime';
 import {takeUntil as takeUntilOperator} from 'rxjs/operator/takeUntil';
+import {delay as delayOperator} from 'rxjs/operator/delay';
 
 /**
  * Represents a strongly-typed chain of RxJS operators.
@@ -71,6 +72,9 @@ export interface StrictRxChain<T> {
 
   call(operator: takeUntilOperatorType<T>, notifier: Observable<any>): StrictRxChain<T>;
 
+  call(operator: delayOperatorType<T>, delay: number | Date, scheduler?: IScheduler):
+        StrictRxChain<T>;
+
   subscribe(fn: (t: T) => void): Subscription;
 
   result(): Observable<T>;
@@ -89,6 +93,7 @@ export class StartWithBrand { private _; }
 export class DebounceTimeBrand { private _; }
 export class AuditTimeBrand { private _; }
 export class TakeUntilBrand { private _; }
+export class DelayBrand { private _; }
 
 
 export type finallyOperatorType<T> = typeof _finallyOperator & FinallyBrand;
@@ -103,6 +108,7 @@ export type startWithOperatorType<T> = typeof startWithOperator & StartWithBrand
 export type debounceTimeOperatorType<T> = typeof debounceTimeOperator & DebounceTimeBrand;
 export type auditTimeOperatorType<T> = typeof auditTimeOperator & AuditTimeBrand;
 export type takeUntilOperatorType<T> = typeof takeUntilOperator & TakeUntilBrand;
+export type delayOperatorType<T> = typeof delayOperator & DelayBrand;
 
 // We add `Function` to the type intersection to make this nomically different from
 // `finallyOperatorType` while still being structurally the same. Without this, TypeScript tries to
@@ -122,3 +128,4 @@ export const debounceTime =
     debounceTimeOperator as typeof debounceTimeOperator & DebounceTimeBrand & Function;
 export const auditTime = auditTimeOperator as typeof auditTimeOperator & AuditTimeBrand & Function;
 export const takeUntil = takeUntilOperator as typeof takeUntilOperator & TakeUntilBrand & Function;
+export const delay = delayOperator as typeof delayOperator & DelayBrand & Function;

src/lib/autocomplete/autocomplete-trigger.ts

@@ -23,7 +23,7 @@ import {
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';
 import {DOCUMENT} from '@angular/platform-browser';
 import {Directionality} from '@angular/cdk/bidi';
-import {filter, first, RxChain, switchMap} from '@angular/cdk/rxjs';
+import {filter, first, RxChain, switchMap, delay, doOperator} from '@angular/cdk/rxjs';
 import {
   ConnectedPositionStrategy,
   Overlay,
@@ -364,9 +364,8 @@ export class MdAutocompleteTrigger implements ControlValueAccessor, OnDestroy {
       this.autocomplete._setScrollTop(optionOffset);
     } else if (optionOffset + AUTOCOMPLETE_OPTION_HEIGHT > panelTop + AUTOCOMPLETE_PANEL_HEIGHT) {
       // Scroll down to reveal selected option scrolled below the panel bottom
-      const newScrollTop =
-          Math.max(0, optionOffset - AUTOCOMPLETE_PANEL_HEIGHT + AUTOCOMPLETE_OPTION_HEIGHT);
-      this.autocomplete._setScrollTop(newScrollTop);
+      const newScrollTop = optionOffset - AUTOCOMPLETE_PANEL_HEIGHT + AUTOCOMPLETE_OPTION_HEIGHT;
+      this.autocomplete._setScrollTop(Math.max(0, newScrollTop));
     }
   }
 
@@ -376,13 +375,12 @@ export class MdAutocompleteTrigger implements ControlValueAccessor, OnDestroy {
    */
   private _subscribeToClosingActions(): Subscription {
     const firstStable = first.call(this._zone.onStable);
-    const optionChanges = switchMap.call(this.autocomplete.options.changes, () => {
-      this._positionStrategy.recalculateLastPosition();
-
+    const optionChanges = RxChain.from(this.autocomplete.options.changes)
+      .call(doOperator, () => this._positionStrategy.recalculateLastPosition())
       // Defer emitting to the stream until the next tick, because changing
       // bindings in here will cause "changed after checked" errors.
-      return Promise.resolve();
-    });
+      .call(delay, 0)
+      .result();
 
     // When the zone is stable initially, and when the option list changes...
     return RxChain.from(merge(firstStable, optionChanges))

src/lib/autocomplete/autocomplete.spec.ts

@@ -495,6 +495,8 @@ describe('MdAutocomplete', () => {
       tick();
 
       fixture.detectChanges();
+      tick();
+
       expect(input.value).toEqual('', `Expected input value to be empty after reset.`);
     }));
 
@@ -1352,7 +1354,9 @@ describe('MdAutocomplete', () => {
       fixture.detectChanges();
       dispatchFakeEvent(fixture.debugElement.query(By.css('input')).nativeElement, 'focusin');
       tick(1000);
+
       fixture.detectChanges();
+      tick();
 
       Promise.resolve().then(() => {
         let panel = overlayContainerElement.querySelector('.mat-autocomplete-panel') as HTMLElement;

tools/package-tools/rollup-globals.ts

@@ -71,6 +71,7 @@ export const rollupGlobals = {
   'rxjs/operator/switchMap': 'Rx.Observable.prototype',
   'rxjs/operator/takeUntil': 'Rx.Observable.prototype',
   'rxjs/operator/toPromise': 'Rx.Observable.prototype',
+  'rxjs/operator/delay': 'Rx.Observable.prototype',
 
   'rxjs/add/observable/merge': 'Rx.Observable',
   'rxjs/add/observable/fromEvent': 'Rx.Observable',