feat(cdk/coercion): add coercion for string arrays

src/cdk/coercion/public-api.ts

@@ -11,3 +11,4 @@ export * from './number-property';
 export * from './array';
 export * from './css-pixel-value';
 export * from './element';
+export * from './string-array';

src/cdk/coercion/string-array.spec.ts

@@ -0,0 +1,32 @@
+import {coerceStringArray} from '@angular/cdk/coercion/string-array';
+
+describe('coerceStringArray', () => {
+  it('should split a string', () => {
+    expect(coerceStringArray('x y  z 1')).toEqual(['x', 'y', 'z', '1']);
+  });
+
+  it('should map values to string in an array', () => {
+    expect(coerceStringArray(['x', 1, true, null, undefined, ['arr', 'ay'], { data: false }]))
+      .toEqual(['x', '1', 'true', 'null', 'undefined', 'arr,ay', '[object Object]']);
+  });
+
+  it('should work with a custom delimiter', () => {
+    expect(coerceStringArray('1::2::3::4', '::')).toEqual(['1', '2', '3', '4']);
+  });
+
+  it('should trim values and remove empty values', () => {
+    expect(coerceStringArray(',  x,  ,, ', ',')).toEqual(['x']);
+  });
+
+  it('should map non-string values to string', () => {
+    expect(coerceStringArray(0)).toEqual(['0']);
+  });
+
+  it('should return an empty array for null', () => {
+    expect(coerceStringArray(null)).toEqual([]);
+  });
+
+  it('should return an empty array for undefined', () => {
+    expect(coerceStringArray(undefined)).toEqual([]);
+  });
+});

src/cdk/coercion/string-array.ts

@@ -0,0 +1,40 @@
+/**
+ * @license
+ * Copyright Google LLC 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
+ */
+
+/**
+ * Coerces a value to an array of trimmed non-empty strings.
+ * Any input that is not an array, `null` or `undefined` will be turned into a string
+ * via `toString()` and subsequently split with the given separator.
+ * `null` and `undefined` will result in an empty array.
+ * This results in the following outcomes:
+ * - `null` -> `[]`
+ * - `[null]` -> `["null"]`
+ * - `["a", "b ", " "]` -> `["a", "b"]`
+ * - `[1, [2, 3]]` -> `["1", "2,3"]`
+ * - `[{ a: 0 }]` -> `["[object Object]"]`
+ * - `{ a: 0 }` -> `["[object", "Object]"]`
+ *
+ * Useful for defining CSS classes or table columns.
+ * @param value the value to coerce into an array of strings
+ * @param separator split-separator if value isn't an array
+ */
+export function coerceStringArray(value: any, separator: string | RegExp = /\s+/): string[] {
+  const result = [];
+
+  if (value != null) {
+    const sourceValues = Array.isArray(value) ? value : `${value}`.split(separator);
+    for (const sourceValue of sourceValues) {
+      const trimmedString = `${sourceValue}`.trim();
+      if (trimmedString) {
+        result.push(trimmedString);
+      }
+    }
+  }
+
+  return result;
+}

src/material/autocomplete/autocomplete.ts

@@ -7,7 +7,7 @@
  */
 
 import {ActiveDescendantKeyManager} from '@angular/cdk/a11y';
-import {BooleanInput, coerceBooleanProperty} from '@angular/cdk/coercion';
+import {BooleanInput, coerceBooleanProperty, coerceStringArray} from '@angular/cdk/coercion';
 import {
   AfterContentInit,
   ChangeDetectionStrategy,
@@ -169,10 +169,10 @@ export abstract class _MatAutocompleteBase extends _MatAutocompleteMixinBase imp
    * inside the overlay container to allow for easy styling.
    */
   @Input('class')
-  set classList(value: string) {
+  set classList(value: string | string[]) {
     if (value && value.length) {
-      this._classList = value.split(' ').reduce((classList, className) => {
-        classList[className.trim()] = true;
+      this._classList = coerceStringArray(value).reduce((classList, className) => {
+        classList[className] = true;
         return classList;
       }, {} as {[key: string]: boolean});
     } else {

src/material/datepicker/datepicker-base.ts

@@ -7,7 +7,7 @@
  */
 
 import {Directionality} from '@angular/cdk/bidi';
-import {BooleanInput, coerceBooleanProperty} from '@angular/cdk/coercion';
+import {BooleanInput, coerceBooleanProperty, coerceStringArray} from '@angular/cdk/coercion';
 import {ESCAPE, UP_ARROW} from '@angular/cdk/keycodes';
 import {
   Overlay,
@@ -307,9 +307,6 @@ export abstract class MatDatepickerBase<C extends MatDatepickerControl<D>, S,
   @Output() readonly viewChanged: EventEmitter<MatCalendarView> =
     new EventEmitter<MatCalendarView>(true);
 
-  /** Classes to be passed to the date picker panel. Supports the same syntax as `ngClass`. */
-  @Input() panelClass: string | string[];
-
   /** Function that can be used to add custom CSS classes to dates. */
   @Input() dateClass: MatCalendarCellClassFunction<D>;
 
@@ -319,6 +316,16 @@ export abstract class MatDatepickerBase<C extends MatDatepickerControl<D>, S,
   /** Emits when the datepicker has been closed. */
   @Output('closed') closedStream: EventEmitter<void> = new EventEmitter<void>();
 
+  /**
+   * Classes to be passed to the date picker panel.
+   * Supports string and string array values, similar to `ngClass`.
+   */
+  @Input()
+  get panelClass(): string | string[] { return this._panelClass; }
+  set panelClass(value: string | string[]) {
+    this._panelClass = coerceStringArray(value);
+  }
+  private _panelClass: string[];
 
   /** Whether the calendar is open. */
   @Input()

src/material/datepicker/datepicker.spec.ts

@@ -2037,6 +2037,47 @@ describe('MatDatepicker', () => {
     subscription.unsubscribe();
   });
 
+  describe('panelClass input', () => {
+    let fixture: ComponentFixture<PanelClassDatepicker>;
+    let testComponent: PanelClassDatepicker;
+
+    beforeEach(fakeAsync(() => {
+      fixture = createComponent(PanelClassDatepicker, [MatNativeDateModule]);
+      fixture.detectChanges();
+
+      testComponent = fixture.componentInstance;
+    }));
+
+    afterEach(fakeAsync(() => {
+      testComponent.datepicker.close();
+      fixture.detectChanges();
+      flush();
+    }));
+
+    it('should accept a single class', () => {
+      testComponent.panelClass = 'foobar';
+      fixture.detectChanges();
+      expect(testComponent.datepicker.panelClass).toEqual(['foobar']);
+    });
+
+    it('should accept multiple classes', () => {
+      testComponent.panelClass = 'foo bar';
+      fixture.detectChanges();
+      expect(testComponent.datepicker.panelClass).toEqual(['foo', 'bar']);
+    });
+
+    it('should work with ngClass', () => {
+      testComponent.panelClass = ['foo', 'bar'];
+      testComponent.datepicker.open();
+      fixture.detectChanges();
+
+      const datepickerContent = testComponent.datepicker['_dialogRef']!!.componentInstance;
+      const actualClasses = datepickerContent._elementRef.nativeElement.children[1].classList;
+      expect(actualClasses.contains('foo')).toBe(true);
+      expect(actualClasses.contains('bar')).toBe(true);
+    });
+  });
+
 });
 
 /**
@@ -2400,3 +2441,16 @@ class DatepickerInputWithCustomValidator {
   min: Date;
   max: Date;
 }
+
+
+@Component({
+  template: `
+  <input [matDatepicker]="d" [value]="date">
+  <mat-datepicker [panelClass]="panelClass" touchUi #d></mat-datepicker>
+  `,
+})
+class PanelClassDatepicker {
+  date = new Date(0);
+  panelClass: any;
+  @ViewChild('d') datepicker: MatDatepicker<Date>;
+}

tools/public_api_guard/cdk/coercion.d.ts

@@ -14,4 +14,6 @@ export declare function coerceElement<T>(elementOrRef: ElementRef<T> | T): T;
 export declare function coerceNumberProperty(value: any): number;
 export declare function coerceNumberProperty<D>(value: any, fallback: D): number | D;
 
+export declare function coerceStringArray(value: any, separator?: string | RegExp): string[];
+
 export declare type NumberInput = string | number | null | undefined;

tools/public_api_guard/material/autocomplete.d.ts

@@ -8,7 +8,7 @@ export declare abstract class _MatAutocompleteBase extends _MatAutocompleteMixin
     protected abstract _visibleClass: string;
     get autoActiveFirstOption(): boolean;
     set autoActiveFirstOption(value: boolean);
-    set classList(value: string);
+    set classList(value: string | string[]);
     readonly closed: EventEmitter<void>;
     displayWith: ((value: any) => string) | null;
     id: string;