feat(list): Add single select mode.

src/components-examples/material/list/index.ts

@@ -5,17 +5,20 @@ import {MatListModule} from '@angular/material/list';
 import {ListOverviewExample} from './list-overview/list-overview-example';
 import {ListSectionsExample} from './list-sections/list-sections-example';
 import {ListSelectionExample} from './list-selection/list-selection-example';
+import {ListSingleSelectionExample} from './list-single-selection/list-single-selection-example';
 
 export {
   ListOverviewExample,
   ListSectionsExample,
   ListSelectionExample,
+  ListSingleSelectionExample,
 };
 
 const EXAMPLES = [
   ListOverviewExample,
   ListSectionsExample,
   ListSelectionExample,
+  ListSingleSelectionExample,
 ];
 
 @NgModule({

src/components-examples/material/list/list-single-selection/list-single-selection-example.css

@@ -0,0 +1 @@
+/** No styles for this example. */

src/components-examples/material/list/list-single-selection/list-single-selection-example.html

@@ -0,0 +1,9 @@
+<mat-selection-list #shoes [multiple]="false">
+  <mat-list-option *ngFor="let shoe of typesOfShoes">
+    {{shoe}}
+  </mat-list-option>
+</mat-selection-list>
+
+<p>
+  Option selected: {{shoes.selectedOptions.selected}}
+</p>

src/components-examples/material/list/list-single-selection/list-single-selection-example.ts

@@ -0,0 +1,13 @@
+import {Component} from '@angular/core';
+
+/**
+ * @title List with single selection
+ */
+@Component({
+  selector: 'list-single-selection-example',
+  styleUrls: ['list-single-selection-example.css'],
+  templateUrl: 'list-single-selection-example.html',
+})
+export class ListSingleSelectionExample {
+  typesOfShoes: string[] = ['Boots', 'Clogs', 'Loafers', 'Moccasins', 'Sneakers'];
+}

src/dev-app/list/list-demo.html

@@ -162,4 +162,22 @@ <h3 mat-subheader>Dogs</h3>
       <button mat-raised-button (click)="groceries.deselectAll()">Deselect all</button>
     </p>
   </div>
+
+  <div>
+    <h2>Single Selection list</h2>
+
+    <mat-selection-list #favorite 
+                        [(ngModel)]="favoriteOptions"
+                        [multiple]="false"
+                        color="primary">
+      <h3 mat-subheader>Favorite Grocery</h3>
+
+      <mat-list-option value="bananas">Bananas</mat-list-option>
+      <mat-list-option selected value="oranges">Oranges</mat-list-option>
+      <mat-list-option value="apples">Apples</mat-list-option>
+      <mat-list-option value="strawberries" color="warn">Strawberries</mat-list-option>
+    </mat-selection-list>
+
+    <p>Selected: {{favoriteOptions | json}}</p>
+  </div>
 </div>

src/dev-app/list/list-demo.ts

@@ -70,6 +70,8 @@ export class ListDemo {
     this.modelChangeEventCount++;
   }
 
+  favoriteOptions: string[] = [];
+
   alertItem(msg: string) {
     alert(msg);
   }

src/material/list/_list-theme.scss

@@ -33,6 +33,12 @@
       background: mat-color($background, 'hover');
     }
   }
+
+  .mat-list-single-selected-option {
+    &, &:hover, &:focus {
+      background: mat-color($background, hover, 0.12);
+    }
+  }
 }
 
 @mixin mat-list-typography($config) {

src/material/list/list-option.html

@@ -7,6 +7,7 @@
     [matRippleDisabled]="_isRippleDisabled()"></div>
 
   <mat-pseudo-checkbox
+    *ngIf="selectionList.multiple"
     [state]="selected ? 'checked' : 'unchecked'"
     [disabled]="disabled"></mat-pseudo-checkbox>
 

src/material/list/selection-list.spec.ts

@@ -188,6 +188,16 @@ describe('MatSelectionList without forms', () => {
       expect(selectList.selected.length).toBe(0);
     });
 
+    it('should not add the mat-list-single-selected-option class (in multiple mode)', () => {
+      let testListItem = listOptions[2].injector.get<MatListOption>(MatListOption);
+
+      testListItem._handleClick();
+      fixture.detectChanges();
+
+      expect(listOptions[2].nativeElement.classList.contains('mat-list-single-selected-option'))
+          .toBe(false);
+    });
+
     it('should not allow selection of disabled items', () => {
       let testListItem = listOptions[0].injector.get<MatListOption>(MatListOption);
       let selectList =
@@ -882,6 +892,80 @@ describe('MatSelectionList without forms', () => {
       expect(listOption.classList).toContain('mat-list-item-with-avatar');
     });
   });
+
+  describe('with single selection', () => {
+    let fixture: ComponentFixture<SelectionListWithListOptions>;
+    let listOption: DebugElement[];
+    let selectionList: DebugElement;
+
+    beforeEach(async(() => {
+      TestBed.configureTestingModule({
+        imports: [MatListModule],
+        declarations: [
+          SelectionListWithListOptions,
+        ],
+      }).compileComponents();
+
+      fixture = TestBed.createComponent(SelectionListWithListOptions);
+      fixture.componentInstance.multiple = false;
+      listOption = fixture.debugElement.queryAll(By.directive(MatListOption));
+      selectionList = fixture.debugElement.query(By.directive(MatSelectionList))!;
+      fixture.detectChanges();
+    }));
+
+    it('should select one option at a time', () => {
+      const testListItem1 = listOption[1].injector.get<MatListOption>(MatListOption);
+      const testListItem2 = listOption[2].injector.get<MatListOption>(MatListOption);
+      const selectList =
+          selectionList.injector.get<MatSelectionList>(MatSelectionList).selectedOptions;
+
+      expect(selectList.selected.length).toBe(0);
+
+      dispatchFakeEvent(testListItem1._getHostElement(), 'click');
+      fixture.detectChanges();
+
+      expect(selectList.selected).toEqual([testListItem1]);
+      expect(listOption[1].nativeElement.classList.contains('mat-list-single-selected-option'))
+          .toBe(true);
+
+      dispatchFakeEvent(testListItem2._getHostElement(), 'click');
+      fixture.detectChanges();
+
+      expect(selectList.selected).toEqual([testListItem2]);
+      expect(listOption[1].nativeElement.classList.contains('mat-list-single-selected-option'))
+          .toBe(false);
+      expect(listOption[2].nativeElement.classList.contains('mat-list-single-selected-option'))
+          .toBe(true);
+    });
+
+    it('should not show check boxes', () => {
+      expect(fixture.nativeElement.querySelector('mat-pseudo-checkbox')).toBeFalsy();
+    });
+
+    it('should not deselect the target option on click', () => {
+      const testListItem1 = listOption[1].injector.get<MatListOption>(MatListOption);
+      const selectList =
+          selectionList.injector.get<MatSelectionList>(MatSelectionList).selectedOptions;
+
+      expect(selectList.selected.length).toBe(0);
+
+      dispatchFakeEvent(testListItem1._getHostElement(), 'click');
+      fixture.detectChanges();
+
+      expect(selectList.selected).toEqual([testListItem1]);
+
+      dispatchFakeEvent(testListItem1._getHostElement(), 'click');
+      fixture.detectChanges();
+
+      expect(selectList.selected).toEqual([testListItem1]);
+    });
+
+    it('throws an exception when toggling single/multiple mode after bootstrap', () => {
+      fixture.componentInstance.multiple = true;
+      expect(() => fixture.detectChanges()).toThrow(new Error(
+          'Cannot change `multiple` mode of mat-selection-list after initialization.'));
+    });
+  });
 });
 
 describe('MatSelectionList with forms', () => {
@@ -1255,7 +1339,8 @@ describe('MatSelectionList with forms', () => {
     id="selection-list-1"
     (selectionChange)="onValueChange($event)"
     [disableRipple]="listRippleDisabled"
-    [color]="selectionListColor">
+    [color]="selectionListColor"
+    [multiple]="multiple">
     <mat-list-option checkboxPosition="before" disabled="true" value="inbox"
                      [color]="firstOptionColor">
       Inbox (disabled selection-option)
@@ -1274,6 +1359,7 @@ describe('MatSelectionList with forms', () => {
 class SelectionListWithListOptions {
   showLastOption: boolean = true;
   listRippleDisabled = false;
+  multiple = true;
   selectionListColor: ThemePalette;
   firstOptionColor: ThemePalette;
 

src/material/list/selection-list.ts

@@ -40,6 +40,7 @@ import {
   SimpleChanges,
   ViewChild,
   ViewEncapsulation,
+  isDevMode,
 } from '@angular/core';
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';
 import {
@@ -50,6 +51,7 @@ import {
   setLines,
   ThemePalette,
 } from '@angular/material/core';
+
 import {Subject} from 'rxjs';
 import {takeUntil} from 'rxjs/operators';
 
@@ -108,6 +110,7 @@ export class MatSelectionListChange {
     // be placed inside a parent that has one of the other colors with a higher specificity.
     '[class.mat-accent]': 'color !== "primary" && color !== "warn"',
     '[class.mat-warn]': 'color === "warn"',
+    '[class.mat-list-single-selected-option]': 'selected && !selectionList.multiple',
     '[attr.aria-selected]': 'selected',
     '[attr.aria-disabled]': 'disabled',
   },
@@ -255,7 +258,7 @@ export class MatListOption extends _MatListOptionMixinBase implements AfterConte
   }
 
   _handleClick() {
-    if (!this.disabled) {
+    if (!this.disabled && (this.selectionList.multiple || !this.selected)) {
       this.toggle();
 
       // Emit a change event if the selected state of the option changed through user interaction.
@@ -324,7 +327,7 @@ export class MatListOption extends _MatListOptionMixinBase implements AfterConte
     'class': 'mat-selection-list mat-list-base',
     '(blur)': '_onTouched()',
     '(keydown)': '_keydown($event)',
-    'aria-multiselectable': 'true',
+    '[attr.aria-multiselectable]': 'multiple',
     '[attr.aria-disabled]': 'disabled.toString()',
   },
   template: '<ng-content></ng-content>',
@@ -335,6 +338,8 @@ export class MatListOption extends _MatListOptionMixinBase implements AfterConte
 })
 export class MatSelectionList extends _MatSelectionListMixinBase implements CanDisableRipple,
   AfterContentInit, ControlValueAccessor, OnDestroy, OnChanges {
+  private _multiple = true;
+  private _contentInitialized = false;
 
   /** The FocusKeyManager which handles focus. */
   _keyManager: FocusKeyManager<MatListOption>;
@@ -373,8 +378,25 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements CanD
   }
   private _disabled: boolean = false;
 
+  /** Whether selection is limited to one or multiple items (default multiple). */
+  @Input()
+  get multiple(): boolean { return this._multiple; }
+  set multiple(value: boolean) {
+    const newValue = coerceBooleanProperty(value);
+
+    if (newValue !== this._multiple) {
+      if (isDevMode() && this._contentInitialized) {
+        throw new Error(
+            'Cannot change `multiple` mode of mat-selection-list after initialization.');
+      }
+
+      this._multiple = newValue;
+      this.selectedOptions = new SelectionModel(this._multiple, this.selectedOptions.selected);
+    }
+  }
+
   /** The currently selected options. */
-  selectedOptions: SelectionModel<MatListOption> = new SelectionModel<MatListOption>(true);
+  selectedOptions = new SelectionModel<MatListOption>(this._multiple);
 
   /** View to model callback that should be called whenever the selected options change. */
   private _onChange: (value: any) => void = (_: any) => {};
@@ -397,6 +419,8 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements CanD
   }
 
   ngAfterContentInit(): void {
+    this._contentInitialized = true;
+
     this._keyManager = new FocusKeyManager<MatListOption>(this.options)
       .withWrap()
       .withTypeAhead()
@@ -589,7 +613,7 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements CanD
     if (focusedIndex != null && this._isValidIndex(focusedIndex)) {
       let focusedOption: MatListOption = this.options.toArray()[focusedIndex];
 
-      if (focusedOption && !focusedOption.disabled) {
+      if (focusedOption && !focusedOption.disabled && (this._multiple || !focusedOption.selected)) {
         focusedOption.toggle();
 
         // Emit a change event because the focused option changed its state through user
@@ -642,4 +666,5 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements CanD
 
   static ngAcceptInputType_disabled: BooleanInput;
   static ngAcceptInputType_disableRipple: BooleanInput;
+  static ngAcceptInputType_multiple: BooleanInput;
 }

tools/public_api_guard/material/list.d.ts

@@ -94,6 +94,7 @@ export declare class MatSelectionList extends _MatSelectionListMixinBase impleme
     color: ThemePalette;
     compareWith: (o1: any, o2: any) => boolean;
     disabled: boolean;
+    multiple: boolean;
     options: QueryList<MatListOption>;
     selectedOptions: SelectionModel<MatListOption>;
     readonly selectionChange: EventEmitter<MatSelectionListChange>;
@@ -116,7 +117,8 @@ export declare class MatSelectionList extends _MatSelectionListMixinBase impleme
     writeValue(values: string[]): void;
     static ngAcceptInputType_disableRipple: BooleanInput;
     static ngAcceptInputType_disabled: BooleanInput;
-    static ɵcmp: i0.ɵɵComponentDefWithMeta<MatSelectionList, "mat-selection-list", ["matSelectionList"], { "disableRipple": "disableRipple"; "tabIndex": "tabIndex"; "color": "color"; "compareWith": "compareWith"; "disabled": "disabled"; }, { "selectionChange": "selectionChange"; }, ["options"]>;
+    static ngAcceptInputType_multiple: BooleanInput;
+    static ɵcmp: i0.ɵɵComponentDefWithMeta<MatSelectionList, "mat-selection-list", ["matSelectionList"], { "disableRipple": "disableRipple"; "tabIndex": "tabIndex"; "color": "color"; "compareWith": "compareWith"; "disabled": "disabled"; "multiple": "multiple"; }, { "selectionChange": "selectionChange"; }, ["options"]>;
     static ɵfac: i0.ɵɵFactoryDef<MatSelectionList>;
 }