111 lines
3.3 KiB
TypeScript
111 lines
3.3 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 {Attribute, Directive, Host, Input, OnInit, TemplateRef, ViewContainerRef} from '@angular/core';
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import {isPresent} from '../facade/lang';
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import {NgLocalization, getPluralCategory} from '../localization';
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import {SwitchView} from './ng_switch';
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/**
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* `ngPlural` is an i18n directive that displays DOM sub-trees that match the switch expression
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* value, or failing that, DOM sub-trees that match the switch expression's pluralization category.
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*
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* To use this directive you must provide a container element that sets the `[ngPlural]` attribute
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* to a
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* switch expression.
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* - Inner elements defined with an `[ngPluralCase]` attribute will display based on their
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* expression.
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* - If `[ngPluralCase]` is set to a value starting with `=`, it will only display if the value
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* matches the switch expression exactly.
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* - Otherwise, the view will be treated as a "category match", and will only display if exact
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* value matches aren't found and the value maps to its category for the defined locale.
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*
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* ```typescript
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* @Component({
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* selector: 'app',
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* // best practice is to define the locale at the application level
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* providers: [{provide: LOCALE_ID, useValue: 'en_US'}]
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* })
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* @View({
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* template: `
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* <p>Value = {{value}}</p>
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* <button (click)="inc()">Increment</button>
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*
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* <div [ngPlural]="value">
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* <template ngPluralCase="=0">there is nothing</template>
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* <template ngPluralCase="=1">there is one</template>
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* <template ngPluralCase="few">there are a few</template>
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* <template ngPluralCase="other">there is some number</template>
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* </div>
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* `,
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* directives: [NgPlural, NgPluralCase]
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* })
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* export class App {
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* value = 'init';
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*
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* inc() {
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* this.value = this.value === 'init' ? 0 : this.value + 1;
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* }
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* }
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*
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* ```
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* @experimental
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*/
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@Directive({selector: '[ngPlural]'})
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export class NgPlural {
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private _switchValue: number;
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private _activeView: SwitchView;
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private _caseViews: {[k: string]: SwitchView} = {};
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constructor(private _localization: NgLocalization) {}
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@Input()
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set ngPlural(value: number) {
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this._switchValue = value;
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this._updateView();
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}
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addCase(value: string, switchView: SwitchView): void { this._caseViews[value] = switchView; }
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/** @internal */
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_updateView(): void {
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this._clearViews();
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var key =
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getPluralCategory(this._switchValue, Object.keys(this._caseViews), this._localization);
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this._activateView(this._caseViews[key]);
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}
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/** @internal */
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_clearViews() {
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if (isPresent(this._activeView)) this._activeView.destroy();
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}
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/** @internal */
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_activateView(view: SwitchView) {
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if (!isPresent(view)) return;
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this._activeView = view;
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this._activeView.create();
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}
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}
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/**
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* @experimental
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*/
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@Directive({selector: '[ngPluralCase]'})
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export class NgPluralCase {
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constructor(
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@Attribute('ngPluralCase') public value: string, template: TemplateRef<Object>,
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viewContainer: ViewContainerRef, @Host() ngPlural: NgPlural) {
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ngPlural.addCase(value, new SwitchView(viewContainer, template));
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}
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}
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