angular/modules/@angular/common/src/pipes/i18n_plural_pipe.ts
2016-07-07 08:48:37 -07:00

76 lines
2.0 KiB
TypeScript

/**
* @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 {Pipe, PipeTransform} from '@angular/core';
import {StringWrapper, isBlank, isStringMap} from '../facade/lang';
import {NgLocalization, getPluralCategory} from '../localization';
import {InvalidPipeArgumentException} from './invalid_pipe_argument_exception';
const _INTERPOLATION_REGEXP: RegExp = /#/g;
/**
* Maps a value to a string that pluralizes the value properly.
*
* ## Usage
*
* expression | i18nPlural:mapping
*
* where `expression` is a number and `mapping` is an object that mimics the ICU format,
* see http://userguide.icu-project.org/formatparse/messages
*
* ## Example
*
* ```
* class MyLocalization extends NgLocalization {
* getPluralCategory(value: any) {
* if(value > 1) {
* return 'other';
* }
* }
* }
*
* @Component({
* selector: 'app',
* template: `
* <div>
* {{ messages.length | i18nPlural: messageMapping }}
* </div>
* `,
* providers: [{provide: NgLocalization, useClass: MyLocalization}]
* })
*
* class MyApp {
* messages: any[];
* messageMapping: {[k:string]: string} = {
* '=0': 'No messages.',
* '=1': 'One message.',
* 'other': '# messages.'
* }
* ...
* }
* ```
*
* @experimental
*/
@Pipe({name: 'i18nPlural', pure: true})
export class I18nPluralPipe implements PipeTransform {
constructor(private _localization: NgLocalization) {}
transform(value: number, pluralMap: {[count: string]: string}): string {
if (isBlank(value)) return '';
if (!isStringMap(pluralMap)) {
throw new InvalidPipeArgumentException(I18nPluralPipe, pluralMap);
}
const key = getPluralCategory(value, Object.getOwnPropertyNames(pluralMap), this._localization);
return StringWrapper.replaceAll(pluralMap[key], _INTERPOLATION_REGEXP, value.toString());
}
}