feat(ivy): use i18n locale data to determine the plural form of ICU expressions (#29249)

Plural ICU expressions depend on the locale (different languages have different plural forms). Until now the locale was hard coded as `en-US`.
For compatibility reasons, if you use ivy with AOT and bootstrap your app with `bootstrapModule` then the `LOCALE_ID` token will be set automatically for ivy, which is then used to get the correct plural form.
If you use JIT, you need to define the `LOCALE_ID` provider on the module that you bootstrap.
For `TestBed` you can use either `configureTestingModule` or `overrideProvider` to define that provider.
If you don't use the compat mode and start your app with `renderComponent` you need to call `ɵsetLocaleId` manually to define the `LOCALE_ID` before bootstrap. We expect this to change once we start adding the new i18n APIs, so don't rely on this function (there's a reason why it's a private export).
PR Close #29249

packages/common/src/i18n/locale_data.ts

@@ -6,10 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-/**
- * @publicApi
- */
-export const LOCALE_DATA: {[localeId: string]: any} = {};
+import {ɵLOCALE_DATA as LOCALE_DATA, ɵLocaleDataIndex as LocaleDataIndex} from '@angular/core';
 
 /**
  * Register global data to be used internally by Angular. See the
@@ -33,32 +30,6 @@ export function registerLocaleData(data: any, localeId?: string | any, extraData
   }
 }
 
-/**
- * Index of each type of locale data from the locale data array
- */
-export const enum LocaleDataIndex {
-  LocaleId = 0,
-  DayPeriodsFormat,
-  DayPeriodsStandalone,
-  DaysFormat,
-  DaysStandalone,
-  MonthsFormat,
-  MonthsStandalone,
-  Eras,
-  FirstDayOfWeek,
-  WeekendRange,
-  DateFormat,
-  TimeFormat,
-  DateTimeFormat,
-  NumberSymbols,
-  NumberFormats,
-  CurrencySymbol,
-  CurrencyName,
-  Currencies,
-  PluralCase,
-  ExtraData
-}
-
 /**
  * Index of each type of locale data from the extra locale data array
  */

packages/common/src/i18n/locale_data_api.ts

@@ -6,9 +6,9 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import localeEn from './locale_en';
-import {LOCALE_DATA, LocaleDataIndex, ExtraLocaleDataIndex, CurrencyIndex} from './locale_data';
+import {ɵLocaleDataIndex as LocaleDataIndex, ɵfindLocaleData as findLocaleData, ɵgetLocalePluralCase} from '@angular/core';
 import {CURRENCIES_EN, CurrenciesSymbols} from './currencies';
+import {CurrencyIndex, ExtraLocaleDataIndex} from './locale_data';
 
 /**
  * Format styles that can be used to represent numbers.
@@ -31,7 +31,8 @@ export enum NumberFormatStyle {
  * @see `NgPluralCase`
  * @see [Internationalization (i18n) Guide](https://angular.io/guide/i18n)
  *
- * @publicApi */
+ * @publicApi
+ */
 export enum Plural {
   Zero = 0,
   One = 1,
@@ -485,19 +486,11 @@ function getLocaleCurrencies(locale: string): {[code: string]: CurrenciesSymbols
 }
 
 /**
- * Retrieves the plural function used by ICU expressions to determine the plural case to use
- * for a given locale.
- * @param locale A locale code for the locale format rules to use.
- * @returns The plural function for the locale.
- * @see `NgPlural`
- * @see [Internationalization (i18n) Guide](https://angular.io/guide/i18n)
- *
+ * @alias core/ɵgetLocalePluralCase
  * @publicApi
  */
-export function getLocalePluralCase(locale: string): (value: number) => Plural {
-  const data = findLocaleData(locale);
-  return data[LocaleDataIndex.PluralCase];
-}
+export const getLocalePluralCase: (locale: string) => ((value: number) => Plural) =
+    ɵgetLocalePluralCase;
 
 function checkFullData(data: any) {
   if (!data[LocaleDataIndex.ExtraData]) {
@@ -609,37 +602,7 @@ function extractTime(time: string): Time {
   return {hours: +h, minutes: +m};
 }
 
-/**
- * Finds the locale data for a given locale.
- *
- * @param locale The locale code.
- * @returns The locale data.
- * @see [Internationalization (i18n) Guide](https://angular.io/guide/i18n)
- *
- * @publicApi
- */
-export function findLocaleData(locale: string): any {
-  const normalizedLocale = locale.toLowerCase().replace(/_/g, '-');
 
-  let match = LOCALE_DATA[normalizedLocale];
-  if (match) {
-    return match;
-  }
-
-  // let's try to find a parent locale
-  const parentLocale = normalizedLocale.split('-')[0];
-  match = LOCALE_DATA[parentLocale];
-
-  if (match) {
-    return match;
-  }
-
-  if (parentLocale === 'en') {
-    return localeEn;
-  }
-
-  throw new Error(`Missing locale data for the locale "${locale}".`);
-}
 
 /**
  * Retrieves the currency symbol for a given currency code.

packages/common/src/i18n/locale_en.ts

@@ -1,41 +0,0 @@
-/**
- * @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
- */
-
-// THIS CODE IS GENERATED - DO NOT MODIFY
-// See angular/tools/gulp-tasks/cldr/extract.js
-
-const u = undefined;
-
-function plural(n: number): number {
-  let i = Math.floor(Math.abs(n)), v = n.toString().replace(/^[^.]*\.?/, '').length;
-  if (i === 1 && v === 0) return 1;
-  return 5;
-}
-
-export default [
-  'en', [['a', 'p'], ['AM', 'PM'], u], [['AM', 'PM'], u, u],
-  [
-    ['S', 'M', 'T', 'W', 'T', 'F', 'S'], ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
-    ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
-    ['Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa']
-  ],
-  u,
-  [
-    ['J', 'F', 'M', 'A', 'M', 'J', 'J', 'A', 'S', 'O', 'N', 'D'],
-    ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
-    [
-      'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September',
-      'October', 'November', 'December'
-    ]
-  ],
-  u, [['B', 'A'], ['BC', 'AD'], ['Before Christ', 'Anno Domini']], 0, [6, 0],
-  ['M/d/yy', 'MMM d, y', 'MMMM d, y', 'EEEE, MMMM d, y'],
-  ['h:mm a', 'h:mm:ss a', 'h:mm:ss a z', 'h:mm:ss a zzzz'], ['{1}, {0}', u, '{1} \'at\' {0}', u],
-  ['.', ',', ';', '%', '+', '-', 'E', '×', '‰', '∞', 'NaN', ':'],
-  ['#,##0.###', '#,##0%', '¤#,##0.00', '#E0'], '$', 'US Dollar', {}, plural
-];