i18n: Add create-i18n function

packages/i18n/CHANGELOG.md

@@ -4,7 +4,7 @@
 
 - Add `isRTL` function  ([#20298](https://github.com/WordPress/gutenberg/pull/20298))
 - Include TypeScript type declarations ([#18942](https://github.com/WordPress/gutenberg/pull/18942))
-
+- Add `createI18n` method to allow creation of multiple i18n instances ([#21182](https://github.com/WordPress/gutenberg/pull/21182))
 
 ## 3.1.0 (2018-11-15)
 

packages/i18n/README.md

@@ -27,6 +27,19 @@ For a complete example, see the [Internationalization section of the Block Edito
 
 <!-- START TOKEN(Autogenerated API docs) -->
 
+<a name="createI18n" href="#createI18n">#</a> **createI18n**
+
+Create an i18n instance
+
+_Parameters_
+
+-   _initialData_ `[LocaleData]`: Locale data configuration.
+-   _initialDomain_ `[string]`: Domain for which configuration applies.
+
+_Returns_
+
+-   `I18n`: I18n instance
+
 <a name="isRTL" href="#isRTL">#</a> **isRTL**
 
 Check if current locale is RTL.

packages/i18n/src/create-i18n.js

@@ -0,0 +1,200 @@
+/**
+ * External dependencies
+ */
+import Tannin from 'tannin';
+
+/**
+ * @typedef {Record<string,any>} LocaleData
+ */
+
+/**
+ * Default locale data to use for Tannin domain when not otherwise provided.
+ * Assumes an English plural forms expression.
+ *
+ * @type {LocaleData}
+ */
+const DEFAULT_LOCALE_DATA = {
+	'': {
+		/** @param {number} n */
+		plural_forms( n ) {
+			return n === 1 ? 0 : 1;
+		},
+	},
+};
+
+/**
+ * An i18n instance
+ *
+ * @typedef {Object} I18n
+ * @property {Function} setLocaleData Merges locale data into the Tannin instance by domain. Accepts data in a
+ *                                    Jed-formatted JSON object shape.
+ * @property {Function} __            Retrieve the translation of text.
+ * @property {Function} _x            Retrieve translated string with gettext context.
+ * @property {Function} _n            Translates and retrieves the singular or plural form based on the supplied
+ *                                    number.
+ * @property {Function} _nx           Translates and retrieves the singular or plural form based on the supplied
+ *                                    number, with gettext context.
+ * @property {Function} isRTL         Check if current locale is RTL.
+ */
+
+/**
+ * Create an i18n instance
+ *
+ * @param {LocaleData} [initialData]    Locale data configuration.
+ * @param {string}     [initialDomain]  Domain for which configuration applies.
+ * @return {I18n}                       I18n instance
+ */
+export const createI18n = ( initialData, initialDomain ) => {
+	/**
+	 * The underlying instance of Tannin to which exported functions interface.
+	 *
+	 * @type {Tannin}
+	 */
+	const tannin = new Tannin( {} );
+
+	/**
+	 * Merges locale data into the Tannin instance by domain. Accepts data in a
+	 * Jed-formatted JSON object shape.
+	 *
+	 * @see http://messageformat.github.io/Jed/
+	 *
+	 * @param {LocaleData} [data]   Locale data configuration.
+	 * @param {string}     [domain] Domain for which configuration applies.
+	 */
+	const setLocaleData = ( data, domain = 'default' ) => {
+		tannin.data[ domain ] = {
+			...DEFAULT_LOCALE_DATA,
+			...tannin.data[ domain ],
+			...data,
+		};
+
+		// Populate default domain configuration (supported locale date which omits
+		// a plural forms expression).
+		tannin.data[ domain ][ '' ] = {
+			...DEFAULT_LOCALE_DATA[ '' ],
+			...tannin.data[ domain ][ '' ],
+		};
+	};
+
+	/**
+	 * Wrapper for Tannin's `dcnpgettext`. Populates default locale data if not
+	 * otherwise previously assigned.
+	 *
+	 * @param {string|undefined} domain   Domain to retrieve the translated text.
+	 * @param {string|undefined} context  Context information for the translators.
+	 * @param {string}           single   Text to translate if non-plural. Used as
+	 *                                    fallback return value on a caught error.
+	 * @param {string}           [plural] The text to be used if the number is
+	 *                                    plural.
+	 * @param {number}           [number] The number to compare against to use
+	 *                                    either the singular or plural form.
+	 *
+	 * @return {string} The translated string.
+	 */
+	const dcnpgettext = (
+		domain = 'default',
+		context,
+		single,
+		plural,
+		number
+	) => {
+		if ( ! tannin.data[ domain ] ) {
+			setLocaleData( undefined, domain );
+		}
+
+		return tannin.dcnpgettext( domain, context, single, plural, number );
+	};
+
+	/**
+	 * Retrieve the translation of text.
+	 *
+	 * @see https://developer.wordpress.org/reference/functions/__/
+	 *
+	 * @param {string} text     Text to translate.
+	 * @param {string} [domain] Domain to retrieve the translated text.
+	 *
+	 * @return {string} Translated text.
+	 */
+	const __ = ( text, domain ) => {
+		return dcnpgettext( domain, undefined, text );
+	};
+
+	/**
+	 * Retrieve translated string with gettext context.
+	 *
+	 * @see https://developer.wordpress.org/reference/functions/_x/
+	 *
+	 * @param {string} text     Text to translate.
+	 * @param {string} context  Context information for the translators.
+	 * @param {string} [domain] Domain to retrieve the translated text.
+	 *
+	 * @return {string} Translated context string without pipe.
+	 */
+	const _x = ( text, context, domain ) => {
+		return dcnpgettext( domain, context, text );
+	};
+
+	/**
+	 * Translates and retrieves the singular or plural form based on the supplied
+	 * number.
+	 *
+	 * @see https://developer.wordpress.org/reference/functions/_n/
+	 *
+	 * @param {string} single   The text to be used if the number is singular.
+	 * @param {string} plural   The text to be used if the number is plural.
+	 * @param {number} number   The number to compare against to use either the
+	 *                          singular or plural form.
+	 * @param {string} [domain] Domain to retrieve the translated text.
+	 *
+	 * @return {string} The translated singular or plural form.
+	 */
+	const _n = ( single, plural, number, domain ) => {
+		return dcnpgettext( domain, undefined, single, plural, number );
+	};
+
+	/**
+	 * Translates and retrieves the singular or plural form based on the supplied
+	 * number, with gettext context.
+	 *
+	 * @see https://developer.wordpress.org/reference/functions/_nx/
+	 *
+	 * @param {string} single   The text to be used if the number is singular.
+	 * @param {string} plural   The text to be used if the number is plural.
+	 * @param {number} number   The number to compare against to use either the
+	 *                          singular or plural form.
+	 * @param {string} context  Context information for the translators.
+	 * @param {string} [domain] Domain to retrieve the translated text.
+	 *
+	 * @return {string} The translated singular or plural form.
+	 */
+	const _nx = ( single, plural, number, context, domain ) => {
+		return dcnpgettext( domain, context, single, plural, number );
+	};
+
+	/**
+	 * Check if current locale is RTL.
+	 *
+	 * **RTL (Right To Left)** is a locale property indicating that text is written from right to left.
+	 * For example, the `he` locale (for Hebrew) specifies right-to-left. Arabic (ar) is another common
+	 * language written RTL. The opposite of RTL, LTR (Left To Right) is used in other languages,
+	 * including English (`en`, `en-US`, `en-GB`, etc.), Spanish (`es`), and French (`fr`).
+	 *
+	 * @return {boolean} Whether locale is RTL.
+	 */
+	const isRTL = () => {
+		return 'rtl' === _x( 'ltr', 'text direction' );
+	};
+
+	if ( initialData ) {
+		setLocaleData( initialData, initialDomain );
+	}
+
+	return {
+		setLocaleData,
+		__,
+		_x,
+		_n,
+		_nx,
+		isRTL,
+	};
+};

packages/i18n/src/default-i18n.js

@@ -0,0 +1,96 @@
+/**
+ * Internal dependencies
+ */
+import { createI18n } from './create-i18n';
+
+const i18n = createI18n();
+
+/*
+ * Comments in this file are duplicated from ./i18n due to
+ * https://github.com/WordPress/gutenberg/pull/20318#issuecomment-590837722
+ */
+
+/**
+ * @typedef {import('./create-i18n').LocaleData} LocaleData
+ */
+
+/**
+ * Merges locale data into the Tannin instance by domain. Accepts data in a
+ * Jed-formatted JSON object shape.
+ *
+ * @see http://messageformat.github.io/Jed/
+ *
+ * @param {LocaleData} [data]   Locale data configuration.
+ * @param {string}     [domain] Domain for which configuration applies.
+ */
+export const setLocaleData = i18n.setLocaleData.bind( i18n );
+
+/**
+ * Retrieve the translation of text.
+ *
+ * @see https://developer.wordpress.org/reference/functions/__/
+ *
+ * @param {string} text     Text to translate.
+ * @param {string} [domain] Domain to retrieve the translated text.
+ *
+ * @return {string} Translated text.
+ */
+export const __ = i18n.__.bind( i18n );
+
+/**
+ * Retrieve translated string with gettext context.
+ *
+ * @see https://developer.wordpress.org/reference/functions/_x/
+ *
+ * @param {string} text     Text to translate.
+ * @param {string} context  Context information for the translators.
+ * @param {string} [domain] Domain to retrieve the translated text.
+ *
+ * @return {string} Translated context string without pipe.
+ */
+export const _x = i18n._x.bind( i18n );
+
+/**
+ * Translates and retrieves the singular or plural form based on the supplied
+ * number.
+ *
+ * @see https://developer.wordpress.org/reference/functions/_n/
+ *
+ * @param {string} single   The text to be used if the number is singular.
+ * @param {string} plural   The text to be used if the number is plural.
+ * @param {number} number   The number to compare against to use either the
+ *                          singular or plural form.
+ * @param {string} [domain] Domain to retrieve the translated text.
+ *
+ * @return {string} The translated singular or plural form.
+ */
+export const _n = i18n._n.bind( i18n );
+
+/**
+ * Translates and retrieves the singular or plural form based on the supplied
+ * number, with gettext context.
+ *
+ * @see https://developer.wordpress.org/reference/functions/_nx/
+ *
+ * @param {string} single   The text to be used if the number is singular.
+ * @param {string} plural   The text to be used if the number is plural.
+ * @param {number} number   The number to compare against to use either the
+ *                          singular or plural form.
+ * @param {string} context  Context information for the translators.
+ * @param {string} [domain] Domain to retrieve the translated text.
+ *
+ * @return {string} The translated singular or plural form.
+ */
+export const _nx = i18n._nx.bind( i18n );
+
+/**
+ * Check if current locale is RTL.
+ *
+ * **RTL (Right To Left)** is a locale property indicating that text is written from right to left.
+ * For example, the `he` locale (for Hebrew) specifies right-to-left. Arabic (ar) is another common
+ * language written RTL. The opposite of RTL, LTR (Left To Right) is used in other languages,
+ * including English (`en`, `en-US`, `en-GB`, etc.), Spanish (`es`), and French (`fr`).
+ *
+ * @return {boolean} Whether locale is RTL.
+ */
+export const isRTL = i18n.isRTL.bind( i18n );