44 lines
2.1 KiB
Plaintext
44 lines
2.1 KiB
Plaintext
/*
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* Copyright 2020 Adobe. All rights reserved.
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* This file is licensed to you under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License. You may obtain a copy
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* of the License at http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under
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* the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
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* OF ANY KIND, either express or implied. See the License for the specific language
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* governing permissions and limitations under the License.
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*/
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// https://en.wikipedia.org/wiki/Right-to-left
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const RTL_SCRIPTS = new Set(['Arab', 'Syrc', 'Samr', 'Mand', 'Thaa', 'Mend', 'Nkoo', 'Adlm', 'Rohg', 'Hebr']);
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const RTL_LANGS = new Set(['ae', 'ar', 'arc', 'bcc', 'bqi', 'ckb', 'dv', 'fa', 'glk', 'he', 'ku', 'mzn', 'nqo', 'pnb', 'ps', 'sd', 'ug', 'ur', 'yi']);
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/**
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* Determines if a locale is read right to left using [Intl.Locale]{@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale}.
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*/
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export function isRTL(localeString: string): boolean {
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// If the Intl.Locale API is available, use it to get the locale's text direction.
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if (Intl.Locale) {
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let locale = new Intl.Locale(localeString).maximize();
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// Use the text info object to get the direction if possible.
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// @ts-ignore - this was implemented as a property by some browsers before it was standardized as a function.
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// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getTextInfo
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let textInfo = typeof locale.getTextInfo === 'function' ? locale.getTextInfo() : locale.textInfo;
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if (textInfo) {
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return textInfo.direction === 'rtl';
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}
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// Fallback: guess using the script.
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// This is more accurate than guessing by language, since languages can be written in multiple scripts.
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if (locale.script) {
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return RTL_SCRIPTS.has(locale.script);
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}
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}
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// If not, just guess by the language (first part of the locale)
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let lang = localeString.split('-')[0];
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return RTL_LANGS.has(lang);
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}
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