import UnsupportedOperationException from '../UnsupportedOperationException';
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import CharacterSetECI from '../common/CharacterSetECI';
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/**
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* Responsible for en/decoding strings.
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*/
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export default class StringEncoding {
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/**
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* Decodes some Uint8Array to a string format.
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*/
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static decode(bytes, encoding) {
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const encodingName = this.encodingName(encoding);
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if (this.customDecoder) {
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return this.customDecoder(bytes, encodingName);
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}
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// Increases browser support.
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if (typeof TextDecoder === 'undefined' || this.shouldDecodeOnFallback(encodingName)) {
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return this.decodeFallback(bytes, encodingName);
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}
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return new TextDecoder(encodingName).decode(bytes);
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}
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/**
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* Checks if the decoding method should use the fallback for decoding
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* once Node TextDecoder doesn't support all encoding formats.
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*
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* @param encodingName
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*/
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static shouldDecodeOnFallback(encodingName) {
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return !StringEncoding.isBrowser() && encodingName === 'ISO-8859-1';
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}
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/**
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* Encodes some string into a Uint8Array.
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*/
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static encode(s, encoding) {
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const encodingName = this.encodingName(encoding);
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if (this.customEncoder) {
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return this.customEncoder(s, encodingName);
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}
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// Increases browser support.
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if (typeof TextEncoder === 'undefined') {
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return this.encodeFallback(s);
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}
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// TextEncoder only encodes to UTF8 by default as specified by encoding.spec.whatwg.org
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return new TextEncoder().encode(s);
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}
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static isBrowser() {
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return (typeof window !== 'undefined' && {}.toString.call(window) === '[object Window]');
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}
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/**
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* Returns the string value from some encoding character set.
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*/
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static encodingName(encoding) {
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return typeof encoding === 'string'
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? encoding
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: encoding.getName();
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}
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/**
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* Returns character set from some encoding character set.
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*/
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static encodingCharacterSet(encoding) {
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if (encoding instanceof CharacterSetECI) {
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return encoding;
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}
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return CharacterSetECI.getCharacterSetECIByName(encoding);
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}
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/**
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* Runs a fallback for the native decoding funcion.
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*/
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static decodeFallback(bytes, encoding) {
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const characterSet = this.encodingCharacterSet(encoding);
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if (StringEncoding.isDecodeFallbackSupported(characterSet)) {
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let s = '';
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for (let i = 0, length = bytes.length; i < length; i++) {
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let h = bytes[i].toString(16);
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if (h.length < 2) {
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h = '0' + h;
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}
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s += '%' + h;
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}
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return decodeURIComponent(s);
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}
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if (characterSet.equals(CharacterSetECI.UnicodeBigUnmarked)) {
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return String.fromCharCode.apply(null, new Uint16Array(bytes.buffer));
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}
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throw new UnsupportedOperationException(`Encoding ${this.encodingName(encoding)} not supported by fallback.`);
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}
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static isDecodeFallbackSupported(characterSet) {
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return characterSet.equals(CharacterSetECI.UTF8) ||
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characterSet.equals(CharacterSetECI.ISO8859_1) ||
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characterSet.equals(CharacterSetECI.ASCII);
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}
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/**
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* Runs a fallback for the native encoding funcion.
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*
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* @see https://stackoverflow.com/a/17192845/4367683
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*/
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static encodeFallback(s) {
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const encodedURIstring = btoa(unescape(encodeURIComponent(s)));
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const charList = encodedURIstring.split('');
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const uintArray = [];
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for (let i = 0; i < charList.length; i++) {
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uintArray.push(charList[i].charCodeAt(0));
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}
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return new Uint8Array(uintArray);
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}
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}
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