/**
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* Set of CharsetEncoders for a given input string
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*
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* Invariants:
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* - The list contains only encoders from CharacterSetECI (list is shorter then the list of encoders available on
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* the platform for which ECI values are defined).
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* - The list contains encoders at least one encoder for every character in the input.
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* - The first encoder in the list is always the ISO-8859-1 encoder even of no character in the input can be encoded
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* by it.
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* - If the input contains a character that is not in ISO-8859-1 then the last two entries in the list will be the
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* UTF-8 encoder and the UTF-16BE encoder.
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*
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* @author Alex Geller
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*/
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import Charset from '../util/Charset';
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import StandardCharsets from '../util/StandardCharsets';
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import StringEncoding from '../util/StringEncoding';
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import StringUtils from './StringUtils';
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class CharsetEncoder {
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constructor(charset) {
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this.charset = charset;
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this.name = charset.name;
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}
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canEncode(c) {
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try {
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return StringEncoding.encode(c, this.charset) != null;
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}
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catch (ex) {
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return false;
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}
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}
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}
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export class ECIEncoderSet {
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/**
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* Constructs an encoder set
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*
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* @param stringToEncode the string that needs to be encoded
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* @param priorityCharset The preferred {@link Charset} or null.
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* @param fnc1 fnc1 denotes the character in the input that represents the FNC1 character or -1 for a non-GS1 bar
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* code. When specified, it is considered an error to pass it as argument to the methods canEncode() or encode().
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*/
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constructor(stringToEncode, priorityCharset, fnc1) {
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this.ENCODERS = [
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'IBM437',
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'ISO-8859-2',
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'ISO-8859-3',
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'ISO-8859-4',
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'ISO-8859-5',
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'ISO-8859-6',
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'ISO-8859-7',
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'ISO-8859-8',
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'ISO-8859-9',
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'ISO-8859-10',
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'ISO-8859-11',
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'ISO-8859-13',
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'ISO-8859-14',
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'ISO-8859-15',
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'ISO-8859-16',
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'windows-1250',
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'windows-1251',
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'windows-1252',
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'windows-1256',
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'Shift_JIS',
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].map(name => new CharsetEncoder(Charset.forName(name)));
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this.encoders = [];
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const neededEncoders = [];
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// we always need the ISO-8859-1 encoder. It is the default encoding
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neededEncoders.push(new CharsetEncoder(StandardCharsets.ISO_8859_1));
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let needUnicodeEncoder = priorityCharset != null && priorityCharset.name.startsWith('UTF');
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// Walk over the input string and see if all characters can be encoded with the list of encoders
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for (let i = 0; i < stringToEncode.length; i++) {
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let canEncode = false;
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for (const encoder of neededEncoders) {
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const singleCharacter = stringToEncode.charAt(i);
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const c = singleCharacter.charCodeAt(0);
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if (c === fnc1 || encoder.canEncode(singleCharacter)) {
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canEncode = true;
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break;
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}
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}
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if (!canEncode) {
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// for the character at position i we don't yet have an encoder in the list
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for (const encoder of this.ENCODERS) {
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if (encoder.canEncode(stringToEncode.charAt(i))) {
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// Good, we found an encoder that can encode the character. We add him to the list and continue scanning
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// the input
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neededEncoders.push(encoder);
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canEncode = true;
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break;
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}
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}
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}
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if (!canEncode) {
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// The character is not encodeable by any of the single byte encoders so we remember that we will need a
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// Unicode encoder.
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needUnicodeEncoder = true;
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}
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}
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if (neededEncoders.length === 1 && !needUnicodeEncoder) {
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// the entire input can be encoded by the ISO-8859-1 encoder
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this.encoders = [neededEncoders[0]];
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}
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else {
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// we need more than one single byte encoder or we need a Unicode encoder.
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// In this case we append a UTF-8 and UTF-16 encoder to the list
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this.encoders = [];
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let index = 0;
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for (const encoder of neededEncoders) {
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this.encoders[index++] = encoder;
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}
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// this.encoders[index] = new CharsetEncoder(StandardCharsets.UTF_8);
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// this.encoders[index + 1] = new CharsetEncoder(StandardCharsets.UTF_16BE);
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}
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// Compute priorityEncoderIndex by looking up priorityCharset in encoders
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let priorityEncoderIndexValue = -1;
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if (priorityCharset != null) {
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for (let i = 0; i < this.encoders.length; i++) {
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if (this.encoders[i] != null &&
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priorityCharset.name === this.encoders[i].name) {
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priorityEncoderIndexValue = i;
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break;
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}
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}
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}
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this.priorityEncoderIndex = priorityEncoderIndexValue;
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// invariants
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// if(this?.encoders?.[0].name !== StandardCharsets.ISO_8859_1)){
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// throw new Error("ISO-8859-1 must be the first encoder");
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// }
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}
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length() {
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return this.encoders.length;
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}
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getCharsetName(index) {
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if (!(index < this.length())) {
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throw new Error('index must be less than length');
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}
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return this.encoders[index].name;
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}
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getCharset(index) {
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if (!(index < this.length())) {
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throw new Error('index must be less than length');
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}
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return this.encoders[index].charset;
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}
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getECIValue(encoderIndex) {
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return this.encoders[encoderIndex].charset.getValueIdentifier();
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}
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/*
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* returns -1 if no priority charset was defined
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*/
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getPriorityEncoderIndex() {
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return this.priorityEncoderIndex;
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}
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canEncode(c, encoderIndex) {
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if (!(encoderIndex < this.length())) {
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throw new Error('index must be less than length');
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}
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return true;
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}
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encode(c, encoderIndex) {
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if (!(encoderIndex < this.length())) {
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throw new Error('index must be less than length');
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}
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return StringEncoding.encode(StringUtils.getCharAt(c), this.encoders[encoderIndex].name);
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}
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}
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