'use strict';
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/**
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* Converter
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*
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* @param {string|Array} srcAlphabet
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* @param {string|Array} dstAlphabet
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* @constructor
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*/
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function Converter(srcAlphabet, dstAlphabet) {
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if (!srcAlphabet || !dstAlphabet || !srcAlphabet.length || !dstAlphabet.length) {
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throw new Error('Bad alphabet');
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}
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this.srcAlphabet = srcAlphabet;
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this.dstAlphabet = dstAlphabet;
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}
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/**
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* Convert number from source alphabet to destination alphabet
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*
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* @param {string|Array} number - number represented as a string or array of points
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*
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* @returns {string|Array}
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*/
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Converter.prototype.convert = function(number) {
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var i, divide, newlen,
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numberMap = {},
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fromBase = this.srcAlphabet.length,
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toBase = this.dstAlphabet.length,
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length = number.length,
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result = typeof number === 'string' ? '' : [];
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if (!this.isValid(number)) {
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throw new Error('Number "' + number + '" contains of non-alphabetic digits (' + this.srcAlphabet + ')');
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}
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if (this.srcAlphabet === this.dstAlphabet) {
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return number;
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}
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for (i = 0; i < length; i++) {
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numberMap[i] = this.srcAlphabet.indexOf(number[i]);
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}
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do {
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divide = 0;
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newlen = 0;
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for (i = 0; i < length; i++) {
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divide = divide * fromBase + numberMap[i];
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if (divide >= toBase) {
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numberMap[newlen++] = parseInt(divide / toBase, 10);
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divide = divide % toBase;
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} else if (newlen > 0) {
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numberMap[newlen++] = 0;
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}
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}
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length = newlen;
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result = this.dstAlphabet.slice(divide, divide + 1).concat(result);
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} while (newlen !== 0);
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return result;
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};
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/**
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* Valid number with source alphabet
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*
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* @param {number} number
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*
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* @returns {boolean}
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*/
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Converter.prototype.isValid = function(number) {
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var i = 0;
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for (; i < number.length; ++i) {
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if (this.srcAlphabet.indexOf(number[i]) === -1) {
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return false;
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}
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}
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return true;
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};
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module.exports = Converter;
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