@nuintun/qrcode/esm/encoder/segments/Alphanumeric.js

A pure JavaScript QRCode encode and decode library.

/**
 * @module QRCode
 * @package @nuintun/qrcode
 * @license MIT
 * @version 5.0.2
 * @author nuintun <nuintun@qq.com>
 * @description A pure JavaScript QRCode encode and decode library.
 * @see https://github.com/nuintun/qrcode#readme
 */

import { Mode } from '../../common/Mode.js';
import { BitArray } from '../../common/BitArray.js';
import { assertContent } from '../utils/asserts.js';
import { ALPHANUMERIC_MAPPING } from '../../common/encoding/mapping.js';

/**
 * @module Alphanumeric
 */
function getAlphanumericCode(character) {
  const code = ALPHANUMERIC_MAPPING.get(character);
  if (code != null) {
    return code;
  }
  throw new Error(`illegal alphanumeric character: ${character}`);
}
class Alphanumeric {
  #content;
  /**
   * @constructor
   * @param content The content to encode.
   */
  constructor(content) {
    assertContent(content);
    this.#content = content;
  }
  /**
   * @property mode
   * @description The mode of the segment.
   */
  get mode() {
    return Mode.ALPHANUMERIC;
  }
  /**
   * @property content
   * @description The content of the segment.
   */
  get content() {
    return this.#content;
  }
  /**
   * @method encode
   * @description Encode the segment.
   */
  encode() {
    const bits = new BitArray();
    const content = Array.from(this.#content);
    const { length } = content;
    for (let i = 0; i < length; ) {
      const code1 = getAlphanumericCode(content[i]);
      if (i + 1 < length) {
        const code2 = getAlphanumericCode(content[i + 1]);
        // Encode two alphanumeric letters in 11 bits.
        bits.append(code1 * 45 + code2, 11);
        i += 2;
      } else {
        // Encode one alphanumeric letter in six bits.
        bits.append(code1, 6);
        i++;
      }
    }
    return bits;
  }
}

export { Alphanumeric };