@nuintun/qrcode/esm/encoder/segments/Numeric.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 { NUMERIC_MAPPING } from '../../common/encoding/mapping.js';

/**
 * @module Numeric
 */
function getNumericCode(character) {
  const code = NUMERIC_MAPPING.get(character);
  if (code != null) {
    return code;
  }
  throw new Error(`illegal numeric character: ${character}`);
}
class Numeric {
  #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.NUMERIC;
  }
  /**
   * @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 = getNumericCode(content[i]);
      if (i + 2 < length) {
        // Encode three numeric letters in ten bits.
        const code2 = getNumericCode(content[i + 1]);
        const code3 = getNumericCode(content[i + 2]);
        bits.append(code1 * 100 + code2 * 10 + code3, 10);
        i += 3;
      } else if (i + 1 < length) {
        // Encode two numeric letters in seven bits.
        const code2 = getNumericCode(content[i + 1]);
        bits.append(code1 * 10 + code2, 7);
        i += 2;
      } else {
        // Encode one numeric letter in four bits.
        bits.append(code1, 4);
        i++;
      }
    }
    return bits;
  }
}

export { Numeric };