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1'use strict'2 3/**4 * DefaultMessageAllocator constructor5 * @constructor6 */7function DefaultMessageIdProvider () {8  if (!(this instanceof DefaultMessageIdProvider)) {9    return new DefaultMessageIdProvider()10  }11 12  /**13   * MessageIDs starting with 114   * ensure that nextId is min. 1, see https://github.com/mqttjs/MQTT.js/issues/81015   */16  this.nextId = Math.max(1, Math.floor(Math.random() * 65535))17}18 19/**20 * allocate21 *22 * Get the next messageId.23 * @return unsigned int24 */25DefaultMessageIdProvider.prototype.allocate = function () {26  // id becomes current state of this.nextId and increments afterwards27  const id = this.nextId++28  // Ensure 16 bit unsigned int (max 65535, nextId got one higher)29  if (this.nextId === 65536) {30    this.nextId = 131  }32  return id33}34 35/**36 * getLastAllocated37 * Get the last allocated messageId.38 * @return unsigned int39 */40DefaultMessageIdProvider.prototype.getLastAllocated = function () {41  return (this.nextId === 1) ? 65535 : (this.nextId - 1)42}43 44/**45 * register46 * Register messageId. If success return true, otherwise return false.47 * @param { unsigned int } - messageId to register,48 * @return boolean49 */50DefaultMessageIdProvider.prototype.register = function (messageId) {51  return true52}53 54/**55 * deallocate56 * Deallocate messageId.57 * @param { unsigned int } - messageId to deallocate,58 */59DefaultMessageIdProvider.prototype.deallocate = function (messageId) {60}61 62/**63 * clear64 * Deallocate all messageIds.65 */66DefaultMessageIdProvider.prototype.clear = function () {67}68 69module.exports = DefaultMessageIdProvider70