luhn-generator/update/node_modules/readable-stream/lib/internal/streams/BufferList.js

A generator of numbers that passes the validation of Luhn algorithm or Luhn formula, also known as the 'modulus 10' or 'mod 10' algorithm

'use strict';

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Buffer = require('safe-buffer').Buffer;
var util = require('util');

function copyBuffer(src, target, offset) {
  src.copy(target, offset);
}

module.exports = function () {
  function BufferList() {
    _classCallCheck(this, BufferList);

    this.head = null;
    this.tail = null;
    this.length = 0;
  }

  BufferList.prototype.push = function push(v) {
    var entry = { data: v, next: null };
    if (this.length > 0) this.tail.next = entry;else this.head = entry;
    this.tail = entry;
    ++this.length;
  };

  BufferList.prototype.unshift = function unshift(v) {
    var entry = { data: v, next: this.head };
    if (this.length === 0) this.tail = entry;
    this.head = entry;
    ++this.length;
  };

  BufferList.prototype.shift = function shift() {
    if (this.length === 0) return;
    var ret = this.head.data;
    if (this.length === 1) this.head = this.tail = null;else this.head = this.head.next;
    --this.length;
    return ret;
  };

  BufferList.prototype.clear = function clear() {
    this.head = this.tail = null;
    this.length = 0;
  };

  BufferList.prototype.join = function join(s) {
    if (this.length === 0) return '';
    var p = this.head;
    var ret = '' + p.data;
    while (p = p.next) {
      ret += s + p.data;
    }return ret;
  };

  BufferList.prototype.concat = function concat(n) {
    if (this.length === 0) return Buffer.alloc(0);
    if (this.length === 1) return this.head.data;
    var ret = Buffer.allocUnsafe(n >>> 0);
    var p = this.head;
    var i = 0;
    while (p) {
      copyBuffer(p.data, ret, i);
      i += p.data.length;
      p = p.next;
    }
    return ret;
  };

  return BufferList;
}();

if (util && util.inspect && util.inspect.custom) {
  module.exports.prototype[util.inspect.custom] = function () {
    var obj = util.inspect({ length: this.length });
    return this.constructor.name + ' ' + obj;
  };
}