common-errors/lib/helpers/class-generator.js

Common error classes and utility functions

var globalize = require('../internal/globalize');

module.exports = function generateErrorClass(name, options){
  options = options || {};
  if(options.subclass) console.warn("options.subclass is deprecated. use options.extends instead.");
  options.extends = options.extends || options.subclass || Error;
  options.args = options.args || ['message', 'inner_error'];
  options.generateMessage = options.generateMessage || null;
  options.globalize = options.globalize === false ? false : true;

  validateInput(name);
  validateArrayInput(options.args);

  var classConstructor = function classConstructor(){
    if(this.global_initialize) this.global_initialize(Class);

    this.args = arguments;
    for(var i = 0; i<options.args.length; i++){
      this[options.args[i]] = arguments[i];
    }
    this.name = name;
    if(this.generateMessage) this.message = this.generateMessage();
    Class.captureStackTrace(this, Class);
  };

  var classGeneratorFn = new Function('classConstructor', [
    "return function ", name, "(", options.args.join(', '), "){",
      "if(!(this instanceof ", name, ")) {",
        "var instance = Object.create(", name, ".prototype);",
        "classConstructor.apply(instance, arguments);",
        "return instance;",
      "} else {",
        "classConstructor.apply(this, arguments);",
      "}",
    "};",
  ].join(''));
  var Class = classGeneratorFn(classConstructor);

  Class.prototype = Object.create(options.extends.prototype);
  Class.prototype.constructor = Class;
  Class.super_ = options.extends; // Backwards compatible with util.inherits implementation

  Class.prototype.generateMessage = options.generateMessage;

  Class.captureStackTrace = function captureStackTrace(error, error_class){
    Error.captureStackTrace(error, error_class);
    if(error.inner_error && error.inner_error.stack) error.stack += "\n--- inner error ---\n" + error.inner_error.stack;
  }

  if(options.globalize) globalize(Class);
  return Class;
}

var validateInput = function validateInput(str){
  if(typeof str != 'string' || !/^[\-\w]+$/.test(str)) throw new Error("Unsafe or invalid string '" + (str || '').toString() + "' used to generate Error class.");
}
var validateArrayInput = function validateArrayInput(array){
  if(!array || !Array.isArray(array)) throw new Error("Unsafe or invalid args used to generate Error class.");
  for(var i = 0; i<array.length; i++) validateInput(array[i]);
}