Enum

Enum.js

//FIXME: This is not released yet. https://github.com/mdevils/node-jscs/pull/548
/* jscs: disable disallowDanglingUnderscores */

/**
 * A module representing the Enum data type.
 * @module utilities/types/Enum
 */

"use strict";

var _                     = require("lodash"),
    FunctionCallError     = require("../errors").FunctionCallError,
    MissingParameterError = FunctionCallError.MissingParameterError,
    InvalidParameterError = FunctionCallError.InvalidParameterError;

/**
 * Enumeration of values. Often used to describle possible values of a state
 * variable.
 * @param {Array} values Array of Strings that will be assigned a value in
 *                       order. (Starting at 0)
 */
function Enum(values) {
  if (_.isUndefined(values)) {
    throw new MissingParameterError(
      null,
      "You need to instanciate Enum with an Array of Strings."
    );
  }

  if (!_.isArray(values)) {
    throw new InvalidParameterError(
      null,
      "You need to instanciate Enum with an Array of Strings.",
      values
    );
  }

  var self = this;

  this._values = values;
  this.length = this._values.length;

  _.forEach(this._values, function (value, index) {
    self[value] = index;
  });

  Object.freeze(this);
}

/**
 * Returns the maximum possible value for the Enum.
 * @return {Number} Biggest value in the Enum. (Last one)
 */
Enum.prototype.getMax = function () {
  return this.length - 1;
};

/**
 * Returns the original Array provided to create the Enum.
 * @return {Array} Array of Strings initially provided to the constructor.
 */
Enum.prototype.getList = function () {
  return this._values;
};

/**
 * Returns mapping of the Enum keys with their associated numerical value.
 * @return {Object} Object literal with the Enum values mapping.
 */
Enum.prototype.getValues = function () {
  var self = this;

  return this._values.map(function (value) {
    return self[value];
  });
};
/* jscs: enable */