itsa-utils/lib/idgenerator.js

ITSA's utility functions

"use strict";

var UNDEFINED_NS = "__undefined__",
    namespaces = {};

/**
 * Collection of various utility functions.
 *
 *
 * <i>Copyright (c) 2014 ITSA - https://github.com/itsa</i>
 * New BSD License - http://choosealicense.com/licenses/bsd-3-clause/
 *
 * @module utils
 * @class Utils
 * @static
*/


/**
 * Generates an unique id with the signature: "namespace-follownr"
 *
 * @example
 *
 *     var generator = require("itsa-utils").idGenerator;
 *
 *     console.log(generator()); // --> 1
 *     console.log(generator()); // --> 2
 *     console.log(generator(1000)); // --> 1000
 *     console.log(generator()); // --> 1001
 *     console.log(generator("Parcel, 500")); // -->"Parcel-500"
 *     console.log(generator("Parcel")); // -->"Parcel-501"
 *
 *
 * @method idGenerator
 * @param [namespace] {String} namespace to prepend the generated id.
 *        When ignored, the generator just returns a number.
 * @param [start] {Number} startvalue for the next generated id. Any further generated id"s will preceed this id.
 *        If `start` is lower or equal than the last generated id, it will be ignored.
 * @return {Number|String} an unique id. Either a number, or a String (digit prepended with "namespace-")
 */
module.exports.idGenerator = function(namespace, start) {
	// in case `start` is set at first argument, transform into (null, start)
	(typeof namespace==="number") && (start=namespace) && (namespace=null);
	namespace || (namespace=UNDEFINED_NS);

	if (!namespaces[namespace]) {
		namespaces[namespace] = start || 1;
	}
	else if (start && (namespaces[namespace]<start)) {
		namespaces[namespace] = start;
	}
	return (namespace===UNDEFINED_NS) ? namespaces[namespace]++ : namespace+"-"+namespaces[namespace]++;
};