michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0:  * Date: 14 Mar 2001
michael@0:  *
michael@0:  * SUMMARY: Utility functions for testing objects -
michael@0:  *
michael@0:  * Suppose obj is an instance of a native type, e.g. Number.
michael@0:  * Then obj.toString() invokes Number.prototype.toString().
michael@0:  * We would also like to access Object.prototype.toString().
michael@0:  *
michael@0:  * The difference is this: suppose obj = new Number(7).
michael@0:  * Invoking Number.prototype.toString() on this just returns 7.
michael@0:  * Object.prototype.toString() on this returns '[object Number]'.
michael@0:  *
michael@0:  * The getJSType() function below will return '[object Number]' for us.
michael@0:  * The getJSClass() function returns 'Number', the [[Class]] property of obj.
michael@0:  * See ECMA-262 Edition 3,  13-Oct-1999,  Section 8.6.2 
michael@0:  */
michael@0: //-----------------------------------------------------------------------------
michael@0: 
michael@0: 
michael@0: var cnNoObject = 'Unexpected Error!!! Parameter to this function must be an object';
michael@0: var cnNoClass = 'Unexpected Error!!! Cannot find Class property';
michael@0: var cnObjectToString = Object.prototype.toString;
michael@0: var GLOBAL = 'global';
michael@0: 
michael@0: // checks that it's safe to call findType()
michael@0: function getJSType(obj)
michael@0: {
michael@0:   if (isObject(obj))
michael@0:     return findType(obj);
michael@0:   return cnNoObject;
michael@0: }
michael@0: 
michael@0: 
michael@0: // checks that it's safe to call findType()
michael@0: function getJSClass(obj)
michael@0: {
michael@0:   if (isObject(obj))
michael@0:     return findClass(findType(obj));
michael@0:   return cnNoObject;
michael@0: }
michael@0: 
michael@0: 
michael@0: function findType(obj)
michael@0: {
michael@0:   return cnObjectToString.apply(obj);
michael@0: }
michael@0: 
michael@0: 
michael@0: // given '[object Number]',  return 'Number'
michael@0: function findClass(sType)
michael@0: {
michael@0:   var re =  /^\[.*\s+(\w+)\s*\]$/;
michael@0:   var a = sType.match(re);
michael@0:  
michael@0:   if (a && a[1])
michael@0:     return a[1];
michael@0:   return cnNoClass;
michael@0: }
michael@0: 
michael@0: 
michael@0: function isObject(obj)
michael@0: {
michael@0:   return obj instanceof Object;
michael@0: }
michael@0: