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      1 /*
      2 * The contents of this file are subject to the Netscape Public
      3 * License Version 1.1 (the "License"); you may not use this file
      4 * except in compliance with the License. You may obtain a copy of
      5 * the License at http://www.mozilla.org/NPL/
      6 *
      7 * Software distributed under the License is distributed on an "AS
      8 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
      9 * implied. See the License for the specific language governing
     10 * rights and limitations under the License.
     11 *
     12 * The Original Code is mozilla.org code.
     13 *
     14 * The Initial Developer of the Original Code is Netscape
     15 * Communications Corporation.  Portions created by Netscape are
     16 * Copyright (C) 1998 Netscape Communications Corporation. All
     17 * Rights Reserved.
     18 *
     19 * Contributor(s): pschwartau (at) netscape.com
     20 * Date: 14 Mar 2001
     21 *
     22 * SUMMARY: Utility functions for testing objects -
     23 *
     24 * Suppose obj is an instance of a native type, e.g. Number.
     25 * Then obj.toString() invokes Number.prototype.toString().
     26 * We would also like to access Object.prototype.toString().
     27 *
     28 * The difference is this: suppose obj = new Number(7).
     29 * Invoking Number.prototype.toString() on this just returns 7.
     30 * Object.prototype.toString() on this returns '[object Number]'.
     31 *
     32 * The getJSType() function below will return '[object Number]' for us.
     33 * The getJSClass() function returns 'Number', the [[Class]] property of obj.
     34 * See ECMA-262 Edition 3,  13-Oct-1999,  Section 8.6.2
     35 */
     36 //-------------------------------------------------------------------------------------------------
     37 var cnNoObject = 'Unexpected Error!!! Parameter to this function must be an object';
     38 var cnNoClass = 'Unexpected Error!!! Cannot find Class property';
     39 var cnObjectToString = Object.prototype.toString;
     40 
     41 
     42 // checks that it's safe to call findType()
     43 function getJSType(obj)
     44 {
     45   if (isObject(obj))
     46     return findType(obj);
     47   return cnNoObject;
     48 }
     49 
     50 
     51 // checks that it's safe to call findType()
     52 function getJSClass(obj)
     53 {
     54   if (isObject(obj))
     55     return findClass(findType(obj));
     56   return cnNoObject;
     57 }
     58 
     59 
     60 function findType(obj)
     61 {
     62   return cnObjectToString.apply(obj);
     63 }
     64 
     65 
     66 // given '[object Number]',  return 'Number'
     67 function findClass(sType)
     68 {
     69   var re =  /^\[.*\s+(\w+)\s*\]$/;
     70   var a = sType.match(re);
     71 
     72   if (a && a[1])
     73     return a[1];
     74   return cnNoClass;
     75 }
     76 
     77 
     78 function isObject(obj)
     79 {
     80   return obj instanceof Object;
     81 }
     82