lib/dojo/AdapterRegistry.js

   1 /*
   2         Copyright (c) 2004-2011, The Dojo Foundation All Rights Reserved.
   3         Available via Academic Free License >= 2.1 OR the modified BSD license.
   4         see: http://dojotoolkit.org/license for details
   5 */
   6
   7
   8 if(!dojo._hasResource["dojo.AdapterRegistry"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
   9 dojo._hasResource["dojo.AdapterRegistry"] = true;
  10 dojo.provide("dojo.AdapterRegistry");
  11
  12
  13 dojo.AdapterRegistry = function(/*Boolean?*/ returnWrappers){
  14         //      summary:
  15         //              A registry to make contextual calling/searching easier.
  16         //      description:
  17         //              Objects of this class keep list of arrays in the form [name, check,
  18         //              wrap, directReturn] that are used to determine what the contextual
  19         //              result of a set of checked arguments is. All check/wrap functions
  20         //              in this registry should be of the same arity.
  21         //      example:
  22         //      |       // create a new registry
  23         //      |       var reg = new dojo.AdapterRegistry();
  24         //      |       reg.register("handleString",
  25         //      |               dojo.isString,
  26         //      |               function(str){
  27         //      |                       // do something with the string here
  28         //      |               }
  29         //      |       );
  30         //      |       reg.register("handleArr",
  31         //      |               dojo.isArray,
  32         //      |               function(arr){
  33         //      |                       // do something with the array here
  34         //      |               }
  35         //      |       );
  36         //      |
  37         //      |       // now we can pass reg.match() *either* an array or a string and
  38         //      |       // the value we pass will get handled by the right function
  39         //      |       reg.match("someValue"); // will call the first function
  40         //      |       reg.match(["someValue"]); // will call the second
  41
  42         this.pairs = [];
  43         this.returnWrappers = returnWrappers || false; // Boolean
  44 };
  45
  46 dojo.extend(dojo.AdapterRegistry, {
  47         register: function(/*String*/ name, /*Function*/ check, /*Function*/ wrap, /*Boolean?*/ directReturn, /*Boolean?*/ override){
  48                 //      summary:
  49                 //              register a check function to determine if the wrap function or
  50                 //              object gets selected
  51                 //      name:
  52                 //              a way to identify this matcher.
  53                 //      check:
  54                 //              a function that arguments are passed to from the adapter's
  55                 //              match() function.  The check function should return true if the
  56                 //              given arguments are appropriate for the wrap function.
  57                 //      directReturn:
  58                 //              If directReturn is true, the value passed in for wrap will be
  59                 //              returned instead of being called. Alternately, the
  60                 //              AdapterRegistry can be set globally to "return not call" using
  61                 //              the returnWrappers property. Either way, this behavior allows
  62                 //              the registry to act as a "search" function instead of a
  63                 //              function interception library.
  64                 //      override:
  65                 //              If override is given and true, the check function will be given
  66                 //              highest priority. Otherwise, it will be the lowest priority
  67                 //              adapter.
  68                 this.pairs[((override) ? "unshift" : "push")]([name, check, wrap, directReturn]);
  69         },
  70
  71         match: function(/* ... */){
  72                 // summary:
  73                 //              Find an adapter for the given arguments. If no suitable adapter
  74                 //              is found, throws an exception. match() accepts any number of
  75                 //              arguments, all of which are passed to all matching functions
  76                 //              from the registered pairs.
  77                 for(var i = 0; i < this.pairs.length; i++){
  78                         var pair = this.pairs[i];
  79                         if(pair[1].apply(this, arguments)){
  80                                 if((pair[3])||(this.returnWrappers)){
  81                                         return pair[2];
  82                                 }else{
  83                                         return pair[2].apply(this, arguments);
  84                                 }
  85                         }
  86                 }
  87                 throw new Error("No match found");
  88         },
  89
  90         unregister: function(name){
  91                 // summary: Remove a named adapter from the registry
  92
  93                 // FIXME: this is kind of a dumb way to handle this. On a large
  94                 // registry this will be slow-ish and we can use the name as a lookup
  95                 // should we choose to trade memory for speed.
  96                 for(var i = 0; i < this.pairs.length; i++){
  97                         var pair = this.pairs[i];
  98                         if(pair[0] == name){
  99                                 this.pairs.splice(i, 1);
 100                                 return true;
 101                         }
 102                 }
 103                 return false;
 104         }
 105 });
 106
 107 }