lib/dojo/data/util/sorter.js.uncompressed.js

   1 define("dojo/data/util/sorter", ["../../_base/lang"], function(lang){
   2         // module:
   3         //              dojo/data/util/sorter
   4         // summary:
   5         //              TODOC
   6
   7 var sorter = {};
   8 lang.setObject("dojo.data.util.sorter", sorter);
   9
  10 sorter.basicComparator = function(      /*anything*/ a,
  11                                                                                                         /*anything*/ b){
  12         // summary:
  13         //              Basic comparison function that compares if an item is greater or less than another item
  14         // description:
  15         //              returns 1 if a > b, -1 if a < b, 0 if equal.
  16         //              'null' values (null, undefined) are treated as larger values so that they're pushed to the end of the list.
  17         //              And compared to each other, null is equivalent to undefined.
  18
  19         //null is a problematic compare, so if null, we set to undefined.
  20         //Makes the check logic simple, compact, and consistent
  21         //And (null == undefined) === true, so the check later against null
  22         //works for undefined and is less bytes.
  23         var r = -1;
  24         if(a === null){
  25                 a = undefined;
  26         }
  27         if(b === null){
  28                 b = undefined;
  29         }
  30         if(a == b){
  31                 r = 0;
  32         }else if(a > b || a == null){
  33                 r = 1;
  34         }
  35         return r; //int {-1,0,1}
  36 };
  37
  38 sorter.createSortFunction = function(   /* attributes[] */sortSpec, /*dojo/data/api/Read*/ store){
  39         // summary:
  40         //              Helper function to generate the sorting function based off the list of sort attributes.
  41         // description:
  42         //              The sort function creation will look for a property on the store called 'comparatorMap'.  If it exists
  43         //              it will look in the mapping for comparisons function for the attributes.  If one is found, it will
  44         //              use it instead of the basic comparator, which is typically used for strings, ints, booleans, and dates.
  45         //              Returns the sorting function for this particular list of attributes and sorting directions.
  46         // sortSpec:
  47         //              A JS object that array that defines out what attribute names to sort on and whether it should be descenting or asending.
  48         //              The objects should be formatted as follows:
  49         // |    {
  50         // |            attribute: "attributeName-string" || attribute,
  51         // |            descending: true|false;   // Default is false.
  52         // |    }
  53         // store:
  54         //              The datastore object to look up item values from.
  55
  56         var sortFunctions=[];
  57
  58         function createSortFunction(attr, dir, comp, s){
  59                 //Passing in comp and s (comparator and store), makes this
  60                 //function much faster.
  61                 return function(itemA, itemB){
  62                         var a = s.getValue(itemA, attr);
  63                         var b = s.getValue(itemB, attr);
  64                         return dir * comp(a,b); //int
  65                 };
  66         }
  67         var sortAttribute;
  68         var map = store.comparatorMap;
  69         var bc = sorter.basicComparator;
  70         for(var i = 0; i < sortSpec.length; i++){
  71                 sortAttribute = sortSpec[i];
  72                 var attr = sortAttribute.attribute;
  73                 if(attr){
  74                         var dir = (sortAttribute.descending) ? -1 : 1;
  75                         var comp = bc;
  76                         if(map){
  77                                 if(typeof attr !== "string" && ("toString" in attr)){
  78                                          attr = attr.toString();
  79                                 }
  80                                 comp = map[attr] || bc;
  81                         }
  82                         sortFunctions.push(createSortFunction(attr,
  83                                 dir, comp, store));
  84                 }
  85         }
  86         return function(rowA, rowB){
  87                 var i=0;
  88                 while(i < sortFunctions.length){
  89                         var ret = sortFunctions[i++](rowA, rowB);
  90                         if(ret !== 0){
  91                                 return ret;//int
  92                         }
  93                 }
  94                 return 0; //int
  95         }; // Function
  96 };
  97
  98 return sorter;
  99 });