define(["../../_base/lang"], function(lang){
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// module:
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// dojo/data/util/sorter
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// summary:
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// TODOC
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var sorter = {};
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lang.setObject("dojo.data.util.sorter", sorter);
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sorter.basicComparator = function( /*anything*/ a,
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/*anything*/ b){
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// summary:
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// Basic comparison function that compares if an item is greater or less than another item
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// description:
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// returns 1 if a > b, -1 if a < b, 0 if equal.
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// 'null' values (null, undefined) are treated as larger values so that they're pushed to the end of the list.
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// And compared to each other, null is equivalent to undefined.
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//null is a problematic compare, so if null, we set to undefined.
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//Makes the check logic simple, compact, and consistent
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//And (null == undefined) === true, so the check later against null
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//works for undefined and is less bytes.
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var r = -1;
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if(a === null){
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a = undefined;
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}
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if(b === null){
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b = undefined;
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}
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if(a == b){
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r = 0;
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}else if(a > b || a == null){
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r = 1;
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}
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return r; //int {-1,0,1}
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};
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sorter.createSortFunction = function( /* attributes[] */sortSpec, /*dojo/data/api/Read*/ store){
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// summary:
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// Helper function to generate the sorting function based off the list of sort attributes.
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// description:
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// The sort function creation will look for a property on the store called 'comparatorMap'. If it exists
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// it will look in the mapping for comparisons function for the attributes. If one is found, it will
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// use it instead of the basic comparator, which is typically used for strings, ints, booleans, and dates.
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// Returns the sorting function for this particular list of attributes and sorting directions.
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// sortSpec:
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// A JS object that array that defines out what attribute names to sort on and whether it should be descenting or asending.
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// The objects should be formatted as follows:
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// | {
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// | attribute: "attributeName-string" || attribute,
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// | descending: true|false; // Default is false.
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// | }
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// store:
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// The datastore object to look up item values from.
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var sortFunctions=[];
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function createSortFunction(attr, dir, comp, s){
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//Passing in comp and s (comparator and store), makes this
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//function much faster.
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return function(itemA, itemB){
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var a = s.getValue(itemA, attr);
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var b = s.getValue(itemB, attr);
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return dir * comp(a,b); //int
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};
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}
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var sortAttribute;
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var map = store.comparatorMap;
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var bc = sorter.basicComparator;
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for(var i = 0; i < sortSpec.length; i++){
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sortAttribute = sortSpec[i];
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var attr = sortAttribute.attribute;
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if(attr){
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var dir = (sortAttribute.descending) ? -1 : 1;
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var comp = bc;
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if(map){
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if(typeof attr !== "string" && ("toString" in attr)){
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attr = attr.toString();
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}
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comp = map[attr] || bc;
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}
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sortFunctions.push(createSortFunction(attr,
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dir, comp, store));
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}
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}
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return function(rowA, rowB){
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var i=0;
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while(i < sortFunctions.length){
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var ret = sortFunctions[i++](rowA, rowB);
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if(ret !== 0){
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return ret;//int
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}
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}
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return 0; //int
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}; // Function
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};
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return sorter;
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});
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