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tt-rss/lib/dojo/data/util/sorter.js

103 lines
3.3 KiB
JavaScript

/*
Copyright (c) 2004-2010, The Dojo Foundation All Rights Reserved.
Available via Academic Free License >= 2.1 OR the modified BSD license.
see: http://dojotoolkit.org/license for details
*/
if(!dojo._hasResource["dojo.data.util.sorter"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
dojo._hasResource["dojo.data.util.sorter"] = true;
dojo.provide("dojo.data.util.sorter");
dojo.data.util.sorter.basicComparator = function( /*anything*/ a,
/*anything*/ b){
// summary:
// Basic comparision function that compares if an item is greater or less than another item
// description:
// returns 1 if a > b, -1 if a < b, 0 if equal.
// 'null' values (null, undefined) are treated as larger values so that they're pushed to the end of the list.
// And compared to each other, null is equivalent to undefined.
//null is a problematic compare, so if null, we set to undefined.
//Makes the check logic simple, compact, and consistent
//And (null == undefined) === true, so the check later against null
//works for undefined and is less bytes.
var r = -1;
if(a === null){
a = undefined;
}
if(b === null){
b = undefined;
}
if(a == b){
r = 0;
}else if(a > b || a == null){
r = 1;
}
return r; //int {-1,0,1}
};
dojo.data.util.sorter.createSortFunction = function( /* attributes array */sortSpec,
/*dojo.data.core.Read*/ store){
// summary:
// Helper function to generate the sorting function based off the list of sort attributes.
// description:
// The sort function creation will look for a property on the store called 'comparatorMap'. If it exists
// it will look in the mapping for comparisons function for the attributes. If one is found, it will
// use it instead of the basic comparator, which is typically used for strings, ints, booleans, and dates.
// Returns the sorting function for this particular list of attributes and sorting directions.
//
// sortSpec: array
// A JS object that array that defines out what attribute names to sort on and whether it should be descenting or asending.
// The objects should be formatted as follows:
// {
// attribute: "attributeName-string" || attribute,
// descending: true|false; // Default is false.
// }
// store: object
// The datastore object to look up item values from.
//
var sortFunctions=[];
function createSortFunction(attr, dir, comp, s){
//Passing in comp and s (comparator and store), makes this
//function much faster.
return function(itemA, itemB){
var a = s.getValue(itemA, attr);
var b = s.getValue(itemB, attr);
return dir * comp(a,b); //int
};
}
var sortAttribute;
var map = store.comparatorMap;
var bc = dojo.data.util.sorter.basicComparator;
for(var i = 0; i < sortSpec.length; i++){
sortAttribute = sortSpec[i];
var attr = sortAttribute.attribute;
if(attr){
var dir = (sortAttribute.descending) ? -1 : 1;
var comp = bc;
if(map){
if(typeof attr !== "string" && ("toString" in attr)){
attr = attr.toString();
}
comp = map[attr] || bc;
}
sortFunctions.push(createSortFunction(attr,
dir, comp, store));
}
}
return function(rowA, rowB){
var i=0;
while(i < sortFunctions.length){
var ret = sortFunctions[i++](rowA, rowB);
if(ret !== 0){
return ret;//int
}
}
return 0; //int
}; // Function
};
}