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'use strict';
exports.type = 'perItem';
exports.active = true;
exports.description = 'Sorts children of <defs> to improve compression';
/**
* Sorts children of defs in order to improve compression.
* Sorted first by frequency then by element name length then by element name (to ensure grouping).
*
* @param {Object} item current iteration item
* @return {Boolean} if false, item will be filtered out
*
* @author David Leston
*/
exports.fn = function(item) {
if (item.isElem('defs')) {
if (item.content) {
var frequency = item.content.reduce(function (frequency, child) {
if (child.elem in frequency) {
frequency[child.elem]++;
} else {
frequency[child.elem] = 1;
}
return frequency;
}, {});
item.content.sort(function (a, b) {
var frequencyComparison = frequency[b.elem] - frequency[a.elem];
if (frequencyComparison !== 0 ) {
return frequencyComparison;
}
var lengthComparison = b.elem.length - a.elem.length;
if (lengthComparison !== 0) {
return lengthComparison;
}
return a.elem != b.elem ? a.elem > b.elem ? -1 : 1 : 0;
});
}
return true;
}
};