// TODO: use something more complex like timsort?
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var floor = Math.floor;
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var mergeSort = function (array, comparefn) {
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var length = array.length;
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var middle = floor(length / 2);
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return length < 8 ? insertionSort(array, comparefn) : merge(
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mergeSort(array.slice(0, middle), comparefn),
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mergeSort(array.slice(middle), comparefn),
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comparefn
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);
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};
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var insertionSort = function (array, comparefn) {
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var length = array.length;
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var i = 1;
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var element, j;
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while (i < length) {
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j = i;
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element = array[i];
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while (j && comparefn(array[j - 1], element) > 0) {
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array[j] = array[--j];
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}
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if (j !== i++) array[j] = element;
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} return array;
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};
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var merge = function (left, right, comparefn) {
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var llength = left.length;
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var rlength = right.length;
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var lindex = 0;
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var rindex = 0;
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var result = [];
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while (lindex < llength || rindex < rlength) {
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if (lindex < llength && rindex < rlength) {
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result.push(comparefn(left[lindex], right[rindex]) <= 0 ? left[lindex++] : right[rindex++]);
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} else {
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result.push(lindex < llength ? left[lindex++] : right[rindex++]);
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}
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} return result;
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};
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module.exports = mergeSort;
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