var arraySlice = require('../internals/array-slice-simple');
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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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array,
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mergeSort(arraySlice(array, 0, middle), comparefn),
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mergeSort(arraySlice(array, 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 (array, 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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while (lindex < llength || rindex < rlength) {
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array[lindex + rindex] = (lindex < llength && rindex < rlength)
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? comparefn(left[lindex], right[rindex]) <= 0 ? left[lindex++] : right[rindex++]
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: lindex < llength ? left[lindex++] : right[rindex++];
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} return array;
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};
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module.exports = mergeSort;
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