area51/lib/collections/quick-sort.js

Experimental prototypes of alien things built in JavaScript. The bits may end up living in a different package.

"use strict";

Object.defineProperty(exports, "__esModule", {
	value: true
});
exports["default"] = quickSort;

var _arrayUtilJs = require("./array-util.js");

function partition(array, low, high) {
	var i = low,
	    j = high + 1,
	    v = array[low];

	while (true) {

		while (array[++i] < v) {
			if (i === high) break;
		}
		while (v < array[--j]) {
			if (j === low) break;
		}
		if (i >= j) break;
		(0, _arrayUtilJs.swap)(array, i, j);
	}

	(0, _arrayUtilJs.swap)(array, low, j);

	return j;
}

function partitionWithCompare(array, low, high, compare) {
	var i = low,
	    j = high + 1,
	    v = array[low];

	while (true) {

		while (compare(array[++i], v) === -1) {
			if (i === high) break;
		}
		while (compare(v, array[--j]) === -1) {
			if (j === low) break;
		}
		if (i >= j) break;
		(0, _arrayUtilJs.swap)(array, i, j);
	}

	(0, _arrayUtilJs.swap)(array, low, j);

	return j;
}

function performSort(array, low, high) {
	if (high <= low) return;

	var j = partition(array, low, high);
	performSort(array, low, j - 1);
	performSort(array, j + 1, high);
}

function performSortWithCompare(array, low, high, compare) {
	if (high <= low) return;

	var j = partitionWithCompare(array, low, high, compare);
	performSortWithCompare(array, low, j - 1, compare);
	performSortWithCompare(array, j + 1, high, compare);
}

function quickSort(array, compare, indexStart, length) {
	indexStart = indexStart || 0;
	length = length || array.length;

	if (compare) performSortWithCompare(array, indexStart, length - 1, compare);else performSort(array, indexStart, length - 1);
}

module.exports = exports["default"];