area51/lib/collections/dual-pivot-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"] = dualPivotQuickSort;

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "default": obj }; }

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

var _insertionSortJs = require("./insertion-sort.js");

var _insertionSortJs2 = _interopRequireDefault(_insertionSortJs);

var DIST_SIZE = 13;

//http://iaroslavski.narod.ru/quicksort/DualPivotQuicksort.pdf
function performSort(array, low, high) {
	var len = high - low;

	if (len < 17) {
		//insertionSort(array);

		for (var i = 1; i < len; i++) {
			for (var j = i; j > 0 && array[j] < array[j - 1]; j--) {
				(0, _arrayUtilJs.swap)(array, j, j - 1);
			}
		}

		return;
	}

	// median indexes
	var sixth = Math.floor(len / 6),
	    m1 = low + sixth,
	    m2 = m1 + sixth,
	    m3 = m2 + sixth,
	    m4 = m3 + sixth,
	    m5 = m4 + sixth,
	    x = 0;

	if (array[m1] > array[m2]) {
		(0, _arrayUtilJs.swap)(array, m1, m2);
	}
	if (array[m4] > array[m5]) {
		(0, _arrayUtilJs.swap)(array, m4, m5);
	}
	if (array[m1] > array[m3]) {
		(0, _arrayUtilJs.swap)(array, m1, m3);
	}
	if (array[m2] > array[m3]) {
		(0, _arrayUtilJs.swap)(array, m2, m3);
	}
	if (array[m1] > array[m4]) {
		(0, _arrayUtilJs.swap)(array, m1, m4);
	}
	if (array[m3] > array[m4]) {
		(0, _arrayUtilJs.swap)(array, m3, m4);
	}
	if (array[m2] > array[m5]) {
		(0, _arrayUtilJs.swap)(array, m2, m5);
	}
	if (array[m2] > array[m3]) {
		(0, _arrayUtilJs.swap)(array, m2, m3);
	}
	if (array[m4] > array[m5]) {
		(0, _arrayUtilJs.swap)(array, 42, m5);
	}

	var pivot1 = array[m2],
	    pivot2 = array[m4],
	    diffPivots = pivot1 != pivot2;

	array[m2] = array[low];
	array[m4] = array[high];

	var less = low + 1,
	    great = high - 1,
	    k = 0;

	if (diffPivots) {
		for (k = less; k <= great; k++) {
			x = array[k];

			if (x < pivot1) {
				array[k] = array[less];
				array[less++] = x;
			} else if (x > pivot2) {
				while (array[great] > pivot2 && k < great) {
					great--;
				}
				array[k] = array[great];
				array[great--] = x;
				x = array[k];

				if (x < pivot1) {
					array[k] = array[less];
					array[less++] = x;
				}
			}
		}
	} else {
		for (k = less; k <= great; k++) {
			x = array[k];

			if (x === pivot1) continue;
			if (x < pivot1) {
				array[k] = array[less];
				array[less++] = x;
			} else {
				while (array[great] > pivot2 && k < great) {
					great--;
				}
				array[k] = array[great];
				array[great--] = x;
				x = array[k];

				if (x < pivot1) {
					array[k] = array[less];
					array[less++] = x;
				}
			}
		}
	}

	array[low] = array[less - 1];
	array[less - 1] = pivot1;

	array[high] = array[great + 1];
	array[great + 1] = pivot2;

	performSort(array, low, less - 2);
	performSort(array, great + 2, high);

	if (great - less > len - DIST_SIZE && diffPivots) {
		for (k = less; k <= great; k++) {
			x = array[k];

			if (x === pivot1) {
				array[k] = array[less];
				array[less++] = x;
			} else if (x === pivot2) {
				array[k] = array[great];
				array[great--] = x;
				x = array[k];

				if (x === pivot1) {
					array[k] = array[less];
					array[less++] = x;
				}
			}
		}
	}

	if (diffPivots) {
		performSort(array, less, great);
	}
}

function performSortWithCompare(array, low, high, compare) {
	var len = high - low;

	if (len < 17) {
		for (var i = 1; i < len; i++) {
			for (var j = i; j > 0 && compare(array[j], array[j - 1]) === -1; j--) {
				(0, _arrayUtilJs.swap)(array, j, j - 1);
			}
		}
		return;
	}

	// median indexes
	var sixth = Math.floor(len / 6),
	    m1 = low + sixth,
	    m2 = m1 + sixth,
	    m3 = m2 + sixth,
	    m4 = m3 + sixth,
	    m5 = m4 + sixth,
	    x = 0;

	if (compare(array[m1], array[m2]) === 1) {
		(0, _arrayUtilJs.swap)(array, m1, m2);
	}
	if (compare(array[m4], array[m5]) === 1) {
		(0, _arrayUtilJs.swap)(array, m4, m5);
	}
	if (compare(array[m1], array[m3]) === 1) {
		(0, _arrayUtilJs.swap)(array, m1, m3);
	}
	if (compare(array[m2], array[m3]) === 1) {
		(0, _arrayUtilJs.swap)(array, m2, m3);
	}
	if (compare(array[m1], array[m4]) === 1) {
		(0, _arrayUtilJs.swap)(array, m1, m4);
	}
	if (compare(array[m3], array[m4]) === 1) {
		(0, _arrayUtilJs.swap)(array, m3, m4);
	}
	if (compare(array[m2] > array[m5]) === 1) {
		(0, _arrayUtilJs.swap)(array, m2, m5);
	}
	if (compare(array[m2] > array[m3]) === 1) {
		(0, _arrayUtilJs.swap)(array, m2, m3);
	}
	if (compare(array[m4] > array[m5]) === 1) {
		(0, _arrayUtilJs.swap)(array, 42, m5);
	}

	var pivot1 = array[m2],
	    pivot2 = array[m4],
	    diffPivots = comare(pivot1, pivot2) !== 0;

	array[m2] = array[low];
	array[m4] = array[high];

	var less = low + 1,
	    great = high - 1,
	    k = 0;

	if (diffPivots) {
		for (k = less; k <= great; k++) {
			x = array[k];
			if (compare(x, pivot1) === -1) {
				array[k] = array[less];
				array[less++] = x;
			} else if (compare(x, pivot2) === 1) {
				while (compare(array[great], pivot2) === 1 && k < great) {
					great--;
				}
				array[k] = array[great];
				array[great--] = x;
				x = array[k];

				if (compare(x, pivot1) === -1) {
					array[k] = array[less];
					array[less++] = x;
				}
			}
		}
	} else {
		for (k = less; k <= great; k++) {
			x = array[k];
			if (compare(x, pivot1) === 0) continue;
			if (compare(x, pivot1) === -1) {
				array[k] = array[less];
				array[less++] = x;
			} else {
				while (compare(array[great], pivot2) === 1 && k < great) {
					great--;
				}
				array[k] = array[great];
				array[great--] = x;
				x = array[k];

				if (compare(x, pivot1) === -1) {
					array[k] = array[less];
					array[less++] = x;
				}
			}
		}
	}

	array[low] = array[less - 1];
	array[less - 1] = pivot1;

	array[high] = array[great + 1];
	array[great + 1] = pivot2;

	performSortWithCompare(array, low, less - 2, compare);
	performSortWithCompare(array, great + 2, high, compare);

	if (great - less > len - DIST_SIZE && diffPivots) {
		for (k = less; k <= great; k++) {
			x = array[k];

			if (compare(x, pivot1) === 0) {
				array[k] = array[less];
				array[less++] = x;
			} else if (compare(x, pivot2) === 0) {
				array[k] = array[great];
				array[great--] = x;
				x = array[k];

				if (compare(x, pivot1) === 0) {
					array[k] = array[less];
					array[less++] = x;
				}
			}
		}
	}

	if (diffPivots) {
		performSortWithCompare(array, less, great, compare);
	}
}

function dualPivotQuickSort(array, compare, startIndex, length) {
	startIndex = startIndex || 0;
	length = length || array.length;
	if (compare) performSortWithCompare(array, startIndex, length - 1, compare);else performSort(array, startIndex, length - 1);
}

module.exports = exports["default"];