💥 refactor!: Split isPartitioned and firstInversion.

BREAKING CHANGE: The API has changed.

Author: make-github-pseudonymous-again

src/index.js

@@ -1,2 +1,6 @@
-export * from './partition/index.js';
-export * from './utils/index.js';
+export {default as hoare} from './partition/hoare.js';
+export {default as lomuto} from './partition/lomuto.js';
+export {default as yaroslavskiy} from './partition/yaroslavskiy.js';
+export {default as firstInversion} from './utils/firstInversion.js';
+export {default as isPartitioned} from './utils/isPartitioned.js';
+export {default as whole} from './utils/whole.js';

src/partition/hoare.js

@@ -1,8 +1,15 @@
+import assert from 'assert';
+
 /**
- * HYP : i < j
+ * @param {Function} compare
+ * @param {Array} a
+ * @param {number} i
+ * @param {number} j
+ * @return {number}
  */
+const hoare = (compare, a, i, j) => {
+	assert(i < j);
 
-export function hoare(compare, a, i, j) {
 	const o = i;
 	const x = a[o];
 
@@ -41,4 +48,6 @@ export function hoare(compare, a, i, j) {
 		a[i] = a[j];
 		a[j] = t;
 	}
-}
+};
+
+export default hoare;

src/partition/index.js

@@ -1,8 +1,15 @@
+import assert from 'assert';
+
 /**
- * HYP : i < j
+ * @param {Function} compare
+ * @param {Array} a
+ * @param {number} i
+ * @param {number} j
+ * @return {number}
  */
+const lomuto = (compare, a, i, j) => {
+	assert(i < j);
 
-export function lomuto(compare, a, i, j) {
 	const p = a[i];
 	let k = i + 1;
 
@@ -24,4 +31,6 @@ export function lomuto(compare, a, i, j) {
 	a[k - 1] = p;
 
 	return k - 1;
-}
+};
+
+export default lomuto;

src/partition/lomuto.js

@@ -1,10 +1,16 @@
+import assert from 'assert';
+
 /**
- * HYP : i < j
+ * See http://cs.stackexchange.com/a/24099/20711
  *
- * http://cs.stackexchange.com/a/24099/20711
+ * @param {Function} compare
+ * @param {Array} a
+ * @param {number} i
+ * @param {number} j
+ * @return {[number, number]}
  */
-
-export function yaroslavskiy(compare, a, i, j) {
+const yaroslavskiy = (compare, a, i, j) => {
+	assert(i < j);
 	--j;
 
 	// Choose outermost elements as pivots
@@ -64,4 +70,6 @@ export function yaroslavskiy(compare, a, i, j) {
 	a[g] = t2;
 
 	return [l, g];
-}
+};
+
+export default yaroslavskiy;

src/partition/yaroslavskiy.js

@@ -0,0 +1,24 @@
+/**
+ * Checks whether range [left,right[ of array is partitioned according to pivot
+ * p. Returns the index of the first inversion.
+ *
+ * @param {Function} compare
+ * @param {ArrayLike} array
+ * @param {number} left
+ * @param {number} right
+ * @param {number} p
+ * @return {number}
+ */
+const firstInversion = (compare, array, left, right, p) => {
+	for (let k = left; k < p; ++k) {
+		if (compare(array[k], array[p]) > 0) return k;
+	}
+
+	for (let k = p + 1; k < right; ++k) {
+		if (compare(array[k], array[p]) < 0) return k;
+	}
+
+	return right;
+};
+
+export default firstInversion;

src/utils/firstInversion.js

@@ -0,0 +1,17 @@
+import firstInversion from './firstInversion.js';
+
+/**
+ * Checks whether range [left,right[ of array is partitioned according to pivot
+ * p.
+ *
+ * @param {Function} compare
+ * @param {ArrayLike} array
+ * @param {number} left
+ * @param {number} right
+ * @param {number} p
+ * @return {boolean}
+ */
+const isPartitioned = (compare, array, left, right, p) =>
+	firstInversion(compare, array, left, right, p) === right;
+
+export default isPartitioned;

src/utils/index.js

@@ -1,5 +1,4 @@
-export function whole(partition) {
-	return function (compare, array) {
-		return partition(compare, array, 0, array.length);
-	};
-}
+const whole = (partition) => (compare, array) =>
+	partition(compare, array, 0, array.length);
+
+export default whole;