Moved levenshtein to utils

src/core/utils.ts

@@ -7,7 +7,6 @@ import * as path from 'path';
 import Cred from './cred';
 import { Buffer } from 'buffer';
 import type { BackendConstructor } from './backends';
-import levenshtein from './levenshtein';
 
 /**
  * Synchronous recursive makedir.
@@ -46,6 +45,100 @@ export async function bufferValidator(v: object): Promise<void> {
 	}
 }
 
+/*
+ * Levenshtein distance, from the `js-levenshtein` NPM module.
+ * Copied here to avoid complexity of adding another CommonJS module dependency.
+ */
+
+function _min(d0: number, d1: number, d2: number, bx: number, ay: number): number {
+	return d0 < d1 || d2 < d1 ? (d0 > d2 ? d2 + 1 : d0 + 1) : bx === ay ? d1 : d1 + 1;
+}
+
+/**
+ * Calculates levenshtein distance.
+ * @param a
+ * @param b
+ */
+function levenshtein(a: string, b: string): number {
+	if (a === b) {
+		return 0;
+	}
+
+	if (a.length > b.length) {
+		const tmp = a;
+		a = b;
+		b = tmp;
+	}
+
+	let la = a.length;
+	let lb = b.length;
+
+	while (la > 0 && a.charCodeAt(la - 1) === b.charCodeAt(lb - 1)) {
+		la--;
+		lb--;
+	}
+
+	let offset = 0;
+
+	while (offset < la && a.charCodeAt(offset) === b.charCodeAt(offset)) {
+		offset++;
+	}
+
+	la -= offset;
+	lb -= offset;
+
+	if (la === 0 || lb === 1) {
+		return lb;
+	}
+
+	const vector = new Array<number>(la << 1);
+
+	for (let y = 0; y < la; ) {
+		vector[la + y] = a.charCodeAt(offset + y);
+		vector[y] = ++y;
+	}
+
+	let x: number;
+	let d0: number;
+	let d1: number;
+	let d2: number;
+	let d3: number;
+	for (x = 0; x + 3 < lb; ) {
+		const bx0 = b.charCodeAt(offset + (d0 = x));
+		const bx1 = b.charCodeAt(offset + (d1 = x + 1));
+		const bx2 = b.charCodeAt(offset + (d2 = x + 2));
+		const bx3 = b.charCodeAt(offset + (d3 = x + 3));
+		let dd = (x += 4);
+		for (let y = 0; y < la; ) {
+			const ay = vector[la + y];
+			const dy = vector[y];
+			d0 = _min(dy, d0, d1, bx0, ay);
+			d1 = _min(d0, d1, d2, bx1, ay);
+			d2 = _min(d1, d2, d3, bx2, ay);
+			dd = _min(d2, d3, dd, bx3, ay);
+			vector[y++] = dd;
+			d3 = d2;
+			d2 = d1;
+			d1 = d0;
+			d0 = dy;
+		}
+	}
+
+	let dd: number = 0;
+	for (; x < lb; ) {
+		const bx0 = b.charCodeAt(offset + (d0 = x));
+		dd = ++x;
+		for (let y = 0; y < la; y++) {
+			const dy = vector[y];
+			vector[y] = dd = dy < d0 || dd < d0 ? (dy > dd ? dd + 1 : dy + 1) : bx0 === vector[la + y] ? d0 : d0 + 1;
+			d0 = dy;
+		}
+	}
+
+	return dd;
+}
+
+
 /**
  * Checks that the given options object is valid for the file system options.
  * @hidden