stylelint/lib/utils/levenshteinDistance.js

A mighty, modern CSS linter.

/* @flow */
'use strict';

/**
 * Compute levenshtein distance, see https://en.wikipedia.org/wiki/Levenshtein_distance for more info
 * @param {string} firstStr first string
 * @param {string} secondStr second string
 * @param {number} [maxDistance=99] maximum distance, if distance is greater then returns -1
 * @returns {number} computed distance
 */
module.exports = function levenshteinDistance(
	firstStr /*: string*/,
	secondStr /*: string*/,
	maxDistance /*: number*/ = 99,
) /*: number*/ {
	if (Math.abs(firstStr.length - secondStr.length) > maxDistance) return -1;

	if (firstStr.length === 0 || secondStr.length === 0) return firstStr.length || secondStr.length;

	let line = new Uint32Array(firstStr.length + 1);

	for (let i = 0; i < line.length; i++) {
		line[i] = i;
	}

	for (let i = 0; i < secondStr.length; i++) {
		const newLine = line.slice();

		newLine[0] = i + 1;
		let min = newLine[0];

		for (let j = 1; j < line.length; j++) {
			newLine[j] = Math.min(
				line[j - 1] + (secondStr[i] === firstStr[j - 1] ? 0 : 1),
				line[j] + 1,
				newLine[j - 1] + 1,
			);

			if (newLine[j] < min) min = newLine[j];
		}

		if (min > maxDistance) {
			return -1;
		}

		line = newLine;
	}

	return line[line.length - 1] > maxDistance ? -1 : line[line.length - 1];
};