locutus
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Locutus other languages' standard libraries to JavaScript for fun and educational purposes
70 lines (69 loc) • 2.34 kB
JavaScript
export function levenshtein(s1, s2, costIns, costRep, costDel) {
// discuss at: https://locutus.io/php/levenshtein/
// parity verified: PHP 8.3
// original by: Carlos R. L. Rodrigues (https://www.jsfromhell.com)
// bugfixed by: Onno Marsman (https://twitter.com/onnomarsman)
// revised by: Andrea Giammarchi (https://webreflection.blogspot.com)
// reimplemented by: Brett Zamir (https://brett-zamir.me)
// reimplemented by: Alexander M Beedie
// reimplemented by: Rafał Kukawski (https://blog.kukawski.pl)
// example 1: levenshtein('Kevin van Zonneveld', 'Kevin van Sommeveld')
// returns 1: 3
// example 2: levenshtein("carrrot", "carrots")
// returns 2: 2
// example 3: levenshtein("carrrot", "carrots", 2, 3, 4)
// returns 3: 6
// var LEVENSHTEIN_MAX_LENGTH = 255 // PHP limits the function to max 255 character-long strings
costIns = costIns == null ? 1 : +costIns;
costRep = costRep == null ? 1 : +costRep;
costDel = costDel == null ? 1 : +costDel;
if (s1 === s2) {
return 0;
}
const l1 = s1.length;
const l2 = s2.length;
if (l1 === 0) {
return l2 * costIns;
}
if (l2 === 0) {
return l1 * costDel;
}
// Enable the 3 lines below to set the same limits on string length as PHP does
// if (l1 > LEVENSHTEIN_MAX_LENGTH || l2 > LEVENSHTEIN_MAX_LENGTH) {
// return -1;
// }
const chars1 = s1.split('');
const chars2 = s2.split('');
let p1 = new Array(l2 + 1);
let p2 = new Array(l2 + 1);
let i1;
let i2;
let c0;
let c1;
let c2;
let tmp;
const at = (arr, idx) => arr[idx] ?? 0;
for (i2 = 0; i2 <= l2; i2++) {
p1[i2] = i2 * costIns;
}
for (i1 = 0; i1 < l1; i1++) {
p2[0] = at(p1, 0) + costDel;
for (i2 = 0; i2 < l2; i2++) {
c0 = at(p1, i2) + (chars1[i1] === chars2[i2] ? 0 : costRep);
c1 = at(p1, i2 + 1) + costDel;
if (c1 < c0) {
c0 = c1;
}
c2 = at(p2, i2) + costIns;
if (c2 < c0) {
c0 = c2;
}
p2[i2 + 1] = c0;
}
tmp = p1;
p1 = p2;
p2 = tmp;
}
c0 = at(p1, l2);
return c0;
}