setup-python/node_modules/leven/index.js
Danny McCormick 39c08a0eaa Initial pass
2019-06-26 21:12:00 -04:00

86 lines
1.5 KiB
JavaScript

/* eslint-disable no-nested-ternary */
'use strict';
var arr = [];
var charCodeCache = [];
module.exports = function (a, b) {
if (a === b) {
return 0;
}
var swap = a;
// Swapping the strings if `a` is longer than `b` so we know which one is the
// shortest & which one is the longest
if (a.length > b.length) {
a = b;
b = swap;
}
var aLen = a.length;
var bLen = b.length;
if (aLen === 0) {
return bLen;
}
if (bLen === 0) {
return aLen;
}
// Performing suffix trimming:
// We can linearly drop suffix common to both strings since they
// don't increase distance at all
// Note: `~-` is the bitwise way to perform a `- 1` operation
while (aLen > 0 && (a.charCodeAt(~-aLen) === b.charCodeAt(~-bLen))) {
aLen--;
bLen--;
}
if (aLen === 0) {
return bLen;
}
// Performing prefix trimming
// We can linearly drop prefix common to both strings since they
// don't increase distance at all
var start = 0;
while (start < aLen && (a.charCodeAt(start) === b.charCodeAt(start))) {
start++;
}
aLen -= start;
bLen -= start;
if (aLen === 0) {
return bLen;
}
var bCharCode;
var ret;
var tmp;
var tmp2;
var i = 0;
var j = 0;
while (i < aLen) {
charCodeCache[start + i] = a.charCodeAt(start + i);
arr[i] = ++i;
}
while (j < bLen) {
bCharCode = b.charCodeAt(start + j);
tmp = j++;
ret = j;
for (i = 0; i < aLen; i++) {
tmp2 = bCharCode === charCodeCache[start + i] ? tmp : tmp + 1;
tmp = arr[i];
ret = arr[i] = tmp > ret ? tmp2 > ret ? ret + 1 : tmp2 : tmp2 > tmp ? tmp + 1 : tmp2;
}
}
return ret;
};