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