78 lines
1.7 KiB
JavaScript
Executable File
78 lines
1.7 KiB
JavaScript
Executable File
'use strict';
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const array = [];
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const charCodeCache = [];
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const leven = (left, right) => {
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if (left === right) {
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return 0;
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}
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const swap = left;
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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 (left.length > right.length) {
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left = right;
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right = swap;
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}
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let leftLength = left.length;
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let rightLength = right.length;
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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 (leftLength > 0 && (left.charCodeAt(~-leftLength) === right.charCodeAt(~-rightLength))) {
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leftLength--;
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rightLength--;
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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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let start = 0;
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while (start < leftLength && (left.charCodeAt(start) === right.charCodeAt(start))) {
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start++;
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}
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leftLength -= start;
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rightLength -= start;
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if (leftLength === 0) {
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return rightLength;
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}
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let bCharCode;
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let result;
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let temp;
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let temp2;
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let i = 0;
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let j = 0;
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while (i < leftLength) {
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charCodeCache[i] = left.charCodeAt(start + i);
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array[i] = ++i;
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}
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while (j < rightLength) {
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bCharCode = right.charCodeAt(start + j);
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temp = j++;
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result = j;
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for (i = 0; i < leftLength; i++) {
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temp2 = bCharCode === charCodeCache[i] ? temp : temp + 1;
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temp = array[i];
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// eslint-disable-next-line no-multi-assign
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result = array[i] = temp > result ? temp2 > result ? result + 1 : temp2 : temp2 > temp ? temp + 1 : temp2;
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}
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}
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return result;
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};
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module.exports = leven;
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// TODO: Remove this for the next major release
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module.exports.default = leven;
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