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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* NLP, which stands for Natural Language Processing, is a module that provides
* an entry point to various methods to interface with human language.
*
* At least, that's the goal. Eventually. Right now, the find toolbar only really
* needs the Levenshtein distance algorithm.
*/
export var NLP = {
/**
* Calculate the Levenshtein distance between two words.
* The implementation of this method was heavily inspired by
* http://locutus.io/php/strings/levenshtein/index.html
* License: MIT.
*
* @param {String} word1 Word to compare against
* @param {String} word2 Word that may be different
* @param {Number} costIns The cost to insert a character
* @param {Number} costRep The cost to replace a character
* @param {Number} costDel The cost to delete a character
* @return {Number}
*/
levenshtein(word1 = "", word2 = "", costIns = 1, costRep = 1, costDel = 1) {
if (word1 === word2) {
return 0;
}
let l1 = word1.length;
let l2 = word2.length;
if (!l1) {
return l2 * costIns;
}
if (!l2) {
return l1 * costDel;
}
let p1 = new Array(l2 + 1);
let p2 = new Array(l2 + 1);
let i1, i2, c0, c1, c2, tmp;
for (i2 = 0; i2 <= l2; i2++) {
p1[i2] = i2 * costIns;
}
for (i1 = 0; i1 < l1; i1++) {
p2[0] = p1[0] + costDel;
for (i2 = 0; i2 < l2; i2++) {
c0 = p1[i2] + (word1[i1] === word2[i2] ? 0 : costRep);
c1 = p1[i2 + 1] + costDel;
if (c1 < c0) {
c0 = c1;
}
c2 = p2[i2] + costIns;
if (c2 < c0) {
c0 = c2;
}
p2[i2 + 1] = c0;
}
tmp = p1;
p1 = p2;
p2 = tmp;
}
c0 = p1[l2];
return c0;
},
};
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