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