53 lines
1.3 KiB
JavaScript
53 lines
1.3 KiB
JavaScript
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var makeString = require('./helper/makeString');
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/**
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* Based on the implementation here: https://github.com/hiddentao/fast-levenshtein
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*/
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module.exports = function levenshtein(str1, str2) {
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'use strict';
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str1 = makeString(str1);
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str2 = makeString(str2);
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// Short cut cases
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if (str1 === str2) return 0;
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if (!str1 || !str2) return Math.max(str1.length, str2.length);
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// two rows
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var prevRow = new Array(str2.length + 1);
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// initialise previous row
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for (var i = 0; i < prevRow.length; ++i) {
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prevRow[i] = i;
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}
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// calculate current row distance from previous row
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for (i = 0; i < str1.length; ++i) {
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var nextCol = i + 1;
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for (var j = 0; j < str2.length; ++j) {
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var curCol = nextCol;
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// substution
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nextCol = prevRow[j] + ( (str1.charAt(i) === str2.charAt(j)) ? 0 : 1 );
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// insertion
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var tmp = curCol + 1;
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if (nextCol > tmp) {
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nextCol = tmp;
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}
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// deletion
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tmp = prevRow[j + 1] + 1;
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if (nextCol > tmp) {
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nextCol = tmp;
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}
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// copy current col value into previous (in preparation for next iteration)
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prevRow[j] = curCol;
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}
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// copy last col value into previous (in preparation for next iteration)
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prevRow[j] = nextCol;
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}
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return nextCol;
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};
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