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node_modules/fast-levenshtein/levenshtein.js
| 136 lines
| 3.8 KiB
| application/javascript
| JavascriptLexer
|
r789 | (function() { | |||
'use strict'; | ||||
var collator; | ||||
try { | ||||
collator = (typeof Intl !== "undefined" && typeof Intl.Collator !== "undefined") ? Intl.Collator("generic", { sensitivity: "base" }) : null; | ||||
} catch (err){ | ||||
console.log("Collator could not be initialized and wouldn't be used"); | ||||
} | ||||
// arrays to re-use | ||||
var prevRow = [], | ||||
str2Char = []; | ||||
/** | ||||
* Based on the algorithm at http://en.wikipedia.org/wiki/Levenshtein_distance. | ||||
*/ | ||||
var Levenshtein = { | ||||
/** | ||||
* Calculate levenshtein distance of the two strings. | ||||
* | ||||
* @param str1 String the first string. | ||||
* @param str2 String the second string. | ||||
* @param [options] Additional options. | ||||
* @param [options.useCollator] Use `Intl.Collator` for locale-sensitive string comparison. | ||||
* @return Integer the levenshtein distance (0 and above). | ||||
*/ | ||||
get: function(str1, str2, options) { | ||||
var useCollator = (options && collator && options.useCollator); | ||||
var str1Len = str1.length, | ||||
str2Len = str2.length; | ||||
// base cases | ||||
if (str1Len === 0) return str2Len; | ||||
if (str2Len === 0) return str1Len; | ||||
// two rows | ||||
var curCol, nextCol, i, j, tmp; | ||||
// initialise previous row | ||||
for (i=0; i<str2Len; ++i) { | ||||
prevRow[i] = i; | ||||
str2Char[i] = str2.charCodeAt(i); | ||||
} | ||||
prevRow[str2Len] = str2Len; | ||||
var strCmp; | ||||
if (useCollator) { | ||||
// calculate current row distance from previous row using collator | ||||
for (i = 0; i < str1Len; ++i) { | ||||
nextCol = i + 1; | ||||
for (j = 0; j < str2Len; ++j) { | ||||
curCol = nextCol; | ||||
// substution | ||||
strCmp = 0 === collator.compare(str1.charAt(i), String.fromCharCode(str2Char[j])); | ||||
nextCol = prevRow[j] + (strCmp ? 0 : 1); | ||||
// insertion | ||||
tmp = curCol + 1; | ||||
if (nextCol > tmp) { | ||||
nextCol = tmp; | ||||
} | ||||
// deletion | ||||
tmp = prevRow[j + 1] + 1; | ||||
if (nextCol > tmp) { | ||||
nextCol = tmp; | ||||
} | ||||
// copy current col value into previous (in preparation for next iteration) | ||||
prevRow[j] = curCol; | ||||
} | ||||
// copy last col value into previous (in preparation for next iteration) | ||||
prevRow[j] = nextCol; | ||||
} | ||||
} | ||||
else { | ||||
// calculate current row distance from previous row without collator | ||||
for (i = 0; i < str1Len; ++i) { | ||||
nextCol = i + 1; | ||||
for (j = 0; j < str2Len; ++j) { | ||||
curCol = nextCol; | ||||
// substution | ||||
strCmp = str1.charCodeAt(i) === str2Char[j]; | ||||
nextCol = prevRow[j] + (strCmp ? 0 : 1); | ||||
// insertion | ||||
tmp = curCol + 1; | ||||
if (nextCol > tmp) { | ||||
nextCol = tmp; | ||||
} | ||||
// deletion | ||||
tmp = prevRow[j + 1] + 1; | ||||
if (nextCol > tmp) { | ||||
nextCol = tmp; | ||||
} | ||||
// copy current col value into previous (in preparation for next iteration) | ||||
prevRow[j] = curCol; | ||||
} | ||||
// copy last col value into previous (in preparation for next iteration) | ||||
prevRow[j] = nextCol; | ||||
} | ||||
} | ||||
return nextCol; | ||||
} | ||||
}; | ||||
// amd | ||||
if (typeof define !== "undefined" && define !== null && define.amd) { | ||||
define(function() { | ||||
return Levenshtein; | ||||
}); | ||||
} | ||||
// commonjs | ||||
else if (typeof module !== "undefined" && module !== null && typeof exports !== "undefined" && module.exports === exports) { | ||||
module.exports = Levenshtein; | ||||
} | ||||
// web worker | ||||
else if (typeof self !== "undefined" && typeof self.postMessage === 'function' && typeof self.importScripts === 'function') { | ||||
self.Levenshtein = Levenshtein; | ||||
} | ||||
// browser main thread | ||||
else if (typeof window !== "undefined" && window !== null) { | ||||
window.Levenshtein = Levenshtein; | ||||
} | ||||
}()); | ||||