+// source
+// https://github.com/hiddentao/fast-levenshtein/blob/2.0.6/levenshtein.js
(function() {
'use strict';
- /**
- * Extend an Object with another Object's properties.
- *
- * The source objects are specified as additional arguments.
- *
- * @param dst Object the object to extend.
- *
- * @return Object the final object.
- */
- var _extend = function(dst) {
- var sources = Array.prototype.slice.call(arguments, 1);
- for (var i=0; i<sources.length; ++i) {
- var src = sources[i];
- for (var p in src) {
- if (src.hasOwnProperty(p)) dst[p] = src[p];
- }
- }
- return dst;
- };
-
-
- /**
- * Defer execution of given function.
- * @param {Function} func
- */
- var _defer = function(func) {
- if (typeof setImmediate === 'function') {
- return setImmediate(func);
- } else {
- return setTimeout(func, 0);
- }
- };
+ 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.
*
* @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) {
+ get: function(str1, str2, options) {
+ var useCollator = (options && collator && options.useCollator);
+
+ var str1Len = str1.length,
+ str2Len = str2.length;
+
// base cases
- if (str1 === str2) return 0;
- if (str1.length === 0) return str2.length;
- if (str2.length === 0) return str1.length;
+ if (str1Len === 0) return str2Len;
+ if (str2Len === 0) return str1Len;
// two rows
- var prevRow = new Array(str2.length + 1),
- curCol, nextCol, i, j, tmp;
+ var curCol, nextCol, i, j, tmp;
// initialise previous row
- for (i=0; i<prevRow.length; ++i) {
+ for (i=0; i<str2Len; ++i) {
prevRow[i] = i;
+ str2Char[i] = str2.charCodeAt(i);
}
+ prevRow[str2Len] = str2Len;
- // calculate current row distance from previous row
- for (i=0; i<str1.length; ++i) {
- nextCol = i + 1;
+ 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<str2.length; ++j) {
- curCol = nextCol;
+ for (j = 0; j < str2Len; ++j) {
+ curCol = nextCol;
- // substution
- nextCol = prevRow[j] + ( (str1.charAt(i) === str2.charAt(j)) ? 0 : 1 );
- // insertion
- tmp = curCol + 1;
- if (nextCol > tmp) {
- nextCol = tmp;
- }
- // deletion
- tmp = prevRow[j + 1] + 1;
- if (nextCol > tmp) {
- nextCol = tmp;
- }
+ // substution
+ strCmp = 0 === collator.compare(str1.charAt(i), String.fromCharCode(str2Char[j]));
- // copy current col value into previous (in preparation for next iteration)
- prevRow[j] = curCol;
- }
+ nextCol = prevRow[j] + (strCmp ? 0 : 1);
- // copy last col value into previous (in preparation for next iteration)
- prevRow[j] = nextCol;
- }
+ // insertion
+ tmp = curCol + 1;
+ if (nextCol > tmp) {
+ nextCol = tmp;
+ }
+ // deletion
+ tmp = prevRow[j + 1] + 1;
+ if (nextCol > tmp) {
+ nextCol = tmp;
+ }
- return nextCol;
- },
+ // copy current col value into previous (in preparation for next iteration)
+ prevRow[j] = curCol;
+ }
- /**
- * Asynchronously calculate levenshtein distance of the two strings.
- *
- * @param str1 String the first string.
- * @param str2 String the second string.
- * @param cb Function callback function with signature: function(Error err, int distance)
- * @param [options] Object additional options.
- * @param [options.progress] Function progress callback with signature: function(percentComplete)
- */
- getAsync: function(str1, str2, cb, options) {
- options = _extend({}, {
- progress: null
- }, options);
+ // 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;
- // base cases
- if (str1 === str2) return cb(null, 0);
- if (str1.length === 0) return cb(null, str2.length);
- if (str2.length === 0) return cb(null, str1.length);
+ for (j = 0; j < str2Len; ++j) {
+ curCol = nextCol;
- // two rows
- var prevRow = new Array(str2.length + 1),
- curCol, nextCol,
- i, j, tmp,
- startTime, currentTime;
+ // substution
+ strCmp = str1.charCodeAt(i) === str2Char[j];
- // initialise previous row
- for (i=0; i<prevRow.length; ++i) {
- prevRow[i] = i;
- }
+ nextCol = prevRow[j] + (strCmp ? 0 : 1);
- nextCol = 1;
- i = 0;
- j = -1;
-
- var __calculate = function() {
- // reset timer
- startTime = new Date().valueOf();
- currentTime = startTime;
-
- // keep going until one second has elapsed
- while (currentTime - startTime < 1000) {
- // reached end of current row?
- if (str2.length <= (++j)) {
- // copy current into previous (in preparation for next iteration)
- prevRow[j] = nextCol;
-
- // if already done all chars
- if (str1.length <= (++i)) {
- return cb(null, nextCol);
+ // insertion
+ tmp = curCol + 1;
+ if (nextCol > tmp) {
+ nextCol = tmp;
}
- // else if we have more left to do
- else {
- nextCol = i + 1;
- j = 0;
+ // deletion
+ tmp = prevRow[j + 1] + 1;
+ if (nextCol > tmp) {
+ nextCol = tmp;
}
- }
-
- // calculation
- curCol = nextCol;
- // substution
- nextCol = prevRow[j] + ( (str1.charAt(i) === str2.charAt(j)) ? 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 current into previous (in preparation for next iteration)
- prevRow[j] = curCol;
-
- // get current time
- currentTime = new Date().valueOf();
+ // copy last col value into previous (in preparation for next iteration)
+ prevRow[j] = nextCol;
}
-
- // send a progress update?
- if (null !== options.progress) {
- try {
- options.progress.call(null, (i * 100.0/ str1.length));
- } catch (err) {
- return cb('Progress callback: ' + err.toString());
- }
- }
-
- // next iteration
- _defer(__calculate);
- };
-
- __calculate();
+ }
+ return nextCol;
}
};