From 563e401a4f3880da88bfc69cf51be5a1becd4c66 Mon Sep 17 00:00:00 2001
From: Ian Coleman <coleman.ian@gmail.com>
Date: Mon, 15 Aug 2016 16:15:43 +1000
Subject: Words not in list show error with suggestion

---
 src/js/levenshtein.js | 211 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 211 insertions(+)
 create mode 100644 src/js/levenshtein.js

(limited to 'src/js/levenshtein.js')

diff --git a/src/js/levenshtein.js b/src/js/levenshtein.js
new file mode 100644
index 0000000..3051ec5
--- /dev/null
+++ b/src/js/levenshtein.js
@@ -0,0 +1,211 @@
+(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);
+    }
+  };
+
+  /**
+   * 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.
+     * @return Integer the levenshtein distance (0 and above).
+     */
+    get: function(str1, str2) {
+      // base cases
+      if (str1 === str2) return 0;
+      if (str1.length === 0) return str2.length;
+      if (str2.length === 0) return str1.length;
+
+      // two rows
+      var prevRow  = new Array(str2.length + 1),
+          curCol, nextCol, i, j, tmp;
+
+      // initialise previous row
+      for (i=0; i<prevRow.length; ++i) {
+        prevRow[i] = i;
+      }
+
+      // calculate current row distance from previous row
+      for (i=0; i<str1.length; ++i) {
+        nextCol = i + 1;
+
+        for (j=0; j<str2.length; ++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;
+          }
+
+          // 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;
+    },
+
+    /**
+     * 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);
+
+      // 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);
+
+      // two rows
+      var prevRow  = new Array(str2.length + 1),
+          curCol, nextCol,
+          i, j, tmp,
+          startTime, currentTime;
+
+      // initialise previous row
+      for (i=0; i<prevRow.length; ++i) {
+        prevRow[i] = i;
+      }
+
+      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);
+            }
+            // else if we have more left to do
+            else {
+              nextCol = i + 1;
+              j = 0;
+            }
+          }
+
+          // 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 into previous (in preparation for next iteration)
+          prevRow[j] = curCol;
+
+          // get current time
+          currentTime = new Date().valueOf();
+        }
+
+        // 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();
+    }
+
+  };
+
+  // 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;
+  }
+}());
+
-- 
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