Refactored TfIdfSearchIndex change to fix test while (hopefully) still preserving previous scope optimization

Author: Brian Vaughn

source/SearchIndex/TfIdfSearchIndex.js

@@ -112,7 +112,20 @@ export class TfIdfSearchIndex implements ISearchIndex {
     var tokenToIdfCache = this._tokenToIdfCache;
     var uidFieldName = this._uidFieldName;
 
-    function calculateIdf(token : string, documents : Array<Object>) : number {
+    var calculateTfIdf = this._createCalculateTfIdf();
+
+    // Return documents sorted by TF-IDF
+    return documents.sort((documentA, documentB) =>
+      calculateTfIdf(tokens, documentB, corpus) -
+      calculateTfIdf(tokens, documentA, corpus)
+    );
+  }
+
+  _createCalculateIdf () : Function {
+    var tokenMap = this._tokenMap;
+    var tokenToIdfCache = this._tokenToIdfCache;
+
+    return function calculateIdf(token : string, documents : Array<Object>) : number {
       if (!tokenToIdfCache[token]) {
         var numDocumentsWithToken:number = tokenMap[token] && tokenMap[token].$numDocumentOccurrences || 0;
 
@@ -121,8 +134,14 @@ export class TfIdfSearchIndex implements ISearchIndex {
 
       return tokenToIdfCache[token];
     }
+  }
 
-    function calculateTfIdf(tokens : Array<string>, document : Object, documents : Array<Object>) : number {
+  _createCalculateTfIdf () : Function {
+    var tokenMap = this._tokenMap;
+    var uidFieldName = this._uidFieldName;
+    var calculateIdf = this._createCalculateIdf();
+
+    return function calculateTfIdf(tokens : Array<string>, document : Object, documents : Array<Object>) : number {
       var score:number = 0;
 
       for (var i = 0, numTokens = tokens.length; i < numTokens; ++i) {
@@ -145,11 +164,5 @@ export class TfIdfSearchIndex implements ISearchIndex {
 
       return score;
     }
-
-    // Return documents sorted by TF-IDF
-    return documents.sort((documentA, documentB) =>
-      calculateTfIdf(tokens, documentB, corpus) -
-      calculateTfIdf(tokens, documentA, corpus)
-    );
   }
 };

source/SearchIndex/TfIdfSearchIndex.test.js

@@ -41,7 +41,8 @@ describe('Search', function() {
   };
 
   var assertIdf = function(term, numDocumentsWithToken) {
-    expect(search.searchIndex._calculateIdf(term, search._documents)).toEqual(calculateIdf(numDocumentsWithToken));
+    var _calculateIdf = search.searchIndex._createCalculateIdf();
+    expect(_calculateIdf(term, search._documents)).toEqual(calculateIdf(numDocumentsWithToken));
   };
 
   it('should handle special words like "constructor"', function () {
@@ -79,7 +80,8 @@ describe('Search', function() {
   };
 
   var assertTfIdf = function(terms, document, expectedTfIdf) {
-    expect(search.searchIndex._calculateTfIdf(terms, document, search._documents)).toEqual(expectedTfIdf);
+    var _calculateTfIdf = search.searchIndex._createCalculateTfIdf();
+    expect(_calculateTfIdf(terms, document, search._documents)).toEqual(expectedTfIdf);
   };
 
   describe('TF-IDF', function() {