CCan specify custom string comparison function

lib/cursor.js

@@ -145,7 +145,7 @@ Cursor.prototype._exec = function(callback) {
       var criterion, compare, i;
       for (i = 0; i < criteria.length; i++) {
         criterion = criteria[i];
-        compare = criterion.direction * model.compareThings(model.getDotValue(a, criterion.key), model.getDotValue(b, criterion.key));
+        compare = criterion.direction * model.compareThings(model.getDotValue(a, criterion.key), model.getDotValue(b, criterion.key), self.db.compareStrings);
         if (compare !== 0) {
           return compare;
         }

lib/datastore.js

@@ -21,6 +21,7 @@ var customUtils = require('./customUtils')
  * @param {Function} options.onload Optional, if autoload is used this will be called after the load database with the error object as parameter. If you don't pass it the error will be thrown
  * @param {Function} options.afterSerialization/options.beforeDeserialization Optional, serialization hooks
  * @param {Number} options.corruptAlertThreshold Optional, threshold after which an alert is thrown if too much data is corrupt
+ * @param {Function} options.compareStrings Optional, string comparison function that overrides default for sorting
  */
 function Datastore (options) {
   var filename;
@@ -45,6 +46,9 @@ function Datastore (options) {
     this.filename = filename;
   }
 
+  // String comparison function
+  this.compareStrings = options.compareStrings;
+
   // Persistence handling
   this.persistence = new Persistence({ db: this, nodeWebkitAppName: options.nodeWebkitAppName
                                       , afterSerialization: options.afterSerialization

lib/model.js

@@ -183,9 +183,12 @@ function compareArrays (a, b) {
  * In the case of objects and arrays, we deep-compare
  * If two objects dont have the same type, the (arbitrary) type hierarchy is: undefined, null, number, strings, boolean, dates, arrays, objects
  * Return -1 if a < b, 1 if a > b and 0 if a = b (note that equality here is NOT the same as defined in areThingsEqual!)
+ *
+ * @param {Function} _compareStrings String comparing function, returning -1, 0 or 1, overriding default string comparison (useful for languages with accented letters)
  */
-function compareThings (a, b) {
+function compareThings (a, b, _compareStrings) {
-  var aKeys, bKeys, comp, i;
+  var aKeys, bKeys, comp, i
+    , compareStrings = _compareStrings || compareNSB;
 
   // undefined
   if (a === undefined) { return b === undefined ? 0 : -1; }
@@ -200,8 +203,8 @@ function compareThings (a, b) {
   if (typeof b === 'number') { return typeof a === 'number' ? compareNSB(a, b) : 1; }
 
   // Strings
-  if (typeof a === 'string') { return typeof b === 'string' ? compareNSB(a, b) : -1; }
+  if (typeof a === 'string') { return typeof b === 'string' ? compareStrings(a, b) : -1; }
-  if (typeof b === 'string') { return typeof a === 'string' ? compareNSB(a, b) : 1; }
+  if (typeof b === 'string') { return typeof a === 'string' ? compareStrings(a, b) : 1; }
 
   // Booleans
   if (typeof a === 'boolean') { return typeof b === 'boolean' ? compareNSB(a, b) : -1; }

test/cursor.test.js

@@ -191,6 +191,31 @@ describe('Cursor', function () {
       });
     });
 
+    it("Sorting strings with custom string comparison function", function (done) {
+      var db = new Datastore({ inMemoryOnly: true, autoload: true
+                             , compareStrings: function (a, b) { return a.length - b.length; }
+                             });
+
+      db.insert({ name: 'alpha' });
+      db.insert({ name: 'charlie' });
+      db.insert({ name: 'zulu' });
+
+      db.find({}).sort({ name: 1 }).exec(function (err, docs) {
+        _.pluck(docs, 'name')[0].should.equal('zulu');
+        _.pluck(docs, 'name')[1].should.equal('alpha');
+        _.pluck(docs, 'name')[2].should.equal('charlie');
+
+        delete db.compareStrings;
+        db.find({}).sort({ name: 1 }).exec(function (err, docs) {
+          _.pluck(docs, 'name')[0].should.equal('alpha');
+          _.pluck(docs, 'name')[1].should.equal('charlie');
+          _.pluck(docs, 'name')[2].should.equal('zulu');
+
+          done();
+        });
+      });
+    });
+
     it('With an empty collection', function (done) {
       async.waterfall([
         function (cb) {

test/model.test.js

@@ -813,6 +813,11 @@ describe('Model', function () {
       model.compareThings({ a: 42, b: 312, c: 54 }, { b: 313, a: 42 }).should.equal(-1);
     });
 
+    it('Can specify custom string comparison function', function () {
+      model.compareThings('hello', 'bloup', function (a, b) { return a < b ? -1 : 1; }).should.equal(1);
+      model.compareThings('hello', 'bloup', function (a, b) { return a > b ? -1 : 1; }).should.equal(-1);
+    });
+
   });   // ==== End of 'Comparing things' ==== //