Add an implementation of the knuth-fisher-yates shuffle, using the ne…

…w set_random method in Parrot

src/query/Provider.winxed

@@ -162,6 +162,13 @@ class Rosella.Query.Provider
         return new_data;
     }
 
+    function shuffle(var data)
+    {
+        var new_data = self.to_array(data);
+        Rosella.Query.knuth_fisher_yates_shuffle(new_data);
+        return new_data;
+    }
+
     // Return the list of keys of the aggregate
     function keys(var data)
     {

src/query/Query.winxed

@@ -86,6 +86,19 @@ namespace Rosella.Query
         }
     }
 
+    function knuth_fisher_yates_shuffle(var d)
+    {
+        int i = elements(d);
+        var rand = new 'Integer';
+        for (int i = elements(d) - 1; i > 0; i--) {
+            rand.set_random(i + 1);
+            int n = rand;
+            var v = d[i];
+            d[i] = d[n];
+            d[n] = v;
+        }
+    }
+
     function install_to_type(var type)
     {
         var type_class = Rosella.get_type_class(type);

src/query/Queryable.winxed

@@ -104,6 +104,12 @@ class Rosella.Query.Queryable
         return self.as_queryable(result);
     }
 
+    function shuffle()
+    {
+        var result = self.provider.shuffle(self.data);
+        return self.as_queryable(result);
+    }
+
     // Return a count of elements
     function count(var func [optional], int has_func [opt_flag])
     {