1 files changed, 60 insertions, 0 deletions
diff --git a/src/System.Web.Mvc/RouteValuesHelpers.cs b/src/System.Web.Mvc/RouteValuesHelpers.cs
new file mode 100644
index 00000000..4e4b6904
--- /dev/null
+++ b/src/System.Web.Mvc/RouteValuesHelpers.cs
@@ -0,0 +1,60 @@
+using System.Collections.Generic;
+using System.Web.Routing;
+
+namespace System.Web.Mvc
+{
+    internal static class RouteValuesHelpers
+    {
+        public static RouteValueDictionary GetRouteValues(RouteValueDictionary routeValues)
+        {
+            return (routeValues != null) ? new RouteValueDictionary(routeValues) : new RouteValueDictionary();
+        }
+
+        public static RouteValueDictionary MergeRouteValues(string actionName, string controllerName, RouteValueDictionary implicitRouteValues, RouteValueDictionary routeValues, bool includeImplicitMvcValues)
+        {
+            // Create a new dictionary containing implicit and auto-generated values
+            RouteValueDictionary mergedRouteValues = new RouteValueDictionary();
+
+            if (includeImplicitMvcValues)
+            {
+                // We only include MVC-specific values like 'controller' and 'action' if we are generating an action link.
+                // If we are generating a route link [as to MapRoute("Foo", "any/url", new { controller = ... })], including
+                // the current controller name will cause the route match to fail if the current controller is not the same
+                // as the destination controller.
+
+                object implicitValue;
+                if (implicitRouteValues != null && implicitRouteValues.TryGetValue("action", out implicitValue))
+                {
+                    mergedRouteValues["action"] = implicitValue;
+                }
+
+                if (implicitRouteValues != null && implicitRouteValues.TryGetValue("controller", out implicitValue))
+                {
+                    mergedRouteValues["controller"] = implicitValue;
+                }
+            }
+
+            // Merge values from the user's dictionary/object
+            if (routeValues != null)
+            {
+                foreach (KeyValuePair<string, object> routeElement in GetRouteValues(routeValues))
+                {
+                    mergedRouteValues[routeElement.Key] = routeElement.Value;
+                }
+            }
+
+            // Merge explicit parameters when not null
+            if (actionName != null)
+            {
+                mergedRouteValues["action"] = actionName;
+            }
+
+            if (controllerName != null)
+            {
+                mergedRouteValues["controller"] = controllerName;
+            }
+
+            return mergedRouteValues;
+        }
+    }
+}