Adding support for ViewLocationExpanders to allow modifying view locations

without changing the view engine.

Fixes #1039

samples/MvcSample.Web/HomeController.cs

@@ -97,6 +97,11 @@ namespace MvcSample.Web
             Context.Response.WriteAsync("Hello World raw");
         }
 
+        public ActionResult Language()
+        {
+            return View();
+        }
+
         [Produces("application/json", "application/xml", "application/custom", "text/json", Type = typeof(User))]
         public object ReturnUser()
         {

samples/MvcSample.Web/LanguageViewLocationExpander.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.Mvc;
+using Microsoft.AspNet.Mvc.Razor;
+
+namespace MvcSample.Web
+{
+    /// <summary>
+    /// A <see cref="IViewLocationExpander"/> that replaces adds the language as an extension prefix to view names.
+    /// </summary>
+    /// <example>
+    /// For the default case with no areas, views are generated with the following patterns (assuming controller is
+    /// "Home", action is "Index" and language is "en")
+    /// Views/Home/en/Action
+    /// Views/Home/Action
+    /// Views/Shared/en/Action
+    /// Views/Shared/Action
+    /// </example>
+    public class LanguageViewLocationExpander : IViewLocationExpander
+    {
+        private const string ValueKey = "language";
+        private readonly Func<ActionContext, string> _valueFactory;
+
+        /// <summary>
+        /// Initializes a new instance of <see cref="LanguageViewLocationExpander"/>.
+        /// </summary>
+        /// <param name="valueFactory">A factory that provides tbe language to use for expansion.</param>
+        public LanguageViewLocationExpander(Func<ActionContext, string> valueFactory)
+        {
+            _valueFactory = valueFactory;
+        }
+
+        /// <inheritdoc />
+        public void PopulateValues(ViewLocationExpanderContext context)
+        {
+            var value = _valueFactory(context.ActionContext);
+            if (!string.IsNullOrEmpty(value))
+            {
+                context.Values[ValueKey] = value;
+            }
+        }
+
+        /// <inheritdoc />
+        public virtual IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context,
+                                                               IEnumerable<string> viewLocations)
+        {
+            string value;
+            if (context.Values.TryGetValue(ValueKey, out value))
+            {
+                return ExpandViewLocationsCore(viewLocations, value);
+            }
+
+            return viewLocations;
+        }
+
+        private IEnumerable<string> ExpandViewLocationsCore(IEnumerable<string> viewLocations,
+                                                            string value)
+        {
+            foreach (var location in viewLocations)
+            {
+                yield return location.Replace("{0}", value + "/{0}");
+                yield return location;
+            }
+        }
+    }
+}

samples/MvcSample.Web/Startup.cs

@@ -1,10 +1,10 @@
 using System;
 using Microsoft.AspNet.Builder;
 using Microsoft.AspNet.Mvc;
+using Microsoft.AspNet.Mvc.Razor;
 using Microsoft.AspNet.Routing;
 using Microsoft.Framework.ConfigurationModel;
 using Microsoft.Framework.DependencyInjection;
-using Microsoft.Framework.OptionsModel;
 using MvcSample.Web.Filters;
 using MvcSample.Web.Services;
 
@@ -46,6 +46,12 @@ namespace MvcSample.Web
                     {
                         options.Filters.Add(typeof(PassThroughAttribute), order: 17);
                     });
+                    services.SetupOptions<RazorViewEngineOptions>(options =>
+                    {
+                        var expander = new LanguageViewLocationExpander(
+                            context => context.HttpContext.Request.Query["language"]);
+                        options.ViewLocationExpanders.Insert(0, expander);
+                    });
 
                     // Create the autofac container 
                     ContainerBuilder builder = new ContainerBuilder();

samples/MvcSample.Web/Views/Home/Language.cshtml

@@ -0,0 +1,5 @@
+<ul>
+    <li>COLOR</li>
+    <li>HUMOR</li>
+    <li>ITEMIZE</li>
+</ul>

samples/MvcSample.Web/Views/Home/en-gb/Language.cshtml

@@ -0,0 +1,5 @@
+<ul>
+    <li>COLOUR</li>
+    <li>HUMOUR</li>
+    <li>ITEMISE</li>
+</ul>

samples/MvcSample.Web/Views/Home/fr/Language.cshtml

@@ -0,0 +1,5 @@
+<ul>
+    <li>COULEUR</li>
+    <li>HUMOUR</li>
+    <li>DÉTAILLER</li>
+</ul>

samples/MvcSample.Web/Views/Shared/_Layout.cshtml

@@ -5,6 +5,12 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>@ViewBag.Title - My ASP.NET Application</title>
     <link rel="stylesheet" href="~/content/bootstrap.min.css" />
+    <style>
+        body { padding-top: 60px; }
+        @@media screen and (max-width: 768px) {
+            body { padding-top: 0px; }
+        }
+    </style>
     @RenderSection("header", required: false)
 </head>
 <body>

src/Microsoft.AspNet.Mvc.Core/MvcOptions.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using Microsoft.AspNet.Mvc.Core;
 using Microsoft.AspNet.Mvc.OptionDescriptors;
 using Microsoft.AspNet.Mvc.ReflectedModelBuilder;
@@ -16,7 +15,6 @@ namespace Microsoft.AspNet.Mvc
     public class MvcOptions
     {
         private AntiForgeryOptions _antiForgeryOptions = new AntiForgeryOptions();
-        private RazorViewEngineOptions _viewEngineOptions = new RazorViewEngineOptions();
         private int _maxModelStateErrors = 200;
 
         public MvcOptions()
@@ -71,29 +69,6 @@ namespace Microsoft.AspNet.Mvc
         /// </summary>
         public List<InputFormatterDescriptor> InputFormatters { get; private set; }
 
-        /// <summary>
-        /// Provides programmatic configuration for the default <see cref="Rendering.IViewEngine" />.
-        /// </summary>
-        public RazorViewEngineOptions ViewEngineOptions
-        {
-            get
-            {
-                return _viewEngineOptions;
-            }
-
-            set
-            {
-                if (value == null)
-                {
-                    throw new ArgumentNullException("value",
-                                                    Resources.FormatPropertyOfTypeCannotBeNull("ViewEngineOptions",
-                                                                                               typeof(MvcOptions)));
-                }
-
-                _viewEngineOptions = value;
-            }
-        }
-
         /// <summary>
         /// Gets or sets the maximum number of validation errors that are allowed by this application before further
         /// errors are ignored.
@@ -123,8 +98,8 @@ namespace Microsoft.AspNet.Mvc
         /// Gets a list of the <see cref="ModelValidatorProviderDescriptor" />s used by
         /// <see cref="ModelBinding.CompositeModelValidatorProvider"/>.
         /// </summary>
-        public List<ModelValidatorProviderDescriptor> ModelValidatorProviders { get; } =
-            new List<ModelValidatorProviderDescriptor>();
+        public List<ModelValidatorProviderDescriptor> ModelValidatorProviders { get; }
+            = new List<ModelValidatorProviderDescriptor>();
 
         /// <summary>
         /// Gets a list of descriptors that represent <see cref="Rendering.IViewEngine"/> used

src/Microsoft.AspNet.Mvc.Core/Properties/Resources.Designer.cs

@@ -1354,6 +1354,54 @@ namespace Microsoft.AspNet.Mvc.Core
             return string.Format(CultureInfo.CurrentCulture, GetString("AttributeRoute_AggregateErrorMessage_ErrorNumber"), p0, p1, p2);
         }
 
+        /// <summary>
+        /// Could not find a replacement for view expansion token '{0}'.
+        /// </summary>
+        internal static string TemplatedViewLocationExpander_NoReplacementToken
+        {
+            get { return GetString("TemplatedViewLocationExpander_NoReplacementToken"); }
+        }
+
+        /// <summary>
+        /// Could not find a replacement for view expansion token '{0}'.
+        /// </summary>
+        internal static string FormatTemplatedViewLocationExpander_NoReplacementToken(object p0)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("TemplatedViewLocationExpander_NoReplacementToken"), p0);
+        }
+
+        /// <summary>
+        /// {0} must be executed before {1} can be invoked.
+        /// </summary>
+        internal static string TemplatedExpander_PopulateValuesMustBeInvokedFirst
+        {
+            get { return GetString("TemplatedExpander_PopulateValuesMustBeInvokedFirst"); }
+        }
+
+        /// <summary>
+        /// {0} must be executed before {1} can be invoked.
+        /// </summary>
+        internal static string FormatTemplatedExpander_PopulateValuesMustBeInvokedFirst(object p0, object p1)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("TemplatedExpander_PopulateValuesMustBeInvokedFirst"), p0, p1);
+        }
+
+        /// <summary>
+        /// The result of value factory cannot be null.
+        /// </summary>
+        internal static string TemplatedExpander_ValueFactoryCannotReturnNull
+        {
+            get { return GetString("TemplatedExpander_ValueFactoryCannotReturnNull"); }
+        }
+
+        /// <summary>
+        /// The result of value factory cannot be null.
+        /// </summary>
+        internal static string FormatTemplatedExpander_ValueFactoryCannotReturnNull()
+        {
+            return GetString("TemplatedExpander_ValueFactoryCannotReturnNull");
+        }
+
         /// <summary>
         /// A method '{0}' that defines attribute routed actions must not have attributes that implement '{1}' and do not implement '{2}':{3}{4}
         /// </summary>

src/Microsoft.AspNet.Mvc.Core/Resources.resx

@@ -375,6 +375,15 @@
     <value>Error {0}:{1}{2}</value>
     <comment>{0} is the error number, {1} is Environment.NewLine {2} is the  error message</comment>
   </data>
+  <data name="TemplatedViewLocationExpander_NoReplacementToken" xml:space="preserve">
+    <value>Could not find a replacement for view expansion token '{0}'.</value>
+  </data>
+  <data name="TemplatedExpander_PopulateValuesMustBeInvokedFirst" xml:space="preserve">
+    <value>{0} must be executed before {1} can be invoked.</value>
+  </data>
+  <data name="TemplatedExpander_ValueFactoryCannotReturnNull" xml:space="preserve">
+    <value>The result of value factory cannot be null.</value>
+  </data>
   <data name="AttributeRoute_InvalidHttpConstraints" xml:space="preserve">
     <value>A method '{0}' that defines attribute routed actions must not have attributes that implement '{1}' and do not implement '{2}':{3}{4}</value>
     <comment>{0} is the MethodInfo.FullName, {1} is typeof(IActionHttpMethodProvider).FullName, {2} is typeof(IRouteTemplateProvider).FullName, {3} is Environment.NewLine, {4} is the list of actions and their respective invalid IActionHttpMethodProvider attributes formatted using AttributeRoute_InvalidHttpMethodConstraints_Item</comment>

src/Microsoft.AspNet.Mvc.Core/project.json

@@ -11,7 +11,7 @@
     "Microsoft.AspNet.Mvc.ModelBinding": "",
     "Microsoft.AspNet.Routing": "1.0.0-*",
     "Microsoft.AspNet.Security": "1.0.0-*",
-    "Microsoft.AspNet.Security.DataProtection" : "1.0.0-*",
+    "Microsoft.AspNet.Security.DataProtection": "1.0.0-*",
     "Microsoft.Framework.DependencyInjection": "1.0.0-*",
     "Microsoft.Framework.Runtime.Interfaces":  "1.0.0-*",
     "Microsoft.Framework.Logging": "1.0.0-*",

src/Microsoft.AspNet.Mvc.Razor/Compilation/ExpiringFileInfoCache.cs

@@ -7,7 +7,7 @@ using Microsoft.AspNet.FileSystems;
 using Microsoft.Framework.OptionsModel;
 using Microsoft.Framework.Runtime;
 
-namespace Microsoft.AspNet.Mvc.Core
+namespace Microsoft.AspNet.Mvc.Razor
 {
     /// <summary>
     /// A default implementation for the <see cref="IFileInfoCache"/> interface.
@@ -37,11 +37,11 @@ namespace Microsoft.AspNet.Mvc.Core
         }
 
         public ExpiringFileInfoCache(IApplicationEnvironment env,
-                                     IOptionsAccessor<MvcOptions> optionsAccessor)
+                                     IOptionsAccessor<RazorViewEngineOptions> optionsAccessor)
         {
             // TODO: Inject the IFileSystem but only when we get it from the host
             _fileSystem = new PhysicalFileSystem(env.ApplicationBasePath);
-            _offset = optionsAccessor.Options.ViewEngineOptions.ExpirationBeforeCheckingFilesOnDisk;
+            _offset = optionsAccessor.Options.ExpirationBeforeCheckingFilesOnDisk;
         }
 
         /// <inheritdoc />

src/Microsoft.AspNet.Mvc.Razor/Compilation/IExpiringFileInfoCache.cs

@@ -3,7 +3,7 @@
 
 using Microsoft.AspNet.FileSystems;
 
-namespace Microsoft.AspNet.Mvc.Core
+namespace Microsoft.AspNet.Mvc.Razor
 {
     /// <summary>
     /// Provides cached access to file infos.

src/Microsoft.AspNet.Mvc.Razor/DefaultViewLocationCache.cs

@@ -0,0 +1,81 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    /// <summary>
+    /// Default implementation of <see cref="IViewLocationCache"/>.
+    /// </summary>
+    public class DefaultViewLocationCache : IViewLocationCache
+    {
+        private const char CacheKeySeparator = ':';
+
+        // A mapping of keys generated from ViewLocationExpanderContext to view locations.
+        private readonly ConcurrentDictionary<string, string> _cache;
+
+        /// <summary>
+        /// Initializes a new instance of <see cref="DefaultViewLocationCache"/>.
+        /// </summary>
+        public DefaultViewLocationCache()
+        {
+            _cache = new ConcurrentDictionary<string, string>(StringComparer.Ordinal);
+        }
+
+        /// <inheritdoc />
+        public string Get([NotNull] ViewLocationExpanderContext context)
+        {
+            var cacheKey = GenerateKey(context);
+            string result;
+            _cache.TryGetValue(cacheKey, out result);
+            return result;
+        }
+
+        /// <inheritdoc />
+        public void Set([NotNull] ViewLocationExpanderContext context,
+                        [NotNull] string value)
+        {
+            var cacheKey = GenerateKey(context);
+            _cache.TryAdd(cacheKey, value);
+        }
+
+        internal static string GenerateKey(ViewLocationExpanderContext context)
+        {
+            var keyBuilder = new StringBuilder();
+            var routeValues = context.ActionContext.RouteData.Values;
+            var controller = routeValues.GetValueOrDefault<string>(RazorViewEngine.ControllerKey);
+
+            // format is "{viewName}:{controllerName}:{areaName}:"
+            keyBuilder.Append(context.ViewName)
+                      .Append(CacheKeySeparator)
+                      .Append(controller);
+
+            var area = routeValues.GetValueOrDefault<string>(RazorViewEngine.AreaKey);
+            if (!string.IsNullOrEmpty(area))
+            {
+                keyBuilder.Append(CacheKeySeparator)
+                          .Append(area);
+            }
+
+            if (context.Values != null)
+            {
+                var valuesDictionary = context.Values;
+                foreach (var item in valuesDictionary.OrderBy(k => k.Key, StringComparer.Ordinal))
+                {
+                    keyBuilder.Append(CacheKeySeparator)
+                              .Append(item.Key)
+                              .Append(CacheKeySeparator)
+                              .Append(item.Value);
+                }
+            }
+
+            var cacheKey = keyBuilder.ToString();
+            return cacheKey;
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Razor/IViewLocationCache.cs

@@ -0,0 +1,27 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    /// <summary>
+    /// Specifies the contracts for caching view locations generated by <see cref="IViewLocationExpander"/>.
+    /// </summary>
+    public interface IViewLocationCache
+    {
+        /// <summary>
+        /// Gets a cached view location based on the specified <paramref name="context"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="ViewLocationExpanderContext"/> for the current view location 
+        /// expansion.</param>
+        /// <returns>The cached location, if available, <c>null</c> otherwise.</returns>
+        string Get(ViewLocationExpanderContext context);
+
+        /// <summary>
+        /// Adds a cache entry for values specified by <paramref name="context"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="ViewLocationExpanderContext"/> for the current view location 
+        /// expansion.</param>
+        /// <param name="value">The view location that is to be cached.</param>
+        void Set(ViewLocationExpanderContext context, string value);
+    }
+}

src/Microsoft.AspNet.Mvc.Razor/IViewLocationExpander.cs

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    /// <summary>
+    /// Specifies the contracts for a view location expander that is used by <see cref="RazorViewEngine"/> instances to
+    /// determine search paths for a view.
+    /// </summary>
+    /// <remarks>
+    /// Individual <see cref="IViewLocationExpander"/>s are invoked in two steps:
+    /// (1) <see cref="PopulateValues(ViewLocationExpanderContext)"/> is invoked and each expander
+    /// adds values that it would later consume as part of 
+    /// <see cref="ExpandViewLocations(ViewLocationExpanderContext, IEnumerable{string})"/>.
+    /// The populated values are used to determine a cache key - if all values are identical to the last time
+    /// <see cref="PopulateValues(ViewLocationExpanderContext)"/> was invoked, the cached result
+    /// is used as the view location.
+    /// (2) If no result was found in the cache or if a view was not found at the cached location, 
+    /// <see cref="ExpandViewLocations(ViewLocationExpanderContext, IEnumerable{string})"/> is invoked to determine 
+    /// all potential paths for a view.
+    /// </remarks>
+    public interface IViewLocationExpander
+    {
+        /// <summary>
+        /// Invoked by a <see cref="RazorViewEngine"/> to determine the values that would be consumed by this instance of
+        /// <see cref="IViewLocationExpander"/>. The calculated values are used to determine if the view location has
+        /// changed since the last time it was located.
+        /// </summary>
+        /// <param name="context">The <see cref="ViewLocationExpanderContext"/> for the current view location
+        /// expansion operation.</param>
+        void PopulateValues(ViewLocationExpanderContext context);
+
+        /// <summary>
+        /// Invoked by a <see cref="RazorViewEngine"/> to determine potential locations for a view.
+        /// </summary>
+        /// <param name="context">The <see cref="ViewLocationExpanderContext"/> for the current view location
+        /// expansion operation.</param>
+        /// <param name="values">The sequence of view locations to expand.</param>
+        /// <returns>A list of expanded view locations.</returns>
+        IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context,
+                                                IEnumerable<string> viewLocations);
+    }
+}

src/Microsoft.AspNet.Mvc.Razor/OptionDescriptors/DefaultViewLocationExpanderProvider.cs

@@ -0,0 +1,37 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.Mvc.OptionDescriptors;
+using Microsoft.Framework.DependencyInjection;
+using Microsoft.Framework.OptionsModel;
+
+namespace Microsoft.AspNet.Mvc.Razor.OptionDescriptors
+{
+    /// <inheritdoc />
+    public class DefaultViewLocationExpanderProvider :
+        OptionDescriptorBasedProvider<IViewLocationExpander>, IViewLocationExpanderProvider
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DefaultViewLocationExpanderProvider"/> class.
+        /// </summary>
+        /// <param name="options">An accessor to the <see cref="MvcOptions"/> configured for this application.</param>
+        /// <param name="typeActivator">An <see cref="ITypeActivator"/> instance used to instantiate types.</param>
+        /// <param name="serviceProvider">A <see cref="IServiceProvider"/> instance that retrieves services from the 
+        /// service collection.</param>
+        public DefaultViewLocationExpanderProvider(
+            IOptionsAccessor<RazorViewEngineOptions> optionsAccessor,
+            ITypeActivator typeActivator,
+            IServiceProvider serviceProvider)
+            : base(optionsAccessor.Options.ViewLocationExpanders, typeActivator, serviceProvider)
+        {
+        }
+
+        /// <inheritdoc />
+        public IReadOnlyList<IViewLocationExpander> ViewLocationExpanders
+        {
+            get { return Options; }
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Razor/OptionDescriptors/IViewLocationExpanderProvider.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.AspNet.Mvc.Razor.OptionDescriptors
+{
+    /// <summary>
+    /// Provides an activated collection of <see cref="IViewLocationExpander"/> instances.
+    /// </summary>
+    public interface IViewLocationExpanderProvider
+    {
+        /// <summary>
+        /// Gets a collection of activated <see cref="IViewLocationExpander"/> instances.
+        /// </summary>
+        IReadOnlyList<IViewLocationExpander> ViewLocationExpanders { get; }
+    }
+}

src/Microsoft.AspNet.Mvc.Razor/OptionDescriptors/RazorViewEngineOptions.cs

@@ -2,8 +2,10 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.Mvc.Razor.OptionDescriptors;
 
-namespace Microsoft.AspNet.Mvc.Core
+namespace Microsoft.AspNet.Mvc.Razor
 {
     /// <summary>
     /// Provides programmatic configuration for the default <see cref="Microsoft.AspNet.Mvc.Rendering.IViewEngine"/>.
@@ -38,5 +40,12 @@ namespace Microsoft.AspNet.Mvc.Core
                 }
             }
         }
+
+        /// <summary>
+        /// Get a <see cref="IList{T}"/> of descriptors for <see cref="IViewLocationExpander" />s used by this
+        /// application.
+        /// </summary>
+        public IList<ViewLocationExpanderDescriptor> ViewLocationExpanders { get; }
+            = new List<ViewLocationExpanderDescriptor>();
     }
 }

src/Microsoft.AspNet.Mvc.Razor/OptionDescriptors/ViewLocationExpanderDescriptor.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.AspNet.Mvc.OptionDescriptors;
+
+namespace Microsoft.AspNet.Mvc.Razor.OptionDescriptors
+{
+    /// <summary>
+    /// Encapsulates information that describes an <see cref="IViewLocationExpander"/>.
+    /// </summary>
+    public class ViewLocationExpanderDescriptor : OptionDescriptor<IViewLocationExpander>
+    {
+        /// <summary>
+        /// Creates a new instance of <see cref="ViewLocationExpanderDescriptor"/>.
+        /// </summary>
+        /// <param name="type">A <see cref="IViewLocationExpander"/> type that the descriptor represents.
+        /// </param>
+        public ViewLocationExpanderDescriptor([NotNull] Type type)
+            : base(type)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new instance of <see cref="ViewLocationExpanderDescriptor"/>.
+        /// </summary>
+        /// <param name="viewLocationExpander">An instance of <see cref="IViewLocationExpander"/>
+        /// that the descriptor represents.</param>
+        public ViewLocationExpanderDescriptor([NotNull] IViewLocationExpander viewLocationExpander)
+            : base(viewLocationExpander)
+        {
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Razor/OptionDescriptors/ViewLocationExpanderDescriptorExtensions.cs

@@ -0,0 +1,93 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.Mvc.Razor.OptionDescriptors;
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    /// <summary>
+    /// Extension methods for adding view location expanders to a collection.
+    /// </summary>
+    public static class ViewLocationExpanderDescriptorExtensions
+    {
+        /// <summary>
+        /// Adds a type representing a <see cref="IViewLocationExpander"/> to <paramref name="descriptors"/>.
+        /// </summary>
+        /// <param name="descriptors">A list of <see cref="ViewLocationExpanderDescriptor"/>.</param>
+        /// <param name="viewLocationExpanderType">Type representing an <see cref="IViewLocationExpander"/></param>
+        /// <returns>A <see cref="ViewLocationExpanderDescriptor"/> representing the added instance.</returns>
+        public static ViewLocationExpanderDescriptor Add(
+            [NotNull] this IList<ViewLocationExpanderDescriptor> descriptors,
+            [NotNull] Type viewLocationExpanderType)
+        {
+            var descriptor = new ViewLocationExpanderDescriptor(viewLocationExpanderType);
+            descriptors.Add(descriptor);
+            return descriptor;
+        }
+
+        /// <summary>
+        /// Inserts a type representing a <see cref="IViewLocationExpander"/> in to <paramref name="descriptors"/> at
+        /// the specified <paramref name="index"/>.
+        /// </summary>
+        /// <param name="descriptors">A list of <see cref="ViewLocationExpanderDescriptor"/>.</param>
+        /// <param name="index">The zero-based index at which <paramref name="viewLocationExpanderType"/> 
+        /// should be inserted.</param>
+        /// <param name="viewLocationExpanderType">Type representing an <see cref="IViewLocationExpander"/></param>
+        /// <returns>A <see cref="ViewLocationExpanderDescriptor"/> representing the inserted instance.</returns>
+        public static ViewLocationExpanderDescriptor Insert(
+            [NotNull] this IList<ViewLocationExpanderDescriptor> descriptors,
+            int index,
+            [NotNull] Type viewLocationExpanderType)
+        {
+            if (index < 0 || index > descriptors.Count)
+            {
+                throw new ArgumentOutOfRangeException(nameof(index));
+            }
+
+            var descriptor = new ViewLocationExpanderDescriptor(viewLocationExpanderType);
+            descriptors.Insert(index, descriptor);
+            return descriptor;
+        }
+
+        /// <summary>
+        /// Adds an <see cref="IViewLocationExpander"/> to <paramref name="descriptors"/>.
+        /// </summary>
+        /// <param name="descriptors">A list of <see cref="ViewLocationExpanderDescriptor"/>.</param>
+        /// <param name="viewLocationExpander">An <see cref="IViewLocationExpander"/> instance.</param>
+        /// <returns>A <see cref="ViewLocationExpanderDescriptor"/> representing the added instance.</returns>
+        public static ViewLocationExpanderDescriptor Add(
+            [NotNull] this IList<ViewLocationExpanderDescriptor> descriptors,
+            [NotNull] IViewLocationExpander viewLocationExpander)
+        {
+            var descriptor = new ViewLocationExpanderDescriptor(viewLocationExpander);
+            descriptors.Add(descriptor);
+            return descriptor;
+        }
+
+        /// <summary>
+        /// Insert an <see cref="IViewLocationExpander"/> in to <paramref name="descriptors"/> at the specified
+        /// <paramref name="index"/>.
+        /// </summary>
+        /// <param name="descriptors">A list of <see cref="ViewLocationExpanderDescriptor"/>.</param>
+        /// <param name="index">The zero-based index at which <paramref name="viewLocationExpander"/> 
+        /// should be inserted.</param>
+        /// <param name="viewLocationExpander">An <see cref="IViewLocationExpander"/> instance.</param>
+        /// <returns>A <see cref="ViewLocationExpanderDescriptor"/> representing the added instance.</returns>
+        public static ViewLocationExpanderDescriptor Insert(
+            [NotNull] this IList<ViewLocationExpanderDescriptor> descriptors,
+            int index,
+            [NotNull] IViewLocationExpander viewLocationExpander)
+        {
+            if (index < 0 || index > descriptors.Count)
+            {
+                throw new ArgumentOutOfRangeException(nameof(index));
+            }
+
+            var descriptor = new ViewLocationExpanderDescriptor(viewLocationExpander);
+            descriptors.Insert(index, descriptor);
+            return descriptor;
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Razor/Properties/Resources.Designer.cs

@@ -266,6 +266,22 @@ namespace Microsoft.AspNet.Mvc.Razor
             return string.Format(CultureInfo.CurrentCulture, GetString("ViewContextMustBeSet"), p0, p1);
         }
 
+        /// <summary>
+        /// '{0}' must be a {1} that is generated as result of the call to '{2}'.
+        /// </summary>
+        internal static string ViewLocationCache_KeyMustBeString
+        {
+            get { return GetString("ViewLocationCache_KeyMustBeString"); }
+        }
+
+        /// <summary>
+        /// '{0}' must be a {1} that is generated as result of the call to '{2}'.
+        /// </summary>
+        internal static string FormatViewLocationCache_KeyMustBeString(object p0, object p1, object p2)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("ViewLocationCache_KeyMustBeString"), p0, p1, p2);
+        }
+
         /// <summary>
         /// The '{0}' method must be called before '{1}' can be invoked.
         /// </summary>

src/Microsoft.AspNet.Mvc.Razor/RazorViewEngine.cs

@@ -4,7 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Globalization;
-using System.Linq;
+using Microsoft.AspNet.Mvc.Razor.OptionDescriptors;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.Framework.DependencyInjection;
 
@@ -16,14 +16,16 @@ namespace Microsoft.AspNet.Mvc.Razor
     public class RazorViewEngine : IViewEngine
     {
         private const string ViewExtension = ".cshtml";
+        internal const string ControllerKey = "controller";
+        internal const string AreaKey = "area";
 
-        private static readonly string[] _viewLocationFormats =
+        private static readonly IEnumerable<string> _viewLocationFormats = new[]
         {
             "/Views/{1}/{0}" + ViewExtension,
             "/Views/Shared/{0}" + ViewExtension,
         };
 
-        private static readonly string[] _areaViewLocationFormats =
+        private static readonly IEnumerable<string> _areaViewLocationFormats = new[]
         {
             "/Areas/{2}/Views/{1}/{0}" + ViewExtension,
             "/Areas/{2}/Views/Shared/{0}" + ViewExtension,
@@ -31,27 +33,44 @@ namespace Microsoft.AspNet.Mvc.Razor
         };
 
         private readonly IRazorPageFactory _pageFactory;
+        private readonly IReadOnlyList<IViewLocationExpander> _viewLocationExpanders;
+        private readonly IViewLocationCache _viewLocationCache;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="RazorViewEngine" /> class.
         /// </summary>
         /// <param name="pageFactory">The page factory used for creating <see cref="IRazorPage"/> instances.</param>
-        public RazorViewEngine(IRazorPageFactory pageFactory)
+        public RazorViewEngine(IRazorPageFactory pageFactory,
+                               IViewLocationExpanderProvider viewLocationExpanderProvider,
+                               IViewLocationCache viewLocationCache)
         {
             _pageFactory = pageFactory;
+            _viewLocationExpanders = viewLocationExpanderProvider.ViewLocationExpanders;
+            _viewLocationCache = viewLocationCache;
         }
 
-        public IEnumerable<string> ViewLocationFormats
+        /// <summary>
+        /// Gets the locations where this instance of <see cref="RazorViewEngine"/> will search for views.
+        /// </summary>
+        public virtual IEnumerable<string> ViewLocationFormats
         {
             get { return _viewLocationFormats; }
         }
 
+        /// <summary>
+        /// Gets the locations where this instance of <see cref="RazorViewEngine"/> will search for views within an
+        /// area.
+        /// </summary>
+        public virtual IEnumerable<string> AreaViewLocationFormats
+        {
+            get { return _areaViewLocationFormats; }
+        }
+
         /// <inheritdoc />
         public ViewEngineResult FindView([NotNull] ActionContext context,
                                          [NotNull] string viewName)
         {
-            var viewEngineResult = CreateViewEngineResult(context, viewName, partial: false);
-            return viewEngineResult;
+            return CreateViewEngineResult(context, viewName, partial: false);
         }
 
         /// <inheritdoc />
@@ -81,22 +100,77 @@ namespace Microsoft.AspNet.Mvc.Razor
             }
             else
             {
-                var routeValues = context.RouteData.Values;
-                var controllerName = routeValues.GetValueOrDefault<string>("controller");
-                var areaName = routeValues.GetValueOrDefault<string>("area");
-                var potentialPaths = GetViewSearchPaths(viewName, controllerName, areaName);
+                return LocateViewFromViewLocations(context, viewName, partial);
+            }
+        }
 
-                foreach (var path in potentialPaths)
+        private ViewEngineResult LocateViewFromViewLocations(ActionContext context,
+                                                             string viewName,
+                                                             bool partial)
+        {
+            // Initialize the dictionary for the typical case of having controller and action tokens.
+            var routeValues = context.RouteData.Values;
+            var areaName = routeValues.GetValueOrDefault<string>(AreaKey);
+
+            // Only use the area view location formats if we have an area token.
+            var viewLocations = !string.IsNullOrEmpty(areaName) ? AreaViewLocationFormats :
+                                                                  ViewLocationFormats;
+
+            var expanderContext = new ViewLocationExpanderContext(context, viewName);
+            if (_viewLocationExpanders.Count > 0)
+            {
+                expanderContext.Values = new Dictionary<string, string>(StringComparer.Ordinal);
+
+                // 1. Populate values from viewLocationExpanders.
+                foreach (var expander in _viewLocationExpanders)
                 {
-                    var page = _pageFactory.CreateInstance(path);
-                    if (page != null)
-                    {
-                        return CreateFoundResult(context, page, path, partial);
-                    }
+                    expander.PopulateValues(expanderContext);
+                }
+            }
+
+            // 2. With the values that we've accumumlated so far, check if we have a cached result.
+            var viewLocation = _viewLocationCache.Get(expanderContext);
+            if (!string.IsNullOrEmpty(viewLocation))
+            {
+                var page = _pageFactory.CreateInstance(viewLocation);
+
+                if (page != null)
+                {
+                    // 2a. We found a IRazorPage at the cached location.
+                    return CreateFoundResult(context, page, viewName, partial);
+                }
+            }
+
+            // 2b. We did not find a cached location or did not find a IRazorPage at the cached location.
+            // The cached value has expired and we need to look up the page.
+            foreach (var expander in _viewLocationExpanders)
+            {
+                viewLocations = expander.ExpandViewLocations(expanderContext, viewLocations);
+            }
+
+            // 3. Use the expanded locations to look up a page.
+            var controllerName = routeValues.GetValueOrDefault<string>(ControllerKey);
+            var searchedLocations = new List<string>();
+            foreach (var path in viewLocations)
+            {
+                var transformedPath = string.Format(CultureInfo.InvariantCulture,
+                                                    path,
+                                                    viewName,
+                                                    controllerName,
+                                                    areaName);
+                var page = _pageFactory.CreateInstance(transformedPath);
+                if (page != null)
+                {
+                    // 3a. We found a page. Cache the set of values that produced it and return a found result.
+                    _viewLocationCache.Set(expanderContext, transformedPath);
+                    return CreateFoundResult(context, page, transformedPath, partial);
                 }
 
-                return ViewEngineResult.NotFound(viewName, potentialPaths);
+                searchedLocations.Add(transformedPath);
             }
+
+            // 3b. We did not find a page for any of the paths.
+            return ViewEngineResult.NotFound(viewName, searchedLocations);
         }
 
         private ViewEngineResult CreateFoundResult(ActionContext actionContext,
@@ -117,26 +191,5 @@ namespace Microsoft.AspNet.Mvc.Razor
         {
             return name[0] == '~' || name[0] == '/';
         }
-
-        private IEnumerable<string> GetViewSearchPaths(string viewName, string controllerName, string areaName)
-        {
-            IEnumerable<string> unformattedPaths;
-
-            if (string.IsNullOrEmpty(areaName))
-            {
-                // If no areas then no need to search area locations.
-                unformattedPaths = _viewLocationFormats;
-            }
-            else
-            {
-                // If there's an area provided only search area view locations
-                unformattedPaths = _areaViewLocationFormats;
-            }
-
-            var formattedPaths = unformattedPaths.Select(path =>
-                string.Format(CultureInfo.InvariantCulture, path, viewName, controllerName, areaName));
-
-            return formattedPaths;
-        }
     }
 }

src/Microsoft.AspNet.Mvc.Razor/Resources.resx

@@ -165,6 +165,9 @@
   <data name="ViewContextMustBeSet" xml:space="preserve">
     <value>'{0} must be set to access '{1}'.</value>
   </data>
+  <data name="ViewLocationCache_KeyMustBeString" xml:space="preserve">
+    <value>'{0}' must be a {1} that is generated as result of the call to '{2}'.</value>
+  </data>
   <data name="ViewMustBeContextualized" xml:space="preserve">
     <value>The '{0}' method must be called before '{1}' can be invoked.</value>
   </data>

src/Microsoft.AspNet.Mvc.Razor/ViewLocationExpanderContext.cs

@@ -0,0 +1,36 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    /// <summary>
+    /// A context for containing information for <see cref="IViewLocationExpander"/>.
+    /// </summary>
+    public class ViewLocationExpanderContext
+    {
+        public ViewLocationExpanderContext([NotNull] ActionContext actionContext,
+                                           [NotNull] string viewName)
+        {
+            ActionContext = actionContext;
+            ViewName = viewName;
+        }
+
+        /// <summary>
+        /// Gets the <see cref="ActionContext"/> for the current executing action.
+        /// </summary>
+        public ActionContext ActionContext { get; private set; }
+
+        /// <summary>
+        /// Gets the view name 
+        /// </summary>
+        public string ViewName { get; private set; }
+
+        /// <summary>
+        /// Gets or sets the <see cref="IDictionary{TKey, TValue}"/> that is populated with values as part of
+        /// <see cref="IViewLocationExpander.PopulateValues(ViewLocationExpanderContext)"/>.
+        /// </summary>
+        public IDictionary<string, string> Values { get; set; }
+    }
+}

src/Microsoft.AspNet.Mvc/MvcOptionsSetup.cs

@@ -3,6 +3,7 @@
 
 using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.Razor;
+using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.Framework.OptionsModel;
 
 namespace Microsoft.AspNet.Mvc

src/Microsoft.AspNet.Mvc/MvcServices.cs

@@ -10,6 +10,7 @@ using Microsoft.AspNet.Mvc.ModelBinding;
 using Microsoft.AspNet.Mvc.OptionDescriptors;
 using Microsoft.AspNet.Mvc.Razor;
 using Microsoft.AspNet.Mvc.Razor.Compilation;
+using Microsoft.AspNet.Mvc.Razor.OptionDescriptors;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.AspNet.Mvc.Routing;
 using Microsoft.AspNet.Security;
@@ -53,6 +54,11 @@ namespace Microsoft.AspNet.Mvc
             yield return describe.Singleton<IViewStartProvider, ViewStartProvider>();
             yield return describe.Transient<IRazorView, RazorView>();
 
+            // Transient since the IViewLocationExpanders returned by the instance is cached by view engines.
+            yield return describe.Transient<IViewLocationExpanderProvider, DefaultViewLocationExpanderProvider>();
+            // Caches view locations that are valid for the lifetime of the application.
+            yield return describe.Singleton<IViewLocationCache, DefaultViewLocationCache>();
+
             yield return describe.Singleton<IRazorPageActivator, RazorPageActivator>();
             // Virtual path view factory needs to stay scoped so views can get get scoped services.
             yield return describe.Scoped<IRazorPageFactory, VirtualPathRazorPageFactory>();

test/Microsoft.AspNet.Mvc.FunctionalTests/ViewEngineTests.cs

@@ -101,5 +101,42 @@ component-content";
             // Assert
             Assert.Equal(expected, body.Trim());
         }
+
+        public static IEnumerable<object[]> RazorViewEngine_UsesAllExpandedPathsToLookForViewsData
+        {
+            get
+            {
+                var expected1 = string.Join(Environment.NewLine,
+                                            "expander-index",
+                                            "gb-partial");
+                yield return new[] { "gb", expected1 };
+
+                var expected2 = string.Join(Environment.NewLine,
+                                            "fr-index",
+                                            "fr-partial");
+                yield return new[] { "fr", expected2 };
+
+                var expected3 = string.Join(Environment.NewLine,
+                                            "expander-index",
+                                            "expander-partial");
+                yield return new[] { "na", expected3 };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(RazorViewEngine_UsesAllExpandedPathsToLookForViewsData))]
+        public async Task RazorViewEngine_UsesViewExpandersForViewsAndPartials(string value, string expected)
+        {
+            // Arrange
+            var server = TestServer.Create(_provider, _app);
+            var client = server.CreateClient();
+
+            // Act
+            var body = await client.GetStringAsync("http://localhost/TemplateExpander?language-expander-value=" +
+                                                   value);
+
+            // Assert
+            Assert.Equal(expected, body.Trim());
+        }
     }
 }

test/Microsoft.AspNet.Mvc.Razor.Test/Compilation/ExpiringFileInfoCacheTest.cs

@@ -10,7 +10,7 @@ using Microsoft.Framework.Runtime;
 using Moq;
 using Xunit;
 
-namespace Microsoft.AspNet.Mvc.Core.Test
+namespace Microsoft.AspNet.Mvc.Razor
 {
     public class ExpiringFileInfoCacheTest
     {
@@ -27,28 +27,28 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             }
         }
 
-        public MvcOptions Options
+        public RazorViewEngineOptions Options
         {
             get
             {
-                return new MvcOptions();
+                return new RazorViewEngineOptions();
             }
         }
 
-        public IOptionsAccessor<MvcOptions> OptionsAccessor
+        public IOptionsAccessor<RazorViewEngineOptions> OptionsAccessor
         {
             get
             {
                 var options = Options;
 
-                var mock = new Mock<IOptionsAccessor<MvcOptions>>(MockBehavior.Strict);
+                var mock = new Mock<IOptionsAccessor<RazorViewEngineOptions>>(MockBehavior.Strict);
                 mock.Setup(oa => oa.Options).Returns(options);
 
                 return mock.Object;
             }
         }
 
-        public ControllableExpiringFileInfoCache GetCache(IOptionsAccessor<MvcOptions> optionsAccessor)
+        public ControllableExpiringFileInfoCache GetCache(IOptionsAccessor<RazorViewEngineOptions> optionsAccessor)
         {
             return new ControllableExpiringFileInfoCache(ApplicationEnvironment, optionsAccessor);
         }
@@ -69,16 +69,16 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             cache.Sleep(offsetMilliseconds);
         }
 
-        public void Sleep(IOptionsAccessor<MvcOptions> accessor, ControllableExpiringFileInfoCache cache, int offsetMilliSeconds)
+        public void Sleep(IOptionsAccessor<RazorViewEngineOptions> accessor, ControllableExpiringFileInfoCache cache, int offsetMilliSeconds)
         {
-            var baseMilliSeconds = (int)accessor.Options.ViewEngineOptions.ExpirationBeforeCheckingFilesOnDisk.TotalMilliseconds;
+            var baseMilliSeconds = (int)accessor.Options.ExpirationBeforeCheckingFilesOnDisk.TotalMilliseconds;
 
             cache.Sleep(baseMilliSeconds + offsetMilliSeconds);
         }
 
-        public void SetExpiration(IOptionsAccessor<MvcOptions> accessor, TimeSpan expiration)
+        public void SetExpiration(IOptionsAccessor<RazorViewEngineOptions> accessor, TimeSpan expiration)
         {
-            accessor.Options.ViewEngineOptions.ExpirationBeforeCheckingFilesOnDisk = expiration;
+            accessor.Options.ExpirationBeforeCheckingFilesOnDisk = expiration;
         }
 
         [Fact]
@@ -87,7 +87,7 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             var optionsAccessor = OptionsAccessor;
 
             // Assert
-            Assert.Equal(2000, optionsAccessor.Options.ViewEngineOptions.ExpirationBeforeCheckingFilesOnDisk.TotalMilliseconds);
+            Assert.Equal(2000, optionsAccessor.Options.ExpirationBeforeCheckingFilesOnDisk.TotalMilliseconds);
         }
 
         [Fact]
@@ -323,7 +323,7 @@ namespace Microsoft.AspNet.Mvc.Core.Test
         public class ControllableExpiringFileInfoCache : ExpiringFileInfoCache
         {
             public ControllableExpiringFileInfoCache(IApplicationEnvironment env,
-                                                     IOptionsAccessor<MvcOptions> optionsAccessor)
+                                                     IOptionsAccessor<RazorViewEngineOptions> optionsAccessor)
                 : base(env, optionsAccessor)
             {
             }

test/Microsoft.AspNet.Mvc.Razor.Test/DefaultViewLocationCacheTest.cs

@@ -0,0 +1,131 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.PipelineCore;
+using Microsoft.AspNet.Routing;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    public class DefaultViewLocationCacheTest
+    {
+        public static IEnumerable<object[]> CacheEntryData
+        {
+            get
+            {
+                yield return new[] { new ViewLocationExpanderContext(GetActionContext(), "test") };
+
+                var areaActionContext = GetActionContext("controller2", "myarea");
+                yield return new[] { new ViewLocationExpanderContext(areaActionContext, "test2") };
+
+                var actionContext = GetActionContext("controller3", "area3");
+                var values = new Dictionary<string, string>(StringComparer.Ordinal)
+                {
+                    { "culture", "fr" },
+                    { "theme", "sleek" }
+                };
+                var expanderContext = new ViewLocationExpanderContext(actionContext, "test3")
+                {
+                    Values = values
+                };
+
+                yield return new [] { expanderContext };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(CacheEntryData))]
+        public void Get_GeneratesCacheKeyIfItemDoesNotExist(ViewLocationExpanderContext context)
+        {
+            // Arrange
+            var cache = new DefaultViewLocationCache();
+
+            // Act
+            var result = cache.Get(context);
+
+            // Assert
+            Assert.Null(result);
+        }
+
+        [Theory]
+        [MemberData(nameof(CacheEntryData))]
+        public void InvokingGetAfterSet_ReturnsCachedItem(ViewLocationExpanderContext context)
+        {
+            // Arrange
+            var cache = new DefaultViewLocationCache();
+            var value = Guid.NewGuid().ToString();
+
+            // Act
+            cache.Set(context, value);
+            var result = cache.Get(context);
+
+            // Assert
+            Assert.Equal(value, result);
+        }
+
+        public static IEnumerable<object[]> CacheKeyData
+        {
+            get
+            {
+                yield return new object[]
+                {
+                    new ViewLocationExpanderContext(GetActionContext(), "test"),
+                    "test:mycontroller"
+                };
+
+                var areaActionContext = GetActionContext("controller2", "myarea");
+                yield return new object[]
+                {
+                    new ViewLocationExpanderContext(areaActionContext, "test2"),
+                    "test2:controller2:myarea"
+                };
+
+                var actionContext = GetActionContext("controller3", "area3");
+                var values = new Dictionary<string, string>(StringComparer.Ordinal)
+                {
+                    { "culture", "fr" },
+                    { "theme", "sleek" }
+                };
+                var expanderContext = new ViewLocationExpanderContext(actionContext, "test3")
+                {
+                    Values = values
+                };
+
+                yield return new object[]
+                {
+                    expanderContext,
+                    "test3:controller3:area3:culture:fr:theme:sleek"
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(CacheKeyData))]
+        public void CacheKeyIsComputedBasedOnValuesInExpander(ViewLocationExpanderContext context, string expected)
+        {
+            // Act
+            var result = DefaultViewLocationCache.GenerateKey(context);
+
+            // Assert
+            Assert.Equal(expected, result);
+        }
+
+        public static ActionContext GetActionContext(string controller = "mycontroller",
+                                                     string area = null)
+        {
+            var routeData = new RouteData
+            {
+                Values = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase)
+            };
+            routeData.Values["controller"] = controller;
+            if (area != null)
+            {
+                routeData.Values["area"] = area;
+            }
+
+            return new ActionContext(new DefaultHttpContext(), routeData, new ActionDescriptor());
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.Razor.Test/OptionDescriptors/DefaultViewLocationExpanderProviderTest.cs

@@ -0,0 +1,71 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.Framework.DependencyInjection;
+using Microsoft.Framework.OptionsModel;
+using Moq;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.Razor.OptionDescriptors
+{
+    public class DefaultViewLocationExpanderProviderTest
+    {
+        [Fact]
+        public void ViewLocationExpanders_ReturnsActivatedListOfExpanders()
+        {
+            // Arrange
+            var service = Mock.Of<ITestService>();
+            var expander = Mock.Of<IViewLocationExpander>();
+            var type = typeof(TestViewLocationExpander);
+            var typeActivator = new TypeActivator();
+            var serviceProvider = new Mock<IServiceProvider>();
+            serviceProvider.Setup(p => p.GetService(typeof(ITestService)))
+                           .Returns(service);
+            var options = new RazorViewEngineOptions();
+            options.ViewLocationExpanders.Add(type);
+            options.ViewLocationExpanders.Add(expander);
+            var accessor = new Mock<IOptionsAccessor<RazorViewEngineOptions>>();
+            accessor.SetupGet(a => a.Options)
+                    .Returns(options);
+            var provider = new DefaultViewLocationExpanderProvider(accessor.Object,
+                                                                   typeActivator,
+                                                                   serviceProvider.Object);
+
+            // Act
+            var result = provider.ViewLocationExpanders;
+
+            // Assert
+            Assert.Equal(2, result.Count);
+            var testExpander = Assert.IsType<TestViewLocationExpander>(result[0]);
+            Assert.Same(service, testExpander.Service);
+            Assert.Same(expander, result[1]);
+        }
+
+        private class TestViewLocationExpander : IViewLocationExpander
+        {
+            public TestViewLocationExpander(ITestService service)
+            {
+                Service = service;
+            }
+
+            public ITestService Service { get; private set; }
+
+            public IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context,
+                                                           IEnumerable<string> viewLocations)
+            {
+                throw new NotImplementedException();
+            }
+
+            public void PopulateValues(ViewLocationExpanderContext context)
+            {
+                throw new NotImplementedException();
+            }
+        }
+
+        public interface ITestService
+        {
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.Razor.Test/OptionDescriptors/ViewLocationExpanderDescriptorExtensionsTest.cs

@@ -0,0 +1,80 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.Mvc.Razor.OptionDescriptors;
+using Moq;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.Razor
+{
+    public class ViewLocationExpanderDescriptorExtensionsTest
+    {
+        [Theory]
+        [InlineData(-1)]
+        [InlineData(5)]
+        public void Insert_WithType_ThrowsIfIndexIsOutOfBounds(int index)
+        {
+            // Arrange
+            var collection = new List<ViewLocationExpanderDescriptor>
+            {
+                new ViewLocationExpanderDescriptor(Mock.Of<IViewLocationExpander>()),
+                new ViewLocationExpanderDescriptor(Mock.Of<IViewLocationExpander>())
+            };
+
+            // Act & Assert
+            Assert.Throws<ArgumentOutOfRangeException>("index",
+                                                       () => collection.Insert(index, typeof(IViewLocationExpander)));
+        }
+
+        [Theory]
+        [InlineData(-2)]
+        [InlineData(3)]
+        public void Insert_WithInstance_ThrowsIfIndexIsOutOfBounds(int index)
+        {
+            // Arrange
+            var collection = new List<ViewLocationExpanderDescriptor>
+            {
+                new ViewLocationExpanderDescriptor(Mock.Of<IViewLocationExpander>()),
+                new ViewLocationExpanderDescriptor(Mock.Of<IViewLocationExpander>())
+            };
+            var expander = Mock.Of<IViewLocationExpander>();
+
+            // Act & Assert
+            Assert.Throws<ArgumentOutOfRangeException>("index", () => collection.Insert(index, expander));
+        }
+
+        [InlineData]
+        public void ViewLocationExpanderDescriptors_AddsTypesAndInstances()
+        {
+            // Arrange
+            var expander = Mock.Of<IViewLocationExpander>();
+            var type = typeof(TestViewLocationExpander);
+            var collection = new List<ViewLocationExpanderDescriptor>();
+
+            // Act
+            collection.Add(expander);
+            collection.Insert(0, type);
+
+            // Assert
+            Assert.Equal(2, collection.Count);
+            Assert.IsType<TestViewLocationExpander>(collection[0].Instance);
+            Assert.Same(expander, collection[0].Instance);
+        }
+
+        private class TestViewLocationExpander : IViewLocationExpander
+        {
+            public IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context,
+                                                           IEnumerable<string> viewLocations)
+            {
+                throw new NotImplementedException();
+            }
+
+            public void PopulateValues(ViewLocationExpanderContext context)
+            {
+                throw new NotImplementedException();
+            }
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.Razor.Test/OptionDescriptors/ViewLocationExpanderDescriptorTest.cs

@@ -0,0 +1,68 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.Testing;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.Razor.OptionDescriptors
+{
+    public class ViewLocationExpanderDescriptorTest
+    {
+        [Fact]
+        public void ConstructorThrows_IfTypeIsNotViewLocationExpander()
+        {
+            // Arrange
+            var viewEngineType = typeof(IViewLocationExpander).FullName;
+            var type = typeof(string);
+            var expected = string.Format("The type '{0}' must derive from '{1}'.",
+                                         type.FullName, viewEngineType);
+
+            // Act & Assert
+            ExceptionAssert.ThrowsArgument(() => new ViewLocationExpanderDescriptor(type), "type", expected);
+        }
+
+        [Fact]
+        public void ConstructorSetsViewLocationExpanderType()
+        {
+            // Arrange
+            var type = typeof(TestViewLocationExpander);
+
+            // Act
+            var descriptor = new ViewLocationExpanderDescriptor(type);
+
+            // Assert
+            Assert.Equal(type, descriptor.OptionType);
+            Assert.Null(descriptor.Instance);
+        }
+
+        [Fact]
+        public void ConstructorSetsViewLocationExpanderAndType()
+        {
+            // Arrange
+            var expander = new TestViewLocationExpander();
+
+            // Act
+            var descriptor = new ViewLocationExpanderDescriptor(expander);
+
+            // Assert
+            Assert.Same(expander, descriptor.Instance);
+            Assert.Equal(expander.GetType(), descriptor.OptionType);
+        }
+
+        private class TestViewLocationExpander : IViewLocationExpander
+        {
+            public IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context,
+                                                           IEnumerable<string> viewLocations)
+            {
+                throw new NotImplementedException();
+            }
+
+            public void PopulateValues(ViewLocationExpanderContext context)
+            {
+                throw new NotImplementedException();
+            }
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.Razor.Test/RazorViewEngineTest.cs

@@ -3,6 +3,8 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
+using Microsoft.AspNet.Mvc.Razor.OptionDescriptors;
 using Microsoft.AspNet.Mvc.Rendering;
 using Microsoft.AspNet.PipelineCore;
 using Microsoft.AspNet.Routing;
@@ -40,7 +42,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         public void FindView_WithFullPathReturnsNotFound_WhenPathDoesNotMatchExtension(string viewName)
         {
             // Arrange
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             var context = GetActionContext(_controllerTestContext);
 
             // Act
@@ -55,7 +57,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         public void FindViewFullPathSucceedsWithCshtmlEnding(string viewName)
         {
             // Arrange
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             // Append .cshtml so the viewname is no longer invalid
             viewName += ".cshtml";
             var context = GetActionContext(_controllerTestContext);
@@ -72,7 +74,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         public void FindPartialView_WithFullPathReturnsNotFound_WhenPathDoesNotMatchExtension(string partialViewName)
         {
             // Arrange
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             var context = GetActionContext(_controllerTestContext);
 
             // Act
@@ -87,7 +89,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         public void FindPartialViewFullPathSucceedsWithCshtmlEnding(string partialViewName)
         {
             // Arrange
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             // Append .cshtml so the viewname is no longer invalid
             partialViewName += ".cshtml";
             var context = GetActionContext(_controllerTestContext);
@@ -104,7 +106,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         {
             // Arrange
             var searchedLocations = new List<string>();
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             var context = GetActionContext(_areaTestContext);
 
             // Act
@@ -112,7 +114,8 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
 
             // Assert
             Assert.False(result.Success);
-            Assert.Equal(new[] {
+            Assert.Equal(new[]
+            {
                 "/Areas/foo/Views/bar/partial.cshtml",
                 "/Areas/foo/Views/Shared/partial.cshtml",
                 "/Views/Shared/partial.cshtml",
@@ -123,7 +126,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         public void FindPartialViewFailureSearchesCorrectLocationsWithoutAreas()
         {
             // Arrange
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             var context = GetActionContext(_controllerTestContext);
 
             // Act
@@ -141,7 +144,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         public void FindViewFailureSearchesCorrectLocationsWithAreas()
         {
             // Arrange
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             var context = GetActionContext(_areaTestContext);
 
             // Act
@@ -160,7 +163,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
         public void FindViewFailureSearchesCorrectLocationsWithoutAreas()
         {
             // Arrange
-            var viewEngine = CreateSearchLocationViewEngineTester();
+            var viewEngine = CreateViewEngine();
             var context = GetActionContext(_controllerTestContext);
 
             // Act
@@ -182,7 +185,7 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory.Setup(p => p.CreateInstance(It.IsAny<string>()))
                        .Returns(Mock.Of<IRazorPage>());
-            var viewEngine = new RazorViewEngine(pageFactory.Object);
+            var viewEngine = CreateViewEngine(pageFactory.Object);
             var context = GetActionContext(_controllerTestContext);
 
             // Act
@@ -194,17 +197,261 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
             Assert.Equal("/Views/bar/test-view.cshtml", result.ViewName);
         }
 
-        private IViewEngine CreateSearchLocationViewEngineTester()
+        [Fact]
+        public void FindView_UsesViewLocationFormat_IfRouteDoesNotContainArea()
         {
+            // Arrange
             var pageFactory = new Mock<IRazorPageFactory>();
-            pageFactory.Setup(vpf => vpf.CreateInstance(It.IsAny<string>()))
-                       .Returns<RazorPage>(null);
+            var page = Mock.Of<IRazorPage>();
+            pageFactory.Setup(p => p.CreateInstance("fake-path1/bar/test-view.rzr"))
+                       .Returns(Mock.Of<IRazorPage>())
+                       .Verifiable();
+            var viewEngine = new OverloadedLocationViewEngine(pageFactory.Object,
+                                                              GetViewLocationExpanders(),
+                                                              GetViewLocationCache());
+            var context = GetActionContext(_controllerTestContext);
 
-            var viewEngine = new RazorViewEngine(pageFactory.Object);
+            // Act
+            var result = viewEngine.FindView(context, "test-view");
+
+            // Assert
+            pageFactory.Verify();
+        }
+
+        [Fact]
+        public void FindView_UsesAreaViewLocationFormat_IfRouteContainsArea()
+        {
+            // Arrange
+            var pageFactory = new Mock<IRazorPageFactory>();
+            var page = Mock.Of<IRazorPage>();
+            pageFactory.Setup(p => p.CreateInstance("fake-area-path/foo/bar/test-view2.rzr"))
+                       .Returns(Mock.Of<IRazorPage>())
+                       .Verifiable();
+            var viewEngine = new OverloadedLocationViewEngine(pageFactory.Object,
+                                                              GetViewLocationExpanders(),
+                                                              GetViewLocationCache());
+            var context = GetActionContext(_areaTestContext);
+
+            // Act
+            var result = viewEngine.FindView(context, "test-view2");
+
+            // Assert
+            pageFactory.Verify();
+        }
+
+        public static IEnumerable<object[]> FindView_UsesViewLocationExpandersToLocateViewsData
+        {
+            get
+            {
+                yield return new object[]
+                {
+                    _controllerTestContext,
+                    new[]
+                    {
+                        "/Views/{1}/{0}.cshtml",
+                        "/Views/Shared/{0}.cshtml"
+                    }
+                };
+
+                yield return new object[]
+                {
+                    _areaTestContext,
+                    new[]
+                    {
+                        "/Areas/{2}/Views/{1}/{0}.cshtml",
+                        "/Areas/{2}/Views/Shared/{0}.cshtml",
+                        "/Views/Shared/{0}.cshtml"
+                    }
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(FindView_UsesViewLocationExpandersToLocateViewsData))]
+        public void FindView_UsesViewLocationExpandersToLocateViews(IDictionary<string, object> routeValues,
+                                                                    IEnumerable<string> expectedSeeds)
+        {
+            // Arrange
+            var pageFactory = new Mock<IRazorPageFactory>();
+            pageFactory.Setup(p => p.CreateInstance("test-string/bar.cshtml"))
+                       .Returns(Mock.Of<IRazorPage>())
+                       .Verifiable();
+            var expander1Result = new[] { "some-seed" };
+            var expander1 = new Mock<IViewLocationExpander>();
+            expander1.Setup(e => e.PopulateValues(It.IsAny<ViewLocationExpanderContext>()))
+                    .Callback((ViewLocationExpanderContext c) =>
+                    {
+                        Assert.NotNull(c.ActionContext);
+                        c.Values["expander-key"] = expander1.ToString();
+                    })
+                    .Verifiable();
+            expander1.Setup(e => e.ExpandViewLocations(It.IsAny<ViewLocationExpanderContext>(),
+                                                      It.IsAny<IEnumerable<string>>()))
+                    .Callback((ViewLocationExpanderContext c, IEnumerable<string> seeds) =>
+                    {
+                        Assert.NotNull(c.ActionContext);
+                        Assert.Equal(expectedSeeds, seeds);
+                    })
+                    .Returns(expander1Result)
+                    .Verifiable();
+
+            var expander2 = new Mock<IViewLocationExpander>();
+            expander2.Setup(e => e.ExpandViewLocations(It.IsAny<ViewLocationExpanderContext>(),
+                                                      It.IsAny<IEnumerable<string>>()))
+                     .Callback((ViewLocationExpanderContext c, IEnumerable<string> seeds) =>
+                     {
+                         Assert.Equal(expander1Result, seeds);
+                     })
+                     .Returns(new[] { "test-string/{1}.cshtml" })
+                     .Verifiable();
+
+            var viewEngine = CreateViewEngine(pageFactory.Object,
+                                 new[] { expander1.Object, expander2.Object });
+            var context = GetActionContext(routeValues);
+
+            // Act
+            var result = viewEngine.FindView(context, "test-view");
+
+            // Assert
+            Assert.True(result.Success);
+            Assert.IsAssignableFrom<IRazorView>(result.View);
+            pageFactory.Verify();
+            expander1.Verify();
+            expander2.Verify();
+        }
+
+        [Fact]
+        public void FindView_CachesValuesIfViewWasFound()
+        {
+            // Arrange
+            var pageFactory = new Mock<IRazorPageFactory>();
+            pageFactory.Setup(p => p.CreateInstance("/Views/bar/baz.cshtml"))
+                       .Verifiable();
+            pageFactory.Setup(p => p.CreateInstance("/Views/Shared/baz.cshtml"))
+                       .Returns(Mock.Of<IRazorPage>())
+                       .Verifiable();
+            var cache = GetViewLocationCache();
+            var cacheMock = Mock.Get<IViewLocationCache>(cache);
+
+            cacheMock.Setup(c => c.Set(It.IsAny<ViewLocationExpanderContext>(), "/Views/Shared/baz.cshtml"))
+                     .Verifiable();
+
+            var viewEngine = CreateViewEngine(pageFactory.Object, cache: cache);
+            var context = GetActionContext(_controllerTestContext);
+
+            // Act
+            var result = viewEngine.FindView(context, "baz");
+
+            // Assert
+            Assert.True(result.Success);
+            pageFactory.Verify();
+            cacheMock.Verify();
+        }
+
+        [Fact]
+        public void FindView_UsesCachedValueIfViewWasFound()
+        {
+            // Arrange
+            var pageFactory = new Mock<IRazorPageFactory>(MockBehavior.Strict);
+            pageFactory.Setup(p => p.CreateInstance("some-view-location"))
+                       .Returns(Mock.Of<IRazorPage>())
+                       .Verifiable();
+            var expander = new Mock<IViewLocationExpander>(MockBehavior.Strict);
+            expander.Setup(v => v.PopulateValues(It.IsAny<ViewLocationExpanderContext>()))
+                    .Verifiable();
+            var cacheMock = new Mock<IViewLocationCache>();
+            cacheMock.Setup(c => c.Get(It.IsAny<ViewLocationExpanderContext>()))
+                     .Returns("some-view-location")
+                     .Verifiable();
+
+            var viewEngine = CreateViewEngine(pageFactory.Object,
+                                              new[] { expander.Object },
+                                              cacheMock.Object);
+            var context = GetActionContext(_controllerTestContext);
+
+            // Act
+            var result = viewEngine.FindView(context, "baz");
+
+            // Assert
+            Assert.True(result.Success);
+            pageFactory.Verify();
+            cacheMock.Verify();
+            expander.Verify();
+        }
+
+        [Fact]
+        public void FindView_LooksForViewsIfCachedViewDoesNotExist()
+        {
+            // Arrange
+            var pageFactory = new Mock<IRazorPageFactory>();
+            pageFactory.Setup(p => p.CreateInstance("expired-location"))
+                       .Returns((IRazorPage)null)
+                       .Verifiable();
+            pageFactory.Setup(p => p.CreateInstance("some-view-location"))
+                       .Returns(Mock.Of<IRazorPage>())
+                       .Verifiable();
+            var cacheMock = new Mock<IViewLocationCache>();
+            cacheMock.Setup(c => c.Get(It.IsAny<ViewLocationExpanderContext>()))
+                     .Returns("expired-location");
+
+            var expander = new Mock<IViewLocationExpander>();
+            expander.Setup(v => v.PopulateValues(It.IsAny<ViewLocationExpanderContext>()))
+                    .Verifiable();
+            var expanderResult = new[] { "some-view-location" };
+            expander.Setup(v => v.ExpandViewLocations(
+                        It.IsAny<ViewLocationExpanderContext>(), It.IsAny<IEnumerable<string>>()))
+                    .Returns((ViewLocationExpanderContext c, IEnumerable<string> seed) => expanderResult)
+                    .Verifiable();
+
+            var viewEngine = CreateViewEngine(pageFactory.Object,
+                                              new[] { expander.Object },
+                                              cacheMock.Object);
+            var context = GetActionContext(_controllerTestContext);
+
+            // Act
+            var result = viewEngine.FindView(context, "baz");
+
+            // Assert
+            Assert.True(result.Success);
+            pageFactory.Verify();
+            cacheMock.Verify();
+            expander.Verify();
+        }
+
+        private IViewEngine CreateViewEngine(IRazorPageFactory pageFactory = null,
+                                             IEnumerable<IViewLocationExpander> expanders = null,
+                                             IViewLocationCache cache = null)
+        {
+            pageFactory = pageFactory ?? Mock.Of<IRazorPageFactory>();
+            cache = cache ?? GetViewLocationCache();
+            var viewLocationExpanderProvider = GetViewLocationExpanders(expanders);
+
+            var viewEngine = new RazorViewEngine(pageFactory,
+                                                 viewLocationExpanderProvider,
+                                                 cache);
 
             return viewEngine;
         }
 
+        private static IViewLocationExpanderProvider GetViewLocationExpanders(
+            IEnumerable<IViewLocationExpander> expanders = null)
+        {
+            expanders = expanders ?? Enumerable.Empty<IViewLocationExpander>();
+            var viewLocationExpander = new Mock<IViewLocationExpanderProvider>();
+            viewLocationExpander.Setup(v => v.ViewLocationExpanders)
+                                .Returns(expanders.ToList());
+            return viewLocationExpander.Object;
+        }
+
+        private static IViewLocationCache GetViewLocationCache()
+        {
+            var cacheMock = new Mock<IViewLocationCache>();
+            cacheMock.Setup(c => c.Get(It.IsAny<ViewLocationExpanderContext>()))
+                     .Returns<string>(null);
+
+            return cacheMock.Object;
+        }
+
         private static ActionContext GetActionContext(IDictionary<string, object> routeValues,
                                                       IRazorView razorView = null)
         {
@@ -217,5 +464,31 @@ namespace Microsoft.AspNet.Mvc.Razor.Test
             var routeData = new RouteData { Values = routeValues };
             return new ActionContext(httpContext, routeData, new ActionDescriptor());
         }
+
+        private class OverloadedLocationViewEngine : RazorViewEngine
+        {
+            public OverloadedLocationViewEngine(IRazorPageFactory pageFactory,
+                                                IViewLocationExpanderProvider expanderProvider,
+                                                IViewLocationCache cache)
+                : base(pageFactory, expanderProvider, cache)
+            {
+            }
+
+            public override IEnumerable<string> ViewLocationFormats
+            {
+                get
+                {
+                    return new[] { "fake-path1/{1}/{0}.rzr" };
+                }
+            }
+
+            public override IEnumerable<string> AreaViewLocationFormats
+            {
+                get
+                {
+                    return new[] { "fake-area-path/{2}/{1}/{0}.rzr" };
+                }
+            }
+        }
     }
 }

test/WebSites/RazorWebSite/Controllers/TemplateExpander.cs

@@ -0,0 +1,16 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.AspNet.Mvc;
+
+namespace RazorWebSite.Controllers
+{
+    public class TemplateExpander : Controller
+    {
+        public ViewResult Index()
+        {
+            return View();
+        }
+    }
+}

test/WebSites/RazorWebSite/Services/LanguageViewLocationExpander.cs

@@ -0,0 +1,69 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNet.Mvc;
+using Microsoft.AspNet.Mvc.Razor;
+
+namespace RazorWebSite
+{
+    /// <summary>
+    /// A <see cref="IViewLocationExpander"/> that replaces adds the language as an extension prefix to view names.
+    /// </summary>
+    /// <example>
+    /// For the default case with no areas, views are generated with the following patterns (assuming controller is
+    /// "Home", action is "Index" and language is "en")
+    /// Views/Home/en/Action
+    /// Views/Home/Action
+    /// Views/Shared/en/Action
+    /// Views/Shared/Action
+    /// </example>
+    public class LanguageViewLocationExpander : IViewLocationExpander
+    {
+        private const string ValueKey = "language";
+        private readonly Func<ActionContext, string> _valueFactory;
+
+        /// <summary>
+        /// Initializes a new instance of <see cref="LanguageViewLocationExpander"/>.
+        /// </summary>
+        /// <param name="valueFactory">A factory that provides tbe language to use for expansion.</param>
+        public LanguageViewLocationExpander(Func<ActionContext, string> valueFactory)
+        {
+            _valueFactory = valueFactory;
+        }
+
+        /// <inheritdoc />
+        public void PopulateValues(ViewLocationExpanderContext context)
+        {
+            var value = _valueFactory(context.ActionContext);
+            if (!string.IsNullOrEmpty(value))
+            {
+                context.Values[ValueKey] = value;
+            }
+        }
+
+        /// <inheritdoc />
+        public virtual IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context,
+                                                               IEnumerable<string> viewLocations)
+        {
+            string value;
+            if (context.Values.TryGetValue(ValueKey, out value))
+            {
+                return ExpandViewLocationsCore(viewLocations, value);
+            }
+
+            return viewLocations;
+        }
+
+        private IEnumerable<string> ExpandViewLocationsCore(IEnumerable<string> viewLocations,
+                                                            string value)
+        {
+            foreach (var location in viewLocations)
+            {
+                yield return location.Replace("{0}", value + "/{0}");
+                yield return location;
+            }
+        }
+    }
+}

test/WebSites/RazorWebSite/Startup.cs

@@ -1,4 +1,6 @@
 using Microsoft.AspNet.Builder;
+using Microsoft.AspNet.Mvc;
+using Microsoft.AspNet.Mvc.Razor;
 using Microsoft.Framework.DependencyInjection;
 
 namespace RazorWebSite
@@ -15,6 +17,12 @@ namespace RazorWebSite
                 // Add MVC services to the services container
                 services.AddMvc(configuration);
                 services.AddTransient<InjectedHelper>();
+                services.SetupOptions<RazorViewEngineOptions>(options =>
+                {
+                    var expander = new LanguageViewLocationExpander(
+                            context => context.HttpContext.Request.Query["language-expander-value"]);
+                    options.ViewLocationExpanders.Add(expander);
+                });
             });
 
             // Add MVC to the request pipeline

test/WebSites/RazorWebSite/Views/TemplateExpander/Index.cshtml

@@ -0,0 +1,2 @@
+expander-index
+@await Html.PartialAsync("_Partial")

test/WebSites/RazorWebSite/Views/TemplateExpander/_Partial.cshtml

@@ -0,0 +1 @@
+expander-partial

test/WebSites/RazorWebSite/Views/TemplateExpander/fr/Index.cshtml

@@ -0,0 +1,2 @@
+fr-index
+@await Html.PartialAsync("_Partial")

test/WebSites/RazorWebSite/Views/TemplateExpander/fr/_Partial.cshtml

@@ -0,0 +1 @@
+fr-partial

test/WebSites/RazorWebSite/Views/TemplateExpander/gb/_Partial.cshtml

@@ -0,0 +1 @@
+gb-partial