From 9c4d5dcf5c1e055360ae488e70ebac4eb8826672 Mon Sep 17 00:00:00 2001
From: "N. Taylor Mullen" <nimullen@microsoft.com>
Date: Tue, 18 Nov 2014 16:03:59 -0800
Subject: [PATCH] React to aspnet/Razor#214 mvchook changes.

---
 .../MvcRazorParser.cs                         | 36 +++++++++++++++----
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorParser.cs b/src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorParser.cs
index efcc0f8c4e..70770fbb31 100644
--- a/src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorParser.cs
+++ b/src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorParser.cs
@@ -6,6 +6,7 @@ using System.Linq;
 using Microsoft.AspNet.Razor.Generator.Compiler;
 using Microsoft.AspNet.Razor.Parser;
 using Microsoft.AspNet.Razor.Parser.SyntaxTree;
+using Microsoft.AspNet.Razor.Parser.TagHelpers;
 using Microsoft.AspNet.Razor.TagHelpers;
 
 namespace Microsoft.AspNet.Mvc.Razor
@@ -33,16 +34,37 @@ namespace Microsoft.AspNet.Mvc.Razor
         /// <inheritdoc />
         protected override IEnumerable<TagHelperDescriptor> GetTagHelperDescriptors([NotNull] Block documentRoot)
         {
-            var descriptors = base.GetTagHelperDescriptors(documentRoot);
+            // Grab all the @addtaghelper chunks from view starts and construct TagHelperDirectiveDescriptors
+            var directiveDescriptors = _viewStartChunks.OfType<AddTagHelperChunk>()
+                                                       .Select(chunk => new TagHelperDirectiveDescriptor(
+                                                            chunk.LookupText,
+                                                            TagHelperDirectiveType.AddTagHelper));
 
-            // TODO: https://github.com/aspnet/Razor/issues/112 Needs to support RemvoeHelperChunks too.
+            var visitor = new ViewStartAddRemoveTagHelperVisitor(TagHelperDescriptorResolver,
+                                                                 directiveDescriptors);
+            var descriptors = visitor.GetDescriptors(documentRoot);
 
-            // Grab all the @addTagHelper chunks from view starts
-            var viewStartDescriptors = _viewStartChunks.OfType<AddTagHelperChunk>()
-                                                       .Select(c => c.LookupText)
-                                                       .SelectMany(TagHelperDescriptorResolver.Resolve);
+            return descriptors;
+        }
 
-            return descriptors.Concat(viewStartDescriptors);
+        private class ViewStartAddRemoveTagHelperVisitor : AddOrRemoveTagHelperSpanVisitor
+        {
+            private readonly IEnumerable<TagHelperDirectiveDescriptor> _viewStartDirectiveDescriptors;
+
+            public ViewStartAddRemoveTagHelperVisitor(
+                ITagHelperDescriptorResolver descriptorResolver,
+                IEnumerable<TagHelperDirectiveDescriptor> viewStartDirectiveDescriptors)
+                : base(descriptorResolver)
+            {
+                _viewStartDirectiveDescriptors = viewStartDirectiveDescriptors;
+            }
+
+            protected override TagHelperDescriptorResolutionContext GetTagHelperDescriptorResolutionContext(
+                IEnumerable<TagHelperDirectiveDescriptor> descriptors)
+            {
+                return base.GetTagHelperDescriptorResolutionContext(
+                    _viewStartDirectiveDescriptors.Concat(descriptors));
+            }
         }
     }
 }
\ No newline at end of file