Reacting to Razor changes for removing Generate*() method.

Author: sornaks

src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorHost.cs

@@ -92,15 +92,13 @@ public MvcRazorHost(ICodeTreeCache codeTreeCache)
                     ScopeManagerBeginMethodName = nameof(TagHelperScopeManager.Begin),
                     ScopeManagerEndMethodName = nameof(TagHelperScopeManager.End),
 
-                    OutputGenerateStartTagMethodName = nameof(TagHelperOutput.GenerateStartTag),
-                    OutputGenerateContentMethodName = nameof(TagHelperOutput.GenerateContent),
-                    OutputGenerateEndTagMethodName = nameof(TagHelperOutput.GenerateEndTag),
-
                     // Can't use nameof because RazorPage is not accessible here.
                     CreateTagHelperMethodName = "CreateTagHelper",
                     StartTagHelperWritingScopeMethodName = "StartTagHelperWritingScope",
                     EndTagHelperWritingScopeMethodName = "EndTagHelperWritingScope",
-                    HtmlEncoderPropertyName = "HtmlEncoder",
+
+                    WriteTagHelperAsyncMethodName = "WriteTagHelperAsync",
+                    WriteTagHelperToAsyncMethodName = "WriteTagHelperToAsync",
                 })
             {
                 ResolveUrlMethodName = "Href",

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

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Security.Claims;
@@ -250,25 +251,88 @@ public TagHelperContent EndTagHelperWritingScope()
         }
 
         /// <summary>
-        /// Writes an <see cref="ITextWriterCopyable"/> to the <see cref="Output"/>.
+        /// Writes the content of a specified <paramref name="tagHelperExecutionContext"/>.
         /// </summary>
-        /// <param name="copyableTextWriter">Contains the data to be written.</param>
-        public void Write(ITextWriterCopyable copyableTextWriter)
+        /// <param name="tagHelperExecutionContext">The execution context containing the content.</param>
+        /// <returns>
+        /// A <see cref="Task"/> that on completion writes the <paramref name="tagHelperExecutionContext"/> content.
+        /// </returns>
+        public async Task WriteTagHelperAsync([NotNull] TagHelperExecutionContext tagHelperExecutionContext)
         {
-            WriteTo(Output, copyableTextWriter);
+            await WriteTagHelperToAsync(Output, tagHelperExecutionContext);
         }
 
         /// <summary>
-        /// Writes an <see cref="ITextWriterCopyable"/> to the <paramref name="writer"/>.
+        /// Writes the content of a specified <paramref name="tagHelperExecutionContext"/> to the specified
+        /// <paramref name="writer"/>.
         /// </summary>
-        /// <param name="writer">The <see cref="TextWriter"/> to which the
-        /// <paramref name="copyableTextWriter"/> is written.</param>
-        /// <param name="copyableTextWriter">Contains the data to be written.</param>
-        public void WriteTo([NotNull] TextWriter writer, ITextWriterCopyable copyableTextWriter)
+        /// <param name="writer">The <see cref="TextWriter"/> instance to write to.</param>
+        /// <param name="tagHelperExecutionContext">The execution context containing the content.</param>
+        /// <returns>
+        /// A <see cref="Task"/> that on completion writes the <paramref name="tagHelperExecutionContext"/> content
+        /// to the <paramref name="writer"/>.
+        /// </returns>
+        public async Task WriteTagHelperToAsync(
+            [NotNull] TextWriter writer,
+            [NotNull] TagHelperExecutionContext tagHelperExecutionContext)
         {
-            if (copyableTextWriter != null)
+            var tagHelperOutput = tagHelperExecutionContext.Output;
+            var isTagNameNullOrWhitespace = string.IsNullOrWhiteSpace(tagHelperOutput.TagName);
+
+            if (!isTagNameNullOrWhitespace)
             {
-                copyableTextWriter.CopyTo(writer);
+                writer.Write('<');
+                writer.Write(tagHelperOutput.TagName);
+
+                foreach (var attribute in tagHelperOutput.Attributes)
+                {
+                    var value = HtmlEncoder.HtmlEncode(attribute.Value);
+                    writer.Write(' ');
+                    writer.Write(attribute.Key);
+                    writer.Write("=\"");
+                    writer.Write(value);
+                    writer.Write('"');
+                }
+
+                if (tagHelperOutput.SelfClosing)
+                {
+                    writer.Write(" /");
+                }
+
+                writer.Write('>');
+            }
+
+            if (isTagNameNullOrWhitespace || !tagHelperOutput.SelfClosing)
+            {
+                WriteTagHelperContentTo(writer, tagHelperOutput.PreContent);
+                if (tagHelperOutput.IsContentModified)
+                {
+                    WriteTagHelperContentTo(writer, tagHelperOutput.Content);
+                }
+                else if (tagHelperExecutionContext.ChildContentRetrieved)
+                {
+                    var childContent = await tagHelperExecutionContext.GetChildContentAsync();
+                    WriteTagHelperContentTo(writer, childContent);
+                }
+                else
+                {
+                    await tagHelperExecutionContext.ExecuteChildContentAsync();
+                }
+
+                WriteTagHelperContentTo(writer, tagHelperOutput.PostContent);
+            }
+
+            if (!isTagNameNullOrWhitespace && !tagHelperOutput.SelfClosing)
+            {
+                writer.Write(string.Format(CultureInfo.InvariantCulture, "</{0}>", tagHelperOutput.TagName));
+            }
+        }
+
+        private void WriteTagHelperContentTo(TextWriter writer, TagHelperContent content)
+        {
+            foreach (var entry in content)
+            {
+                writer.Write(entry);
             }
         }
 
@@ -310,20 +374,7 @@ public virtual void WriteTo([NotNull] TextWriter writer, object value)
                     }
                     else
                     {
-                        // This path is called when GetChildContentAsync() is called in tag helper
-                        // and content is not set.
-                        var tagHelperContent = value as TagHelperContent;
-                        if (tagHelperContent != null)
-                        {
-                            foreach (var entry in tagHelperContent)
-                            {
-                                writer.Write(entry);
-                            }
-                        }
-                        else
-                        {
-                            WriteTo(writer, value.ToString());
-                        }
+                        WriteTo(writer, value.ToString());
                     }
                 }
             }

src/Microsoft.AspNet.Mvc.TagHelpers/OptionTagHelper.cs

@@ -85,7 +85,7 @@ public override async Task ProcessAsync(TagHelperContext context, TagHelperOutpu
 
                     // Select this <option/> element if value attribute or content matches a selected value. Callers
                     // encode values as-needed while executing child content. But TagHelperOutput itself
-                    // encodes attribute values later, when GenerateStartTag() is called.
+                    // encodes attribute values later, when start tag is generated.
                     bool selected;
                     if (Value != null)
                     {

test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles/Output/Runtime/ModelExpressionTagHelper.cs

@@ -42,7 +42,7 @@ public ASPV_TestFiles_Input_ModelExpressionTagHelper_cshtml()
         #pragma warning disable 1998
         public override async Task ExecuteAsync()
         {
-            __tagHelperRunner = __tagHelperRunner ?? new Microsoft.AspNet.Razor.Runtime.TagHelpers.TagHelperRunner(HtmlEncoder);
+            __tagHelperRunner = __tagHelperRunner ?? new Microsoft.AspNet.Razor.Runtime.TagHelpers.TagHelperRunner();
             BeginContext(120, 2, true);
             WriteLiteral("\r\n");
             EndContext();
@@ -58,22 +58,7 @@ public override async Task ExecuteAsync()
 #line hidden
             __tagHelperExecutionContext.AddTagHelperAttribute("for", __Microsoft_AspNet_Mvc_Razor_InputTestTagHelper.For);
             __tagHelperExecutionContext.Output = __tagHelperRunner.RunAsync(__tagHelperExecutionContext).Result;
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateStartTag());
-            Write(__tagHelperExecutionContext.Output.GeneratePreContent());
-            if (__tagHelperExecutionContext.Output.IsContentModified)
-            {
-                Write(__tagHelperExecutionContext.Output.GenerateContent());
-            }
-            else if (__tagHelperExecutionContext.ChildContentRetrieved)
-            {
-                Write(__tagHelperExecutionContext.GetChildContentAsync().Result);
-            }
-            else
-            {
-                __tagHelperExecutionContext.ExecuteChildContentAsync().Wait();
-            }
-            Write(__tagHelperExecutionContext.Output.GeneratePostContent());
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateEndTag());
+            WriteTagHelperAsync(__tagHelperExecutionContext).Wait();
             __tagHelperExecutionContext = __tagHelperScopeManager.End();
             BeginContext(146, 2, true);
             WriteLiteral("\r\n");
@@ -90,22 +75,7 @@ public override async Task ExecuteAsync()
 #line hidden
             __tagHelperExecutionContext.AddTagHelperAttribute("for", __Microsoft_AspNet_Mvc_Razor_InputTestTagHelper.For);
             __tagHelperExecutionContext.Output = __tagHelperRunner.RunAsync(__tagHelperExecutionContext).Result;
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateStartTag());
-            Write(__tagHelperExecutionContext.Output.GeneratePreContent());
-            if (__tagHelperExecutionContext.Output.IsContentModified)
-            {
-                Write(__tagHelperExecutionContext.Output.GenerateContent());
-            }
-            else if (__tagHelperExecutionContext.ChildContentRetrieved)
-            {
-                Write(__tagHelperExecutionContext.GetChildContentAsync().Result);
-            }
-            else
-            {
-                __tagHelperExecutionContext.ExecuteChildContentAsync().Wait();
-            }
-            Write(__tagHelperExecutionContext.Output.GeneratePostContent());
-            WriteLiteral(__tagHelperExecutionContext.Output.GenerateEndTag());
+            WriteTagHelperAsync(__tagHelperExecutionContext).Wait();
             __tagHelperExecutionContext = __tagHelperScopeManager.End();
         }
         #pragma warning restore 1998