Added CodeGen for TagHelper content mode redesign.

- Modified the CSharpTagHelperCodeRenderer to understand a single line of TagHelper rendering (instead of doing different things based on ContentBehavior).
- Modified existing CodeGen output to reflect new content changes.

#221

Author: N. Taylor Mullen

src/Microsoft.AspNet.Razor/Generator/Compiler/CodeBuilder/CSharp/CSharpTagHelperCodeRenderer.cs

@@ -58,7 +58,7 @@ public void RenderTagHelper(TagHelperChunk chunk)
         {
             var tagHelperDescriptors = chunk.Descriptors;
 
-            RenderBeginTagHelperScope(chunk.TagName);
+            RenderBeginTagHelperScope(chunk.TagName, chunk.Children);
 
             RenderTagHelpersCreation(chunk);
 
@@ -71,11 +71,15 @@ public void RenderTagHelper(TagHelperChunk chunk)
 
             RenderUnboundHTMLAttributes(unboundHTMLAttributes);
 
-            // TODO: Modify code generation to handle all content modes
-            //RenderRunTagHelpers(bufferedBody: false);
-            //RenderTagOutput(_tagHelperContext.OutputGenerateStartTagMethodName);
-            //RenderTagHelperBody(chunk.Children, bufferBody: false);
-            //RenderTagOutput(_tagHelperContext.OutputGenerateEndTagMethodName);
+            RenderRunTagHelpers();
+
+            RenderTagOutput(_tagHelperContext.OutputGenerateStartTagMethodName);
+            RenderTagOutput(_tagHelperContext.OutputGeneratePreContentMethodName);
+
+            RenderTagHelperContent();
+
+            RenderTagOutput(_tagHelperContext.OutputGeneratePostContentMethodName);
+            RenderTagOutput(_tagHelperContext.OutputGenerateEndTagMethodName);
 
             RenderEndTagHelpersScope();
         }
@@ -85,11 +89,13 @@ internal static string GetVariableName(TagHelperDescriptor descriptor)
             return "__" + descriptor.TypeName.Replace('.', '_');
         }
 
-        private void RenderBeginTagHelperScope(string tagName)
+        private void RenderBeginTagHelperScope(string tagName, IList<Chunk> children)
         {
             // Scopes/execution contexts are a runtime feature.
             if (_designTimeMode)
             {
+                // Render all of the tag helper children inline for intellisense.
+                _bodyVisitor.Accept(children);
                 return;
             }
 
@@ -104,6 +110,30 @@ private void RenderBeginTagHelperScope(string tagName)
             _writer.WriteStringLiteral(tagName)
                    .WriteParameterSeparator()
                    .WriteStringLiteral(GenerateUniqueId())
+                   .WriteParameterSeparator();
+
+            // We remove the target writer so TagHelper authors can retrieve content.
+            var oldWriter = _context.TargetWriterName;
+            _context.TargetWriterName = null;
+
+            // Disabling instrumentation inside TagHelper bodies since we never know if it's accurate
+            var oldInstrumentation = _context.Host.EnableInstrumentation;
+            _context.Host.EnableInstrumentation = false;
+
+            using (_writer.BuildAsyncLambda(endLine: false))
+            {
+                // Render all of the tag helper children.
+                _bodyVisitor.Accept(children);
+            }
+
+            _context.Host.EnableInstrumentation = oldInstrumentation;
+
+            _context.TargetWriterName = oldWriter;
+
+            _writer.WriteParameterSeparator()
+                   .Write(_tagHelperContext.StartWritingScopeMethodName)
+                   .WriteParameterSeparator()
+                   .Write(_tagHelperContext.EndWritingScopeMethodName)
                    .WriteEndMethodInvocation();
         }
 
@@ -302,18 +332,72 @@ private void RenderUnboundHTMLAttributes(IEnumerable<KeyValuePair<string, Chunk>
             }
         }
 
-        private void RenderTagHelperBody(IList<Chunk> children, bool bufferBody)
+        private void RenderTagHelperContent()
         {
-            // If we want to buffer the body we need to create a writing scope to capture the body content.
-            if (bufferBody)
+            // Rendering output is a runtime feature.
+            if (_designTimeMode)
             {
-                // Render all of the tag helper children in a buffered writing scope.
-                BuildBufferedWritingScope(children);
+                return;
             }
-            else
+
+            _writer.Write("if (")
+                   .Write(ExecutionContextVariableName)
+                   .Write(".")
+                   .Write(_tagHelperContext.ExecutionContextOutputPropertyName)
+                   .Write(".")
+                   .Write(_tagHelperContext.OutputContentSetPropertyName)
+                   .WriteLine(")");
+
+            // Render the body of the if statement, at this point in the codegen the TagHelperOutput's Content was set
+            // so we should just render its Content, no need to forcefully execute the child content.
+            using (_writer.BuildScope())
             {
-                // Render all of the tag helper children.
-                _bodyVisitor.Accept(children);
+                RenderTagOutput(_tagHelperContext.OutputGenerateContentMethodName);
+            }
+
+            _writer.Write("else if (")
+                   .Write(ExecutionContextVariableName)
+                   .Write(".")
+                   .Write(_tagHelperContext.ExecutionContextChildContentRetrievedPropertyName)
+                   .WriteLine(")");
+
+            // Render the body of the else if statement, at this point in the codegen the GetChildContentAsync method 
+            // was invoked but the TagHelperOutput's Content was not set. Call into GetChildContentAsync to retrieve
+            // the cached value of the content so we don't execute the child content twice.
+            using (_writer.BuildScope())
+            {
+                CSharpCodeVisitor.RenderPreWriteStart(_writer, _context);
+
+                _writer.WriteInstanceMethodInvocation(ExecutionContextVariableName,
+                                                      _tagHelperContext.ExecutionContextGetChildContentAsyncMethodName,
+                                                      endLine: false);
+
+                _writer.Write(".Result")
+                       .WriteEndMethodInvocation();
+            }
+
+            _writer.WriteLine("else");
+
+            // Render the body of the else statement, at this point in the codegen the GetChildContentAsync method 
+            // was not invoked and the TagHelperOutput's Content was not set. Call into ExecuteChildContentAsync to
+            // to execute and render child content.
+            using (_writer.BuildScope())
+            {
+                if (!string.IsNullOrEmpty(_context.TargetWriterName))
+                {
+                    _writer.WriteMethodInvocation(_tagHelperContext.StartWritingScopeMethodName, _context.TargetWriterName);
+                }
+
+                _writer.WriteInstanceMethodInvocation(
+                    ExecutionContextVariableName,
+                    _tagHelperContext.ExecutionContextExecuteChildContentAsyncMethodName,
+                    endLine: false);
+                _writer.WriteLine(".Wait();");
+
+                if (!string.IsNullOrEmpty(_context.TargetWriterName))
+                {
+                    _writer.WriteMethodInvocation(_tagHelperContext.EndWritingScopeMethodName);
+                }
             }
         }
 
@@ -348,7 +432,7 @@ private void RenderTagOutput(string tagOutputMethodName)
                    .WriteEndMethodInvocation();
         }
 
-        private void RenderRunTagHelpers(bool bufferedBody)
+        private void RenderRunTagHelpers()
         {
             // No need to run anything in design time mode.
             if (_designTimeMode)
@@ -362,15 +446,9 @@ private void RenderRunTagHelpers(bool bufferedBody)
                    .Write(" = ")
                    .WriteStartInstanceMethodInvocation(RunnerVariableName,
                                                        _tagHelperContext.RunnerRunAsyncMethodName);
-            _writer.Write(ExecutionContextVariableName);
-
-            if (bufferedBody)
-            {
-                _writer.WriteParameterSeparator()
-                       .Write(StringValueBufferVariableName);
-            }
 
-            _writer.WriteEndMethodInvocation(endLine: false)
+            _writer.Write(ExecutionContextVariableName)
+                   .WriteEndMethodInvocation(endLine: false)
                    .WriteLine(".Result;");
         }
 

src/Microsoft.AspNet.Razor/Generator/GeneratedTagHelperContext.cs

@@ -23,7 +23,9 @@ public GeneratedTagHelperContext()
             OutputGenerateContentMethodName = "GenerateContent";
             OutputGeneratePostContentMethodName = "GeneratePostContent";
             OutputGenerateEndTagMethodName = "GenerateEndTag";
+            ExecutionContextChildContentRetrievedPropertyName = "ChildContentRetrieved";
             ExecutionContextExecuteChildContentAsyncMethodName = "ExecuteChildContentAsync";
+            ExecutionContextGetChildContentAsyncMethodName = "GetChildContentAsync";
             ExecutionContextAddMethodName = "Add";
             ExecutionContextAddTagHelperAttributeMethodName = "AddTagHelperAttribute";
             ExecutionContextAddHtmlAttributeMethodName = "AddHtmlAttribute";
@@ -85,11 +87,23 @@ public GeneratedTagHelperContext()
         /// </summary>
         public string OutputGenerateEndTagMethodName { get; set; }
 
+        /// <summary>
+        /// The name of the <see cref="ExecutionContextTypeName"/> property that indicates if child content has 
+        /// been retrieved
+        /// </summary>
+        public string ExecutionContextChildContentRetrievedPropertyName { get; set; }
+
         /// <summary>
         /// The name of the <see cref="ExecutionContextTypeName"/> method used to execute tag helper child content.
         /// </summary>
         public string ExecutionContextExecuteChildContentAsyncMethodName { get; set; }
 
+        /// <summary>
+        /// The name of the <see cref="ExecutionContextTypeName"/> method used to execute and retrieve tag helper 
+        /// child content.
+        /// </summary>
+        public string ExecutionContextGetChildContentAsyncMethodName { get; set; }
+
         /// <summary>
         /// The name of the <see cref="ExecutionContextTypeName"/> method used to add tag helper attributes.
         /// </summary>

test/Microsoft.AspNet.Razor.Test/Generator/CSharpTagHelperRenderingTest.cs

@@ -174,8 +174,8 @@ public static TheoryData DesignTimeTagHelperTestData
                             BuildLineMapping(documentAbsoluteIndex: 189,
                                              documentLineIndex: 6,
                                              documentCharacterOffsetIndex: 40,
-                                             generatedAbsoluteIndex: 1599,
-                                             generatedLineIndex: 44,
+                                             generatedAbsoluteIndex: 1540,
+                                             generatedLineIndex: 43,
                                              generatedCharacterOffsetIndex: 40,
                                              contentLength: 4)
                         }
@@ -188,17 +188,17 @@ public static TheoryData DesignTimeTagHelperTestData
                         {
                             BuildLineMapping(14, 0, 479, 15, 14, 11),
                             BuildLineMapping(30, 2, 1, 995, 35, 0, 48),
-                            BuildLineMapping(157, 7, 32, 1177, 45, 6, 12),
-                            BuildLineMapping(205, 9, 1260, 50, 0, 12),
-                            BuildLineMapping(218, 9, 13, 1356, 56, 12, 27),
-                            BuildLineMapping(346, 12, 1754, 68, 0, 48),
-                            BuildLineMapping(440, 15, 46, 2004, 78, 6, 8),
-                            BuildLineMapping(457, 15, 63, 2267, 85, 40, 4),
-                            BuildLineMapping(501, 16, 31, 2384, 88, 6, 30),
-                            BuildLineMapping(568, 17, 30, 2733, 97, 0, 10),
-                            BuildLineMapping(601, 17, 63, 2815, 103, 0, 8),
-                            BuildLineMapping(632, 17, 94, 2895, 109, 0, 1),
-                            BuildLineMapping(639, 18, 3149, 118, 0, 15),
+                            BuildLineMapping(205, 9, 1113, 44, 0, 12),
+                            BuildLineMapping(218, 9, 13, 1209, 50, 12, 27),
+                            BuildLineMapping(346, 12, 1607, 62, 0, 48),
+                            BuildLineMapping(440, 15, 46, 1798, 71, 6, 8),
+                            BuildLineMapping(457, 15, 63, 2061, 78, 40, 4),
+                            BuildLineMapping(501, 16, 31, 2237, 82, 6, 30),
+                            BuildLineMapping(568, 17, 30, 2586, 91, 0, 10),
+                            BuildLineMapping(601, 17, 63, 2668, 97, 0, 8),
+                            BuildLineMapping(632, 17, 94, 2748, 103, 0, 1),
+                            BuildLineMapping(639, 18, 3002, 112, 0, 15),
+                            BuildLineMapping(157, 7, 32, 3151, 119, 6, 12),
                             BuildLineMapping(680, 21, 3234, 124, 0, 1)
                         }
                     }