Add TextAreaTagHelper and Microsoft.AspNet.Mvc.TagHelpers project

- rest of #1243 and all of #1244
- needs a few utility methods for copying `TagBuilder` to `TagHelperOutput`
- but works as-is

Author: dougbu

Mvc.sln

@@ -100,6 +100,8 @@ Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.Mvc.WebApi
 EndProject
 Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "TagHelperSample.Web", "samples\TagHelperSample.Web\TagHelperSample.Web.kproj", "{2223120F-D675-40DA-8CD8-11DC14A0B2C7}"
 EndProject
+Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.Mvc.TagHelpers", "src\Microsoft.AspNet.Mvc.TagHelpers\Microsoft.AspNet.Mvc.TagHelpers.kproj", "{B2347320-308E-4D2B-AEC8-005DFA68B0C9}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -530,6 +532,16 @@ Global
 		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
 		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|Mixed Platforms.Build.0 = Release|Any CPU
 		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|x86.ActiveCfg = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Mixed Platforms.ActiveCfg = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Mixed Platforms.Build.0 = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Mixed Platforms.Build.0 = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|x86.ActiveCfg = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -578,5 +590,6 @@ Global
 		{B2B7BC91-688E-4C1E-A71F-CE948D958DDF} = {16703B76-C9F7-4C75-AE6C-53D92E308E3C}
 		{5DE8E4D9-AACD-4B5F-819F-F091383FB996} = {3BA657BF-28B1-42DA-B5B0-1C4601FCF7B1}
 		{2223120F-D675-40DA-8CD8-11DC14A0B2C7} = {DAAE4C74-D06F-4874-A166-33305D2643CE}
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9} = {32285FA4-6B46-4D6B-A840-2B13E4C8B58E}
 	EndGlobalSection
 EndGlobal

src/Microsoft.AspNet.Mvc.TagHelpers/Microsoft.AspNet.Mvc.TagHelpers.kproj

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">14.0</VisualStudioVersion>
+    <VSToolsPath Condition="'$(VSToolsPath)' == ''">$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)</VSToolsPath>
+  </PropertyGroup>
+
+  <Import Project="$(VSToolsPath)\AspNet\Microsoft.Web.AspNet.Props" Condition="'$(VSToolsPath)' != ''" />
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>b2347320-308e-4d2b-aec8-005dfa68b0c9</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <RootNamespace>Microsoft.AspNet.Mvc.TagHelpers</RootNamespace>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <SchemaVersion>2.0</SchemaVersion>
+  </PropertyGroup>
+  <Import Project="$(VSToolsPath)\AspNet\Microsoft.Web.AspNet.targets" Condition="'$(VSToolsPath)' != ''" />
+</Project>

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

@@ -0,0 +1,57 @@
+// 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 Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Razor.Runtime.TagHelpers;
+
+namespace Microsoft.AspNet.Mvc.TagHelpers
+{
+    /// <summary>
+    /// <see cref="ITagHelper"/> implementation targeting &lt;textarea&gt; elements.
+    /// </summary>
+    public class TextAreaTagHelper : TagHelper
+    {
+        [Activate]
+        private IHtmlGenerator Generator { get; set; }
+
+        [Activate]
+        private ViewContext ViewContext { get; set; }
+
+        /// <summary>
+        /// An expression to be evaluated against the current model.
+        /// </summary>
+        public ModelExpression For { get; set; }
+
+        /// <inheritdoc />
+        /// <remarks>Does nothing unless user binds "for" attribute in Razor source.</remarks>
+        public override void Process(TagHelperContext context, TagHelperOutput output)
+        {
+            if (For != null)
+            {
+                var tagBuilder = Generator.GenerateTextArea(
+                    ViewContext,
+                    For.Metadata,
+                    For.Name,
+                    rows: 0,
+                    columns: 0,
+                    htmlAttributes: null);
+
+                if (tagBuilder != null)
+                {
+                    foreach (var attribute in tagBuilder.Attributes)
+                    {
+                        // TODO: Should special-case the "class" attribute.
+                        if (!output.Attributes.ContainsKey(attribute.Key))
+                        {
+                            output.Attributes.Add(attribute.Key, attribute.Value);
+                        }
+                    }
+
+                    output.Content = tagBuilder.InnerHtml;
+                    output.SelfClosing = false;
+                    output.TagName = tagBuilder.TagName;
+                }
+            }
+        }
+    }
+}

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

@@ -0,0 +1,15 @@
+{
+  "dependencies": {
+    "Microsoft.AspNet.Mvc.Razor": ""
+  },
+  "frameworks": {
+    "aspnet50": {
+      "dependencies": {}
+    },
+    "aspnetcore50": {
+      "dependencies": {
+        "System.Runtime": "4.0.20.0"
+      }
+    }
+  }
+}