Avoid memory allocation and improve performance, part 1

src/React.AspNet/ActionHtmlString.cs

@@ -0,0 +1,77 @@
+/*
+ *  Copyright (c) 2014-Present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+using System;
+using System.IO;
+
+#if LEGACYASPNET
+using System.Text;
+using System.Web;
+#else
+using System.Text.Encodings.Web;
+using IHtmlString = Microsoft.AspNetCore.Html.IHtmlContent;
+#endif
+
+#if LEGACYASPNET
+namespace React.Web.Mvc
+#else
+namespace React.AspNet
+#endif
+{
+	/// <summary>
+	/// IHtmlString or IHtmlString action wrapper implementation
+	/// </summary>
+	public class ActionHtmlString : IHtmlString
+	{
+		private readonly Action<TextWriter> _textWriter;
+
+		/// <summary>
+		/// Constructor IHtmlString or IHtmlString action wrapper implementation
+		/// </summary>
+		/// <param name="textWriter"></param>
+		public ActionHtmlString(Action<TextWriter> textWriter)
+		{
+			_textWriter = textWriter;
+		}
+
+#if LEGACYASPNET
+		[ThreadStatic]
+		private static StringWriter _sharedStringWriter;
+
+		/// <summary>Returns an HTML-encoded string.</summary>
+		/// <returns>An HTML-encoded string.</returns>
+		public string ToHtmlString()
+		{
+			var stringWriter = _sharedStringWriter;
+			if (stringWriter != null)
+			{
+				stringWriter.GetStringBuilder().Clear();
+			}
+			else
+			{
+				_sharedStringWriter = stringWriter = new StringWriter(new StringBuilder(512));
+			}
+
+			_textWriter(stringWriter);
+			return stringWriter.ToString();
+		}
+#else
+		/// <summary>
+		/// Writes the content by encoding it with the specified <paramref name="encoder" />
+		/// to the specified <paramref name="writer" />.
+		/// </summary>
+		/// <param name="writer">The <see cref="T:System.IO.TextWriter" /> to which the content is written.</param>
+		/// <param name="encoder">The <see cref="T:System.Text.Encodings.Web.HtmlEncoder" /> which encodes the content to be written.</param>
+		public void WriteTo(TextWriter writer, HtmlEncoder encoder)
+		{
+			_textWriter(writer);
+		}
+#endif
+	}
+}

src/React.AspNet/HtmlHelperExtensions.cs

@@ -12,13 +12,10 @@
 
 #if LEGACYASPNET
 using System.Web;
-using System.Web.Mvc;
 using IHtmlHelper = System.Web.Mvc.HtmlHelper;
 #else
-using System.Text.Encodings.Web;
 using Microsoft.AspNetCore.Mvc.Rendering;
 using IHtmlString = Microsoft.AspNetCore.Html.IHtmlContent;
-using Microsoft.AspNetCore.Html;
 #endif
 
 #if LEGACYASPNET
@@ -32,7 +29,6 @@ namespace React.AspNet
 	/// </summary>
 	public static class HtmlHelperExtensions
 	{
-
 		/// <summary>
 		/// Gets the React environment
 		/// </summary>
@@ -70,24 +66,28 @@ public static IHtmlString React<T>(
 			Action<Exception, string, string> exceptionHandler = null
 		)
 		{
-			try
+			return new ActionHtmlString(writer =>
 			{
-				var reactComponent = Environment.CreateComponent(componentName, props, containerId, clientOnly, serverOnly);
-				if (!string.IsNullOrEmpty(htmlTag))
+				try
 				{
-					reactComponent.ContainerTag = htmlTag;
+					var reactComponent = Environment.CreateComponent(componentName, props, containerId, clientOnly, serverOnly);
+					if (!string.IsNullOrEmpty(htmlTag))
+					{
+						reactComponent.ContainerTag = htmlTag;
+					}
+
+					if (!string.IsNullOrEmpty(containerClass))
+					{
+						reactComponent.ContainerClass = containerClass;
+					}
+
+					reactComponent.RenderHtml(writer, clientOnly, serverOnly, exceptionHandler);
 				}
-				if (!string.IsNullOrEmpty(containerClass))
+				finally
 				{
-					reactComponent.ContainerClass = containerClass;
+					Environment.ReturnEngineToPool();
 				}
-				var result = reactComponent.RenderHtml(clientOnly, serverOnly, exceptionHandler);
-				return new HtmlString(result);
-			}
-			finally
-			{
-				Environment.ReturnEngineToPool();
-			}
+			});
 		}
 
 		/// <summary>
@@ -116,25 +116,30 @@ public static IHtmlString ReactWithInit<T>(
 			Action<Exception, string, string> exceptionHandler = null
 		)
 		{
-			try
+			return new ActionHtmlString(writer =>
 			{
-				var reactComponent = Environment.CreateComponent(componentName, props, containerId, clientOnly);
-				if (!string.IsNullOrEmpty(htmlTag))
+				try
 				{
-					reactComponent.ContainerTag = htmlTag;
+					var reactComponent = Environment.CreateComponent(componentName, props, containerId, clientOnly);
+					if (!string.IsNullOrEmpty(htmlTag))
+					{
+						reactComponent.ContainerTag = htmlTag;
+					}
+
+					if (!string.IsNullOrEmpty(containerClass))
+					{
+						reactComponent.ContainerClass = containerClass;
+					}
+
+					reactComponent.RenderHtml(writer, clientOnly, exceptionHandler: exceptionHandler);
+					writer.WriteLine();
+					WriteScriptTag(writer, bodyWriter => reactComponent.RenderJavaScript(bodyWriter));
 				}
-				if (!string.IsNullOrEmpty(containerClass))
+				finally
 				{
-					reactComponent.ContainerClass = containerClass;
+					Environment.ReturnEngineToPool();
 				}
-				var html = reactComponent.RenderHtml(clientOnly, exceptionHandler: exceptionHandler);
-
-				return new HtmlString(html + System.Environment.NewLine + RenderToString(GetScriptTag(reactComponent.RenderJavaScript())));
-			}
-			finally
-			{
-				Environment.ReturnEngineToPool();
-			}
+			});
 		}
 
 		/// <summary>
@@ -144,55 +149,34 @@ public static IHtmlString ReactWithInit<T>(
 		/// <returns>JavaScript for all components</returns>
 		public static IHtmlString ReactInitJavaScript(this IHtmlHelper htmlHelper, bool clientOnly = false)
 		{
-			try
-			{
-				return GetScriptTag(Environment.GetInitJavaScript(clientOnly));
-			}
-			finally
+			return new ActionHtmlString(writer =>
 			{
-				Environment.ReturnEngineToPool();
-			}
+				try
+				{
+					WriteScriptTag(writer, bodyWriter => Environment.GetInitJavaScript(bodyWriter, clientOnly));
+				}
+				finally
+				{
+					Environment.ReturnEngineToPool();
+				}
+			});
 		}
 
-		private static IHtmlString GetScriptTag(string script)
+		private static void WriteScriptTag(TextWriter writer, Action<TextWriter> bodyWriter)
 		{
-#if LEGACYASPNET
-			var tag = new TagBuilder("script")
-			{
-				InnerHtml = script,
-			};
-
+			writer.Write("<script");
 			if (Environment.Configuration.ScriptNonceProvider != null)
 			{
-				tag.Attributes.Add("nonce", Environment.Configuration.ScriptNonceProvider());
+				writer.Write(" nonce=\"");
+				writer.Write(Environment.Configuration.ScriptNonceProvider());
+				writer.Write("\"");
 			}
 
-			return new HtmlString(tag.ToString());
-#else
-			var tag = new TagBuilder("script");
-			tag.InnerHtml.AppendHtml(script);
+			writer.Write(">");
 
-			if (Environment.Configuration.ScriptNonceProvider != null)
-			{
-				tag.Attributes.Add("nonce", Environment.Configuration.ScriptNonceProvider());
-			}
+			bodyWriter(writer);
 
-			return tag;
-#endif
-		}
-
-		// In ASP.NET Core, you can no longer call `.ToString` on `IHtmlString`
-		private static string RenderToString(IHtmlString source)
-		{
-#if LEGACYASPNET
-			return source.ToString();
-#else
-			using (var writer = new StringWriter())
-			{
-				source.WriteTo(writer, HtmlEncoder.Default);
-				return writer.ToString();
-			}
-#endif
+			writer.Write("</script>");
 		}
 	}
 }

src/React.Core/IReactComponent.cs

@@ -8,6 +8,7 @@
  */
 
 using System;
+using System.IO;
 
 namespace React
 {
@@ -63,5 +64,24 @@ public interface IReactComponent
 		/// </summary>
 		/// <returns>JavaScript</returns>
 		string RenderJavaScript();
+
+		/// <summary>
+		/// Renders the HTML for this component. This will execute the component server-side and
+		/// return the rendered HTML.
+		/// </summary>
+		/// <param name="writer">The <see cref="T:System.IO.TextWriter" /> to which the content is written</param>
+		/// <param name="renderContainerOnly">Only renders component container. Used for client-side only rendering.</param>
+		/// <param name="renderServerOnly">Only renders the common HTML mark up and not any React specific data attributes. Used for server-side only rendering.</param>
+		/// <param name="exceptionHandler">A custom exception handler that will be called if a component throws during a render. Args: (Exception ex, string componentName, string containerId)</param>
+		/// <returns>HTML</returns>
+		void RenderHtml(TextWriter writer, bool renderContainerOnly = false, bool renderServerOnly = false, Action<Exception, string, string> exceptionHandler = null);
+
+		/// <summary>
+		/// Renders the JavaScript required to initialise this component client-side. This will
+		/// initialise the React component, which includes attach event handlers to the
+		/// server-rendered HTML.
+		/// </summary>
+		/// <returns>JavaScript</returns>
+		void RenderJavaScript(TextWriter writer);
 	}
 }

src/React.Core/IReactEnvironment.cs

@@ -8,6 +8,8 @@
  */
 
 
+using System.IO;
+
 namespace React
 {
 	/// <summary>
@@ -100,6 +102,15 @@ public interface IReactEnvironment
 		/// <returns>JavaScript for all components</returns>
 		string GetInitJavaScript(bool clientOnly = false);
 
+		/// <summary>
+		/// Renders the JavaScript required to initialise all components client-side. This will 
+		/// attach event handlers to the server-rendered HTML.
+		/// </summary>
+		/// <param name="writer">The <see cref="T:System.IO.TextWriter" /> to which the content is written</param>
+		/// <param name="clientOnly">True if server-side rendering will be bypassed. Defaults to false.</param>
+		/// <returns>JavaScript for all components</returns>
+		void GetInitJavaScript(TextWriter writer, bool clientOnly = false);
+
 		/// <summary>
 		/// Gets the JSX Transformer for this environment.
 		/// </summary>

src/React.Core/IReactSiteConfiguration.cs

@@ -207,5 +207,16 @@ public interface IReactSiteConfiguration
 		/// <param name="provider"></param>
 		/// <returns></returns>
 		IReactSiteConfiguration SetScriptNonceProvider(Func<string> provider);
+
+		/// <summary>
+		/// Get or set boolean that specifies whether the component should be checked to ensure that it exists.
+		/// </summary>
+		bool ComponentExistsChecks { get; set; }
+
+		/// <summary>
+		/// Sets whether the component should be checked to ensure that it exists.
+		/// </summary>
+		/// <returns>The configuration, for chaining</returns>
+		IReactSiteConfiguration SetComponentExistsChecks(bool componentExistsChecks);
 	}
 }