Removed engine-specific logic from configuration and the engine factory

src/React.Core/IReactSiteConfiguration.cs

@@ -113,17 +113,15 @@ public interface IReactSiteConfiguration
 		/// </summary>
 		IReactSiteConfiguration SetMaxUsagesPerEngine(int? maxUsagesPerEngine);
 
-		/// <summary>
-		/// Gets or sets whether the MSIE engine should be used if V8 is unavailable.
+		///<summary>
+		/// Gets or sets the name of the default JavaScript engine.
 		/// </summary>
-		[Obsolete("This should be managed in the JavaScriptEngineSwitcher configuration instead")]
-		bool AllowMsieEngine { get; set; }
+		string DefaultEngineName { get; set; }
 		/// <summary>
-		/// Sets whether the MSIE engine should be used if V8 is unavailable.
+		/// Sets the name of the default JavaScript engine.
 		/// </summary>
-		/// <returns></returns>
-		[Obsolete("This should be managed in the JavaScriptEngineSwitcher configuration instead")]
-		IReactSiteConfiguration SetAllowMsieEngine(bool allowMsieEngine);
+		/// <param name="defaultEngineName">Name of a default JavaScript engine.</param>
+		IReactSiteConfiguration SetDefaultEngineName(string defaultEngineName);
 
 		/// <summary>
 		/// Gets or sets whether the built-in version of React is loaded. If <c>false</c>, you must

src/React.Core/JavaScriptEngineFactory.cs

@@ -5,12 +5,6 @@
 using System.Reflection;
 using System.Threading;
 using JavaScriptEngineSwitcher.Core;
-using JavaScriptEngineSwitcher.Msie;
-#if NET40
-using JavaScriptEngineSwitcher.V8;
-#else
-using JavaScriptEngineSwitcher.ChakraCore;
-#endif
 using JSPool;
 using React.Exceptions;
 
@@ -68,7 +62,7 @@ IFileSystem fileSystem
 			_config = config;
 			_fileSystem = fileSystem;
 #pragma warning disable 618
-			_factory = GetFactory(_jsEngineSwitcher, config.AllowMsieEngine);
+			_factory = GetFactory(_jsEngineSwitcher);
 #pragma warning restore 618
 			if (_config.ReuseJavaScriptEngines)
 			{
@@ -237,11 +231,12 @@ public virtual PooledJsEngine GetEngine()
 		/// The first functioning JavaScript engine with the lowest priority will be used.
 		/// </summary>
 		/// <returns>Function to create JavaScript engine</returns>
-		private static Func<IJsEngine> GetFactory(JsEngineSwitcher jsEngineSwitcher, bool allowMsie)
+		private Func<IJsEngine> GetFactory(JsEngineSwitcher jsEngineSwitcher)
 		{
-			EnsureJsEnginesRegistered(jsEngineSwitcher, allowMsie);
+			EnsureJsEnginesRegistered(jsEngineSwitcher);
 
-			string defaultEngineName = jsEngineSwitcher.DefaultEngineName;
+			// First try the config's default
+			string defaultEngineName = _config.DefaultEngineName;
 			if (!string.IsNullOrWhiteSpace(defaultEngineName))
 			{
 				var engineFactory = jsEngineSwitcher.EngineFactories.Get(defaultEngineName);
@@ -252,18 +247,19 @@ private static Func<IJsEngine> GetFactory(JsEngineSwitcher jsEngineSwitcher, boo
 				else
 				{
 					throw new ReactEngineNotFoundException(
-						"Could not find a factory that creates an instance of the JavaScript " +
+						"Could not find a factory that creates an instance of the default JavaScript " +
 						"engine with name `" + defaultEngineName + "`.");
 				}
 			}
 
+			// Since our config doesn't care, just get the first working factory
 			foreach (var engineFactory in jsEngineSwitcher.EngineFactories)
 			{
 				IJsEngine engine = null;
 				try
 				{
 					engine = engineFactory.CreateEngine();
-					if (EngineIsUsable(engine, allowMsie))
+					if (EngineIsUsable(engine))
 					{
 						// Success! Use this one.
 						return engineFactory.CreateEngine;
@@ -284,38 +280,18 @@ private static Func<IJsEngine> GetFactory(JsEngineSwitcher jsEngineSwitcher, boo
 			}
 
 			// Epic fail, none of the engines worked. Nothing we can do now.
-			// Throw an error relevant to the engine they should be able to use.
-#if NET40
-			if (JavaScriptEngineUtils.EnvironmentSupportsClearScript())
-			{
-				JavaScriptEngineUtils.EnsureEngineFunctional<V8JsEngine, ClearScriptV8InitialisationException>(
-					ex => new ClearScriptV8InitialisationException(ex)
-				);
-			}
-#endif
-#if NET40 || NETSTANDARD1_6
-			if (JavaScriptEngineUtils.EnvironmentSupportsVroomJs())
-			{
-				JavaScriptEngineUtils.EnsureEngineFunctional<VroomJsEngine, VroomJsInitialisationException>(
-					ex => new VroomJsInitialisationException(ex.Message)
-				);
-			}
-#endif
 			throw new ReactEngineNotFoundException();
 		}
 
 		/// <summary>
 		/// Performs a sanity check to ensure the specified engine type is usable.
 		/// </summary>
 		/// <param name="engine">Engine to test</param>
-		/// <param name="allowMsie">Whether the MSIE engine can be used</param>
-		/// <returns></returns>
-		private static bool EngineIsUsable(IJsEngine engine, bool allowMsie)
+		/// <returns>Whether the engine is usable.</returns>
+		private static bool EngineIsUsable(IJsEngine engine)
 		{
 			// Perform a sanity test to ensure this engine is usable
-			var isUsable = engine.Evaluate<int>("1 + 1") == 2;
-			var isMsie = engine is MsieJsEngine;
-			return isUsable && (!isMsie || allowMsie);
+			return engine.Evaluate<int>("1 + 1") == 2;
 		}
 
 		/// <summary>
@@ -360,33 +336,23 @@ public void EnsureValidState()
 		/// registers some default engines.
 		/// </summary>
 		/// <param name="jsEngineSwitcher">JavaScript Engine Switcher instance</param>
-		/// <param name="allowMsie">Whether to allow the MSIE JS engine</param>
-		private static void EnsureJsEnginesRegistered(JsEngineSwitcher jsEngineSwitcher, bool allowMsie)
+		private static void EnsureJsEnginesRegistered(JsEngineSwitcher jsEngineSwitcher)
 		{
-			if (jsEngineSwitcher.EngineFactories.Any())
+			if (!string.IsNullOrWhiteSpace(jsEngineSwitcher.DefaultEngineName))
 			{
-				// Engines have been registered, nothing to do here!
-				return;
+				jsEngineSwitcher.CreateDefaultEngine();
 			}
 
-			Trace.WriteLine(
-				"No JavaScript engines were registered, falling back to a default config! It is " +
-				"recommended that you configure JavaScriptEngineSwitcher in your app. See " +
-				"https://github.com/Taritsyn/JavaScriptEngineSwitcher/wiki/Registration-of-JS-engines " +
-				"for more information."
-			);
-
-#if NET40
-			jsEngineSwitcher.EngineFactories.AddV8();
-#endif
-			jsEngineSwitcher.EngineFactories.Add(new VroomJsEngine.Factory());
-			if (allowMsie)
+			if (!jsEngineSwitcher.EngineFactories.Any())
 			{
-				jsEngineSwitcher.EngineFactories.AddMsie();
+				throw new ReactEngineNotFoundException(
+					"No JavaScript engines were registered! " +
+					"Set the configuration's PreferredEngineName to choose a default. " +
+					"Alternately, configure JavaScriptEngineSwitcher in your app. See " +
+					"https://github.com/Taritsyn/JavaScriptEngineSwitcher/wiki/Registration-of-JS-engines " +
+					"for more detailed information."
+				);
 			}
-#if !NET40
-			jsEngineSwitcher.EngineFactories.AddChakraCore();
-#endif
 		}
 	}
 }

src/React.Core/ReactSiteConfiguration.cs

@@ -10,6 +10,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using JavaScriptEngineSwitcher.Core;
 using Newtonsoft.Json;
 using React.Exceptions;
 
@@ -37,7 +38,6 @@ public ReactSiteConfiguration()
 		{
 			BabelConfig = new BabelConfig();
 			ReuseJavaScriptEngines = true;
-			AllowMsieEngine = true;
 			LoadBabel = true;
 			LoadReact = true;
 			JsonSerializerSettings = new JsonSerializerSettings
@@ -215,18 +215,28 @@ public IReactSiteConfiguration SetMaxUsagesPerEngine(int? maxUsagesPerEngine)
 			return this;
 		}
 
-		/// <summary>
-		/// Gets or sets whether the MSIE engine should be used if V8 is unavailable.
+		///<summary>
+		/// Gets or sets the name of the default JsEngineSwitcher engine.
 		/// </summary>
-		public bool AllowMsieEngine { get; set; }
+		public string DefaultEngineName
+		{
+			get
+			{
+				return JsEngineSwitcher.Instance.DefaultEngineName;
+			}
+			set
+			{
+				JsEngineSwitcher.Instance.DefaultEngineName = value;
+			}
+		}
 
 		/// <summary>
-		/// Sets whether the MSIE engine should be used if V8 is unavailable.
+		/// Sets the name of the default JsEngineSwitcher engine.
 		/// </summary>
-		/// <returns></returns>
-		public IReactSiteConfiguration SetAllowMsieEngine(bool allowMsieEngine)
+		/// <param name="defaultEngineName">Name of a default JsEngineSwitcher engine.</param>
+		public IReactSiteConfiguration SetDefaultEngineName(string defaultEngineName)
 		{
-			AllowMsieEngine = allowMsieEngine;
+			DefaultEngineName = defaultEngineName;
 			return this;
 		}