Imported Upstream version 5.18.0.142

Former-commit-id: 7467d4b717762eeaf652d77f1486dd11ffb1ff1f

mcs/class/corlib/Mono/DependencyInjector.cs

@@ -0,0 +1,90 @@
+//
+// DependencyInjector.cs
+//
+// Author:
+//       Martin Baulig <mabaul@microsoft.com>
+//
+// Copyright (c) 2018 Xamarin, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+#if !(MONOTOUCH || MONODROID)
+using System.Reflection;
+#endif
+
+namespace Mono
+{
+	static class DependencyInjector
+	{
+		/*
+		 * Allows us to use code from `System.dll` in `mscorlib.dll`.
+		 * 
+		 */
+		internal static ISystemDependencyProvider SystemProvider {
+			get {
+				if (systemDependency != null)
+					return systemDependency;
+
+				lock (locker) {
+					if (systemDependency != null)
+						return systemDependency;
+
+					// Not using `MOBILE` as a conditional here because we want to use this on full-aot.
+#if !(MONOTOUCH || MONODROID)
+					// On Mobile, we initializes this during system startup.
+					systemDependency = ReflectionLoad ();
+#endif
+					if (systemDependency == null)
+						throw new PlatformNotSupportedException ("Cannot get `ISystemDependencyProvider`.");
+
+					return systemDependency;
+				}
+			}
+		}
+
+		internal static void Register (ISystemDependencyProvider provider)
+		{
+			lock (locker) {
+				if (systemDependency != null && systemDependency != provider)
+					throw new InvalidOperationException ();
+				systemDependency = provider;
+			}
+		}
+
+#if !(MONOTOUCH || MONODROID)
+		const string TypeName = "Mono.SystemDependencyProvider, " + Consts.AssemblySystem;
+
+		static ISystemDependencyProvider ReflectionLoad ()
+		{
+			var type = Type.GetType (TypeName);
+			if (type == null)
+				return null;
+
+			var prop = type.GetProperty ("Instance", BindingFlags.Static | BindingFlags.Instance | BindingFlags.Public);
+			if (prop == null)
+				return null;
+
+			return (ISystemDependencyProvider)prop.GetValue (null);
+		}
+#endif
+
+		static object locker = new object ();
+		static ISystemDependencyProvider systemDependency;
+	}
+}