59 lines
2.8 KiB
C#
59 lines
2.8 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="FastDelegateCreator.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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namespace System.Web.Util {
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using System;
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using System.Reflection;
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using System.Reflection.Emit;
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using System.Security.Permissions;
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// Helper utility to quickly create a Delegate by calling its unmanaged ctor
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[SecurityPermission(SecurityAction.LinkDemand, Unrestricted = true)]
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internal static class FastDelegateCreator<TDelegate> where TDelegate : class {
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private static readonly Func<object, IntPtr, TDelegate> _factory = GetFactory();
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// obj is the 'this' pointer (potentially null)
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// method is RuntimeMethodHandle.GetFunctionPointer()
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internal static TDelegate BindTo(object obj, IntPtr method) {
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return _factory(obj, method);
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}
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// obj is the 'this' pointer (potentially null)
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// method is the MethodInfo to bind to
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internal static TDelegate BindTo(object obj, MethodInfo method) {
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return BindTo(obj, method.MethodHandle.GetFunctionPointer());
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}
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// Assert needed since we'll be asked to create delegates to potentially private / protected methods
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[ReflectionPermission(SecurityAction.Assert, MemberAccess = true)]
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private static Func<object, IntPtr, TDelegate> GetFactory() {
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// All delegates have a .ctor(object @object, IntPtr method), but since we can't call this
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// directly from C# we just need to LCG it.
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ConstructorInfo delegateCtor = typeof(TDelegate).GetConstructor(new Type[] { typeof(object), typeof(IntPtr) });
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// Define method FastCreateDelegate_X: (object, IntPtr) -> TDelegate
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DynamicMethod dynamicMethod = new DynamicMethod(
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name: "FastCreateDelegate_" + typeof(TDelegate).Name,
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returnType: typeof(TDelegate),
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parameterTypes: new Type[] { typeof(object), typeof(IntPtr) },
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owner: typeof(FastDelegateCreator<TDelegate>),
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skipVisibility: true);
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// return new TDelegate(obj, method);
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ILGenerator ilGen = dynamicMethod.GetILGenerator();
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ilGen.Emit(OpCodes.Ldarg_0); // Stack contains ('this')
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ilGen.Emit(OpCodes.Ldarg_1); // Stack contains ('this', 'method')
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ilGen.Emit(OpCodes.Newobj, delegateCtor); // Stack contains (delegate)
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ilGen.Emit(OpCodes.Ret);
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return (Func<object, IntPtr, TDelegate>)dynamicMethod.CreateDelegate(typeof(Func<object, IntPtr, TDelegate>));
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}
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}
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}
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