// Protocol Buffers - Google's data interchange format // Copyright 2008 Google Inc. All rights reserved. // http://github.com/jskeet/dotnet-protobufs/ // Original C++/Java/Python code: // http://code.google.com/p/protobuf/ // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. using System; using System.Reflection; namespace Google.Protobuf.FieldAccess { /// <summary> /// The methods in this class are somewhat evil, and should not be tampered with lightly. /// Basically they allow the creation of relatively weakly typed delegates from MethodInfos /// which are more strongly typed. They do this by creating an appropriate strongly typed /// delegate from the MethodInfo, and then calling that within an anonymous method. /// Mind-bending stuff (at least to your humble narrator) but the resulting delegates are /// very fast compared with calling Invoke later on. /// </summary> internal static class ReflectionUtil { /// <summary> /// Empty Type[] used when calling GetProperty to force property instead of indexer fetching. /// </summary> internal static readonly Type[] EmptyTypes = new Type[0]; /// <summary> /// Creates a delegate which will execute the given method and then return /// the result as an object. /// </summary> public static Func<T, object> CreateUpcastDelegate<T>(MethodInfo method) { // The tricky bit is invoking CreateCreateUpcastDelegateImpl with the right type parameters MethodInfo openImpl = typeof(ReflectionUtil).GetMethod("CreateUpcastDelegateImpl"); MethodInfo closedImpl = openImpl.MakeGenericMethod(typeof(T), method.ReturnType); return (Func<T, object>) closedImpl.Invoke(null, new object[] {method}); } /// <summary> /// Method used solely for implementing CreateUpcastDelegate. Public to avoid trust issues /// in low-trust scenarios. /// </summary> public static Func<TSource, object> CreateUpcastDelegateImpl<TSource, TResult>(MethodInfo method) { // Convert the reflection call into an open delegate, i.e. instead of calling x.Method() // we'll call getter(x). Func<TSource, TResult> getter = ReflectionUtil.CreateDelegateFunc<TSource, TResult>(method); // Implicit upcast to object (within the delegate) return source => getter(source); } /// <summary> /// Creates a delegate which will execute the given method after casting the parameter /// down from object to the required parameter type. /// </summary> public static Action<T, object> CreateDowncastDelegate<T>(MethodInfo method) { MethodInfo openImpl = typeof(ReflectionUtil).GetMethod("CreateDowncastDelegateImpl"); MethodInfo closedImpl = openImpl.MakeGenericMethod(typeof(T), method.GetParameters()[0].ParameterType); return (Action<T, object>) closedImpl.Invoke(null, new object[] {method}); } public static Action<TSource, object> CreateDowncastDelegateImpl<TSource, TParam>(MethodInfo method) { // Convert the reflection call into an open delegate, i.e. instead of calling x.Method(y) we'll // call Method(x, y) Action<TSource, TParam> call = ReflectionUtil.CreateDelegateAction<TSource, TParam>(method); return (source, parameter) => call(source, (TParam) parameter); } /// <summary> /// Creates a delegate which will execute the given method after casting the parameter /// down from object to the required parameter type. /// </summary> public static Action<T, object> CreateDowncastDelegateIgnoringReturn<T>(MethodInfo method) { MethodInfo openImpl = typeof(ReflectionUtil).GetMethod("CreateDowncastDelegateIgnoringReturnImpl"); MethodInfo closedImpl = openImpl.MakeGenericMethod(typeof(T), method.GetParameters()[0].ParameterType, method.ReturnType); return (Action<T, object>) closedImpl.Invoke(null, new object[] {method}); } public static Action<TSource, object> CreateDowncastDelegateIgnoringReturnImpl<TSource, TParam, TReturn>( MethodInfo method) { // Convert the reflection call into an open delegate, i.e. instead of calling x.Method(y) we'll // call Method(x, y) Func<TSource, TParam, TReturn> call = ReflectionUtil.CreateDelegateFunc<TSource, TParam, TReturn>(method); return delegate(TSource source, object parameter) { call(source, (TParam) parameter); }; } internal static Func<TResult> CreateDelegateFunc<TResult>(MethodInfo method) { object tdelegate = Delegate.CreateDelegate(typeof(Func<TResult>), null, method); return (Func<TResult>)tdelegate; } internal static Func<T, TResult> CreateDelegateFunc<T, TResult>(MethodInfo method) { object tdelegate = Delegate.CreateDelegate(typeof(Func<T, TResult>), null, method); return (Func<T, TResult>)tdelegate; } internal static Func<T1, T2, TResult> CreateDelegateFunc<T1, T2, TResult>(MethodInfo method) { object tdelegate = Delegate.CreateDelegate(typeof(Func<T1, T2, TResult>), null, method); return (Func<T1, T2, TResult>)tdelegate; } internal static Action<T> CreateDelegateAction<T>(MethodInfo method) { object tdelegate = Delegate.CreateDelegate(typeof(Action<T>), null, method); return (Action<T>)tdelegate; } internal static Action<T1, T2> CreateDelegateAction<T1, T2>(MethodInfo method) { object tdelegate = Delegate.CreateDelegate(typeof(Action<T1, T2>), null, method); return (Action<T1, T2>)tdelegate; } } }