1 #region Copyright notice and license 2 // Protocol Buffers - Google's data interchange format 3 // Copyright 2008 Google Inc. All rights reserved. 4 // https://developers.google.com/protocol-buffers/ 5 // 6 // Redistribution and use in source and binary forms, with or without 7 // modification, are permitted provided that the following conditions are 8 // met: 9 // 10 // * Redistributions of source code must retain the above copyright 11 // notice, this list of conditions and the following disclaimer. 12 // * Redistributions in binary form must reproduce the above 13 // copyright notice, this list of conditions and the following disclaimer 14 // in the documentation and/or other materials provided with the 15 // distribution. 16 // * Neither the name of Google Inc. nor the names of its 17 // contributors may be used to endorse or promote products derived from 18 // this software without specific prior written permission. 19 // 20 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 23 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 24 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 30 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 #endregion 32 33 using System; 34 using System.Collections.Generic; 35 using System.Linq.Expressions; 36 using System.Reflection; 37 38 namespace Google.Protobuf.Reflection 39 { 40 /// <summary> 41 /// The methods in this class are somewhat evil, and should not be tampered with lightly. 42 /// Basically they allow the creation of relatively weakly typed delegates from MethodInfos 43 /// which are more strongly typed. They do this by creating an appropriate strongly typed 44 /// delegate from the MethodInfo, and then calling that within an anonymous method. 45 /// Mind-bending stuff (at least to your humble narrator) but the resulting delegates are 46 /// very fast compared with calling Invoke later on. 47 /// </summary> 48 internal static class ReflectionUtil 49 { 50 /// <summary> 51 /// Empty Type[] used when calling GetProperty to force property instead of indexer fetching. 52 /// </summary> 53 internal static readonly Type[] EmptyTypes = new Type[0]; 54 55 /// <summary> 56 /// Creates a delegate which will cast the argument to the appropriate method target type, 57 /// call the method on it, then convert the result to object. 58 /// </summary> CreateFuncIMessageObject(MethodInfo method)59 internal static Func<IMessage, object> CreateFuncIMessageObject(MethodInfo method) 60 { 61 ParameterExpression parameter = Expression.Parameter(typeof(IMessage), "p"); 62 Expression downcast = Expression.Convert(parameter, method.DeclaringType); 63 Expression call = Expression.Call(downcast, method); 64 Expression upcast = Expression.Convert(call, typeof(object)); 65 return Expression.Lambda<Func<IMessage, object>>(upcast, parameter).Compile(); 66 } 67 68 /// <summary> 69 /// Creates a delegate which will cast the argument to the appropriate method target type, 70 /// call the method on it, then convert the result to the specified type. 71 /// </summary> CreateFuncIMessageT(MethodInfo method)72 internal static Func<IMessage, T> CreateFuncIMessageT<T>(MethodInfo method) 73 { 74 ParameterExpression parameter = Expression.Parameter(typeof(IMessage), "p"); 75 Expression downcast = Expression.Convert(parameter, method.DeclaringType); 76 Expression call = Expression.Call(downcast, method); 77 Expression upcast = Expression.Convert(call, typeof(T)); 78 return Expression.Lambda<Func<IMessage, T>>(upcast, parameter).Compile(); 79 } 80 81 /// <summary> 82 /// Creates a delegate which will execute the given method after casting the first argument to 83 /// the target type of the method, and the second argument to the first parameter type of the method. 84 /// </summary> CreateActionIMessageObject(MethodInfo method)85 internal static Action<IMessage, object> CreateActionIMessageObject(MethodInfo method) 86 { 87 ParameterExpression targetParameter = Expression.Parameter(typeof(IMessage), "target"); 88 ParameterExpression argParameter = Expression.Parameter(typeof(object), "arg"); 89 Expression castTarget = Expression.Convert(targetParameter, method.DeclaringType); 90 Expression castArgument = Expression.Convert(argParameter, method.GetParameters()[0].ParameterType); 91 Expression call = Expression.Call(castTarget, method, castArgument); 92 return Expression.Lambda<Action<IMessage, object>>(call, targetParameter, argParameter).Compile(); 93 } 94 95 /// <summary> 96 /// Creates a delegate which will execute the given method after casting the first argument to 97 /// the target type of the method. 98 /// </summary> CreateActionIMessage(MethodInfo method)99 internal static Action<IMessage> CreateActionIMessage(MethodInfo method) 100 { 101 ParameterExpression targetParameter = Expression.Parameter(typeof(IMessage), "target"); 102 Expression castTarget = Expression.Convert(targetParameter, method.DeclaringType); 103 Expression call = Expression.Call(castTarget, method); 104 return Expression.Lambda<Action<IMessage>>(call, targetParameter).Compile(); 105 } 106 } 107 }