[8295] | 1 | // Protocol Buffers - Google's data interchange format
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| 2 | // Copyright 2008 Google Inc. All rights reserved.
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| 3 | // http://github.com/jskeet/dotnet-protobufs/
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| 4 | // Original C++/Java/Python code:
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| 5 | // http://code.google.com/p/protobuf/
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| 6 | //
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| 7 | // Redistribution and use in source and binary forms, with or without
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| 8 | // modification, are permitted provided that the following conditions are
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| 9 | // met:
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| 10 | //
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| 11 | // * Redistributions of source code must retain the above copyright
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| 12 | // notice, this list of conditions and the following disclaimer.
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| 13 | // * Redistributions in binary form must reproduce the above
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| 14 | // copyright notice, this list of conditions and the following disclaimer
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| 15 | // in the documentation and/or other materials provided with the
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| 16 | // distribution.
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| 17 | // * Neither the name of Google Inc. nor the names of its
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| 18 | // contributors may be used to endorse or promote products derived from
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| 19 | // this software without specific prior written permission.
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| 20 | //
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| 21 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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| 22 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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| 23 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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| 24 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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| 25 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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| 26 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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| 27 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 28 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 29 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 30 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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| 31 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 32 | using System;
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| 33 | using System.Reflection;
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| 34 |
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| 35 | namespace Google.ProtocolBuffers.FieldAccess
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| 36 | {
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| 37 | /// <summary>
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| 38 | /// The methods in this class are somewhat evil, and should not be tampered with lightly.
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| 39 | /// Basically they allow the creation of relatively weakly typed delegates from MethodInfos
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| 40 | /// which are more strongly typed. They do this by creating an appropriate strongly typed
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| 41 | /// delegate from the MethodInfo, and then calling that within an anonymous method.
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| 42 | /// Mind-bending stuff (at least to your humble narrator) but the resulting delegates are
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| 43 | /// very fast compared with calling Invoke later on.
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| 44 | /// </summary>
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| 45 | internal static class ReflectionUtil
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| 46 | {
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| 47 | /// <summary>
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| 48 | /// Creates a delegate which will execute the given method and then return
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| 49 | /// the result as an object.
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| 50 | /// </summary>
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| 51 | public static Func<T, object> CreateUpcastDelegate<T>(MethodInfo method)
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| 52 | {
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| 53 | // The tricky bit is invoking CreateCreateUpcastDelegateImpl with the right type parameters
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| 54 | MethodInfo openImpl = typeof (ReflectionUtil).GetMethod("CreateUpcastDelegateImpl");
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| 55 | MethodInfo closedImpl = openImpl.MakeGenericMethod(typeof (T), method.ReturnType);
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| 56 | return (Func<T, object>) closedImpl.Invoke(null, new object[] {method});
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| 57 | }
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| 58 |
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| 59 | /// <summary>
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| 60 | /// Method used solely for implementing CreateUpcastDelegate. Public to avoid trust issues
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| 61 | /// in low-trust scenarios, e.g. Silverlight.
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| 62 | /// TODO(jonskeet): Check any of this actually works in Silverlight...
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| 63 | /// </summary>
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| 64 | public static Func<TSource, object> CreateUpcastDelegateImpl<TSource, TResult>(MethodInfo method)
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| 65 | {
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| 66 | // Convert the reflection call into an open delegate, i.e. instead of calling x.Method()
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| 67 | // we'll call getter(x).
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| 68 | Func<TSource, TResult> getter =
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| 69 | (Func<TSource, TResult>) Delegate.CreateDelegate(typeof (Func<TSource, TResult>), null, method);
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| 70 |
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| 71 | // Implicit upcast to object (within the delegate)
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| 72 | return delegate(TSource source) { return getter(source); };
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| 73 | }
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| 74 |
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| 75 | /// <summary>
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| 76 | /// Creates a delegate which will execute the given method after casting the parameter
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| 77 | /// down from object to the required parameter type.
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| 78 | /// </summary>
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| 79 | public static Action<T, object> CreateDowncastDelegate<T>(MethodInfo method)
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| 80 | {
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| 81 | MethodInfo openImpl = typeof (ReflectionUtil).GetMethod("CreateDowncastDelegateImpl");
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| 82 | MethodInfo closedImpl = openImpl.MakeGenericMethod(typeof (T), method.GetParameters()[0].ParameterType);
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| 83 | return (Action<T, object>) closedImpl.Invoke(null, new object[] {method});
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| 84 | }
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| 85 |
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| 86 | public static Action<TSource, object> CreateDowncastDelegateImpl<TSource, TParam>(MethodInfo method)
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| 87 | {
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| 88 | // Convert the reflection call into an open delegate, i.e. instead of calling x.Method(y) we'll
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| 89 | // call Method(x, y)
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| 90 | Action<TSource, TParam> call =
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| 91 | (Action<TSource, TParam>) Delegate.CreateDelegate(typeof (Action<TSource, TParam>), null, method);
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| 92 |
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| 93 | return delegate(TSource source, object parameter) { call(source, (TParam) parameter); };
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| 94 | }
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| 95 |
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| 96 | /// <summary>
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| 97 | /// Creates a delegate which will execute the given method after casting the parameter
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| 98 | /// down from object to the required parameter type.
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| 99 | /// </summary>
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| 100 | public static Action<T, object> CreateDowncastDelegateIgnoringReturn<T>(MethodInfo method)
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| 101 | {
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| 102 | MethodInfo openImpl = typeof (ReflectionUtil).GetMethod("CreateDowncastDelegateIgnoringReturnImpl");
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| 103 | MethodInfo closedImpl = openImpl.MakeGenericMethod(typeof (T), method.GetParameters()[0].ParameterType,
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| 104 | method.ReturnType);
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| 105 | return (Action<T, object>) closedImpl.Invoke(null, new object[] {method});
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| 106 | }
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| 107 |
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| 108 | public static Action<TSource, object> CreateDowncastDelegateIgnoringReturnImpl<TSource, TParam, TReturn>(
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| 109 | MethodInfo method)
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| 110 | {
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| 111 | // Convert the reflection call into an open delegate, i.e. instead of calling x.Method(y) we'll
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| 112 | // call Method(x, y)
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| 113 | Func<TSource, TParam, TReturn> call = (Func<TSource, TParam, TReturn>)
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| 114 | Delegate.CreateDelegate(typeof (Func<TSource, TParam, TReturn>), null,
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| 115 | method);
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| 116 |
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| 117 | return delegate(TSource source, object parameter) { call(source, (TParam) parameter); };
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| 118 | }
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| 119 |
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| 120 | /// <summary>
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| 121 | /// Creates a delegate which will execute the given static method and cast the result up to IBuilder.
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| 122 | /// </summary>
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| 123 | public static Func<IBuilder> CreateStaticUpcastDelegate(MethodInfo method)
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| 124 | {
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| 125 | MethodInfo openImpl = typeof (ReflectionUtil).GetMethod("CreateStaticUpcastDelegateImpl");
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| 126 | MethodInfo closedImpl = openImpl.MakeGenericMethod(method.ReturnType);
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| 127 | return (Func<IBuilder>) closedImpl.Invoke(null, new object[] {method});
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| 128 | }
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| 129 |
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| 130 | public static Func<IBuilder> CreateStaticUpcastDelegateImpl<T>(MethodInfo method)
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| 131 | {
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| 132 | Func<T> call = (Func<T>) Delegate.CreateDelegate(typeof (Func<T>), null, method);
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| 133 | return delegate { return (IBuilder) call(); };
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| 134 | }
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| 135 | }
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| 136 | } |
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