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80 lines
3.2 KiB
80 lines
3.2 KiB
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.md in the project root for license information.
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using System.Collections.Generic;
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using System.Linq.Expressions;
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using System.Reflection;
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namespace Microsoft.AspNet.SignalR.Hubs
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{
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internal class HubMethodDispatcher
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{
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private HubMethodExecutor _executor;
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public HubMethodDispatcher(MethodInfo methodInfo)
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{
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_executor = GetExecutor(methodInfo);
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MethodInfo = methodInfo;
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}
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private delegate object HubMethodExecutor(IHub hub, object[] parameters);
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private delegate void VoidHubMethodExecutor(IHub hub, object[] parameters);
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public MethodInfo MethodInfo { get; private set; }
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public object Execute(IHub hub, object[] parameters)
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{
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return _executor(hub, parameters);
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}
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private static HubMethodExecutor GetExecutor(MethodInfo methodInfo)
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{
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// Parameters to executor
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ParameterExpression hubParameter = Expression.Parameter(typeof(IHub), "hub");
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ParameterExpression parametersParameter = Expression.Parameter(typeof(object[]), "parameters");
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// Build parameter list
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List<Expression> parameters = new List<Expression>();
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ParameterInfo[] paramInfos = methodInfo.GetParameters();
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for (int i = 0; i < paramInfos.Length; i++)
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{
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ParameterInfo paramInfo = paramInfos[i];
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BinaryExpression valueObj = Expression.ArrayIndex(parametersParameter, Expression.Constant(i));
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UnaryExpression valueCast = Expression.Convert(valueObj, paramInfo.ParameterType);
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// valueCast is "(Ti) parameters[i]"
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parameters.Add(valueCast);
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}
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// Call method
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UnaryExpression instanceCast = (!methodInfo.IsStatic) ? Expression.Convert(hubParameter, methodInfo.ReflectedType) : null;
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MethodCallExpression methodCall = Expression.Call(instanceCast, methodInfo, parameters);
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// methodCall is "((TController) hub) method((T0) parameters[0], (T1) parameters[1], ...)"
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// Create function
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if (methodCall.Type == typeof(void))
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{
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Expression<VoidHubMethodExecutor> lambda = Expression.Lambda<VoidHubMethodExecutor>(methodCall, hubParameter, parametersParameter);
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VoidHubMethodExecutor voidExecutor = lambda.Compile();
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return WrapVoidAction(voidExecutor);
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}
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else
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{
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// must coerce methodCall to match HubMethodExecutor signature
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UnaryExpression castMethodCall = Expression.Convert(methodCall, typeof(object));
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Expression<HubMethodExecutor> lambda = Expression.Lambda<HubMethodExecutor>(castMethodCall, hubParameter, parametersParameter);
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return lambda.Compile();
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}
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}
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private static HubMethodExecutor WrapVoidAction(VoidHubMethodExecutor executor)
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{
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return delegate(IHub hub, object[] parameters)
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{
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executor(hub, parameters);
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return null;
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};
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}
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}
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}
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