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/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation. All rights reserved.
*
* This software is subject to the Microsoft Public License (Ms-PL).
* A copy of the license can be found in the license.htm file included
* in this distribution.
*
* You must not remove this notice, or any other, from this software.
*
* ***************************************************************************/
namespace System.Web.Mvc {
using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
// The methods in this class don't perform error checking; that is the responsibility of the
// caller.
internal sealed class ActionMethodDispatcher {
private delegate object ActionExecutor(ControllerBase controller, object[] parameters);
private delegate void VoidActionExecutor(ControllerBase controller, object[] parameters);
private ActionExecutor _executor;
public ActionMethodDispatcher(MethodInfo methodInfo) {
_executor = GetExecutor(methodInfo);
MethodInfo = methodInfo;
}
public MethodInfo MethodInfo {
get;
private set;
}
public object Execute(ControllerBase controller, object[] parameters) {
return _executor(controller, parameters);
}
private static ActionExecutor GetExecutor(MethodInfo methodInfo) {
// Parameters to executor
ParameterExpression controllerParameter = Expression.Parameter(typeof(ControllerBase), "controller");
ParameterExpression parametersParameter = Expression.Parameter(typeof(object[]), "parameters");
// Build parameter list
List<Expression> parameters = new List<Expression>();
ParameterInfo[] paramInfos = methodInfo.GetParameters();
for (int i = 0; i < paramInfos.Length; i++) {
ParameterInfo paramInfo = paramInfos[i];
BinaryExpression valueObj = Expression.ArrayIndex(parametersParameter, Expression.Constant(i));
UnaryExpression valueCast = Expression.Convert(valueObj, paramInfo.ParameterType);
// valueCast is "(Ti) parameters[i]"
parameters.Add(valueCast);
}
// Call method
UnaryExpression instanceCast = (!methodInfo.IsStatic) ? Expression.Convert(controllerParameter, methodInfo.ReflectedType) : null;
MethodCallExpression methodCall = methodCall = Expression.Call(instanceCast, methodInfo, parameters);
// methodCall is "((TController) controller) method((T0) parameters[0], (T1) parameters[1], ...)"
// Create function
if (methodCall.Type == typeof(void)) {
Expression<VoidActionExecutor> lambda = Expression.Lambda<VoidActionExecutor>(methodCall, controllerParameter, parametersParameter);
VoidActionExecutor voidExecutor = lambda.Compile();
return WrapVoidAction(voidExecutor);
}
else {
// must coerce methodCall to match ActionExecutor signature
UnaryExpression castMethodCall = Expression.Convert(methodCall, typeof(object));
Expression<ActionExecutor> lambda = Expression.Lambda<ActionExecutor>(castMethodCall, controllerParameter, parametersParameter);
return lambda.Compile();
}
}
private static ActionExecutor WrapVoidAction(VoidActionExecutor executor) {
return delegate(ControllerBase controller, object[] parameters) {
executor(controller, parameters);
return null;
};
}
}
}
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