75 lines
3.3 KiB
C#
75 lines
3.3 KiB
C#
namespace System.Web.Mvc {
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using System;
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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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// The methods in this class don't perform error checking; that is the responsibility of the
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// caller.
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internal sealed class ActionMethodDispatcher {
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private delegate object ActionExecutor(ControllerBase controller, object[] parameters);
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private delegate void VoidActionExecutor(ControllerBase controller, object[] parameters);
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private ActionExecutor _executor;
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public ActionMethodDispatcher(MethodInfo methodInfo) {
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_executor = GetExecutor(methodInfo);
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MethodInfo = methodInfo;
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}
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public MethodInfo MethodInfo {
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get;
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private set;
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}
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public object Execute(ControllerBase controller, object[] parameters) {
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return _executor(controller, parameters);
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}
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private static ActionExecutor GetExecutor(MethodInfo methodInfo) {
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// Parameters to executor
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ParameterExpression controllerParameter = Expression.Parameter(typeof(ControllerBase), "controller");
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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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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(controllerParameter, methodInfo.ReflectedType) : null;
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MethodCallExpression methodCall = methodCall = Expression.Call(instanceCast, methodInfo, parameters);
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// methodCall is "((TController) controller) 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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Expression<VoidActionExecutor> lambda = Expression.Lambda<VoidActionExecutor>(methodCall, controllerParameter, parametersParameter);
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VoidActionExecutor voidExecutor = lambda.Compile();
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return WrapVoidAction(voidExecutor);
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}
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else {
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// must coerce methodCall to match ActionExecutor signature
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UnaryExpression castMethodCall = Expression.Convert(methodCall, typeof(object));
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Expression<ActionExecutor> lambda = Expression.Lambda<ActionExecutor>(castMethodCall, controllerParameter, parametersParameter);
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return lambda.Compile();
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}
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}
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private static ActionExecutor WrapVoidAction(VoidActionExecutor executor) {
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return delegate(ControllerBase controller, object[] parameters) {
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executor(controller, 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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