protected T CreateDelegate()
{
var parameters = new List <Type> ();
parameters.Add(this.GetType());
parameters.AddRange(this.Method.GetParameters().Select(p => p.ParameterType));
var method = new DynamicMethod("WeakDelegateDynamic", this.Method.ReturnType,
parameters.ToArray(), this.GetType(), true);
var hasReturnType = (this.Method.ReturnType != typeof(void));
if (this.Method.IsGenericMethod)
{
method.MakeGenericMethod(this.Method.GetGenericArguments());
}
var il = method.GetILGenerator();
// IL Code should be equivalent of...
/*
* var target = this.Reference.Target;
* if (!CheckDelegate())
* return;
*
* return this.Method(args);
*
*/
// Create our labels
var returnLabel = il.DefineLabel();
var callLabel = il.DefineLabel();
// Define our local variables
il.DeclareLocal(typeof(object));
il.DeclareLocal(hasReturnType ? this.Method.ReturnType : typeof(int));
il.DeclareLocal(typeof(bool));
// Load the target value on to the stack to keep it alive
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Call, GetReferenceMethod);
il.Emit(OpCodes.Callvirt, WeakReferenceGetTargetMethod);
il.Emit(OpCodes.Stloc_0);
// Call CheckDelegate
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Call, CheckDelegateMethod);
il.Emit(OpCodes.Stloc_2);
// If it did not return true then return immediately
il.Emit(OpCodes.Ldloc_2);
il.Emit(OpCodes.Brtrue_S, callLabel);
il.Emit(OpCodes.Ldc_I4_0);
il.Emit(OpCodes.Stloc_1);
il.Emit(OpCodes.Br_S, returnLabel);
// Load our target and all of our arguments
il.MarkLabel(callLabel);
il.Emit(OpCodes.Ldloc_0);
for (int i = 0; i < this.Method.GetParameters().Length; i++)
{
il.Emit(OpCodes.Ldarg, i + 1);
}
// Call our method and return
il.Emit(this.Method.IsVirtual ? OpCodes.Callvirt : OpCodes.Call, this.Method);
if (hasReturnType)
{
il.Emit(OpCodes.Stloc_1);
}
il.Emit(OpCodes.Br_S, returnLabel);
il.MarkLabel(returnLabel);
if (hasReturnType)
{
il.Emit(OpCodes.Ldloc_1);
}
il.Emit(OpCodes.Ret);
return(method.CreateDelegate(this.Type, this) as T);
}
