public static Delegate CreateMethodCaller(Type delegateType, MethodInfo method)
{
// arguments checks
if (!typeof(Delegate).IsAssignableFrom(delegateType))
{
throw new ArgumentException("delegateType does not represents a delegate", nameof(delegateType));
}
// read delegate info
var methodInfo = delegateType.GetMethod("Invoke");
var delegateArgs = methodInfo?.GetParameters().Select(x => x.ParameterType).ToArray() ?? Type.EmptyTypes;
var retType = methodInfo.ReturnType != typeof(void) ? methodInfo.ReturnType : null;
// read method info
var methodArgs = method.GetParameters().Select(x => x.ParameterType).ToArray();
var argsCount = methodArgs.Length;
//
Type this_ = method.IsStatic ? null : (method.DeclaringType.IsValueType ? method.DeclaringType.MakeByRefType() : method.DeclaringType);
var arguments = Enumerable.Empty <Type>();
if (this_ != null)
{
arguments = arguments.Append(this_);
argsCount++;
}
arguments = arguments.Concat(methodArgs);
if (delegateArgs.Length != argsCount)
{
throw new Exception("deletage's arguments count does not match method's arguments count");
}
DynamicMethod wrapper = new DynamicMethod($"method_{method.DeclaringType.Name}_{method.Name}", retType, arguments.ToArray(), typeof(Dynamic), true);
IILGenerator gen = wrapper.GetILGenerator().AsInterface();
int argIndex = 0;
if (this_ != null)
{
if (this_.IsValueType)
{
// Struct;
gen.Ldarga_S((byte)argIndex++);
}
else
{
// Class; ref Struct;
gen.Ldarg((byte)argIndex++);
}
}
for (int i = 0; i < methodArgs.Length; i++)
{
gen.Ldarg((byte)argIndex++);
}
gen
.Call(method)
.Ret();
return(wrapper.CreateDelegate(delegateType));
}
