public static MethodBuilder CreateDelegateImplementation(TypeBuilder typeBuilder, FieldBuilder targetField, MethodInfo mi)
{
MethodBuilder methodBuilder = typeBuilder.DefineMethod(mi.Name,
MethodAttributes.Public | MethodAttributes.Virtual,
mi.ReturnType,
mi.GetParameters().Select(param => param.ParameterType).ToArray());
ILGenerator il = methodBuilder.GetILGenerator();
#region forwarding implementation
LocalBuilder baseReturn = null;
if (mi.ReturnType != typeof(void))
{
baseReturn = il.DeclareLocal(mi.ReturnType);
}
// Call the target method
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldfld, targetField);
var parameters = mi.GetParameters();
// Load the call parameters
for (int i = 0; i < parameters.Length; i++)
{
CodeGenUtil.EmitLoadArgument(il, i);
}
// Make the call
MethodInfo callTarget = targetField.FieldType.GetMethod(mi.Name, parameters.Select(pi => pi.ParameterType).ToArray());
il.Emit(OpCodes.Callvirt, callTarget);
if (mi.ReturnType != typeof(void))
{
il.Emit(OpCodes.Stloc_0);
il.Emit(OpCodes.Ldloc_0);
}
il.Emit(OpCodes.Ret);
#endregion
return(methodBuilder);
}
static DuckTypingProxyFactory()
{
_assemblyBuilder = CodeGenUtil.CreateAssemblyBuilder(_assemblyName);
_moduleBuilder = CodeGenUtil.CreateModuleBuilder(_assemblyBuilder, _assemblyName);
}
public Type GenerateProxyType(Type typeOfIMyDuck, Type typeOfOtherDuck)
{
TypeAttributes newAttributes = TypeAttributes.Public | TypeAttributes.Class;
TypeBuilder typeBuilder = _moduleBuilder.DefineType(typeOfOtherDuck.Name + "_DuckTypingProxy" + new Guid().ToString(), newAttributes);
// Add interface implementation
typeBuilder.AddInterfaceImplementation(typeOfIMyDuck);
FieldBuilder targetField = typeBuilder.DefineField("target", typeOfOtherDuck, FieldAttributes.Private);
foreach (MethodInfo mi in typeOfIMyDuck.GetMethods())
{
CodeGenUtil.CreateDelegateImplementation(typeBuilder, targetField, mi);
}
foreach (PropertyInfo pi in typeOfIMyDuck.GetProperties())
{
PropertyBuilder pb = typeBuilder.DefineProperty(
pi.Name,
pi.Attributes,
pi.PropertyType,
pi.GetIndexParameters().Select(param => param.ParameterType).ToArray()
);
MethodInfo getMi = pi.GetGetMethod();
if (getMi != null)
{
MethodBuilder getMethod = CodeGenUtil.CreateDelegateImplementation(typeBuilder, targetField, getMi);
pb.SetGetMethod(getMethod);
}
MethodInfo setMi = pi.GetSetMethod();
if (setMi != null)
{
MethodBuilder setMethod = CodeGenUtil.CreateDelegateImplementation(typeBuilder, targetField, setMi);
pb.SetSetMethod(setMethod);
}
}
//Constructor
ConstructorBuilder ctorBuilder = typeBuilder.DefineConstructor(
MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
CallingConventions.HasThis,
new Type[] { typeOfOtherDuck });
ctorBuilder.DefineParameter(1, ParameterAttributes.None, "target");
ILGenerator il = ctorBuilder.GetILGenerator();
// Call base class constructor
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Call, CodeGenUtil.GetConstructorInfo(() => new object()));
// Initialize the target field
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Stfld, targetField);
il.Emit(OpCodes.Ret);
Type result = typeBuilder.CreateType();
#if DEBUG
_assemblyBuilder.Save(_assemblyName + ".dll");
#endif
return(result);
}