/// <summary>
/// Create an advice that runs before the advised method.
/// </summary>
/// <param name="reflection">Reflection</param>
/// <param name="advice">Delegate used to emit code to be invoked before the advised method</param>
/// <returns>Advice</returns>
static public Advice Before(this Advice.Style.IReflection reflection, Action <ILGenerator> advice)
{
return(new Advice((_Method, _Pointer, _Boundary) =>
{
var _signature = _Method.Signature();
var _type = _Method.ReturnType();
var _method = new DynamicMethod(string.Empty, _type, _signature, _Method.Module, true);
var _body = _method.GetILGenerator();
if (_Boundary != null) //TODO dynamic implementation of boundary will avoid redirection overhead.
{
_body.Emit(advice);
_body.Emit(OpCodes.Ret);
_method.Prepare();
var _action = new DynamicMethod(string.Empty, Runtime.Void, new Type[] { Metadata <object> .Type, Metadata <object> .Type, Metadata <object[]> .Type }, true);
var _redirection = _action.GetILGenerator();
if (_signature.Instance != null)
{
_redirection.Emit(OpCodes.Ldarg_1);
if (_signature.Instance.IsValueType)
{
_redirection.Emit(OpCodes.Unbox_Any, _signature.Instance);
}
else
{
_redirection.Emit(OpCodes.Castclass, _signature.Instance);
}
}
for (var _index = 0; _index < _signature.Length; _index++)
{
var _parameter = _signature[_index];
_redirection.Emit(OpCodes.Ldarg_2);
_redirection.Emit(OpCodes.Ldc_I4, _index); //TODO shortcut
_redirection.Emit(OpCodes.Ldelem_Ref);
if (_parameter.IsValueType)
{
_redirection.Emit(OpCodes.Unbox_Any, _parameter);
}
else
{
_redirection.Emit(OpCodes.Castclass, _parameter);
}
}
_redirection.Emit(OpCodes.Call, _method);
_redirection.Emit(OpCodes.Ret);
_action.Prepare();
return _Boundary.Combine(new Advice.Boundary.Advanced.Before.Singleton(_Method, _action.CreateDelegate(Metadata <Action <object, object[]> > .Type, null) as Action <object, object[]>));
}
else
{
_body.Emit(advice);
_body.Emit(_signature, false);
_body.Emit(_Pointer, _type, _signature);
_body.Emit(OpCodes.Ret);
_method.Prepare();
return _method;
}
}));
}
/// <summary>
/// After
/// </summary>
/// <param name="reflection">Reflection</param>
/// <returns>After</returns>
static public Advice.Style.Reflection.IAfter After(this Advice.Style.IReflection reflection)
{
return(null);
}