/// <summary>
/// Gets the managed type that an object needs to be coverted to in order for it to be able
/// to be represented as a Variant.
///
/// In general, there is a many-to-many mapping between Type and VarEnum. However, this method
/// returns a simple mapping that is needed for the current implementation. The reason for the
/// many-to-many relation is:
/// 1. Int32 maps to VT_I4 as well as VT_ERROR, and Decimal maps to VT_DECIMAL and VT_CY. However,
/// this changes if you throw the wrapper types into the mix.
/// 2. There is no Type to represent COM types. __ComObject is a private type, and Object is too
/// general.
/// </summary>
internal static Type GetManagedMarshalType(VarEnum varEnum)
{
Debug.Assert((varEnum & VarEnum.VT_BYREF) == 0);
if (varEnum == VarEnum.VT_CY)
{
return(typeof(CurrencyWrapper));
}
if (Variant.IsPrimitiveType(varEnum))
{
return(s_comToManagedPrimitiveTypes[varEnum]);
}
switch (varEnum)
{
case VarEnum.VT_EMPTY:
case VarEnum.VT_NULL:
case VarEnum.VT_UNKNOWN:
case VarEnum.VT_DISPATCH:
case VarEnum.VT_VARIANT:
return(typeof(Object));
case VarEnum.VT_ERROR:
return(typeof(ErrorWrapper));
default:
throw Error.UnexpectedVarEnum(varEnum);
}
}
internal Expression Clear()
{
if (IsByRef)
{
if (_argBuilder is StringArgBuilder)
{
Debug.Assert(TempVariable != null);
return(Expression.Call(typeof(Marshal).GetMethod(nameof(Marshal.FreeBSTR)), TempVariable));
}
if (_argBuilder is DispatchArgBuilder)
{
Debug.Assert(TempVariable != null);
return(Release(TempVariable));
}
if (_argBuilder is UnknownArgBuilder)
{
Debug.Assert(TempVariable != null);
return(Release(TempVariable));
}
if (_argBuilder is VariantArgBuilder)
{
Debug.Assert(TempVariable != null);
return(Expression.Call(TempVariable, typeof(Variant).GetMethod(nameof(Variant.Clear))));
}
return(null);
}
switch (_targetComType)
{
case VarEnum.VT_EMPTY:
case VarEnum.VT_NULL:
return(null);
case VarEnum.VT_BSTR:
case VarEnum.VT_UNKNOWN:
case VarEnum.VT_DISPATCH:
case VarEnum.VT_ARRAY:
case VarEnum.VT_RECORD:
case VarEnum.VT_VARIANT:
// paramVariants._elementN.Clear()
return(Expression.Call(_variant, typeof(Variant).GetMethod(nameof(Variant.Clear))));
default:
Debug.Assert(Variant.IsPrimitiveType(_targetComType), "Unexpected VarEnum");
return(null);
}
}
internal Expression InitializeArgumentVariant(MemberExpression variant, Expression parameter)
{
//NOTE: we must remember our variant
//the reason is that argument order does not map exactly to the order of variants for invoke
//and when we are doing clean-up we must be sure we are cleaning the variant we have initialized.
_variant = variant;
if (IsByRef)
{
// temp = argument
// paramVariants._elementN.SetAsByrefT(ref temp)
Debug.Assert(TempVariable == null);
var argExpr = _argBuilder.MarshalToRef(parameter);
TempVariable = Expression.Variable(argExpr.Type, null);
return(Expression.Block(
Expression.Assign(TempVariable, argExpr),
Expression.Call(
variant,
Variant.GetByrefSetter(_targetComType & ~VarEnum.VT_BYREF),
TempVariable
)
));
}
Expression argument = _argBuilder.Marshal(parameter);
// we are forced to special case ConvertibleArgBuilder since it does not have
// a corresponding _targetComType.
if (_argBuilder is ConvertibleArgBuilder)
{
return(Expression.Call(
variant,
typeof(Variant).GetMethod("SetAsIConvertible"),
argument
));
}
if (Variant.IsPrimitiveType(_targetComType) ||
(_targetComType == VarEnum.VT_DISPATCH) ||
(_targetComType == VarEnum.VT_UNKNOWN) ||
(_targetComType == VarEnum.VT_VARIANT) ||
(_targetComType == VarEnum.VT_RECORD) ||
(_targetComType == VarEnum.VT_ARRAY))
{
// paramVariants._elementN.AsT = (cast)argN
return(Expression.Assign(
Expression.Property(
variant,
Variant.GetAccessor(_targetComType)
),
argument
));
}
switch (_targetComType)
{
case VarEnum.VT_EMPTY:
return(null);
case VarEnum.VT_NULL:
// paramVariants._elementN.SetAsNull();
return(Expression.Call(variant, typeof(Variant).GetMethod("SetAsNull")));
default:
Debug.Assert(false, "Unexpected VarEnum");
return(null);
}
}