public override Expression /*!*/ ConvertExpression(Expression /*!*/ expr, ParameterInfo info, Type /*!*/ toType)
{
Type fromType = expr.Type;
// block:
if (fromType == typeof(MissingBlockParam))
{
Debug.Assert(toType == typeof(BlockParam) || toType == typeof(MissingBlockParam));
return(Ast.Constant(null));
}
if (fromType == typeof(BlockParam) && toType == typeof(MissingBlockParam))
{
return(Ast.Constant(null));
}
// protocol conversions:
if (info != null && info.IsDefined(typeof(DefaultProtocolAttribute), false))
{
var action = ProtocolConversionAction.TryGetConversionAction(toType);
if (action != null)
{
// TODO: once we work with MetaObjects, we could inline these dynamic sites:
return(Ast.Dynamic(action, toType, ScopeExpression, expr));
}
throw new InvalidOperationException(String.Format("No default protocol conversion for type {0}.", toType));
}
return(Binder.ConvertExpression(expr, toType, ConversionResultKind.ExplicitCast, ScopeExpression));
}
public override DynamicMetaObject /*!*/ BindConvert(ConvertBinder /*!*/ binder)
{
var protocolConversion = ProtocolConversionAction.TryGetDefaultConversionAction(Context, binder.Type);
if (protocolConversion != null)
{
return(protocolConversion.Bind(this, DynamicMetaObject.EmptyMetaObjects));
}
else
{
return(binder.FallbackConvert(this));
}
}