protected override Expression VisitParameter(ParameterExpression node)
{
object value;
if (parameters.TryGetValue(node.Name, out value))
{
if (ReflectionHelper.IsInstanceOf(node.Type, value) || value == null)
{
var createType = typeof(ObservableConstant <>).MakeGenericType(node.Type);
return((Expression)(ReflectionHelper.GetConstructor(createType).Invoke(new object[] { value })));
}
else
{
var expression = value as Expression;
if (expression != null)
{
return(expression);
}
else
{
throw new InvalidOperationException(string.Format("The provided value {0} for parameter {1} is not valid.", value, node.Type));
}
}
}
else
{
var createType = typeof(ObservableParameter <>).MakeGenericType(node.Type);
return((Expression)(ReflectionHelper.GetConstructor(createType).Invoke(new object[] { node.Name })));
}
}
