Can we reference the expression being evaluated within the natvis rule?

Are there any way to reference the expression being evaluated from the natvis rule?

Here are some examples what I am talking about.

Consider we have color_t type defined as typedef uint32_t color_t;, also let's suppose we have a special variable $_self which references current expression. Now we can write natvis rule:

  <Type Name="color_t">
      <DisplayString>A:{$_self >> 24} R:{($_self>>16) & 0xFF} G:{($_self>>8) & 0xFF} B: {$_self & 0xFF}</DisplayString>
  </Type>

So we can see color information in a human readable format.

Another example. Consider we have some struct in C:

typedef struct
{
  int state;
  //other fields follow
}TCB;

Also there is global variable:

TCB* Running;
I want to make natvis rules that will show the state of the object based on the `state` field and `Running` global variable. If we would have a special variable `$_self` (as above). We could write:
<Type Name="TCB">
  <DisplayString Condition="state==0">Empty</DisplayString>
  <DisplayString Condition="state==0x80 && Running!=&$_self">Ready</DisplayString>
  <DisplayString Condition="state==0x80 && Running==&$_self">Running</DisplayString>
</Type>

The last example could be realized for C++ language using this keyword, but not for C (or I just do not know how).

So are there any way to make such natvis rules? A there any possibility to add some special variable?

The issue provides no file, test, or entry point. Start by searching the repository for natvis handling of Type, DisplayString, and Condition; done means determining whether a self-expression can be exposed in both C and C++ natvis evaluation, or documenting why it cannot.