I currently try to implement a PreProcessor into ANTLR4 for c# and got quite a lot of trouble finding any info about this.
My digging through the GitHub sources of the C# project did not really have been successfull sadly ...

My goal is to retain the token offsets (so that column and line would not be thrown of by a preprocessed stream)
example to roughly explain:

```
 #define foo(bar) foobar(bar + bar * bar / 0.2)
 int smthng = 2;
 smthng += foo(12); //the ; should be at the same spot like the macro was a function

```

hope that you can point me to the correct docs or provide a simple example solution somewhere

kindly regards, Marco

*PS* to note it: i do not seek for a solution in which i pass an already preprocessed stream to ANTLR4 as that will fiddle with the offsets of the code.