Making custom preprocessor directive with a macro

I may not be the first one to ask such question but I’m curious whether it is possible somehow to define a macro that could work on top of a preprocessor directive and behave syntactically exactly the same way.

Consider the following macro as an example:

Code:

macro myrept x*
{
  local e
  match =x , `x
  \{
    e equ 5
    rept 0 \\{
  \}
  match ,
  \{
    e equ x
  \}
  rept e
}

It works just as native rept if given a non-string expression but defaults to certain number of repetitions if a string literal is passed. This particular behaviour might be of little use but that’s just for expository purposes.

Now the macro works just fine when written this way:

Code:

myrept 'Something'
{
  display '!'
}

But if we move the { character to the same line it will obviously fail:

Code:

myrept 'Something' {
  display '!'
}

The reason is pretty straightforward: { token becomes part of the x value. Now one might try to fix this by analysing separately the case when x ends with {. As you might guess, it fails. Say, this match basically just gets ignored:

Code:

match { , {
{
  display '!'
}

So, am I right that we can’t have a wrapper for preprocessor directives with syntactically equivalent behaviour? Or am I missing some possibility here?