set-macro-character function

[prog1]

Is it possible to write a set-macro-character function which takes the previous and the next characters as one of its arguments?

I want to mimic the behavior of the '. character, which is a non terminating character when the characters right before and after it are digits (e.g. 12.34) and a terminating character otherwise (e.g. a.b).

I want to use the same function for the comma, however I can't use set-syntax-from-char because I want to do something more fancy than the period reader function.

Any ideas?

Many thanks.