Processes a string by replacing specific syntactic patterns with what
is returned when the pattern is interpreted as a function call descrip‐
The syntactic patterns are on the form:
This is interpreted as a call:
filename->function(arg1, arg2, ....., argN)
Note that process_string does not recurse over returned replacement
values. If a function returns another syntactic pattern, that descrip‐
tion will not be replaced.
All such occurrences in 'combinestring' is processed and replaced if
the return value is a string. If the return value is not a string the
pattern will remain unreplaced.
Note that both object and arguments are marked optional with the brack‐
ets and that the brackets are not included in the actual pattern.