Function to escape value before PRX function processing?

I'm using (a lot) prx functions (Perl Regular eXpression functions), however in some cases, I use them within a macro function and pass something to search as a parameter, e.g.

%macro test(exp=);
  proc sql noprint;
    select      file
    into        :_input_file trimmed
    from        folder_content
    where       prxmatch("/&exp.$/oi", strip(file))
    ;
  quit;
%mend test

In most cases, this works, except when the value of exp contains PRX metacharacter (e.g. / or parenthesis)

The good practice is to escape such characters, but that's not user friendly.
Let's say I want to search a file /home/user/file.txt, the slashes will make cause the macro to fail, instead I should pass the value \/home\/user\/file.txt

Before implementing my own escaping function, I want to ensure it does not already exist, but I've not been able to find it so far

I expect a **native **SAS function to convert any text value into a "ready to use" value within a PRX function

The / is an implicit m/ for matching. The first character after m is the expression bounder. So, use an initial character such as #. "#&exp.$#oi" - any / in the resolved &exp will be treated as literal /

Mixing regex patterns with macro can be very frustrating and a seeming endless pit of escapism. Consider treating your patterns as data and join them to the data set of concern. Bonus is no macro.

data mypatterns;
  rx = '....'; output;
  rx = '....'; output;
  ...
run;  

proc sql noprint;
  create table matches as 
  select      file
  from        folder_content
  join        mypatterns p
    on        prxmatch (strip(p.rx),strip(file))
  ;
quit;

There is no function like you requested (I am not even sure I could understand what such a function would be expected to do).

But for your example of just wanting the treat the value as a STRING (ie not an actual regular expression) then there is not much that needs to happen.

• Convert any existing \ to \\ to prevent them from being used to escape the next character.
• Add \ to any occurrence of the separator you are using (in your example the /) to escape it.

So if you have macro variable named EXP

%let exp=c:\mixed_up/path ;

You can convert it to something you could use in your WHERE clause

%let want=%qsysfunc(tranwrd(%superq(exp),\,\\));
%let want=%qsysfunc(tranwrd(&want,/,\/));

Which will create:

650  %put &=want;
WANT=c:\\mixed_up\/path

Use something other than /

13   data _null_;
14      x = 'MCLAUREN';
15      x = prxchange("s!(MC)!\u\L$1!i", -1, x);
16      put x=;
17      x = prxchange("s/(MC)/\u\L$1/i", -1, x);
18      put x=;
19   run;

x=McLAUREN
x=McLAUREN