feat: new fcmp stpsrv_header function

all.sas

@@ -147,6 +147,40 @@ options noquotelenmax;
   %end;
 
 %mend mf_existfileref;/**
+  @file
+  @brief Checks if a function exists
+  @details Returns 1 if the function exists, else 0.  Note that this function
+  can be slow as it needs to open the sashelp.vfuncs table.
+
+  Usage:
+
+      %put %mf_existfunction(CAT);
+      %put %mf_existfunction(DOG);
+
+  Full credit to [Bart](https://sasensei.com/user/305) for the vfunc pointer
+  and the tidy approach for pure macro data set filtering.
+  Check out his [SAS Packages](https://github.com/yabwon/SAS_PACKAGES)
+  framework!
+
+  @param [in] name (positional) - function name
+
+  @author Allan Bowe
+**/
+/** @cond */
+
+%macro mf_existfunction(name
+)/*/STORE SOURCE*/;
+
+  %local dsid rc exist;
+  %let dsid=%sysfunc(open(sashelp.vfunc(where=(fncname="%upcase(&name)"))));
+  %let exist = %sysfunc(fetch(&dsid, NOSET));
+  %let rc = %sysfunc(close(&dsid));
+
+  %sysevalf(0 = &exist)
+
+%mend mf_existfunction;
+
+/** @endcond *//**
   @file
   @brief Checks if a variable exists in a data set.
   @details Returns 0 if the variable does NOT exist, and return the position of
@@ -18805,12 +18839,105 @@ run;
 
 %mend ml_json;
 /**
+  @file
+  @brief Provides a replacement for the stpsrv_header function
+  @details The stpsrv_header is normally a built-in function, used to set the
+  headers for SAS 9 Stored Processes as documented here:
+  https://go.documentation.sas.com/doc/en/itechcdc/9.4/stpug/srvhead.htm
+
+  The purpose of this custom function is to provide a replacement when running
+  similar code as a web service against
+  [sasjs/server](https://github.com/sasjs/server).  It operates by creating a
+  text file with the headers.  The location of this text file is determined by
+  a macro variable (`sasjs_stpsrv_header_loc`) which needs to be injected into
+  each service by the calling process, eg:
+
+      %let sasjs_stpsrv_header_loc = C:/temp/some_uuid/stpsrv_header.txt;
+
+  Note - the function works by appending headers to the file.  If multiple same-
+  named headers are provided, they will all be appended - the calling process
+  needs to pick up the last one.  This will mean removing the attribute if the
+  final record has an empty value.
+
+  The function takes the following (positional) parameters:
+
+  | PARAMETER | DESCRIPTION |
+  |------------|-------------|
+  | name $  | name of the header attribute to create|
+  | value  $  | value of the header attribute|
+
+  It returns 0 if successful, or -1 if an error occured.
+
+  Usage:
+
+      %let sasjs_stpsrv_header_loc=%sysfunc(pathname(work))/stpsrv_header.txt;
+
+      %mcf_stpsrv_header(wrap=YES, insert_cmplib=YES)
+
+      data _null_;
+        rc=stpsrv_header('Content-type','application/text');
+        rc=stpsrv_header('Content-disposition',"attachment; filename=file.txt");
+      run;
+
+      data _null_;
+        infile "&sasjs_stpsrv_header_loc";
+        input;
+        putlog _infile_;
+      run;
+
+
+  @param [out] wrap= (NO) Choose YES to add the proc fcmp wrapper.
+  @param [out] insert_cmplib= (NO) Choose YES to insert the package into the
+    CMPLIB reference.
+  @param [out] lib= (work) The output library in which to create the catalog.
+  @param [out] cat= (sasjs) The output catalog in which to create the package.
+  @param [out] pkg= (utils) The output package in which to create the function.
+    Uses a 3 part format:  libref.catalog.package
+
+**/
+
+%macro mcf_stpsrv_header(wrap=NO
+  ,insert_cmplib=NO
+  ,lib=WORK
+  ,cat=SASJS
+  ,pkg=UTILS
+)/*/STORE SOURCE*/;
+
+%if &wrap=YES  %then %do;
+  proc fcmp outcat=&lib..&cat..&pkg;
+%end;
+
+function stpsrv_header(name $, value $);
+  length loc $128 val $512;
+  loc=symget('sasjs_stpsrv_header_loc');
+  val=trim(name)!!': '!!value;
+  length fref $8;
+  rc=filename(fref,loc);
+  if (rc ne 0) then return( -1 );
+  fid = fopen(fref,'a');
+  if (fid = 0) then return( -1 );
+  rc=fput(fid, val);
+  rc=fwrite(fid);
+  rc=fclose(fid);
+  rc=filename(fref);
+  return(0);
+endsub;
+
+%if &wrap=YES %then %do;
+  quit;
+%end;
+
+%if &insert_cmplib=YES %then %do;
+  options insert=(CMPLIB=(&lib..&cat));
+%end;
+
+%mend mcf_stpsrv_header;/**
   @file
   @brief Adds a string to a file
   @details Creates an fcmp function for appending a string to an external file.
   If the file does not exist, it is created.
 
-  The function itself takes the following paramters:
+  The function itself takes the following (positional) parameters:
 
   | PARAMETER | DESCRIPTION |
   |------------|-------------|