match.sas

/*<pre><b>
/ Program   : match.sas
/ Version   : 2.0
/ Author    : Roland Rashleigh-Berry (http://www.datasavantconsulting.com/roland/)
/ Date      : 03-Dec-2012
/ Purpose   : Function-style macro to return elements of a list that match those
/             in a reference list.
/ SubMacros : %words %nodup
/ Notes     : Non-matching list elements are returned in the global macro
/             variable _nomatch_ .
/ Usage     : %let match=%match(aa bb,aa cc);
/             %put %match(aa bb,aa cc); 
/ 
/===============================================================================
/ PARAMETERS:
/-------name------- -------------------------description------------------------
/ ref               (pos) Space-delimited reference list
/ list              (pos) Space-delimited list
/ nodup=yes         By default, remove duplicates from the list
/ casesens=no       By default, case sensitivity is not important.
/ fixcase=no        By default, do not make the case of matching items the same
/                   as the item in the reference list.
/===============================================================================
/ AMENDMENT HISTORY:
/ init --date-- mod-id ----------------------description------------------------
/ rrb  19Mar07         Macro called message added plus header tidy
/ rrb  30Jul07         Header tidy
/ rrb  01May11         Code restructured and missing list allowed (v2.0)
/ rrb  03Dec12         Header tidy (%nodup added to submacro list)
/===============================================================================
/ This is public domain software. No guarantee as to suitability or accuracy is
/ given or implied. User uses this code entirely at their own risk.
/=============================================================================*/


%macro match(ref,list,nodup=yes,casesens=no,fixcase=no);
  %local err errflag list2 nref nlist i j item match refitem;
  %let err=ERR%str(OR);
  %let errflag=0;

  %global _nomatch_;
  %let _nomatch_=;

  %if not %length(&nodup) %then %let nodup=yes;
  %if not %length(&casesens) %then %let casesens=no;
  %if not %length(&fixcase) %then %let fixcase=no;

  %let nodup=%upcase(%substr(&nodup,1,1));
  %let casesens=%upcase(%substr(&casesens,1,1));
  %let fixcase=%upcase(%substr(&fixcase,1,1));

  %if "&nodup" EQ "Y" %then %let list2=%nodup(&list,casesens=&casesens);
  %else %let list2=&list;

  %let nref=%words(&ref);
  %let nlist=%words(&list2);

  %if not &nref %then %do;
    %put &err: (match) No elements in reference list;
    %let errflag=1;
  %end;

  %if &errflag %then %goto exit;

  %if not &nlist %then %goto skip;

  %do i=1 %to &nlist;
    %let item=%scan(&list2,&i,%str( ));
    %let match=NO;
    %do j=1 %to &nref;
      %let refitem=%scan(&ref,&j,%str( ));
      %if "&casesens" EQ "N" %then %do;
        %if "%upcase(&item)" EQ "%upcase(&refitem)" %then %do;
          %let match=YES;
          %let j=&nref;
        %end;
      %end;
      %else %do;
        %if "&item" EQ "&refitem" %then %do;
          %let match=YES;
          %let j=&nref;
        %end;
      %end;
    %end;
    %if &match EQ YES %then %do;
      %if "&fixcase" EQ "N" %then &item;
      %else &refitem;
    %end;
    %else %let _nomatch_=&_nomatch_ &item;
  %end;

  %goto skip;
  %exit: %put &err: (match) Leaving macro due to problem(s) listed.;
  %skip:
%mend match;