feat: new macro for hashing a table (mp_hashdataset)

base/mp_hashdataset.sas

@@ -0,0 +1,74 @@
+/**
+  @file
+  @brief Returns a unique hash for a dataset
+  @details Ignores metadata attributes, used only to hash values. Compared
+  datasets must be in the same order.
+
+      %mp_hashdataset(sashelp.class,outds=myhash);
+
+      data _null_;
+        set work.myhash;
+        put hashkey=;
+      run;
+
+
+  <h4> SAS Macros </h4>
+  @li mf_getattrn.sas
+  @li mf_getuniquename.sas
+  @li mf_getvarlist.sas
+  @li mf_getvartype.sas
+
+  @param [in] libds dataset to hash
+  @param [out] outds= (work.mf_hashdataset) The output dataset to create. This
+  will contain one column (hashkey) with one observation (a hex32.
+  representation of the input hash)
+  |hashkey:$32.|
+  |---|
+  |28ABC74ABFC45F50794237BA5566E6CA|
+
+  @version 9.2
+  @author Allan Bowe
+**/
+
+%macro mp_hashdataset(
+  libds,
+  outds=
+)/*/STORE SOURCE*/;
+  %if %mf_getattrn(&libds,NLOBS)=0 %then %do;
+    %put %str(WARN)ING: Dataset &libds is empty;, or is not a dataset;
+  %end;
+  %else %if %mf_getattrn(&libds,NLOBS)<0 %then %do;
+    %put %str(ERR)OR: Dataset &libds is not a dataset;
+  %end;
+  %else %do;
+    %local keyvar /* roll up the md5 */
+      prevkeyvar /* retain prev record md5 */
+      lastvar /* last var in input ds */
+      varlist var i;
+    /* avoid naming conflict for hash key vars */
+    %let keyvar=%mf_getuniquename();
+    %let prevkeyvar=%mf_getuniquename();
+    %let lastvar=%mf_getuniquename();
+    %let varlist=%mf_getvarlist(&libds);
+    data &outds(rename=(&keyvar=hashkey) keep=&keyvar);
+      length &prevkeyvar &keyvar $32;
+      retain &prevkeyvar;
+      set &libds end=&lastvar;
+      /* hash should include previous row */
+      if _n_>1 then &keyvar=put(md5(&prevkeyvar
+      /* loop every column, hashing every individual value */
+    %do i=1 %to %sysfunc(countw(&varlist));
+      %let var=%scan(&varlist,&i,%str( ));
+      %if %mf_getvartype(&libds,&var)=C %then %do;
+          !!put(md5(trim(&var)),$hex32.)
+      %end;
+      %else %do;
+          !!put(md5(trim(put(&var*1,binary64.))),$hex32.)
+      %end;
+    %end;
+      ),$hex32.);
+      &prevkeyvar=&keyvar;
+      if &lastvar then output;
+    run;
+  %end;
+%mend;