reduced files to barebones

Makefile

@@ -0,0 +1,2 @@
+aregex.so: aregex.c
+	gcc -shared -lgawkextlib -ltre -Wall -g -O2 -fPIC -o aregex.so aregex.c

aregex.c

@@ -4,34 +4,44 @@
  * Distributed under the GNU Pulbic Licence v3
  */
 
-#include "common.h"
-#include <tre/tre.h>  // From the TRE regex lib. https://laurikari.net/tre/
+// Minimal headers:
+#include <stdio.h>
+#include <sys/stat.h>
+#include <gawkapi.h>
+#include <tre/tre.h>
 
-static awk_value_t * do_aregex(int nargs, awk_value_t *result API_FINFO_ARG)
+// Gawkextlib boilerplate:
+static const gawk_api_t *api;	/* for convenience macros to work */
+static awk_ext_id_t ext_id;
+int plugin_is_GPL_compatible;
+
+// Main aregex() function definition
+static awk_value_t * do_aregex(int nargs, awk_value_t *result, struct awk_ext_func *unused)
 {
+  // Variables for reading awk function's arguments
   awk_value_t re;
   awk_value_t str;
   awk_value_t incost;
 
   // Check args if gawk called with lint 
   if (do_lint) {
     if (nargs > 3)
-      lintwarn(ext_id, _("aregex() called with >3 arguments"));
+      lintwarn(ext_id, "aregex() called with >3 arguments");
   }
 
-  // Set the default max cost
+  // Set the default max cost, and test for 3rd argument
   int defcost = 2;
   if (get_argument(2, AWK_NUMBER, &incost)) defcost = incost.num_value ; 
 
-  // If the string arguments are read...
+  // If the string arguments (1st and 2nd) are read...
   if ((get_argument(0, AWK_STRING, &re)) &&     \
       (get_argument(1, AWK_STRING, &str))) {
 
-    // Compile RE
+    // Compile regex
     regex_t preg;
     tre_regcomp(&preg, re.str_value.str, REG_EXTENDED);
 
-    // Set approx grep params
+    // Set approx aregex params
     regaparams_t params = { 0 };
     params.cost_ins   = 1;
     params.cost_del   = 1;
@@ -41,27 +51,30 @@ static awk_value_t * do_aregex(int nargs, awk_value_t *result API_FINFO_ARG)
     params.max_ins    = defcost;
     params.max_subst  = defcost;
     params.max_err    = defcost;
-
+
+    // Create structure for details of match
     regamatch_t match;
     match.nmatch = 0; // No partial match arrays needed
     match.pmatch = 0; //   - ditto -
-
+
+    // Return values
     int treret = 0;
     int rval = 0;
 
     // Do the approx regexp
     treret = tre_regaexec(&preg, str.str_value.str, &match, params, 0);
 
+    // Set the do_aregex() return value depending on tre_regaexec() return:
+    // Return cost (Levenshtein distance) if success, -1 if no match,
+    //   -999 if memory error
     if (treret == REG_NOMATCH) rval = -1;
     else if (treret == REG_ESPACE) {
       rval = -999;
       warning(ext_id, \
-        _("aregex: TRE err.: mem. insufficient to complete the match."));
+        "aregex: TRE err.: mem. insufficient to complete the match.");
+      // TO DO?: update_ERRNO_int(). But which ERRNO?
     }
     else rval = match.cost;
-
-    // Return: cost (Levenshtein distance) if success, -1 if no match,
-    //   -999 if memory error
 
     return make_number(rval, result);
   }
@@ -70,21 +83,17 @@ static awk_value_t * do_aregex(int nargs, awk_value_t *result API_FINFO_ARG)
   return make_null_string(result);
 }
 
+
 // Gawkextlib boilerplate:
 
 static awk_ext_func_t func_table[] = \
     {
      { "aregex", do_aregex, 3, 2, awk_false, NULL  },
     };
 
-static awk_bool_t init_my_module(void)
-{
-  GAWKEXTLIB_COMMON_INIT
-  return awk_true;
-}
+static awk_bool_t (*init_func)(void) = NULL;
 
-static awk_bool_t (*init_func)(void) = init_my_module;
-static const char *ext_version = PACKAGE_STRING;
+static const char *ext_version = "0.1";
 
 dl_load_func(func_table, fmatch, "")
 

test_aregex.awk

@@ -0,0 +1,18 @@
+@load "./aregex.so"
+
+BEGIN {
+  str    = "abcdefghi"
+  cost   = 2
+
+  re     = "^bcdefghij$"
+  print "RE1: '" re "', string: '" str "', cost: " cost ", match dist: " \
+    aregex(re, str, cost)
+
+  re     = "^xcdefghij$"
+  print "RE2: '" re "', string: '" str "', cost: " cost ", match dist: " \
+    aregex(re, str, cost)
+
+  # generate warning with gawk --lint :
+  print "RE3: '" re "', string: '" str "', cost: " cost ", match dist: " \
+    aregex(re, str, cost, "extra1", "extra2")
+}