Fix infinite loop / OOM in regex_match on overlapping matches

lib/src/matching.dart

@@ -658,15 +658,26 @@ class matching {
         if (rx_match == null) {
           break;
         }
+        // rx_match.start/index are relative to `pattern` (the substring),
+        // not to `password`. Treating them as absolute positions, and
+        // re-including the match's last character in the next substring
+        // (`... - 1`), can make `last_index` oscillate between two values
+        // forever for overlapping matches (e.g. two overlapping year-like
+        // digit runs against the recent_year regex), growing `matches`
+        // without bound until the process runs out of memory. Track the
+        // absolute offset explicitly and advance strictly past the
+        // matched token so the loop always makes forward progress.
         String? token = rx_match.group(0);
-        last_index = rx_match.start + rx_match.group(0)!.length - 1;
+        final int abs_start = last_index + rx_match.start;
+        final int abs_end = abs_start + token!.length - 1;
         matches.add(PasswordMatch()
           ..pattern = 'regex'
           ..token = token
-          ..i = rx_match.start
-          ..j = rx_match.start + rx_match.group(0)!.length - 1
+          ..i = abs_start
+          ..j = abs_end
           ..regex_name = name
           ..regex_match = rx_match);
+        last_index = abs_end + 1;
       }
     });
     return sorted(matches);

test/src/matching_test.dart

@@ -775,6 +775,17 @@ void main() {
     }
   });
 
+  test('regex matching terminates on overlapping matches', () {
+    // Regression test: two overlapping recent_year matches (here "2011"
+    // and "2001" sharing the digit at index 3) used to make `regex_match`
+    // compute a non-monotonic cursor and loop forever, growing its match
+    // list without bound until the process ran out of memory.
+    final matches = matching.regex_match('20112001Vi-');
+    expect(matches.length, 2);
+    expect(matches[0].token, '2011');
+    expect(matches[1].token, '2001');
+  });
+
   test('date matching', () {
     for (final sep in ['', ' ', '-', '/', '\\', '_', '.']) {
       final password = "13${sep}2${sep}1921";