Support splitting times like "1. Hälfte des 19. Jahrhunderts"

src/NodaTimeSplitter.php

@@ -1125,6 +1125,33 @@ final class NodaTimeSplitter {
 
     }
 
+    /**
+     * Rewrites special formulations of a date.
+     *
+     * @param string $datum Date.
+     *
+     * @return string|false
+     */
+    private static function _rewrite_special_cases_regular(string $datum):string|false {
+
+        if (\preg_match("/^(1|2)\.\ Hälfte(|\ des)\ [0-9]{2}\.\ Jahrhundert(|s)$/", $datum)) {
+
+            $half = substr($datum, 0, 1);
+            $number = substr(ltrim(substr($datum, 10), "des Hälfte"), 0, 2);
+            if (is_numeric($number)) {
+                $num = (int)$number;
+                $targetCentury = $num - 1;
+                return match((int)$half) {
+                    1 => $targetCentury . "00-" . $targetCentury . "50",
+                    2 => $targetCentury . "50-" . $targetCentury . "99",
+                };
+            }
+        }
+
+        return false;
+
+    }
+
     /**
      * Contains special rules for incorrectly or incompletely spelled out timespan names.
      * To be called by self::attempt_splitting_from_till().
@@ -1401,6 +1428,10 @@ final class NodaTimeSplitter {
             }
         }
 
+        if ($rewrite = self::_rewrite_special_cases_regular($datum)) {
+            return self::attempt_splitting($rewrite);
+        }
+
         return false;
 
     }