improve version list generation

Improve version list generation by the following:
- Handles correctly 405 for the 4.5 version and 311 for 3.11 at the same time.
- Reduces generation of non-existing versions, which speeds up version-dependent command search and memory footprint.
- Function itself runs faster, even though it uses nested loops.

includes/functions.php

@@ -150,14 +150,26 @@ function moosh_moodle_version($topdir, $default = 23) {
 }
 
 function moosh_generate_version_list($upto, $from = 19) {
+    // This function assumes that moodle main version is below 10 and subversions are below or equal to 20.
+
     $upto = intval($upto);
     $from = intval($from);
     if (!($from && $upto) || $from > $upto) {
         throw new Exception("Invalid from or upto value; they must both be > 0 and from must be <= upto");
     }
+
+    $frommain = (int)(substr($from, 0, 1));
+    $fromsub = (int)(substr($from, 1));
+    $uptomain = (int)(substr($upto, 0, 1));
+    $uptosub = (int)(substr($upto, 1));
+
     $versions = array();
-    foreach (range($from, $upto) as $no) {
-        $versions[] = 'Moodle' . $no;
+    foreach (range($frommain, $uptomain) as $nom) {
+        $frsub = ($nom == $frommain) ? $fromsub : 0;
+        $tosub = ($nom == $uptomain) ? $uptosub : 20;
+        foreach(range($frsub, $tosub) as $nos) {
+            $versions[] = 'Moodle' . $nom . $nos;
+        }
     }
     return $versions;
 }
@@ -552,4 +564,4 @@ function string_ends_with($haystack, $needle) {
         return true;
     }
     return substr( $haystack, -$length ) === $needle;
-}
+}