Issue #3421484: Create a twig function that will return list items

Closes #3421484

src/Template/TwigExtension.php

@@ -2,6 +2,8 @@
 
 namespace Drupal\ui_patterns\Template;
 
+use Drupal\Component\Render\MarkupInterface;
+use Drupal\Core\Render\Markup;
 use Twig\Extension\AbstractExtension;
 use Twig\TwigFilter;
 use Twig\TwigFunction;
@@ -35,6 +37,10 @@ class TwigExtension extends AbstractExtension {
         $this,
         'renderPatternPreview',
       ]),
+      new TwigFunction('get_list_values', [
+        $this,
+        'getListValues',
+      ]),
     ];
   }
 
@@ -93,4 +99,33 @@ class TwigExtension extends AbstractExtension {
     ];
   }
 
+  /**
+   * Provides just the list values.
+   *
+   * @param array|\Drupal\Core\Render\Markup $list_values
+   *   Array or Markup string to check.
+   *
+   * @return array
+   *   Empty or list values from field.
+   */
+  public function getListValues(array|Markup $list_values): array {
+    $list = [];
+
+    if ($list_values instanceof MarkupInterface) {
+      $clean_string = preg_replace('/<!--(.|\s)*?-->\s*|\r|\n/', '', $list_values);
+      if ($clean_string) {
+        $list = explode(',', $clean_string);
+      }
+    }
+    else {
+      foreach ($list_values as $key => $list_value) {
+        if (!str_starts_with($key, '#')) {
+          $list[] = $list_value;
+        }
+      }
+    }
+
+    return $list;
+  }
+
 }