Add `ICssClassFormField`

diff --git a/wcfsetup/install/files/lib/system/form/builder/field/ICssClassFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/ICssClassFormField.class.php
new file mode 100644 (file)
index 0000000..dd2bf40
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/form/builder/field/ICssClassFormField.class.php
@@ -0,0 +1,48 @@
+<?php
+namespace wcf\system\form\builder\field;
+
+/**
+ * Represents a form fields that supports CSS classes for the actual form element.
+ *
+ * @author      Matthias Schmidt
+ * @copyright   2001-2020 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Form\Builder\Field
+ * @since       5.4
+ */
+interface ICssClassFormField extends IFormField {
+       /**
+        * Adds the given CSS class to the actual field element and returns this field.
+        *
+        * @throws      \InvalidArgumentException       if the given class is invalid
+        */
+       public function addFieldClass(string $class): self;
+       
+       /**
+        * Adds the given CSS classes to the actual field element and returns this field.
+        *
+        * @throws      \InvalidArgumentException       if any of the given classes is invalid
+        */
+       public function addFieldClasses(array $classes): self;
+       
+       /**
+        * Returns all CSS classes of the actual field element.
+        */
+       public function getFieldClasses(): array;
+       
+       /**
+        * Returns `true` if a CSS class of the actual field element with the given name exists and returns `false` otherwise.
+        *
+        * @throws      \InvalidArgumentException       if the given class is invalid
+        */
+       public function hasFieldClass(string $class): bool;
+       
+       /**
+        * Removes the given CSS class of the actual field element and returns this field.
+        *
+        * If the actual field element does not have the given CSS class, this method silently ignores that fact.
+        * 
+        * @throws      \InvalidArgumentException       if the given class is invalid
+        */
+       public function removeFieldClass(string $class): self;
+}