Add `TCssClassFormField`

diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TCssClassFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TCssClassFormField.class.php
new file mode 100644 (file)
index 0000000..69f5c9c
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TCssClassFormField.class.php
@@ -0,0 +1,93 @@
+<?php
+namespace wcf\system\form\builder\field;
+use wcf\system\form\builder\TFormNode;
+
+/**
+ * Provides default implementations of `ICssClassFormField` methods.
+ *
+ * @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
+ */
+trait TCssClassFormField {
+       /**
+        * CSS classes of this node
+        * @var string[]
+        */
+       protected $fieldClasses = [];
+       
+       /**
+        * 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 $class): self {
+               static::validateClass($class);
+               
+               if (!in_array($class, $this->fieldClasses)) {
+                       $this->fieldClasses[] = $class;
+               }
+               
+               return $this;
+       }
+       
+       /**
+        * 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 $classes): self {
+               foreach ($classes as $class) {
+                       $this->addFieldClass($class);
+               }
+               
+               return $this;
+       }
+       
+       /**
+        * Returns all CSS classes of the actual field element.
+        */
+       public function getFieldClasses(): array {
+               return $this->fieldClasses;
+       }
+       
+       /**
+        * 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 $class): bool {
+               static::validateClass($class);
+               
+               return array_search($class, $this->fieldClasses) !== false;
+       }
+       
+       /**
+        * 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 $class): self {
+               static::validateClass($class);
+               
+               $index = array_search($class, $this->fieldClasses);
+               if ($index !== false) {
+                       unset($this->fieldClasses[$index]);
+               }
+               
+               return $this;
+       }
+       
+       /**
+        * Checks if the given parameter class is a valid CSS class.
+        *
+        * @param       string          $class          checked class
+        *
+        * @throws      \InvalidArgumentException       if the given class is invalid
+        */
+       abstract public static function validateClass($class);
+}