Preserve the leading and trailing whitespace in `<kbd>` on output

Fixes #3536

diff --git a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeKbd.class.php b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeKbd.class.php
new file mode 100644 (file)
index 0000000..72152cb
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeKbd.class.php
@@ -0,0 +1,42 @@
+<?php
+namespace wcf\system\html\output\node;
+use wcf\system\html\node\AbstractHtmlNodeProcessor;
+
+/**
+ * Replaces the leading and trailing space with `&nbsp;` to prevent the browser from implicitly trimming
+ * it on display.
+ * 
+ * @author      Alexander Ebert
+ * @copyright  2001-2020 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Html\Output\Node
+ * @since       5.3
+ */
+class HtmlOutputNodeKbd extends AbstractHtmlOutputNode {
+       /**
+        * @inheritDoc
+        */
+       protected $tagName = 'kbd';
+       
+       /**
+        * @inheritDoc
+        */
+       public function process(array $elements, AbstractHtmlNodeProcessor $htmlNodeProcessor) {
+               /** @var \DOMElement $element */
+               foreach ($elements as $element) {
+                       $textContent = $element->textContent;
+                       
+                       if (mb_strlen($textContent) !== 0) {
+                               if ($textContent[0] === ' ') {
+                                       $textContent = "\u{00A0}" . mb_substr($textContent, 1);
+                               }
+                               
+                               if (mb_substr($textContent, -1, 1) === ' ') {
+                                       $textContent = mb_substr($textContent, 0, -1) . "\u{00A0}";
+                               }
+                               
+                               $element->textContent = $textContent;
+                       }
+               }
+       }
+}