style: add regex redirect formatter

redirect_regex.install

@@ -0,0 +1,38 @@
+<?php
+
+/**
+ * @file
+ * Install, update and uninstall functions for the redirect_regex module.
+ */
+
+use Drupal\Core\Config\Config;
+
+/**
+ * Implements hook_install().
+ */
+function redirect_regex_install() {
+  // Update the redirect view to use the regex source formatter.
+  _redirect_regex_update_view_config();
+}
+
+/**
+ * Update the redirect view configuration to use redirect_regex_source formatter.
+ */
+function _redirect_regex_update_view_config() {
+  $config = \Drupal::service('config.factory')->getEditable('views.view.redirect');
+
+  // Update the field type in the default display.
+  $field_config = &$config->get('display.default.display_options.fields.redirect_source__path');
+  if ($field_config && isset($field_config['type'])) {
+    $field_config['type'] = 'redirect_regex_source';
+    $config->set('display.default.display_options.fields.redirect_source__path', $field_config);
+    $config->save();
+  }
+}
+
+/**
+ * Update redirect view to use regex source formatter.
+ */
+function redirect_regex_update_10001() {
+  _redirect_regex_update_view_config();
+}

src/Plugin/Field/FieldFormatter/RedirectRegexSourceFormatter.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace Drupal\redirect_regex\Plugin\Field\FieldFormatter;
+
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Field\FormatterBase;
+
+/**
+ * Implementation of the 'redirect_regex_source' formatter.
+ *
+ * @FieldFormatter(
+ *   id = "redirect_regex_source",
+ *   label = @Translation("Redirect Regex Source"),
+ *   field_types = {
+ *     "redirect_source",
+ *   }
+ * )
+ */
+class RedirectRegexSourceFormatter extends FormatterBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function viewElements(FieldItemListInterface $items, $langcode) {
+    $elements = [];
+
+    foreach ($items as $delta => $item) {
+      $uri = urldecode($item->getUrl()->toString());
+      $find = '/regex:';
+      if (str_starts_with($uri, $find)) {
+        $uri = '[RegEx] '. substr($uri, strlen($find));
+      }
+      $elements[$delta] = [
+        '#markup' => $uri,
+      ];
+    }
+
+    return $elements;
+  }
+
+}