feat: add PageCache filter

system/Filters/PageCache.php

@@ -0,0 +1,74 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Filters;
+
+use CodeIgniter\Cache\ResponseCache;
+use CodeIgniter\HTTP\CLIRequest;
+use CodeIgniter\HTTP\DownloadResponse;
+use CodeIgniter\HTTP\IncomingRequest;
+use CodeIgniter\HTTP\RedirectResponse;
+use CodeIgniter\HTTP\RequestInterface;
+use CodeIgniter\HTTP\ResponseInterface;
+use Config\Services;
+
+/**
+ * Page Cache filter
+ */
+class PageCache implements FilterInterface
+{
+    private ResponseCache $pageCache;
+
+    public function __construct()
+    {
+        $this->pageCache = Services::responsecache();
+    }
+
+    /**
+     * Checks page cache and return if found.
+     *
+     * @param array|null $arguments
+     */
+    public function before(RequestInterface $request, $arguments = null)
+    {
+        assert($request instanceof CLIRequest || $request instanceof IncomingRequest);
+
+        $response = Services::response();
+
+        $cachedResponse = $this->pageCache->get($request, $response);
+
+        if ($cachedResponse instanceof ResponseInterface) {
+            return $cachedResponse;
+        }
+    }
+
+    /**
+     * Cache the page.
+     *
+     * @param array|null $arguments
+     *
+     * @return void
+     */
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+    {
+        assert($request instanceof CLIRequest || $request instanceof IncomingRequest);
+
+        if (
+            ! $response instanceof DownloadResponse
+            && ! $response instanceof RedirectResponse
+        ) {
+            // Cache it without the performance metrics replaced
+            // so that we can have live speed updates along the way.
+            // Must be run after filters to preserve the Response headers.
+            $this->pageCache->make($request, $response);
+        }
+    }
+}