add files

src/Illuminate/Http/Middleware/SetCacheHeaders.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace Illuminate\Http\Middleware;
+
+use Closure;
+
+class SetCacheHeaders
+{
+    /**
+     * Add cache related HTTP headers.
+     *
+     * @param  \Illuminate\Http\Request  $request
+     * @param  \Closure  $next
+     * @param  string|array  $options
+     * @return \Symfony\Component\HttpFoundation\Response
+     * @throws \InvalidArgumentException
+     */
+    public function handle($request, Closure $next, $options = [])
+    {
+        $response = $next($request);
+
+        if (! $request->isMethodCacheable() || ! $response->getContent()) {
+            return $response;
+        }
+
+        if (is_string($options)) {
+            $options = $this->parseOptions($options);
+        }
+
+        if (isset($options['etag']) && $options['etag'] === true) {
+            $options['etag'] = md5($response->getContent());
+        }
+
+        $response->setCache($options);
+        $response->isNotModified($request);
+
+        return $response;
+    }
+
+    /**
+     * Parse the given header options.
+     *
+     * @param  string  $options
+     * @return array
+     */
+    protected function parseOptions($options)
+    {
+        return collect(explode(';', $options))->mapWithKeys(function ($option) {
+            $data = explode('=', $option, 2);
+
+            return [$data[0] => $data[1] ?? true];
+        })->all();
+    }
+}