[stream] Add a nice API for streaming responses

doc/usage.rst

@@ -464,14 +464,47 @@ Redirects
 You can redirect to another page by returning a redirect response, which
 you can create by calling the ``redirect`` method::
 
-    use Silex\Application;
-
-    $app->get('/', function (Silex\Application $app) {
+    $app->get('/', function () use ($app) {
         return $app->redirect('/hello');
     });
 
 This will redirect from ``/`` to ``/hello``.
 
+Streaming
+---------
+
+It's possible to create a streaming response, which is important in cases
+when you cannot buffer the data being sent.
+
+code-block:: php
+
+    $app->get('/images/{file}', function ($file) use ($app) {
+        if (!file_exists(__DIR__.'/images/'.$file)) {
+            return $app->abort(404, 'The image was not found.');
+        }
+
+        $stream = function () use ($file) {
+            readfile($file);
+        };
+
+        return $app->stream($stream, 200, array('Content-Type' => 'image/png'));
+    });
+
+If you need to send chunks, make sure you call ``ob_flush`` and ``flush`` after
+every chunk.
+
+code-block:: php
+
+    $stream = function () {
+        $fh = fopen('http://www.example.com/', 'rb');
+        while (!feof($fh)) {
+          echo fread($fh, 1024);
+          ob_flush();
+          flush();
+        }
+        fclose($fh);
+    };
+
 Security
 --------
 

src/Silex/Application.php

@@ -29,6 +29,7 @@ use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\RedirectResponse;
+use Symfony\Component\HttpFoundation\StreamedResponse;
 use Symfony\Component\EventDispatcher\Event;
 use Symfony\Component\EventDispatcher\EventDispatcher;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
@@ -299,6 +300,20 @@ class Application extends \Pimple implements HttpKernelInterface, EventSubscribe
         return new RedirectResponse($url, $status);
     }
 
+    /**
+     * Creates a streaming response.
+     *
+     * @param mixed   $callback A valid PHP callback
+     * @param integer $status   The response status code
+     * @param array   $headers  An array of response headers
+     *
+     * @see Symfony\Component\HttpFoundation\StreamedResponse
+     */
+    public function stream($callback = null, $status = 200, $headers = array())
+    {
+        return new StreamedResponse($callback, $status, $headers);
+    }
+
     /**
      * Escapes a text for HTML.
      *

tests/Silex/Tests/StreamTest.php

+<?php
+
+/*
+ * This file is part of the Silex framework.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Silex\Tests;
+
+use Silex\Application;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\StreamedResponse;
+
+/**
+ * Stream test cases.
+ *
+ * @author Igor Wiedler <igor@wiedler.ch>
+ */
+class StreamTest extends \PHPUnit_Framework_TestCase
+{
+    public function testStreamReturnsStreamingResponse()
+    {
+        $app = new Application();
+
+        $response = $app->stream();
+        $this->assertInstanceOf('Symfony\Component\HttpFoundation\StreamedResponse', $response);
+        $this->assertSame(false, $response->getContent());
+    }
+
+    public function testStreamActuallyStreams()
+    {
+        $i = 0;
+
+        $stream = function () use (&$i) {
+            $i++;
+        };
+
+        $app = new Application();
+        $response = $app->stream($stream);
+
+        $this->assertEquals(0, $i);
+
+        $request = Request::create('/stream');
+        $response->prepare($request);
+        $response->sendContent();
+
+        $this->assertEquals(1, $i);
+    }
+}