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<?php
 /*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <[email protected]>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
 
 namespace Symfony\Component\HttpFoundation;
 
 /**
 * StreamedResponse represents a streamed HTTP response.
 *
 * A StreamedResponse uses a callback for its content.
 *
 * The callback should use the standard PHP functions like echo
 * to stream the response back to the client. The flush() method
 * can also be used if needed.
 *
 * @see flush()
 *
 * @author Fabien Potencier <[email protected]>
 */
 class StreamedResponse extends Response
 {
 protected $callback;
 protected $streamed;
 private $headersSent;
 
 /**
 * Constructor.
 *
 * @param callable|null $callback A valid PHP callback or null to set it later
 * @param int           $status   The response status code
 * @param array         $headers  An array of response headers
 */
 public function __construct(callable $callback = null, $status = 200, $headers = array())
 {
 parent::__construct(null, $status, $headers);
 
 if (null !== $callback) {
 $this->setCallback($callback);
 }
 $this->streamed = false;
 $this->headersSent = false;
 }
 
 /**
 * Factory method for chainability.
 *
 * @param callable|null $callback A valid PHP callback or null to set it later
 * @param int           $status   The response status code
 * @param array         $headers  An array of response headers
 *
 * @return static
 */
 public static function create($callback = null, $status = 200, $headers = array())
 {
 return new static($callback, $status, $headers);
 }
 
 /**
 * Sets the PHP callback associated with this Response.
 *
 * @param callable $callback A valid PHP callback
 */
 public function setCallback(callable $callback)
 {
 $this->callback = $callback;
 }
 
 /**
 * {@inheritdoc}
 *
 * This method only sends the headers once.
 */
 public function sendHeaders()
 {
 if ($this->headersSent) {
 return;
 }
 
 $this->headersSent = true;
 
 parent::sendHeaders();
 }
 
 /**
 * {@inheritdoc}
 *
 * This method only sends the content once.
 */
 public function sendContent()
 {
 if ($this->streamed) {
 return;
 }
 
 $this->streamed = true;
 
 if (null === $this->callback) {
 throw new \LogicException('The Response callback must not be null.');
 }
 
 call_user_func($this->callback);
 }
 
 /**
 * {@inheritdoc}
 *
 * @throws \LogicException when the content is not null
 */
 public function setContent($content)
 {
 if (null !== $content) {
 throw new \LogicException('The content cannot be set on a StreamedResponse instance.');
 }
 }
 
 /**
 * {@inheritdoc}
 *
 * @return false
 */
 public function getContent()
 {
 return false;
 }
 }
 
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