StreamedResponse.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * 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 <fabien@symfony.com>
 *
 * @api
 */
class StreamedResponse extends Response {
  protected $callback;
  protected $streamed;

  /**
   * Constructor.
   *
   * @param mixed   $callback A valid PHP callback
   * @param integer $status   The response status code
   * @param array   $headers  An array of response headers
   *
   * @api
   */
  public function __construct($callback = null, $status = 200, $headers = array()) {
    parent::__construct(null, $status, $headers);
    if (null !== $callback) {
      $this
        ->setCallback($callback);
    }
    $this->streamed = false;
  }

  /**
   * {@inheritDoc}
   */
  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 mixed $callback A valid PHP callback
   *
   * @throws \LogicException
   */
  public function setCallback($callback) {
    if (!is_callable($callback)) {
      throw new \LogicException('The Response callback must be a valid PHP callable.');
    }
    $this->callback = $callback;
  }

  /**
   * {@inheritdoc}
   */
  public function prepare(Request $request) {
    $this->headers
      ->set('Cache-Control', 'no-cache');
    return parent::prepare($request);
  }

  /**
   * {@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;
  }

}