# Response

class Response

Response represents an HTTP response.

## Constants

`HTTP_CONTINUE = 100;` |
`HTTP_SWITCHING_PROTOCOLS = 101;` |
`HTTP_PROCESSING = 102; // RFC2518` |
`HTTP_OK = 200;` |
`HTTP_CREATED = 201;` |
`HTTP_ACCEPTED = 202;` |
`HTTP_NON_AUTHORITATIVE_INFORMATION = 203;` |
`HTTP_NO_CONTENT = 204;` |
`HTTP_RESET_CONTENT = 205;` |
`HTTP_PARTIAL_CONTENT = 206;` |
`HTTP_MULTI_STATUS = 207; // RFC4918` |
`HTTP_ALREADY_REPORTED = 208; // RFC5842` |
`HTTP_IM_USED = 226; // RFC3229` |
`HTTP_MULTIPLE_CHOICES = 300;` |
`HTTP_MOVED_PERMANENTLY = 301;` |
`HTTP_FOUND = 302;` |
`HTTP_SEE_OTHER = 303;` |
`HTTP_NOT_MODIFIED = 304;` |
`HTTP_USE_PROXY = 305;` |
`HTTP_RESERVED = 306;` |
`HTTP_TEMPORARY_REDIRECT = 307;` |
`HTTP_PERMANENTLY_REDIRECT = 308; // RFC7238` |
`HTTP_BAD_REQUEST = 400;` |
`HTTP_UNAUTHORIZED = 401;` |
`HTTP_PAYMENT_REQUIRED = 402;` |
`HTTP_FORBIDDEN = 403;` |
`HTTP_NOT_FOUND = 404;` |
`HTTP_METHOD_NOT_ALLOWED = 405;` |
`HTTP_NOT_ACCEPTABLE = 406;` |
`HTTP_PROXY_AUTHENTICATION_REQUIRED = 407;` |
`HTTP_REQUEST_TIMEOUT = 408;` |
`HTTP_CONFLICT = 409;` |
`HTTP_GONE = 410;` |
`HTTP_LENGTH_REQUIRED = 411;` |
`HTTP_PRECONDITION_FAILED = 412;` |
`HTTP_REQUEST_ENTITY_TOO_LARGE = 413;` |
`HTTP_REQUEST_URI_TOO_LONG = 414;` |
`HTTP_UNSUPPORTED_MEDIA_TYPE = 415;` |
`HTTP_REQUESTED_RANGE_NOT_SATISFIABLE = 416;` |
`HTTP_EXPECTATION_FAILED = 417;` |
`HTTP_I_AM_A_TEAPOT = 418; // RFC2324` |
`HTTP_MISDIRECTED_REQUEST = 421; // RFC7540` |
`HTTP_UNPROCESSABLE_ENTITY = 422; // RFC4918` |
`HTTP_LOCKED = 423; // RFC4918` |
`HTTP_FAILED_DEPENDENCY = 424; // RFC4918` |
`HTTP_RESERVED_FOR_WEBDAV_ADVANCED_COLLECTIONS_EXPIRED_PROPOSAL = 425; // RFC2817` |
`HTTP_UPGRADE_REQUIRED = 426; // RFC2817` |
`HTTP_PRECONDITION_REQUIRED = 428; // RFC6585` |
`HTTP_TOO_MANY_REQUESTS = 429; // RFC6585` |
`HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE = 431; // RFC6585` |
`HTTP_UNAVAILABLE_FOR_LEGAL_REASONS = 451;` |
`HTTP_INTERNAL_SERVER_ERROR = 500;` |
`HTTP_NOT_IMPLEMENTED = 501;` |
`HTTP_BAD_GATEWAY = 502;` |
`HTTP_SERVICE_UNAVAILABLE = 503;` |
`HTTP_GATEWAY_TIMEOUT = 504;` |
`HTTP_VERSION_NOT_SUPPORTED = 505;` |
`HTTP_VARIANT_ALSO_NEGOTIATES_EXPERIMENTAL = 506; // RFC2295` |
`HTTP_INSUFFICIENT_STORAGE = 507; // RFC4918` |
`HTTP_LOOP_DETECTED = 508; // RFC5842` |
`HTTP_NOT_EXTENDED = 510; // RFC2774` |
`HTTP_NETWORK_AUTHENTICATION_REQUIRED = 511; // RFC6585` |

## Properties

`ResponseHeaderBag` | `$headers` |  |
`protected string` | `$content` |  |
`protected string` | `$version` |  |
`protected int` | `$statusCode` |  |
`protected string` | `$statusText` |  |
`protected string` | `$charset` |  |
`static array` | `$statusTexts` | Status codes translation table. |

## Methods

`public` | `` | `__construct($content = '', $status = 200, array $headers = array())` | No description |
`public static` | `Response` | `create(mixed $content = '', int $status = 200, array $headers = array())` | Factory method for chainability. |
`public` | `string` | `__toString()` | Returns the Response as an HTTP string. |
`public` | `` | `__clone()` | Clones the current Response instance. |
`public` | `$this` | `prepare(Request $request)` | Prepares the Response before it is sent to the client. |
`public` | `$this` | `sendHeaders()` | Sends HTTP headers. |
`public` | `$this` | `sendContent()` | Sends content for the current web response. |
`public` | `$this` | `send()` | Sends HTTP headers and content. |
`public` | `$this` | `setContent(mixed $content)` | Sets the response content. |
`public` | `string` | `getContent()` | Gets the current response content. |
`public` | `$this` | `setProtocolVersion($version)` | Sets the HTTP protocol version (1.0 or 1.1). |
`public` | `` | `getProtocolVersion()` | Gets the HTTP protocol version. |
`public` | `$this` | `setStatusCode($code, $text = null)` | Sets the response status code. |
`public` | `` | `getStatusCode()` | Retrieves the status code for the current web response. |
`public` | `$this` | `setCharset($charset)` | Sets the response charset. |
`public` | `` | `getCharset()` | Retrieves the response charset. |
`public` | `` | `isCacheable()` | Returns true if the response may safely be kept in a shared (surrogate) cache. |
`public` | `` | `isFresh()` | Returns true if the response is "fresh". |
`public` | `` | `isValidateable()` | Returns true if the response includes headers that can be used to validate the response with the origin server using a conditional GET request. |
`public` | `$this` | `setPrivate()` | Marks the response as "private". |
`public` | `$this` | `setPublic()` | Marks the response as "public". |
`public` | `$this` | `setImmutable($immutable = true)` | Marks the response as "immutable". |
`public` | `` | `isImmutable()` | Returns true if the response is marked as "immutable". |
`public` | `` | `mustRevalidate()` | Returns true if the response must be revalidated by caches. |
`public` | `` | `getDate()` | Returns the Date header as a DateTime instance. |
`public` | `$this` | `setDate(DateTimeInterface $date)` | Sets the Date header. |
`public` | `` | `getAge()` | Returns the age of the response in seconds. |
`public` | `$this` | `expire()` | Marks the response stale by setting the Age header to be equal to the maximum age of the response. |
`public` | `` | `getExpires()` | Returns the value of the Expires header as a DateTime instance. |
`public` | `$this` | `setExpires(DateTimeInterface $date = null)` | Sets the Expires HTTP header with a DateTime instance. |
`public` | `` | `getMaxAge()` | Returns the number of seconds after the time specified in the response's Date header when the response should no longer be considered fresh. |
`public` | `$this` | `setMaxAge($value)` | Sets the number of seconds after which the response should no longer be considered fresh. |
`public` | `$this` | `setSharedMaxAge($value)` | Sets the number of seconds after which the response should no longer be considered fresh by shared caches. |
`public` | `` | `getTtl()` | Returns the response's time-to-live in seconds. |
`public` | `$this` | `setTtl($seconds)` | Sets the response's time-to-live for shared caches in seconds. |
`public` | `$this` | `setClientTtl($seconds)` | Sets the response's time-to-live for private/client caches in seconds. |
`public` | `` | `getLastModified()` | Returns the Last-Modified HTTP header as a DateTime instance. |
`public` | `$this` | `setLastModified(DateTimeInterface $date = null)` | Sets the Last-Modified HTTP header with a DateTime instance. |
`public` | `` | `getEtag()` | Returns the literal value of the ETag HTTP header. |
`public` | `$this` | `setEtag(string|null $etag = null, bool $weak = false)` | Sets the ETag value. |
`public` | `$this` | `setCache($options)` | Sets the response's cache headers (validation and/or expiration). |
`public` | `$this` | `setNotModified()` | Modifies the response so that it conforms to the rules defined for a 304 status code. |
`public` | `` | `hasVary()` | Returns true if the response includes a Vary header. |
`public` | `` | `getVary()` | Returns an array of header names given in the Vary header. |
`public` | `$this` | `setVary(string|array $headers, bool $replace = true)` | Sets the Vary header. |
`public` | `bool` | `isNotModified(Request $request)` | Determines if the Response validators (ETag, Last-Modified) match a conditional value specified in the Request. |
`public` | `` | `isInvalid()` | Is response invalid? |
`public` | `` | `isInformational()` | Is response informative? |
`public` | `` | `isSuccessful()` | Is response successful? |
`public` | `` | `isRedirection()` | Is the response a redirect? |
`public` | `` | `isClientError()` | Is there a client error? |
`public` | `` | `isServerError()` | Was there a server side error? |
`public` | `` | `isOk()` | Is the response OK? |
`public` | `` | `isForbidden()` | Is the response forbidden? |
`public` | `` | `isNotFound()` | Is the response a not found error? |
`public` | `` | `isRedirect($location = null)` | Is the response a redirect of some form? |
`public` | `` | `isEmpty()` | Is the response empty? |
`public static` | `` | `closeOutputBuffers($targetLevel, $flush)` | Cleans or flushes output buffers up to target level. |
`protected` | `` | `ensureIEOverSSLCompatibility(Request $request)` | Checks if we need to remove Cache-Control for SSL encrypted downloads when using IE < 9. |

## Details

at line 193

### `__construct()`

`public __construct($content = '', $status = 200, array $headers = array())`

#### Parameters

| `$content` |
| `$status` |
`array` | `$headers` |

#### Exceptions

InvalidArgumentException | When the HTTP status code is not valid

at line 215

### `create()`

`public static Response create(mixed $content = '', int $status = 200, array $headers = array())`

Factory method for chainability.

Example:

    return Response::create($body, 200)
        ->setSharedMaxAge(300);

#### Parameters

`mixed` | `$content` | The response content, see setContent()
`int` | `$status` | The response status code
`array` | `$headers` | An array of response headers

#### Return Value

`Response` |

at line 231

### `__toString()`

`public string __toString()`

Returns the Response as an HTTP string.

The string representation of the Response is the same as the one that will be sent to the client only if the prepare() method has been called before.

#### Return Value

`string` | The Response as an HTTP string

#### See also

prepare() |

at line 242

### `__clone()`

`public __clone()`

Clones the current Response instance.

at line 256

### `prepare()`

`public $this prepare(Request $request)`

Prepares the Response before it is sent to the client.

This method tweaks the Response to ensure that it is compliant with RFC 2616. Most of the changes are based on the Request that is "associated" with this Response.

#### Parameters

`Request` | `$request` |

#### Return Value

`$this` |

at line 318

### `sendHeaders()`

`public $this sendHeaders()`

Sends HTTP headers.

#### Return Value

`$this` |

at line 352

### `sendContent()`

`public $this sendContent()`

Sends content for the current web response.

#### Return Value

`$this` |

at line 364

### `send()`

`public $this send()`

Sends HTTP headers and content.

#### Return Value

`$this` |

at line 389

### `setContent()`

`public $this setContent(mixed $content)`

Sets the response content.

Valid types are strings, numbers, null, and objects that implement a __toString() method.

#### Parameters

`mixed` | `$content` | Content that can be cast to string

#### Return Value

`$this` |

#### Exceptions

UnexpectedValueException |

at line 405

### `getContent()`

`public string getContent()`

Gets the current response content.

#### Return Value

`string` | Content

at line 417

### `setProtocolVersion()`

`public $this setProtocolVersion($version)`

Sets the HTTP protocol version (1.0 or 1.1).

#### Parameters

| `$version` |

#### Return Value

`$this` |

at line 429

### `getProtocolVersion()`

`public getProtocolVersion()`

Gets the HTTP protocol version.

at line 446

### `setStatusCode()`

`public $this setStatusCode($code, $text = null)`

Sets the response status code.

If the status text is null it will be automatically populated for the known status codes and left empty otherwise.

#### Parameters

| `$code` |
| `$text` |

#### Return Value

`$this` |

#### Exceptions

InvalidArgumentException | When the HTTP status code is not valid

at line 475

### `getStatusCode()`

`public getStatusCode()`

Retrieves the status code for the current web response.

at line 487

### `setCharset()`

`public $this setCharset($charset)`

Sets the response charset.

#### Parameters

| `$charset` |

#### Return Value

`$this` |

at line 499

### `getCharset()`

`public getCharset()`

Retrieves the response charset.

at line 521

### `isCacheable()`

`public isCacheable()`

Returns true if the response may safely be kept in a shared (surrogate) cache.

Responses marked "private" with an explicit Cache-Control directive are considered uncacheable.

Responses with neither a freshness lifetime (Expires, max-age) nor cache validator (Last-Modified, ETag) are considered uncacheable because there is no way to tell when or how to remove them from the cache.

Note that RFC 7231 and RFC 7234 possibly allow for a more permissive implementation, for example "status codes that are defined as cacheable by default [...] can be reused by a cache with heuristic expiration unless otherwise indicated" (https://tools.ietf.org/html/rfc7231#section-6.1)

at line 543

### `isFresh()`

`public isFresh()`

Returns true if the response is "fresh".

Fresh responses may be served from cache without any interaction with the origin. A response is considered fresh when it includes a Cache-Control/max-age indicator or Expires header and the calculated age is less than the freshness lifetime.

at line 554

### `isValidateable()`

`public isValidateable()`

Returns true if the response includes headers that can be used to validate the response with the origin server using a conditional GET request.

at line 568

### `setPrivate()`

`public $this setPrivate()`

Marks the response as "private".

It makes the response ineligible for serving other clients.

#### Return Value

`$this` |

at line 585

### `setPublic()`

`public $this setPublic()`

Marks the response as "public".

It makes the response eligible for serving other clients.

#### Return Value

`$this` |

at line 600

### `setImmutable()`

`public $this setImmutable($immutable = true)`

Marks the response as "immutable".

#### Parameters

| `$immutable` |

#### Return Value

`$this` |

at line 616

### `isImmutable()`

`public isImmutable()`

Returns true if the response is marked as "immutable".

at line 631

### `mustRevalidate()`

`public mustRevalidate()`

Returns true if the response must be revalidated by caches.

This method indicates that the response must not be served stale by a cache in any circumstance without first revalidating with the origin. When present, the TTL of the response should not be overridden to be greater than the value provided by the origin.

at line 643

### `getDate()`

`public getDate()`

Returns the Date header as a DateTime instance.

#### Exceptions

RuntimeException | When the header is not parseable

at line 655

### `setDate()`

`public $this setDate(DateTimeInterface $date)`

Sets the Date header.

#### Parameters

`DateTimeInterface` | `$date` |

#### Return Value

`$this` |

at line 672

### `getAge()`

`public getAge()`

Returns the age of the response in seconds.

at line 686

### `expire()`

`public $this expire()`

Marks the response stale by setting the Age header to be equal to the maximum age of the response.

#### Return Value

`$this` |

at line 700

### `getExpires()`

`public getExpires()`

Returns the value of the Expires header as a DateTime instance.

at line 719

### `setExpires()`

`public $this setExpires(DateTimeInterface $date = null)`

Sets the Expires HTTP header with a DateTime instance.

Passing null as value will remove the header.

#### Parameters

`DateTimeInterface` | `$date` |

#### Return Value

`$this` |

at line 746

### `getMaxAge()`

`public getMaxAge()`

Returns the number of seconds after the time specified in the response's Date header when the response should no longer be considered fresh.

First, it checks for a s-maxage directive, then a max-age directive, and then it falls back on an expires header. It returns null when no maximum age can be established.

at line 772

### `setMaxAge()`

`public $this setMaxAge($value)`

Sets the number of seconds after which the response should no longer be considered fresh.

This methods sets the Cache-Control max-age directive.

#### Parameters

| `$value` |

#### Return Value

`$this` |

at line 788

### `setSharedMaxAge()`

`public $this setSharedMaxAge($value)`

Sets the number of seconds after which the response should no longer be considered fresh by shared caches.

This methods sets the Cache-Control s-maxage directive.

#### Parameters

| `$value` |

#### Return Value

`$this` |

at line 806

### `getTtl()`

`public getTtl()`

Returns the response's time-to-live in seconds.

It returns null when no freshness information is present in the response.

When the responses TTL is <= 0, the response may not be served from cache without first revalidating with the origin.

at line 822

### `setTtl()`

`public $this setTtl($seconds)`

Sets the response's time-to-live for shared caches in seconds.

This method adjusts the Cache-Control/s-maxage directive.

#### Parameters

| `$seconds` |

#### Return Value

`$this` |

at line 838

### `setClientTtl()`

`public $this setClientTtl($seconds)`

Sets the response's time-to-live for private/client caches in seconds.

This method adjusts the Cache-Control/max-age directive.

#### Parameters

| `$seconds` |

#### Return Value

`$this` |

at line 852

### `getLastModified()`

`public getLastModified()`

Returns the Last-Modified HTTP header as a DateTime instance.

#### Exceptions

RuntimeException | When the HTTP header is not parseable

at line 866

### `setLastModified()`

`public $this setLastModified(DateTimeInterface $date = null)`

Sets the Last-Modified HTTP header with a DateTime instance.

Passing null as value will remove the header.

#### Parameters

`DateTimeInterface` | `$date` |

#### Return Value

`$this` |

at line 889

### `getEtag()`

`public getEtag()`

Returns the literal value of the ETag HTTP header.

at line 904

### `setEtag()`

`public $this setEtag(string|null $etag = null, bool $weak = false)`

Sets the ETag value.

#### Parameters

`string|null` | `$etag` | The ETag unique identifier or null to remove the header
`bool` | `$weak` | Whether you want a weak ETag or not

#### Return Value

`$this` |

at line 930

### `setCache()`

`public $this setCache($options)`

Sets the response's cache headers (validation and/or expiration).

Available options are: etag, last_modified, max_age, s_maxage, private, public and immutable.

#### Parameters

| `$options` |

#### Return Value

`$this` |

#### Exceptions

InvalidArgumentException |

at line 987

### `setNotModified()`

`public $this setNotModified()`

Modifies the response so that it conforms to the rules defined for a 304 status code.

This sets the status, removes the body, and discards any headers that MUST NOT be included in 304 responses.

#### Return Value

`$this` |

#### See also

http://tools.ietf.org/html/rfc2616#section-10.3.5 |

at line 1005

### `hasVary()`

`public hasVary()`

Returns true if the response includes a Vary header.

at line 1015

### `getVary()`

`public getVary()`

Returns an array of header names given in the Vary header.

at line 1039

### `setVary()`

`public $this setVary(string|array $headers, bool $replace = true)`

Sets the Vary header.

#### Parameters

`string|array` | `$headers` |
`bool` | `$replace` | Whether to replace the actual value or not (true by default)

#### Return Value

`$this` |

at line 1057

### `isNotModified()`

`public bool isNotModified(Request $request)`

Determines if the Response validators (ETag, Last-Modified) match a conditional value specified in the Request.

If the Response is not modified, it sets the status code to 304 and removes the actual content by calling the setNotModified() method.

#### Parameters

`Request` | `$request` |

#### Return Value

`bool` | true if the Response validators match the Request, false otherwise

at line 1089

### `isInvalid()`

`public isInvalid()`

Is response invalid?

#### See also

http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html |

at line 1099

### `isInformational()`

`public isInformational()`

Is response informative?

at line 1109

### `isSuccessful()`

`public isSuccessful()`

Is response successful?

at line 1119

### `isRedirection()`

`public isRedirection()`

Is the response a redirect?

at line 1129

### `isClientError()`

`public isClientError()`

Is there a client error?

at line 1139

### `isServerError()`

`public isServerError()`

Was there a server side error?

at line 1149

### `isOk()`

`public isOk()`

Is the response OK?

at line 1159

### `isForbidden()`

`public isForbidden()`

Is the response forbidden?

at line 1169

### `isNotFound()`

`public isNotFound()`

Is the response a not found error?

at line 1179

### `isRedirect()`

`public isRedirect($location = null)`

Is the response a redirect of some form?

#### Parameters

| `$location` |

at line 1189

### `isEmpty()`

`public isEmpty()`

Is the response empty?

at line 1201

### `closeOutputBuffers()`

`public static closeOutputBuffers($targetLevel, $flush)`

Cleans or flushes output buffers up to target level.

Resulting level can be greater than target level if a non-removable buffer has been encountered.

#### Parameters

| `$targetLevel` |
| `$flush` |

at line 1223

### `ensureIEOverSSLCompatibility()`

`protected ensureIEOverSSLCompatibility(Request $request)`

Checks if we need to remove Cache-Control for SSL encrypted downloads when using IE < 9.

#### Parameters

`Request` | `$request` |

#### See also

http://support.microsoft.com/kb/323308 |

## Source code

    <?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 App\Khan\Component\HttpFoundation;

    /**
     * Response represents an HTTP response.
     *
     * @author Fabien Potencier <fabien@symfony.com>
     */
    class Response
    {
        const HTTP_CONTINUE = 100;
        const HTTP_SWITCHING_PROTOCOLS = 101;
        const HTTP_PROCESSING = 102;            // RFC2518
        const HTTP_OK = 200;
        const HTTP_CREATED = 201;
        const HTTP_ACCEPTED = 202;
        const HTTP_NON_AUTHORITATIVE_INFORMATION = 203;
        const HTTP_NO_CONTENT = 204;
        const HTTP_RESET_CONTENT = 205;
        const HTTP_PARTIAL_CONTENT = 206;
        const HTTP_MULTI_STATUS = 207;          // RFC4918
        const HTTP_ALREADY_REPORTED = 208;      // RFC5842
        const HTTP_IM_USED = 226;               // RFC3229
        const HTTP_MULTIPLE_CHOICES = 300;
        const HTTP_MOVED_PERMANENTLY = 301;
        const HTTP_FOUND = 302;
        const HTTP_SEE_OTHER = 303;
        const HTTP_NOT_MODIFIED = 304;
        const HTTP_USE_PROXY = 305;
        const HTTP_RESERVED = 306;
        const HTTP_TEMPORARY_REDIRECT = 307;
        const HTTP_PERMANENTLY_REDIRECT = 308;  // RFC7238
        const HTTP_BAD_REQUEST = 400;
        const HTTP_UNAUTHORIZED = 401;
        const HTTP_PAYMENT_REQUIRED = 402;
        const HTTP_FORBIDDEN = 403;
        const HTTP_NOT_FOUND = 404;
        const HTTP_METHOD_NOT_ALLOWED = 405;
        const HTTP_NOT_ACCEPTABLE = 406;
        const HTTP_PROXY_AUTHENTICATION_REQUIRED = 407;
        const HTTP_REQUEST_TIMEOUT = 408;
        const HTTP_CONFLICT = 409;
        const HTTP_GONE = 410;
        const HTTP_LENGTH_REQUIRED = 411;
        const HTTP_PRECONDITION_FAILED = 412;
        const HTTP_REQUEST_ENTITY_TOO_LARGE = 413;
        const HTTP_REQUEST_URI_TOO_LONG = 414;
        const HTTP_UNSUPPORTED_MEDIA_TYPE = 415;
        const HTTP_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
        const HTTP_EXPECTATION_FAILED = 417;
        const HTTP_I_AM_A_TEAPOT = 418;                                               // RFC2324
        const HTTP_MISDIRECTED_REQUEST = 421;                                         // RFC7540
        const HTTP_UNPROCESSABLE_ENTITY = 422;                                        // RFC4918
        const HTTP_LOCKED = 423;                                                      // RFC4918
        const HTTP_FAILED_DEPENDENCY = 424;                                           // RFC4918
        const HTTP_RESERVED_FOR_WEBDAV_ADVANCED_COLLECTIONS_EXPIRED_PROPOSAL = 425;   // RFC2817
        const HTTP_UPGRADE_REQUIRED = 426;                                            // RFC2817
        const HTTP_PRECONDITION_REQUIRED = 428;                                       // RFC6585
        const HTTP_TOO_MANY_REQUESTS = 429;                                           // RFC6585
        const HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE = 431;                             // RFC6585
        const HTTP_UNAVAILABLE_FOR_LEGAL_REASONS = 451;
        const HTTP_INTERNAL_SERVER_ERROR = 500;
        const HTTP_NOT_IMPLEMENTED = 501;
        const HTTP_BAD_GATEWAY = 502;
        const HTTP_SERVICE_UNAVAILABLE = 503;
        const HTTP_GATEWAY_TIMEOUT = 504;
        const HTTP_VERSION_NOT_SUPPORTED = 505;
        const HTTP_VARIANT_ALSO_NEGOTIATES_EXPERIMENTAL = 506;                        // RFC2295
        const HTTP_INSUFFICIENT_STORAGE = 507;                                        // RFC4918
        const HTTP_LOOP_DETECTED = 508;                                               // RFC5842
        const HTTP_NOT_EXTENDED = 510;                                                // RFC2774
        const HTTP_NETWORK_AUTHENTICATION_REQUIRED = 511;                             // RFC6585

        /**
         * @var \Symfony\Component\HttpFoundation\ResponseHeaderBag
         */
        public $headers;

        /**
         * @var string
         */
        protected $content;

        /**
         * @var string
         */
        protected $version;

        /**
         * @var int
         */
        protected $statusCode;

        /**
         * @var string
         */
        protected $statusText;

        /**
         * @var string
         */
        protected $charset;

        /**
         * Status codes translation table.
         *
         * The list of codes is complete according to the
         * {@link http://www.iana.org/assignments/http-status-codes/ Hypertext Transfer Protocol (HTTP) Status Code Registry}
         * (last updated 2016-03-01).
         *
         * Unless otherwise noted, the status code is defined in RFC2616.
         *
         * @var array
         */
        public static $statusTexts = array(
            100 => 'Continue',
            101 => 'Switching Protocols',
            102 => 'Processing',            // RFC2518
            103 => 'Early Hints',
            200 => 'OK',
            201 => 'Created',
            202 => 'Accepted',
            203 => 'Non-Authoritative Information',
            204 => 'No Content',
            205 => 'Reset Content',
            206 => 'Partial Content',
            207 => 'Multi-Status',          // RFC4918
            208 => 'Already Reported',      // RFC5842
            226 => 'IM Used',               // RFC3229
            300 => 'Multiple Choices',
            301 => 'Moved Permanently',
            302 => 'Found',
            303 => 'See Other',
            304 => 'Not Modified',
            305 => 'Use Proxy',
            307 => 'Temporary Redirect',
            308 => 'Permanent Redirect',    // RFC7238
            400 => 'Bad Request',
            401 => 'Unauthorized',
            402 => 'Payment Required',
            403 => 'Forbidden',
            404 => 'Not Found',
            405 => 'Method Not Allowed',
            406 => 'Not Acceptable',
            407 => 'Proxy Authentication Required',
            408 => 'Request Timeout',
            409 => 'Conflict',
            410 => 'Gone',
            411 => 'Length Required',
            412 => 'Precondition Failed',
            413 => 'Payload Too Large',
            414 => 'URI Too Long',
            415 => 'Unsupported Media Type',
            416 => 'Range Not Satisfiable',
            417 => 'Expectation Failed',
            418 => 'I\'m a teapot',                                               // RFC2324
            421 => 'Misdirected Request',                                         // RFC7540
            422 => 'Unprocessable Entity',                                        // RFC4918
            423 => 'Locked',                                                      // RFC4918
            424 => 'Failed Dependency',                                           // RFC4918
            425 => 'Reserved for WebDAV advanced collections expired proposal',   // RFC2817
            426 => 'Upgrade Required',                                            // RFC2817
            428 => 'Precondition Required',                                       // RFC6585
            429 => 'Too Many Requests',                                           // RFC6585
            431 => 'Request Header Fields Too Large',                             // RFC6585
            451 => 'Unavailable For Legal Reasons',                               // RFC7725
            500 => 'Internal Server Error',
            501 => 'Not Implemented',
            502 => 'Bad Gateway',
            503 => 'Service Unavailable',
            504 => 'Gateway Timeout',
            505 => 'HTTP Version Not Supported',
            506 => 'Variant Also Negotiates',                                     // RFC2295
            507 => 'Insufficient Storage',                                        // RFC4918
            508 => 'Loop Detected',                                               // RFC5842
            510 => 'Not Extended',                                                // RFC2774
            511 => 'Network Authentication Required',                             // RFC6585
        );

        /**
         * @throws \InvalidArgumentException When the HTTP status code is not valid
         */
        public function __construct($content = '', $status = 200, array $headers = array())
        {
            $this->headers = new ResponseHeaderBag($headers);
            $this->setContent($content);
            $this->setStatusCode($status);
            $this->setProtocolVersion('1.0');
        }

        /**
         * Factory method for chainability.
         *
         * Example:
         *
         *     return Response::create($body, 200)
         *         ->setSharedMaxAge(300);
         *
         * @param mixed $content The response content, see setContent()
         * @param int   $status  The response status code
         * @param array $headers An array of response headers
         *
         * @return static
         */
        public static function create($content = '', $status = 200, $headers = array())
        {
            return new static($content, $status, $headers);
        }

        /**
         * Returns the Response as an HTTP string.
         *
         * The string representation of the Response is the same as the
         * one that will be sent to the client only if the prepare() method
         * has been called before.
         *
         * @return string The Response as an HTTP string
         *
         * @see prepare()
         */
        public function __toString()
        {
            return
                sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText)."\r\n".
                $this->headers."\r\n".
                $this->getContent();
        }

        /**
         * Clones the current Response instance.
         */
        public function __clone()
        {
            $this->headers = clone $this->headers;
        }

        /**
         * Prepares the Response before it is sent to the client.
         *
         * This method tweaks the Response to ensure that it is
         * compliant with RFC 2616. Most of the changes are based on
         * the Request that is "associated" with this Response.
         *
         * @return $this
         */
        public function prepare(Request $request)
        {
            $headers = $this->headers;

            if ($this->isInformational() || $this->isEmpty()) {
                $this->setContent(null);
                $headers->remove('Content-Type');
                $headers->remove('Content-Length');
            } else {
                // Content-type based on the Request
                if (!$headers->has('Content-Type')) {
                    $format = $request->getRequestFormat();
                    if (null !== $format && $mimeType = $request->getMimeType($format)) {
                        $headers->set('Content-Type', $mimeType);
                    }
                }

                // Fix Content-Type
                $charset = $this->charset ?: 'UTF-8';
                if (!$headers->has('Content-Type')) {
                    $headers->set('Content-Type', 'text/html; charset='.$charset);
                } elseif (0 === stripos($headers->get('Content-Type'), 'text/') && false === stripos($headers->get('Content-Type'), 'charset')) {
                    // add the charset
                    $headers->set('Content-Type', $headers->get('Content-Type').'; charset='.$charset);
                }

                // Fix Content-Length
                if ($headers->has('Transfer-Encoding')) {
                    $headers->remove('Content-Length');
                }

                if ($request->isMethod('HEAD')) {
                    // cf. RFC2616 14.13
                    $length = $headers->get('Content-Length');
                    $this->setContent(null);
                    if ($length) {
                        $headers->set('Content-Length', $length);
                    }
                }
            }

            // Fix protocol
            if ('HTTP/1.0' != $request->server->get('SERVER_PROTOCOL')) {
                $this->setProtocolVersion('1.1');
            }

            // Check if we need to send extra expire info headers
            if ('1.0' == $this->getProtocolVersion() && false !== strpos($this->headers->get('Cache-Control'), 'no-cache')) {
                $this->headers->set('pragma', 'no-cache');
                $this->headers->set('expires', -1);
            }

            $this->ensureIEOverSSLCompatibility($request);

            return $this;
        }

        /**
         * Sends HTTP headers.
         *
         * @return $this
         */
        public function sendHeaders()
        {
            // headers have already been sent by the developer
            if (headers_sent()) {
                return $this;
            }

            // headers
            foreach ($this->headers->allPreserveCaseWithoutCookies() as $name => $values) {
                foreach ($values as $value) {
                    header($name.': '.$value, false, $this->statusCode);
                }
            }

            // status
            header(sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText), true, $this->statusCode);

            // cookies
            foreach ($this->headers->getCookies() as $cookie) {
                if ($cookie->isRaw()) {
                    setrawcookie($cookie->getName(), $cookie->getValue(), $cookie->getExpiresTime(), $cookie->getPath(), $cookie->getDomain(), $cookie->isSecure(), $cookie->isHttpOnly());
                } else {
                    setcookie($cookie->getName(), $cookie->getValue(), $cookie->getExpiresTime(), $cookie->getPath(), $cookie->getDomain(), $cookie->isSecure(), $cookie->isHttpOnly());
                }
            }

            return $this;
        }

        /**
         * Sends content for the current web response.
         *
         * @return $this
         */
        public function sendContent()
        {
            echo $this->content;

            return $this;
        }

        /**
         * Sends HTTP headers and content.
         *
         * @return $this
         */
        public function send()
        {
            $this->sendHeaders();
            $this->sendContent();

            if (function_exists('fastcgi_finish_request')) {
                fastcgi_finish_request();
            } elseif (!\in_array(PHP_SAPI, array('cli', 'phpdbg'), true)) {
                static::closeOutputBuffers(0, true);
            }

            return $this;
        }

        /**
         * Sets the response content.
         *
         * Valid types are strings, numbers, null, and objects that implement a __toString() method.
         *
         * @param mixed $content Content that can be cast to string
         *
         * @return $this
         *
         * @throws \UnexpectedValueException
         */
        public function setContent($content)
        {
            if (null !== $content && !is_string($content) && !is_numeric($content) && !is_callable(array($content, '__toString'))) {
                throw new \UnexpectedValueException(sprintf('The Response content must be a string or object implementing __toString(), "%s" given.', gettype($content)));
            }

            $this->content = (string) $content;

            return $this;
        }

        /**
         * Gets the current response content.
         *
         * @return string Content
         */
        public function getContent()
        {
            return $this->content;
        }

        /**
         * Sets the HTTP protocol version (1.0 or 1.1).
         *
         * @return $this
         *
         * @final
         */
        public function setProtocolVersion($version)
        {
            $this->version = $version;

            return $this;
        }

        /**
         * Gets the HTTP protocol version.
         *
         * @final
         */
        public function getProtocolVersion()
        {
            return $this->version;
        }

        /**
         * Sets the response status code.
         *
         * If the status text is null it will be automatically populated for the known
         * status codes and left empty otherwise.
         *
         * @return $this
         *
         * @throws \InvalidArgumentException When the HTTP status code is not valid
         *
         * @final
         */
        public function setStatusCode($code, $text = null)
        {
            $this->statusCode = $code;
            if ($this->isInvalid()) {
                throw new \InvalidArgumentException(sprintf('The HTTP status code "%s" is not valid.', $code));
            }

            if (null === $text) {
                $this->statusText = isset(self::$statusTexts[$code]) ? self::$statusTexts[$code] : 'unknown status';

                return $this;
            }

            if (false === $text) {
                $this->statusText = '';

                return $this;
            }

            $this->statusText = $text;

            return $this;
        }

        /**
         * Retrieves the status code for the current web response.
         *
         * @final
         */
        public function getStatusCode()
        {
            return $this->statusCode;
        }

        /**
         * Sets the response charset.
         *
         * @return $this
         *
         * @final
         */
        public function setCharset($charset)
        {
            $this->charset = $charset;

            return $this;
        }

        /**
         * Retrieves the response charset.
         *
         * @final
         */
        public function getCharset()
        {
            return $this->charset;
        }

        /**
         * Returns true if the response may safely be kept in a shared (surrogate) cache.
         *
         * Responses marked "private" with an explicit Cache-Control directive are
         * considered uncacheable.
         *
         * Responses with neither a freshness lifetime (Expires, max-age) nor cache
         * validator (Last-Modified, ETag) are considered uncacheable because there is
         * no way to tell when or how to remove them from the cache.
         *
         * Note that RFC 7231 and RFC 7234 possibly allow for a more permissive implementation,
         * for example "status codes that are defined as cacheable by default [...]
         * can be reused by a cache with heuristic expiration unless otherwise indicated"
         * (https://tools.ietf.org/html/rfc7231#section-6.1)
         *
         * @final
         */
        public function isCacheable()
        {
            if (!in_array($this->statusCode, array(200, 203, 300, 301, 302, 404, 410))) {
                return false;
            }

            if ($this->headers->hasCacheControlDirective('no-store') || $this->headers->getCacheControlDirective('private')) {
                return false;
            }

            return $this->isValidateable() || $this->isFresh();
        }

        /**
         * Returns true if the response is "fresh".
         *
         * Fresh responses may be served from cache without any interaction with the
         * origin. A response is considered fresh when it includes a Cache-Control/max-age
         * indicator or Expires header and the calculated age is less than the freshness lifetime.
         *
         * @final
         */
        public function isFresh()
        {
            return $this->getTtl() > 0;
        }

        /**
         * Returns true if the response includes headers that can be used to validate
         * the response with the origin server using a conditional GET request.
         *
         * @final
         */
        public function isValidateable()
        {
            return $this->headers->has('Last-Modified') || $this->headers->has('ETag');
        }

        /**
         * Marks the response as "private".
         *
         * It makes the response ineligible for serving other clients.
         *
         * @return $this
         *
         * @final
         */
        public function setPrivate()
        {
            $this->headers->removeCacheControlDirective('public');
            $this->headers->addCacheControlDirective('private');

            return $this;
        }

        /**
         * Marks the response as "public".
         *
         * It makes the response eligible for serving other clients.
         *
         * @return $this
         *
         * @final
         */
        public function setPublic()
        {
            $this->headers->addCacheControlDirective('public');
            $this->headers->removeCacheControlDirective('private');

            return $this;
        }

        /**
         * Marks the response as "immutable".
         *
         * @return $this
         *
         * @final
         */
        public function setImmutable($immutable = true)
        {
            if ($immutable) {
                $this->headers->addCacheControlDirective('immutable');
            } else {
                $this->headers->removeCacheControlDirective('immutable');
            }

            return $this;
        }

        /**
         * Returns true if the response is marked as "immutable".
         *
         * @final
         */
        public function isImmutable()
        {
            return $this->headers->hasCacheControlDirective('immutable');
        }

        /**
         * Returns true if the response must be revalidated by caches.
         *
         * This method indicates that the response must not be served stale by a
         * cache in any circumstance without first revalidating with the origin.
         * When present, the TTL of the response should not be overridden to be
         * greater than the value provided by the origin.
         *
         * @final
         */
        public function mustRevalidate()
        {
            return $this->headers->hasCacheControlDirective('must-revalidate') || $this->headers->hasCacheControlDirective('proxy-revalidate');
        }

        /**
         * Returns the Date header as a DateTime instance.
         *
         * @throws \RuntimeException When the header is not parseable
         *
         * @final
         */
        public function getDate()
        {
            return $this->headers->getDate('Date');
        }

        /**
         * Sets the Date header.
         *
         * @return $this
         *
         * @final
         */
        public function setDate(\DateTimeInterface $date)
        {
            if ($date instanceof \DateTime) {
                $date = \DateTimeImmutable::createFromMutable($date);
            }

            $date = $date->setTimezone(new \DateTimeZone('UTC'));
            $this->headers->set('Date', $date->format('D, d M Y H:i:s').' GMT');

            return $this;
        }

        /**
         * Returns the age of the response in seconds.
         *
         * @final
         */
        public function getAge()
        {
            if (null !== $age = $this->headers->get('Age')) {
                return (int) $age;
            }

            return max(time() - $this->getDate()->format('U'), 0);
        }

        /**
         * Marks the response stale by setting the Age header to be equal to the maximum age of the response.
         *
         * @return $this
         */
        public function expire()
        {
            if ($this->isFresh()) {
                $this->headers->set('Age', $this->getMaxAge());
            }

            return $this;
        }

        /**
         * Returns the value of the Expires header as a DateTime instance.
         *
         * @final
         */
        public function getExpires()
        {
            try {
                return $this->headers->getDate('Expires');
            } catch (\RuntimeException $e) {
                // according to RFC 2616 invalid date formats (e.g. "0" and "-1") must be treated as in the past
                return \DateTime::createFromFormat('U', time() - 172800);
            }
        }

        /**
         * Sets the Expires HTTP header with a DateTime instance.
         *
         * Passing null as value will remove the header.
         *
         * @return $this
         *
         * @final
         */
        public function setExpires(\DateTimeInterface $date = null)
        {
            if (null === $date) {
                $this->headers->remove('Expires');

                return $this;
            }

            if ($date instanceof \DateTime) {
                $date = \DateTimeImmutable::createFromMutable($date);
            }

            $date = $date->setTimezone(new \DateTimeZone('UTC'));
            $this->headers->set('Expires', $date->format('D, d M Y H:i:s').' GMT');

            return $this;
        }

        /**
         * Returns the number of seconds after the time specified in the response's Date
         * header when the response should no longer be considered fresh.
         *
         * First, it checks for a s-maxage directive, then a max-age directive, and then it falls
         * back on an expires header. It returns null when no maximum age can be established.
         *
         * @final
         */
        public function getMaxAge()
        {
            if ($this->headers->hasCacheControlDirective('s-maxage')) {
                return (int) $this->headers->getCacheControlDirective('s-maxage');
            }

            if ($this->headers->hasCacheControlDirective('max-age')) {
                return (int) $this->headers->getCacheControlDirective('max-age');
            }

            if (null !== $this->getExpires()) {
                return (int) ($this->getExpires()->format('U') - $this->getDate()->format('U'));
            }

            return null;
        }

        /**
         * Sets the number of seconds after which the response should no longer be considered fresh.
         *
         * This methods sets the Cache-Control max-age directive.
         *
         * @return $this
         *
         * @final
         */
        public function setMaxAge($value)
        {
            $this->headers->addCacheControlDirective('max-age', $value);

            return $this;
        }

        /**
         * Sets the number of seconds after which the response should no longer be considered fresh by shared caches.
         *
         * This methods sets the Cache-Control s-maxage directive.
         *
         * @return $this
         *
         * @final
         */
        public function setSharedMaxAge($value)
        {
            $this->setPublic();
            $this->headers->addCacheControlDirective('s-maxage', $value);

            return $this;
        }

        /**
         * Returns the response's time-to-live in seconds.
         *
         * It returns null when no freshness information is present in the response.
         *
         * When the responses TTL is <= 0, the response may not be served from cache without first
         * revalidating with the origin.
         *
         * @final
         */
        public function getTtl()
        {
            $maxAge = $this->getMaxAge();

            return null !== $maxAge ? $maxAge - $this->getAge() : null;
        }

        /**
         * Sets the response's time-to-live for shared caches in seconds.
         *
         * This method adjusts the Cache-Control/s-maxage directive.
         *
         * @return $this
         *
         * @final
         */
        public function setTtl($seconds)
        {
            $this->setSharedMaxAge($this->getAge() + $seconds);

            return $this;
        }

        /**
         * Sets the response's time-to-live for private/client caches in seconds.
         *
         * This method adjusts the Cache-Control/max-age directive.
         *
         * @return $this
         *
         * @final
         */
        public function setClientTtl($seconds)
        {
            $this->setMaxAge($this->getAge() + $seconds);

            return $this;
        }

        /**
         * Returns the Last-Modified HTTP header as a DateTime instance.
         *
         * @throws \RuntimeException When the HTTP header is not parseable
         *
         * @final
         */
        public function getLastModified()
        {
            return $this->headers->getDate('Last-Modified');
        }

        /**
         * Sets the Last-Modified HTTP header with a DateTime instance.
         *
         * Passing null as value will remove the header.
         *
         * @return $this
         *
         * @final
         */
        public function setLastModified(\DateTimeInterface $date = null)
        {
            if (null === $date) {
                $this->headers->remove('Last-Modified');

                return $this;
            }

            if ($date instanceof \DateTime) {
                $date = \DateTimeImmutable::createFromMutable($date);
            }

            $date = $date->setTimezone(new \DateTimeZone('UTC'));
            $this->headers->set('Last-Modified', $date->format('D, d M Y H:i:s').' GMT');

            return $this;
        }

        /**
         * Returns the literal value of the ETag HTTP header.
         *
         * @final
         */
        public function getEtag()
        {
            return $this->headers->get('ETag');
        }

        /**
         * Sets the ETag value.
         *
         * @param string|null $etag The ETag unique identifier or null to remove the header
         * @param bool        $weak Whether you want a weak ETag or not
         *
         * @return $this
         *
         * @final
         */
        public function setEtag($etag = null,$weak = false)
        {
            if (null === $etag) {
                $this->headers->remove('Etag');
            } else {
                if (0 !== strpos($etag, '"')) {
                    $etag = '"'.$etag.'"';
                }

                $this->headers->set('ETag', (true === $weak ? 'W/' : '').$etag);
            }

            return $this;
        }

        /**
         * Sets the response's cache headers (validation and/or expiration).
         *
         * Available options are: etag, last_modified, max_age, s_maxage, private, public and immutable.
         *
         * @return $this
         *
         * @throws \InvalidArgumentException
         *
         * @final
         */
        public function setCache($options)
        {
            if ($diff = array_diff(array_keys($options), array('etag', 'last_modified', 'max_age', 's_maxage', 'private', 'public', 'immutable'))) {
                throw new \InvalidArgumentException(sprintf('Response does not support the following options: "%s".', implode('", "', array_values($diff))));
            }

            if (isset($options['etag'])) {
                $this->setEtag($options['etag']);
            }

            if (isset($options['last_modified'])) {
                $this->setLastModified($options['last_modified']);
            }

            if (isset($options['max_age'])) {
                $this->setMaxAge($options['max_age']);
            }

            if (isset($options['s_maxage'])) {
                $this->setSharedMaxAge($options['s_maxage']);
            }

            if (isset($options['public'])) {
                if ($options['public']) {
                    $this->setPublic();
                } else {
                    $this->setPrivate();
                }
            }

            if (isset($options['private'])) {
                if ($options['private']) {
                    $this->setPrivate();
                } else {
                    $this->setPublic();
                }
            }

            if (isset($options['immutable'])) {
                $this->setImmutable((bool) $options['immutable']);
            }

            return $this;
        }

        /**
         * Modifies the response so that it conforms to the rules defined for a 304 status code.
         *
         * This sets the status, removes the body, and discards any headers
         * that MUST NOT be included in 304 responses.
         *
         * @return $this
         *
         * @see http://tools.ietf.org/html/rfc2616#section-10.3.5
         *
         * @final
         */
        public function setNotModified()
        {
            $this->setStatusCode(304);
            $this->setContent(null);

            // remove headers that MUST NOT be included with 304 Not Modified responses
            foreach (array('Allow', 'Content-Encoding', 'Content-Language', 'Content-Length', 'Content-MD5', 'Content-Type', 'Last-Modified') as $header) {
                $this->headers->remove($header);
            }

            return $this;
        }

        /**
         * Returns true if the response includes a Vary header.
         *
         * @final
         */
        public function hasVary()
        {
            return null !== $this->headers->get('Vary');
        }

        /**
         * Returns an array of header names given in the Vary header.
         *
         * @final
         */
        public function getVary()
        {
            if (!$vary = $this->headers->get('Vary', null, false)) {
                return array();
            }

            $ret = array();
            foreach ($vary as $item) {
                $ret = array_merge($ret, preg_split('/[\s,]+/', $item));
            }

            return $ret;
        }

        /**
         * Sets the Vary header.
         *
         * @param string|array $headers
         * @param bool         $replace Whether to replace the actual value or not (true by default)
         *
         * @return $this
         *
         * @final
         */
        public function setVary($headers, $replace = true)
        {
            $this->headers->set('Vary', $headers, $replace);

            return $this;
        }

        /**
         * Determines if the Response validators (ETag, Last-Modified) match
         * a conditional value specified in the Request.
         *
         * If the Response is not modified, it sets the status code to 304 and
         * removes the actual content by calling the setNotModified() method.
         *
         * @return bool true if the Response validators match the Request, false otherwise
         *
         * @final
         */
        public function isNotModified(Request $request)
        {
            if (!$request->isMethodCacheable()) {
                return false;
            }

            $notModified = false;
            $lastModified = $this->headers->get('Last-Modified');
            $modifiedSince = $request->headers->get('If-Modified-Since');

            if ($etags = $request->getETags()) {
                $notModified = in_array($this->getEtag(), $etags) || in_array('*', $etags);
            }

            if ($modifiedSince && $lastModified) {
                $notModified = strtotime($modifiedSince) >= strtotime($lastModified) && (!$etags || $notModified);
            }

            if ($notModified) {
                $this->setNotModified();
            }

            return $notModified;
        }

        /**
         * Is response invalid?
         *
         * @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
         *
         * @final
         */
        public function isInvalid()
        {
            return $this->statusCode < 100 || $this->statusCode >= 600;
        }

        /**
         * Is response informative?
         *
         * @final
         */
        public function isInformational()
        {
            return $this->statusCode >= 100 && $this->statusCode < 200;
        }

        /**
         * Is response successful?
         *
         * @final
         */
        public function isSuccessful()
        {
            return $this->statusCode >= 200 && $this->statusCode < 300;
        }

        /**
         * Is the response a redirect?
         *
         * @final
         */
        public function isRedirection()
        {
            return $this->statusCode >= 300 && $this->statusCode < 400;
        }

        /**
         * Is there a client error?
         *
         * @final
         */
        public function isClientError()
        {
            return $this->statusCode >= 400 && $this->statusCode < 500;
        }

        /**
         * Was there a server side error?
         *
         * @final
         */
        public function isServerError()
        {
            return $this->statusCode >= 500 && $this->statusCode < 600;
        }

        /**
         * Is the response OK?
         *
         * @final
         */
        public function isOk()
        {
            return 200 === $this->statusCode;
        }

        /**
         * Is the response forbidden?
         *
         * @final
         */
        public function isForbidden()
        {
            return 403 === $this->statusCode;
        }

        /**
         * Is the response a not found error?
         *
         * @final
         */
        public function isNotFound()
        {
            return 404 === $this->statusCode;
        }

        /**
         * Is the response a redirect of some form?
         *
         * @final
         */
        public function isRedirect($location = null)
        {
            return in_array($this->statusCode, array(201, 301, 302, 303, 307, 308)) && (null === $location ?: $location == $this->headers->get('Location'));
        }

        /**
         * Is the response empty?
         *
         * @final
         */
        public function isEmpty()
        {
            return in_array($this->statusCode, array(204, 304));
        }

        /**
         * Cleans or flushes output buffers up to target level.
         *
         * Resulting level can be greater than target level if a non-removable buffer has been encountered.
         *
         * @final
         */
        public static function closeOutputBuffers($targetLevel, $flush)
        {
            $status = ob_get_status(true);
            $level = count($status);
            $flags = PHP_OUTPUT_HANDLER_REMOVABLE | ($flush ? PHP_OUTPUT_HANDLER_FLUSHABLE : PHP_OUTPUT_HANDLER_CLEANABLE);

            while ($level-- > $targetLevel && ($s = $status[$level]) && (!isset($s['del']) ? !isset($s['flags']) || ($s['flags'] & $flags) === $flags : $s['del'])) {
                if ($flush) {
                    ob_end_flush();
                } else {
                    ob_end_clean();
                }
            }
        }

        /**
         * Checks if we need to remove Cache-Control for SSL encrypted downloads when using IE < 9.
         *
         * @see http://support.microsoft.com/kb/323308
         *
         * @final
         */
        protected function ensureIEOverSSLCompatibility(Request $request)
        {
            if (false !== stripos($this->headers->get('Content-Disposition'), 'attachment') && 1 == preg_match('/MSIE (.*?);/i', $request->server->get('HTTP_USER_AGENT'), $match) && true === $request->isSecure()) {
                if ((int) preg_replace('/(MSIE )(.*?);/', '$2', $match[0]) < 9) {
                    $this->headers->remove('Cache-Control');
                }
            }
        }
    }