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   1  <?php
   2  /**
   3   * Zend Framework
   4   *
   5   * LICENSE
   6   *
   7   * This source file is subject to the new BSD license that is bundled
   8   * with this package in the file LICENSE.txt.
   9   * It is also available through the world-wide-web at this URL:
  10   * http://framework.zend.com/license/new-bsd
  11   * If you did not receive a copy of the license and are unable to
  12   * obtain it through the world-wide-web, please send an email
  13   * to [email protected] so we can send you a copy immediately.
  14   *
  15   * @category  Zend
  16   * @package   Zend_Uri
  17   * @copyright  Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
  18   * @license   http://framework.zend.com/license/new-bsd     New BSD License
  19   * @version   $Id: Http.php 24593 2012-01-05 20:35:02Z matthew $
  20   */
  21  
  22  /**
  23   * @see Zend_Uri
  24   */
  25  require_once  'Zend/Uri.php';
  26  
  27  /**
  28   * @see Zend_Validate_Hostname
  29   */
  30  require_once  'Zend/Validate/Hostname.php';
  31  
  32  /**
  33   * HTTP(S) URI handler
  34   *
  35   * @category  Zend
  36   * @package   Zend_Uri
  37   * @uses      Zend_Uri
  38   * @copyright  Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
  39   * @license   http://framework.zend.com/license/new-bsd     New BSD License
  40   */
  41  class Zend_Uri_Http extends Zend_Uri
  42  {
  43      /**
  44       * Character classes for validation regular expressions
  45       */
  46      const CHAR_ALNUM    = 'A-Za-z0-9';
  47      const CHAR_MARK     = '-_.!~*\'()\[\]';
  48      const CHAR_RESERVED = ';\/?:@&=+$,';
  49      const CHAR_SEGMENT  = ':@&=+$,;';
  50      const CHAR_UNWISE   = '{}|\\\\^`';
  51  
  52      /**
  53       * HTTP username
  54       *
  55       * @var string
  56       */
  57      protected $_username = '';
  58  
  59      /**
  60       * HTTP password
  61       *
  62       * @var string
  63       */
  64      protected $_password = '';
  65  
  66      /**
  67       * HTTP host
  68       *
  69       * @var string
  70       */
  71      protected $_host = '';
  72  
  73      /**
  74       * HTTP post
  75       *
  76       * @var string
  77       */
  78      protected $_port = '';
  79  
  80      /**
  81       * HTTP part
  82       *
  83       * @var string
  84       */
  85      protected $_path = '';
  86  
  87      /**
  88       * HTTP query
  89       *
  90       * @var string
  91       */
  92      protected $_query = '';
  93  
  94      /**
  95       * HTTP fragment
  96       *
  97       * @var string
  98       */
  99      protected $_fragment = '';
 100  
 101      /**
 102       * Regular expression grammar rules for validation; values added by constructor
 103       *
 104       * @var array
 105       */
 106      protected $_regex = array();
 107  
 108      /**
 109       * Constructor accepts a string $scheme (e.g., http, https) and a scheme-specific part of the URI
 110       * (e.g., example.com/path/to/resource?query=param#fragment)
 111       *
 112       * @param  string $scheme         The scheme of the URI
 113       * @param  string $schemeSpecific The scheme-specific part of the URI
 114       * @throws Zend_Uri_Exception When the URI is not valid
 115       */
 116      protected function __construct($scheme, $schemeSpecific = '')
 117      {
 118          // Set the scheme
 119          $this->_scheme = $scheme;
 120  
 121          // Set up grammar rules for validation via regular expressions. These
 122          // are to be used with slash-delimited regular expression strings.
 123  
 124          // Escaped special characters (eg. '%25' for '%')
 125          $this->_regex['escaped']    = '%[[:xdigit:]]{2}';
 126  
 127          // Unreserved characters
 128          $this->_regex['unreserved'] = '[' . self::CHAR_ALNUM . self::CHAR_MARK . ']';
 129  
 130          // Segment can use escaped, unreserved or a set of additional chars
 131          $this->_regex['segment']    = '(?:' . $this->_regex['escaped'] . '|[' .
 132              self::CHAR_ALNUM . self::CHAR_MARK . self::CHAR_SEGMENT . '])*';
 133  
 134          // Path can be a series of segmets char strings seperated by '/'
 135          $this->_regex['path']       = '(?:\/(?:' . $this->_regex['segment'] . ')?)+';
 136  
 137          // URI characters can be escaped, alphanumeric, mark or reserved chars
 138          $this->_regex['uric']       = '(?:' . $this->_regex['escaped'] . '|[' .
 139              self::CHAR_ALNUM . self::CHAR_MARK . self::CHAR_RESERVED .
 140  
 141          // If unwise chars are allowed, add them to the URI chars class
 142              (self::$_config['allow_unwise'] ? self::CHAR_UNWISE : '') . '])';
 143  
 144          // If no scheme-specific part was supplied, the user intends to create
 145          // a new URI with this object.  No further parsing is required.
 146          if (strlen($schemeSpecific) === 0) {
 147              return;
 148          }
 149  
 150          // Parse the scheme-specific URI parts into the instance variables.
 151          $this->_parseUri($schemeSpecific);
 152  
 153          // Validate the URI
 154          if ($this->valid() === false) {
 155              require_once  'Zend/Uri/Exception.php';
 156              throw new Zend_Uri_Exception('Invalid URI supplied');
 157          }
 158      }
 159  
 160      /**
 161       * Creates a Zend_Uri_Http from the given string
 162       *
 163       * @param  string $uri String to create URI from, must start with
 164       *                     'http://' or 'https://'
 165       * @throws InvalidArgumentException  When the given $uri is not a string or
 166       *                                   does not start with http:// or https://
 167       * @throws Zend_Uri_Exception        When the given $uri is invalid
 168       * @return Zend_Uri_Http
 169       */
 170      public static function fromString($uri)
 171      {
 172          if (is_string($uri) === false) {
 173              require_once  'Zend/Uri/Exception.php';
 174              throw new Zend_Uri_Exception('$uri is not a string');
 175          }
 176  
 177          $uri            = explode(':', $uri, 2);
 178          $scheme         = strtolower($uri[0]);
 179          $schemeSpecific = isset($uri[1]) === true ? $uri[1] : '';
 180  
 181          if (in_array($scheme, array('http', 'https')) === false) {
 182              require_once  'Zend/Uri/Exception.php';
 183              throw new Zend_Uri_Exception("Invalid scheme: '$scheme'");
 184          }
 185  
 186          $schemeHandler = new Zend_Uri_Http($scheme, $schemeSpecific);
 187          return $schemeHandler;
 188      }
 189  
 190      /**
 191       * Parse the scheme-specific portion of the URI and place its parts into instance variables.
 192       *
 193       * @param  string $schemeSpecific The scheme-specific portion to parse
 194       * @throws Zend_Uri_Exception When scheme-specific decoposition fails
 195       * @throws Zend_Uri_Exception When authority decomposition fails
 196       * @return void
 197       */
 198      protected function _parseUri($schemeSpecific)
 199      {
 200          // High-level decomposition parser
 201          $pattern = '~^((//)([^/?#]*))([^?#]*)(\?([^#]*))?(#(.*))?$~';
 202          $status  = @preg_match($pattern, $schemeSpecific, $matches);
 203          if ($status === false) {
 204              require_once  'Zend/Uri/Exception.php';
 205              throw new Zend_Uri_Exception('Internal error: scheme-specific decomposition failed');
 206          }
 207  
 208          // Failed decomposition; no further processing needed
 209          if ($status === false) {
 210              return;
 211          }
 212  
 213          // Save URI components that need no further decomposition
 214          $this->_path     = isset($matches[4]) === true ? $matches[4] : '';
 215          $this->_query    = isset($matches[6]) === true ? $matches[6] : '';
 216          $this->_fragment = isset($matches[8]) === true ? $matches[8] : '';
 217  
 218          // Additional decomposition to get username, password, host, and port
 219          $combo   = isset($matches[3]) === true ? $matches[3] : '';
 220          $pattern = '~^(([^:@]*)(:([^@]*))?@)?((?(?=[[])[[][^]]+[]]|[^:]+))(:(.*))?$~';        
 221          $status  = @preg_match($pattern, $combo, $matches);
 222          if ($status === false) {
 223              require_once  'Zend/Uri/Exception.php';
 224              throw new Zend_Uri_Exception('Internal error: authority decomposition failed');
 225          }
 226          
 227          // Save remaining URI components
 228          $this->_username = isset($matches[2]) === true ? $matches[2] : '';
 229          $this->_password = isset($matches[4]) === true ? $matches[4] : '';
 230          $this->_host     = isset($matches[5]) === true 
 231                           ? preg_replace('~^\[([^]]+)\]$~', '\1', $matches[5])  // Strip wrapper [] from IPv6 literal
 232                           : '';
 233          $this->_port     = isset($matches[7]) === true ? $matches[7] : '';
 234      }
 235  
 236      /**
 237       * Returns a URI based on current values of the instance variables. If any
 238       * part of the URI does not pass validation, then an exception is thrown.
 239       *
 240       * @throws Zend_Uri_Exception When one or more parts of the URI are invalid
 241       * @return string
 242       */
 243      public function getUri()
 244      {
 245          if ($this->valid() === false) {
 246              require_once  'Zend/Uri/Exception.php';
 247              throw new Zend_Uri_Exception('One or more parts of the URI are invalid');
 248          }
 249  
 250          $password = strlen($this->_password) > 0 ? ":$this->_password" : '';
 251          $auth     = strlen($this->_username) > 0 ? "$this->_username$password@" : '';
 252          $port     = strlen($this->_port) > 0 ? ":$this->_port" : '';
 253          $query    = strlen($this->_query) > 0 ? "?$this->_query" : '';
 254          $fragment = strlen($this->_fragment) > 0 ? "#$this->_fragment" : '';
 255  
 256          return $this->_scheme
 257               . '://'
 258               . $auth
 259               . $this->_host
 260               . $port
 261               . $this->_path
 262               . $query
 263               . $fragment;
 264      }
 265  
 266      /**
 267       * Validate the current URI from the instance variables. Returns true if and only if all
 268       * parts pass validation.
 269       *
 270       * @return boolean
 271       */
 272      public function valid()
 273      {
 274          // Return true if and only if all parts of the URI have passed validation
 275          return $this->validateUsername()
 276             and $this->validatePassword()
 277             and $this->validateHost()
 278             and $this->validatePort()
 279             and $this->validatePath()
 280             and $this->validateQuery()
 281             and $this->validateFragment();
 282      }
 283  
 284      /**
 285       * Returns the username portion of the URL, or FALSE if none.
 286       *
 287       * @return string
 288       */
 289      public function getUsername()
 290      {
 291          return strlen($this->_username) > 0 ? $this->_username : false;
 292      }
 293  
 294      /**
 295       * Returns true if and only if the username passes validation. If no username is passed,
 296       * then the username contained in the instance variable is used.
 297       *
 298       * @param  string $username The HTTP username
 299       * @throws Zend_Uri_Exception When username validation fails
 300       * @return boolean
 301       * @link   http://www.faqs.org/rfcs/rfc2396.html
 302       */
 303      public function validateUsername($username = null)
 304      {
 305          if ($username === null) {
 306              $username = $this->_username;
 307          }
 308  
 309          // If the username is empty, then it is considered valid
 310          if (strlen($username) === 0) {
 311              return true;
 312          }
 313  
 314          // Check the username against the allowed values
 315          $status = @preg_match('/^(?:' . $this->_regex['escaped'] . '|[' .
 316              self::CHAR_ALNUM . self::CHAR_MARK . ';:&=+$,' . '])+$/', $username);
 317  
 318          if ($status === false) {
 319              require_once  'Zend/Uri/Exception.php';
 320              throw new Zend_Uri_Exception('Internal error: username validation failed');
 321          }
 322  
 323          return $status === 1;
 324      }
 325  
 326      /**
 327       * Sets the username for the current URI, and returns the old username
 328       *
 329       * @param  string $username The HTTP username
 330       * @throws Zend_Uri_Exception When $username is not a valid HTTP username
 331       * @return string
 332       */
 333      public function setUsername($username)
 334      {
 335          if ($this->validateUsername($username) === false) {
 336              require_once  'Zend/Uri/Exception.php';
 337              throw new Zend_Uri_Exception("Username \"$username\" is not a valid HTTP username");
 338          }
 339  
 340          $oldUsername     = $this->_username;
 341          $this->_username = $username;
 342  
 343          return $oldUsername;
 344      }
 345  
 346      /**
 347       * Returns the password portion of the URL, or FALSE if none.
 348       *
 349       * @return string
 350       */
 351      public function getPassword()
 352      {
 353          return strlen($this->_password) > 0 ? $this->_password : false;
 354      }
 355  
 356      /**
 357       * Returns true if and only if the password passes validation. If no password is passed,
 358       * then the password contained in the instance variable is used.
 359       *
 360       * @param  string $password The HTTP password
 361       * @throws Zend_Uri_Exception When password validation fails
 362       * @return boolean
 363       * @link   http://www.faqs.org/rfcs/rfc2396.html
 364       */
 365      public function validatePassword($password = null)
 366      {
 367          if ($password === null) {
 368              $password = $this->_password;
 369          }
 370  
 371          // If the password is empty, then it is considered valid
 372          if (strlen($password) === 0) {
 373              return true;
 374          }
 375  
 376          // If the password is nonempty, but there is no username, then it is considered invalid
 377          if (strlen($password) > 0 and strlen($this->_username) === 0) {
 378              return false;
 379          }
 380  
 381          // Check the password against the allowed values
 382          $status = @preg_match('/^(?:' . $this->_regex['escaped'] . '|[' .
 383              self::CHAR_ALNUM . self::CHAR_MARK . ';:&=+$,' . '])+$/', $password);
 384  
 385          if ($status === false) {
 386              require_once  'Zend/Uri/Exception.php';
 387              throw new Zend_Uri_Exception('Internal error: password validation failed.');
 388          }
 389  
 390          return $status == 1;
 391      }
 392  
 393      /**
 394       * Sets the password for the current URI, and returns the old password
 395       *
 396       * @param  string $password The HTTP password
 397       * @throws Zend_Uri_Exception When $password is not a valid HTTP password
 398       * @return string
 399       */
 400      public function setPassword($password)
 401      {
 402          if ($this->validatePassword($password) === false) {
 403              require_once  'Zend/Uri/Exception.php';
 404              throw new Zend_Uri_Exception("Password \"$password\" is not a valid HTTP password.");
 405          }
 406  
 407          $oldPassword     = $this->_password;
 408          $this->_password = $password;
 409  
 410          return $oldPassword;
 411      }
 412  
 413      /**
 414       * Returns the domain or host IP portion of the URL, or FALSE if none.
 415       *
 416       * @return string
 417       */
 418      public function getHost()
 419      {
 420          return strlen($this->_host) > 0 ? $this->_host : false;
 421      }
 422  
 423      /**
 424       * Returns true if and only if the host string passes validation. If no host is passed,
 425       * then the host contained in the instance variable is used.
 426       *
 427       * @param  string $host The HTTP host
 428       * @return boolean
 429       * @uses   Zend_Filter
 430       */
 431      public function validateHost($host = null)
 432      {
 433          if ($host === null) {
 434              $host = $this->_host;
 435          }
 436  
 437          // If the host is empty, then it is considered invalid
 438          if (strlen($host) === 0) {
 439              return false;
 440          }
 441  
 442          // Check the host against the allowed values; delegated to Zend_Filter.
 443          $validate = new Zend_Validate_Hostname(Zend_Validate_Hostname::ALLOW_ALL);
 444  
 445          return $validate->isValid($host);
 446      }
 447  
 448      /**
 449       * Sets the host for the current URI, and returns the old host
 450       *
 451       * @param  string $host The HTTP host
 452       * @throws Zend_Uri_Exception When $host is nota valid HTTP host
 453       * @return string
 454       */
 455      public function setHost($host)
 456      {
 457          if ($this->validateHost($host) === false) {
 458              require_once  'Zend/Uri/Exception.php';
 459              throw new Zend_Uri_Exception("Host \"$host\" is not a valid HTTP host");
 460          }
 461  
 462          $oldHost     = $this->_host;
 463          $this->_host = $host;
 464  
 465          return $oldHost;
 466      }
 467  
 468      /**
 469       * Returns the TCP port, or FALSE if none.
 470       *
 471       * @return string
 472       */
 473      public function getPort()
 474      {
 475          return strlen($this->_port) > 0 ? $this->_port : false;
 476      }
 477  
 478      /**
 479       * Returns true if and only if the TCP port string passes validation. If no port is passed,
 480       * then the port contained in the instance variable is used.
 481       *
 482       * @param  string $port The HTTP port
 483       * @return boolean
 484       */
 485      public function validatePort($port = null)
 486      {
 487          if ($port === null) {
 488              $port = $this->_port;
 489          }
 490  
 491          // If the port is empty, then it is considered valid
 492          if (strlen($port) === 0) {
 493              return true;
 494          }
 495  
 496          // Check the port against the allowed values
 497          return ctype_digit((string) $port) and 1 <= $port and $port <= 65535;
 498      }
 499  
 500      /**
 501       * Sets the port for the current URI, and returns the old port
 502       *
 503       * @param  string $port The HTTP port
 504       * @throws Zend_Uri_Exception When $port is not a valid HTTP port
 505       * @return string
 506       */
 507      public function setPort($port)
 508      {
 509          if ($this->validatePort($port) === false) {
 510              require_once  'Zend/Uri/Exception.php';
 511              throw new Zend_Uri_Exception("Port \"$port\" is not a valid HTTP port.");
 512          }
 513  
 514          $oldPort     = $this->_port;
 515          $this->_port = $port;
 516  
 517          return $oldPort;
 518      }
 519  
 520      /**
 521       * Returns the path and filename portion of the URL.
 522       *
 523       * @return string
 524       */
 525      public function getPath()
 526      {
 527          return strlen($this->_path) > 0 ? $this->_path : '/';
 528      }
 529  
 530      /**
 531       * Returns true if and only if the path string passes validation. If no path is passed,
 532       * then the path contained in the instance variable is used.
 533       *
 534       * @param  string $path The HTTP path
 535       * @throws Zend_Uri_Exception When path validation fails
 536       * @return boolean
 537       */
 538      public function validatePath($path = null)
 539      {
 540          if ($path === null) {
 541              $path = $this->_path;
 542          }
 543  
 544          // If the path is empty, then it is considered valid
 545          if (strlen($path) === 0) {
 546              return true;
 547          }
 548  
 549          // Determine whether the path is well-formed
 550          $pattern = '/^' . $this->_regex['path'] . '$/';
 551          $status  = @preg_match($pattern, $path);
 552          if ($status === false) {
 553              require_once  'Zend/Uri/Exception.php';
 554              throw new Zend_Uri_Exception('Internal error: path validation failed');
 555          }
 556  
 557          return (boolean) $status;
 558      }
 559  
 560      /**
 561       * Sets the path for the current URI, and returns the old path
 562       *
 563       * @param  string $path The HTTP path
 564       * @throws Zend_Uri_Exception When $path is not a valid HTTP path
 565       * @return string
 566       */
 567      public function setPath($path)
 568      {
 569          if ($this->validatePath($path) === false) {
 570              require_once  'Zend/Uri/Exception.php';
 571              throw new Zend_Uri_Exception("Path \"$path\" is not a valid HTTP path");
 572          }
 573  
 574          $oldPath     = $this->_path;
 575          $this->_path = $path;
 576  
 577          return $oldPath;
 578      }
 579  
 580      /**
 581       * Returns the query portion of the URL (after ?), or FALSE if none.
 582       *
 583       * @return string
 584       */
 585      public function getQuery()
 586      {
 587          return strlen($this->_query) > 0 ? $this->_query : false;
 588      }
 589  
 590      /**
 591       * Returns the query portion of the URL (after ?) as a
 592       * key-value-array. If the query is empty an empty array
 593       * is returned
 594       *
 595       * @return array
 596       */
 597      public function getQueryAsArray()
 598      {
 599          $query = $this->getQuery();
 600          $querryArray = array();
 601          if ($query !== false) {
 602              parse_str($query, $querryArray);
 603          }
 604          return $querryArray;
 605      }
 606  
 607      /**
 608       * Returns true if and only if the query string passes validation. If no query is passed,
 609       * then the query string contained in the instance variable is used.
 610       *
 611       * @param  string $query The query to validate
 612       * @throws Zend_Uri_Exception When query validation fails
 613       * @return boolean
 614       * @link   http://www.faqs.org/rfcs/rfc2396.html
 615       */
 616      public function validateQuery($query = null)
 617      {
 618          if ($query === null) {
 619              $query = $this->_query;
 620          }
 621  
 622          // If query is empty, it is considered to be valid
 623          if (strlen($query) === 0) {
 624              return true;
 625          }
 626  
 627          // Determine whether the query is well-formed
 628          $pattern = '/^' . $this->_regex['uric'] . '*$/';
 629          $status  = @preg_match($pattern, $query);
 630          if ($status === false) {
 631              require_once  'Zend/Uri/Exception.php';
 632              throw new Zend_Uri_Exception('Internal error: query validation failed');
 633          }
 634  
 635          return $status == 1;
 636      }
 637  
 638      /**
 639       * Add or replace params in the query string for the current URI, and
 640       * return the old query.
 641       *
 642       * @param  array $queryParams
 643       * @return string Old query string
 644       */
 645      public function addReplaceQueryParameters(array $queryParams)
 646      {
 647          $queryParams = array_merge($this->getQueryAsArray(), $queryParams);
 648          return $this->setQuery($queryParams);
 649      }
 650  
 651      /**
 652       * Remove params in the query string for the current URI, and
 653       * return the old query.
 654       *
 655       * @param  array $queryParamKeys
 656       * @return string Old query string
 657       */
 658      public function removeQueryParameters(array $queryParamKeys)
 659      {
 660          $queryParams = array_diff_key($this->getQueryAsArray(), array_fill_keys($queryParamKeys, 0));
 661          return $this->setQuery($queryParams);
 662      }
 663  
 664      /**
 665       * Set the query string for the current URI, and return the old query
 666       * string This method accepts both strings and arrays.
 667       *
 668       * @param  string|array $query The query string or array
 669       * @throws Zend_Uri_Exception When $query is not a valid query string
 670       * @return string              Old query string
 671       */
 672      public function setQuery($query)
 673      {
 674          $oldQuery = $this->_query;
 675  
 676          // If query is empty, set an empty string
 677          if (empty($query) === true) {
 678              $this->_query = '';
 679              return $oldQuery;
 680          }
 681  
 682          // If query is an array, make a string out of it
 683          if (is_array($query) === true) {
 684              $query = http_build_query($query, '', '&');
 685          } else {
 686              // If it is a string, make sure it is valid. If not parse and encode it
 687              $query = (string) $query;
 688              if ($this->validateQuery($query) === false) {
 689                  parse_str($query, $queryArray);
 690                  $query = http_build_query($queryArray, '', '&');
 691              }
 692          }
 693  
 694          // Make sure the query is valid, and set it
 695          if ($this->validateQuery($query) === false) {
 696              require_once  'Zend/Uri/Exception.php';
 697              throw new Zend_Uri_Exception("'$query' is not a valid query string");
 698          }
 699  
 700          $this->_query = $query;
 701  
 702          return $oldQuery;
 703      }
 704  
 705      /**
 706       * Returns the fragment portion of the URL (after #), or FALSE if none.
 707       *
 708       * @return string|false
 709       */
 710      public function getFragment()
 711      {
 712          return strlen($this->_fragment) > 0 ? $this->_fragment : false;
 713      }
 714  
 715      /**
 716       * Returns true if and only if the fragment passes validation. If no fragment is passed,
 717       * then the fragment contained in the instance variable is used.
 718       *
 719       * @param  string $fragment Fragment of an URI
 720       * @throws Zend_Uri_Exception When fragment validation fails
 721       * @return boolean
 722       * @link   http://www.faqs.org/rfcs/rfc2396.html
 723       */
 724      public function validateFragment($fragment = null)
 725      {
 726          if ($fragment === null) {
 727              $fragment = $this->_fragment;
 728          }
 729  
 730          // If fragment is empty, it is considered to be valid
 731          if (strlen($fragment) === 0) {
 732              return true;
 733          }
 734  
 735          // Determine whether the fragment is well-formed
 736          $pattern = '/^' . $this->_regex['uric'] . '*$/';
 737          $status  = @preg_match($pattern, $fragment);
 738          if ($status === false) {
 739              require_once  'Zend/Uri/Exception.php';
 740              throw new Zend_Uri_Exception('Internal error: fragment validation failed');
 741          }
 742  
 743          return (boolean) $status;
 744      }
 745  
 746      /**
 747       * Sets the fragment for the current URI, and returns the old fragment
 748       *
 749       * @param  string $fragment Fragment of the current URI
 750       * @throws Zend_Uri_Exception When $fragment is not a valid HTTP fragment
 751       * @return string
 752       */
 753      public function setFragment($fragment)
 754      {
 755          if ($this->validateFragment($fragment) === false) {
 756              require_once  'Zend/Uri/Exception.php';
 757              throw new Zend_Uri_Exception("Fragment \"$fragment\" is not a valid HTTP fragment");
 758          }
 759  
 760          $oldFragment     = $this->_fragment;
 761          $this->_fragment = $fragment;
 762  
 763          return $oldFragment;
 764      }
 765  }