[Summary view] [Print] [Text view]

   1  <?php
   2  /**
   3   * Delayed loading of global objects.
   4   *
   5   * This program is free software; you can redistribute it and/or modify
   6   * it under the terms of the GNU General Public License as published by
   7   * the Free Software Foundation; either version 2 of the License, or
   8   * (at your option) any later version.
   9   *
  10   * This program is distributed in the hope that it will be useful,
  11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13   * GNU General Public License for more details.
  14   *
  15   * You should have received a copy of the GNU General Public License along
  16   * with this program; if not, write to the Free Software Foundation, Inc.,
  17   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18   * http://www.gnu.org/copyleft/gpl.html
  19   *
  20   * @file
  21   */
  22  
  23  /**
  24   * Class to implement stub globals, which are globals that delay loading the
  25   * their associated module code by deferring initialisation until the first
  26   * method call.
  27   *
  28   * Note on reference parameters:
  29   *
  30   * If the called method takes any parameters by reference, the __call magic
  31   * here won't work correctly. The solution is to unstub the object before
  32   * calling the method.
  33   *
  34   * Note on unstub loops:
  35   *
  36   * Unstub loops (infinite recursion) sometimes occur when a constructor calls
  37   * another function, and the other function calls some method of the stub. The
  38   * best way to avoid this is to make constructors as lightweight as possible,
  39   * deferring any initialisation which depends on other modules. As a last
  40   * resort, you can use StubObject::isRealObject() to break the loop, but as a
  41   * general rule, the stub object mechanism should be transparent, and code
  42   * which refers to it should be kept to a minimum.
  43   */
  44  class StubObject {
  45      /** @var null|string */
  46      protected $global;
  47  
  48      /** @var null|string */
  49      protected $class;
  50  
  51      /** @var array */
  52      protected $params;
  53  
  54      /**
  55       * Constructor.
  56       *
  57       * @param string $global Name of the global variable.
  58       * @param string $class Name of the class of the real object.
  59       * @param array $params Parameters to pass to constructor of the real object.
  60       */
  61  	public function __construct( $global = null, $class = null, $params = array() ) {
  62          $this->global = $global;
  63          $this->class = $class;
  64          $this->params = $params;
  65      }
  66  
  67      /**
  68       * Returns a bool value whenever $obj is a stub object. Can be used to break
  69       * a infinite loop when unstubbing an object.
  70       *
  71       * @param object $obj Object to check.
  72       * @return bool True if $obj is not an instance of StubObject class.
  73       */
  74  	public static function isRealObject( $obj ) {
  75          return is_object( $obj ) && !$obj instanceof StubObject;
  76      }
  77  
  78      /**
  79       * Unstubs an object, if it is a stub object. Can be used to break a
  80       * infinite loop when unstubbing an object or to avoid reference parameter
  81       * breakage.
  82       *
  83       * @param object $obj Object to check.
  84       * @return void
  85       */
  86  	public static function unstub( &$obj ) {
  87          if ( $obj instanceof StubObject ) {
  88              $obj = $obj->_unstub( 'unstub', 3 );
  89          }
  90      }
  91  
  92      /**
  93       * Function called if any function exists with that name in this object.
  94       * It is used to unstub the object. Only used internally, PHP will call
  95       * self::__call() function and that function will call this function.
  96       * This function will also call the function with the same name in the real
  97       * object.
  98       *
  99       * @param string $name Name of the function called
 100       * @param array $args Arguments
 101       * @return mixed
 102       */
 103  	public function _call( $name, $args ) {
 104          $this->_unstub( $name, 5 );
 105          return call_user_func_array( array( $GLOBALS[$this->global], $name ), $args );
 106      }
 107  
 108      /**
 109       * Create a new object to replace this stub object.
 110       * @return object
 111       */
 112  	public function _newObject() {
 113          return MWFunction::newObj( $this->class, $this->params );
 114      }
 115  
 116      /**
 117       * Function called by PHP if no function with that name exists in this
 118       * object.
 119       *
 120       * @param string $name Name of the function called
 121       * @param array $args Arguments
 122       * @return mixed
 123       */
 124  	public function __call( $name, $args ) {
 125          return $this->_call( $name, $args );
 126      }
 127  
 128      /**
 129       * This function creates a new object of the real class and replace it in
 130       * the global variable.
 131       * This is public, for the convenience of external callers wishing to access
 132       * properties, e.g. eval.php
 133       *
 134       * @param string $name Name of the method called in this object.
 135       * @param int $level Level to go in the stack trace to get the function
 136       *   who called this function.
 137       * @return object The unstubbed version of itself
 138       * @throws MWException
 139       */
 140  	public function _unstub( $name = '_unstub', $level = 2 ) {
 141          static $recursionLevel = 0;
 142  
 143          if ( !$GLOBALS[$this->global] instanceof StubObject ) {
 144              return $GLOBALS[$this->global]; // already unstubbed.
 145          }
 146  
 147          if ( get_class( $GLOBALS[$this->global] ) != $this->class ) {
 148              $fname = __METHOD__ . '-' . $this->global;
 149              wfProfileIn( $fname );
 150              $caller = wfGetCaller( $level );
 151              if ( ++$recursionLevel > 2 ) {
 152                  wfProfileOut( $fname );
 153                  throw new MWException( "Unstub loop detected on call of "
 154                      . "\${$this->global}->$name from $caller\n" );
 155              }
 156              wfDebug( "Unstubbing \${$this->global} on call of "
 157                  . "\${$this->global}::$name from $caller\n" );
 158              $GLOBALS[$this->global] = $this->_newObject();
 159              --$recursionLevel;
 160              wfProfileOut( $fname );
 161              return $GLOBALS[$this->global];
 162          }
 163      }
 164  }
 165  
 166  /**
 167   * Stub object for the user language. It depends of the user preferences and
 168   * "uselang" parameter that can be passed to index.php. This object have to be
 169   * in $wgLang global.
 170   */
 171  class StubUserLang extends StubObject {
 172  
 173  	public function __construct() {
 174          parent::__construct( 'wgLang' );
 175      }
 176  
 177  	public function __call( $name, $args ) {
 178          return $this->_call( $name, $args );
 179      }
 180  
 181      /**
 182       * @return Language
 183       */
 184  	public function _newObject() {
 185          return RequestContext::getMain()->getLanguage();
 186      }
 187  }