includes/StubObject.php

   1 <?php
   2
   3 /**
   4  * Class to implement stub globals, which are globals that delay loading the
   5  * their associated module code by deferring initialisation until the first
   6  * method call.
   7  *
   8  * Note on unstub loops:
   9  *
  10  * Unstub loops (infinite recursion) sometimes occur when a constructor calls
  11  * another function, and the other function calls some method of the stub. The
  12  * best way to avoid this is to make constructors as lightweight as possible,
  13  * deferring any initialisation which depends on other modules. As a last
  14  * resort, you can use StubObject::isRealObject() to break the loop, but as a
  15  * general rule, the stub object mechanism should be transparent, and code
  16  * which refers to it should be kept to a minimum.
  17  */
  18 class StubObject {
  19         var $mGlobal, $mClass, $mParams;
  20
  21         /**
  22          * Constructor.
  23          *
  24          * @param $global String: name of the global variable.
  25          * @param $class String: name of the class of the real object.
  26          * @param $params Array: parameters to pass to contructor of the real
  27          *               object.
  28          */
  29         function __construct( $global = null, $class = null, $params = array() ) {
  30                 $this->mGlobal = $global;
  31                 $this->mClass = $class;
  32                 $this->mParams = $params;
  33         }
  34
  35         /**
  36          * Returns a bool value whetever $obj is a stub object. Can be used to break
  37          * a infinite loop when unstubbing an object.
  38          *
  39          * @param $obj Object to check.
  40          * @return Boolean: true if $obj is not an instance of StubObject class.
  41          */
  42         static function isRealObject( $obj ) {
  43                 return is_object( $obj ) && !($obj instanceof StubObject);
  44         }
  45
  46         /**
  47          * Function called if any function exists with that name in this object.
  48          * It is used to unstub the object. Only used internally, PHP will call
  49          * self::__call() function and that function will call this function.
  50          * This function will also call the function with the same name in the real
  51          * object.
  52          *
  53          * @param $name String: name of the function called
  54          * @param $args Array: arguments
  55          */
  56         function _call( $name, $args ) {
  57                 $this->_unstub( $name, 5 );
  58                 return call_user_func_array( array( $GLOBALS[$this->mGlobal], $name ), $args );
  59         }
  60
  61         /**
  62          * Create a new object to replace this stub object.
  63          */
  64         function _newObject() {
  65                 return MWFunction::newObj( $this->mClass, $this->mParams );
  66         }
  67
  68         /**
  69          * Function called by PHP if no function with that name exists in this
  70          * object.
  71          *
  72          * @param $name String: name of the function called
  73          * @param $args Array: arguments
  74          */
  75         function __call( $name, $args ) {
  76                 return $this->_call( $name, $args );
  77         }
  78
  79         /**
  80          * This function creates a new object of the real class and replace it in
  81          * the global variable.
  82          * This is public, for the convenience of external callers wishing to access
  83          * properties, e.g. eval.php
  84          *
  85          * @param $name String: name of the method called in this object.
  86          * @param $level Integer: level to go in the stact trace to get the function
  87          *               who called this function.
  88          */
  89         function _unstub( $name = '_unstub', $level = 2 ) {
  90                 static $recursionLevel = 0;
  91
  92                 if ( !($GLOBALS[$this->mGlobal] instanceof StubObject) )
  93                         return $GLOBALS[$this->mGlobal]; // already unstubbed.
  94
  95                 if ( get_class( $GLOBALS[$this->mGlobal] ) != $this->mClass ) {
  96                         $fname = __METHOD__.'-'.$this->mGlobal;
  97                         wfProfileIn( $fname );
  98                         $caller = wfGetCaller( $level );
  99                         if ( ++$recursionLevel > 2 ) {
 100                                 throw new MWException( "Unstub loop detected on call of \${$this->mGlobal}->$name from $caller\n" );
 101                         }
 102                         wfDebug( "Unstubbing \${$this->mGlobal} on call of \${$this->mGlobal}::$name from $caller\n" );
 103                         $GLOBALS[$this->mGlobal] = $this->_newObject();
 104                         --$recursionLevel;
 105                         wfProfileOut( $fname );
 106                 }
 107         }
 108 }
 109
 110 /**
 111  * Stub object for the content language of this wiki. This object have to be in
 112  * $wgContLang global.
 113  *
 114  * @deprecated since 1.18
 115  */
 116 class StubContLang extends StubObject {
 117
 118         function __construct() {
 119                 parent::__construct( 'wgContLang' );
 120         }
 121
 122         function __call( $name, $args ) {
 123                 return $this->_call( $name, $args );
 124         }
 125
 126         function _newObject() {
 127                 global $wgLanguageCode;
 128                 $obj = Language::factory( $wgLanguageCode );
 129                 $obj->initEncoding();
 130                 $obj->initContLang();
 131                 return $obj;
 132         }
 133 }
 134
 135 /**
 136  * Stub object for the user language. It depends of the user preferences and
 137  * "uselang" parameter that can be passed to index.php. This object have to be
 138  * in $wgLang global.
 139  */
 140 class StubUserLang extends StubObject {
 141
 142         function __construct() {
 143                 parent::__construct( 'wgLang' );
 144         }
 145
 146         function __call( $name, $args ) {
 147                 return $this->_call( $name, $args );
 148         }
 149
 150         function _newObject() {
 151                 return RequestContext::getMain()->getLang();
 152         }
 153 }