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[mediawiki.git] / includes / SpecialPage.php

<?php
/**
 * SpecialPage: handling special pages and lists thereof.
 *
 * To add a special page in an extension, add to $wgSpecialPages either 
 * an object instance or an array containing the name and constructor 
 * parameters. The latter is preferred for performance reasons. 
 *
 * The object instantiated must be either an instance of SpecialPage or a 
 * sub-class thereof. It must have an execute() method, which sends the HTML 
 * for the special page to $wgOut. The parent class has an execute() method 
 * which distributes the call to the historical global functions. Additionally, 
 * execute() also checks if the user has the necessary access privileges 
 * and bails out if not.
 *
 * To add a core special page, use the similar static list in 
 * SpecialPage::$mList. To remove a core static special page at runtime, use
 * a SpecialPage_initList hook.
 *
 * @addtogroup SpecialPage
 */

/**
 * @access private
 */

/**
 * Parent special page class, also static functions for handling the special
 * page list.
 * @addtogroup SpecialPage
 */
class SpecialPage
{
        /**#@+
         * @access private
         */
        /**
         * The canonical name of this special page
         * Also used for the default <h1> heading, @see getDescription()
         */
        var $mName;
        /**
         * The local name of this special page
         */
        var $mLocalName;
        /**
         * Minimum user level required to access this page, or "" for anyone.
         * Also used to categorise the pages in Special:Specialpages
         */
        var $mRestriction;
        /**
         * Listed in Special:Specialpages?
         */
        var $mListed;
        /**
         * Function name called by the default execute()
         */
        var $mFunction;
        /**
         * File which needs to be included before the function above can be called
         */
        var $mFile;
        /**
         * Whether or not this special page is being included from an article
         */
        var $mIncluding;
        /**
         * Whether the special page can be included in an article
         */
        var $mIncludable;
        /**
         * Query parameters that can be passed through redirects
         */
        var $mAllowedRedirectParams = array();

        static public $mList = array(
                'DoubleRedirects'           => array( 'SpecialPage', 'DoubleRedirects' ),
                'BrokenRedirects'           => array( 'SpecialPage', 'BrokenRedirects' ),
                'Disambiguations'           => array( 'SpecialPage', 'Disambiguations' ),

                'Userlogin'                 => array( 'SpecialPage', 'Userlogin' ),
                'Userlogout'                => array( 'UnlistedSpecialPage', 'Userlogout' ),
                'CreateAccount'             => array( 'SpecialRedirectToSpecial', 'CreateAccount', 'Userlogin', 'signup', array( 'uselang' ) ),
                'Preferences'               => array( 'SpecialPage', 'Preferences' ),
                'Watchlist'                 => array( 'SpecialPage', 'Watchlist' ),

                'Recentchanges'             => array( 'IncludableSpecialPage', 'Recentchanges' ),
                'Upload'                    => array( 'SpecialPage', 'Upload' ),
                'Imagelist'                 => array( 'SpecialPage', 'Imagelist' ),
                'Newimages'                 => array( 'IncludableSpecialPage', 'Newimages' ),
                'Listusers'                 => array( 'SpecialPage', 'Listusers' ),
                'Statistics'                => array( 'SpecialPage', 'Statistics' ),
                'Randompage'                => 'Randompage',
                'Lonelypages'               => array( 'SpecialPage', 'Lonelypages' ),
                'Uncategorizedpages'        => array( 'SpecialPage', 'Uncategorizedpages' ),
                'Uncategorizedcategories'   => array( 'SpecialPage', 'Uncategorizedcategories' ),
                'Uncategorizedimages'       => array( 'SpecialPage', 'Uncategorizedimages' ),
                'Uncategorizedtemplates'    => array( 'SpecialPage', 'Uncategorizedtemplates' ),
                'Unusedcategories'          => array( 'SpecialPage', 'Unusedcategories' ),
                'Unusedimages'              => array( 'SpecialPage', 'Unusedimages' ),
                'Wantedpages'               => array( 'IncludableSpecialPage', 'Wantedpages' ),
                'Wantedcategories'          => array( 'SpecialPage', 'Wantedcategories' ),
                'Mostlinked'                => array( 'SpecialPage', 'Mostlinked' ),
                'Mostlinkedcategories'      => array( 'SpecialPage', 'Mostlinkedcategories' ),
                'Mostlinkedtemplates'       => array( 'SpecialPage', 'Mostlinkedtemplates' ),
                'Mostcategories'            => array( 'SpecialPage', 'Mostcategories' ),
                'Mostimages'                => array( 'SpecialPage', 'Mostimages' ),
                'Mostrevisions'             => array( 'SpecialPage', 'Mostrevisions' ),
                'Fewestrevisions'           => array( 'SpecialPage', 'Fewestrevisions' ),
                'Shortpages'                => array( 'SpecialPage', 'Shortpages' ),
                'Longpages'                 => array( 'SpecialPage', 'Longpages' ),
                'Newpages'                  => array( 'IncludableSpecialPage', 'Newpages' ),
                'Ancientpages'              => array( 'SpecialPage', 'Ancientpages' ),
                'Deadendpages'              => array( 'SpecialPage', 'Deadendpages' ),
                'Protectedpages'            => array( 'SpecialPage', 'Protectedpages' ),
                'Protectedtitles'           => array( 'SpecialPage', 'Protectedtitles' ),
                'Allpages'                  => array( 'IncludableSpecialPage', 'Allpages' ),
                'Prefixindex'               => array( 'IncludableSpecialPage', 'Prefixindex' ) ,
                'Ipblocklist'               => array( 'SpecialPage', 'Ipblocklist' ),
                'Specialpages'              => array( 'UnlistedSpecialPage', 'Specialpages' ),
                'Contributions'             => array( 'SpecialPage', 'Contributions' ),
                'Emailuser'                 => array( 'UnlistedSpecialPage', 'Emailuser' ),
                'Whatlinkshere'             => array( 'SpecialPage', 'Whatlinkshere' ),
                'Recentchangeslinked'       => array( 'UnlistedSpecialPage', 'Recentchangeslinked' ),
                'Movepage'                  => array( 'UnlistedSpecialPage', 'Movepage' ),
                'Blockme'                   => array( 'UnlistedSpecialPage', 'Blockme' ),
                'Resetpass'                 => array( 'UnlistedSpecialPage', 'Resetpass' ),
                'Booksources'               => 'SpecialBookSources',
                'Categories'                => array( 'SpecialPage', 'Categories' ),
                'Export'                    => array( 'SpecialPage', 'Export' ),
                'Version'                   => array( 'SpecialPage', 'Version' ),
                'Allmessages'               => array( 'SpecialPage', 'Allmessages' ),
                'Log'                       => array( 'SpecialPage', 'Log' ),
                'Blockip'                   => array( 'SpecialPage', 'Blockip', 'block' ),
                'Undelete'                  => array( 'SpecialPage', 'Undelete', 'deletedhistory' ),
                'Import'                    => array( 'SpecialPage', 'Import', 'import' ),
                'Lockdb'                    => array( 'SpecialPage', 'Lockdb', 'siteadmin' ),
                'Unlockdb'                  => array( 'SpecialPage', 'Unlockdb', 'siteadmin' ),
                'Userrights'                => 'UserrightsPage',
                'MIMEsearch'                => array( 'SpecialPage', 'MIMEsearch' ),
                'Unwatchedpages'            => array( 'SpecialPage', 'Unwatchedpages', 'unwatchedpages' ),
                'Listredirects'             => array( 'SpecialPage', 'Listredirects' ),
                'Revisiondelete'            => array( 'UnlistedSpecialPage', 'Revisiondelete', 'deleterevision' ),
                'Unusedtemplates'           => array( 'SpecialPage', 'Unusedtemplates' ),
                'Randomredirect'            => 'SpecialRandomredirect',
                'Withoutinterwiki'          => array( 'SpecialPage', 'Withoutinterwiki' ),
                'Filepath'                  => array( 'SpecialPage', 'Filepath' ),

                'Mypage'                    => array( 'SpecialMypage' ),
                'Mytalk'                    => array( 'SpecialMytalk' ),
                'Mycontributions'           => array( 'SpecialMycontributions' ),
                'Listadmins'                => array( 'SpecialRedirectToSpecial', 'Listadmins', 'Listusers', 'sysop' ),
                'MergeHistory'              => array( 'SpecialPage', 'MergeHistory', 'mergehistory' ),
                'Listbots'                  => array( 'SpecialRedirectToSpecial', 'Listbots', 'Listusers', 'bot' ),
                );

        static public $mAliases;
        static public $mListInitialised = false;

        /**#@-*/

        /**
         * Initialise the special page list
         * This must be called before accessing SpecialPage::$mList
         */
        static function initList() {
                global $wgSpecialPages;
                global $wgDisableCounters, $wgDisableInternalSearch, $wgEmailAuthentication;

                if ( self::$mListInitialised ) {
                        return;
                }
                wfProfileIn( __METHOD__ );
                
                # Better to set this now, to avoid infinite recursion in carelessly written hooks
                self::$mListInitialised = true;

                if( !$wgDisableCounters ) {
                        self::$mList['Popularpages'] = array( 'SpecialPage', 'Popularpages' );
                }

                if( !$wgDisableInternalSearch ) {
                        self::$mList['Search'] = array( 'SpecialPage', 'Search' );
                }

                if( $wgEmailAuthentication ) {
                        self::$mList['Confirmemail'] = 'EmailConfirmation';
                }

                # Add extension special pages
                self::$mList = array_merge( self::$mList, $wgSpecialPages );

                # Run hooks
                # This hook can be used to remove undesired built-in special pages
                wfRunHooks( 'SpecialPage_initList', array( &self::$mList ) );
                wfProfileOut( __METHOD__ );
        }

        static function initAliasList() {
                if ( !is_null( self::$mAliases ) ) {
                        return;
                }

                global $wgContLang;
                $aliases = $wgContLang->getSpecialPageAliases();
                $missingPages = self::$mList;
                self::$mAliases = array();
                foreach ( $aliases as $realName => $aliasList ) {
                        foreach ( $aliasList as $alias ) {
                                self::$mAliases[$wgContLang->caseFold( $alias )] = $realName;
                        }
                        unset( $missingPages[$realName] );
                }
                foreach ( $missingPages as $name => $stuff ) {
                        self::$mAliases[$wgContLang->caseFold( $name )] = $name;
                }
        }

        /**
         * Given a special page alias, return the special page name.
         * Returns false if there is no such alias.
         */
        static function resolveAlias( $alias ) {
                global $wgContLang;

                if ( !self::$mListInitialised ) self::initList();
                if ( is_null( self::$mAliases ) ) self::initAliasList();
                $caseFoldedAlias = $wgContLang->caseFold( $alias );
                if ( isset( self::$mAliases[$caseFoldedAlias] ) ) {
                        return self::$mAliases[$caseFoldedAlias];
                } else {
                        return false;
                }
        }

        /**
         * Given a special page name with a possible subpage, return an array 
         * where the first element is the special page name and the second is the
         * subpage.
         */
        static function resolveAliasWithSubpage( $alias ) {
                $bits = explode( '/', $alias, 2 );
                $name = self::resolveAlias( $bits[0] );
                if( !isset( $bits[1] ) ) { // bug 2087
                        $par = NULL;
                } else {
                        $par = $bits[1];
                }
                return array( $name, $par );
        }

        /**
         * Add a page to the list of valid special pages. This used to be the preferred 
         * method for adding special pages in extensions. It's now suggested that you add 
         * an associative record to $wgSpecialPages. This avoids autoloading SpecialPage.
         *
         * @param mixed $page Must either be an array specifying a class name and 
         *                    constructor parameters, or an object. The object,
         *                    when constructed, must have an execute() method which
         *                    sends HTML to $wgOut.
         * @static
         */
        static function addPage( &$page ) {
                if ( !self::$mListInitialised ) {
                        self::initList();
                }
                self::$mList[$page->mName] = $page;
        }

        /**
         * Remove a special page from the list
         * Formerly used to disable expensive or dangerous special pages. The 
         * preferred method is now to add a SpecialPage_initList hook.
         * 
         * @static
         */
        static function removePage( $name ) {
                if ( !self::$mListInitialised ) {
                        self::initList();
                }
                unset( self::$mList[$name] );
        }

        /**
         * Check if a given name exist as a special page or as a special page alias
         * @param $name string: name of a special page
         * @return boolean: true if a special page exists with this name
         */
        static function exists( $name ) {
                global $wgContLang;
                if ( !self::$mListInitialised ) {
                        self::initList();
                }
                if( !self::$mAliases ) {
                        self::initAliasList();
                }

                # Remove special pages inline parameters:
                $bits = explode( '/', $name );
                $name = $wgContLang->caseFold($bits[0]);

                return
                        array_key_exists( $name, self::$mList )
                        or array_key_exists( $name, self::$mAliases )
                ;
        }

        /**
         * Find the object with a given name and return it (or NULL)
         * @static
         * @param string $name
         */
        static function getPage( $name ) {
                if ( !self::$mListInitialised ) {
                        self::initList();
                }
                if ( array_key_exists( $name, self::$mList ) ) {
                        $rec = self::$mList[$name];
                        if ( is_string( $rec ) ) {
                                $className = $rec;
                                self::$mList[$name] = new $className;
                        } elseif ( is_array( $rec ) ) {
                                $className = array_shift( $rec );
                                self::$mList[$name] = wfCreateObject( $className, $rec );
                        }
                        return self::$mList[$name];
                } else {
                        return NULL;
                }
        }

        /**
         * Get a special page with a given localised name, or NULL if there
         * is no such special page.
         */
        static function getPageByAlias( $alias ) {
                $realName = self::resolveAlias( $alias );
                if ( $realName ) {
                        return self::getPage( $realName );
                } else {
                        return NULL;
                }
        }

        /**
         * Return categorised listable special pages for all users
         * @static
         */
        static function getRegularPages() {
                if ( !self::$mListInitialised ) {
                        self::initList();
                }
                $pages = array();

                foreach ( self::$mList as $name => $rec ) {
                        $page = self::getPage( $name );
                        if ( $page->isListed() && !$page->isRestricted() ) {
                                $pages[$name] = $page;
                        }
                }
                return $pages;
        }

        /**
         * Return categorised listable special pages which are available
         * for the current user, but not for everyone
         * @static
         */
        static function getRestrictedPages() {
                global $wgUser;
                if ( !self::$mListInitialised ) {
                        self::initList();
                }
                $pages = array();

                foreach ( self::$mList as $name => $rec ) {
                        $page = self::getPage( $name );
                        if (
                                $page->isListed()
                                and $page->isRestricted()
                                and $page->userCanExecute( $wgUser )
                        ) {
                                $pages[$name] = $page;
                        }
                }
                return $pages;
        }

        /**
         * Execute a special page path.
         * The path     may contain parameters, e.g. Special:Name/Params
         * Extracts the special page name and call the execute method, passing the parameters
         *
         * Returns a title object if the page is redirected, false if there was no such special
         * page, and true if it was successful.
         *
         * @param $title          a title object
         * @param $including      output is being captured for use in {{special:whatever}}
         */
        static function executePath( &$title, $including = false ) {
                global $wgOut, $wgTitle, $wgRequest;
                wfProfileIn( __METHOD__ );

                # FIXME: redirects broken due to this call
                $bits = explode( '/', $title->getDBkey(), 2 );
                $name = $bits[0];
                if( !isset( $bits[1] ) ) { // bug 2087
                        $par = NULL;
                } else {
                        $par = $bits[1];
                }
                $page = SpecialPage::getPageByAlias( $name );
                # Nonexistent?
                if ( !$page ) {
                        if ( !$including ) {
                                $wgOut->setArticleRelated( false );
                                $wgOut->setRobotpolicy( 'noindex,nofollow' );
                                $wgOut->setStatusCode( 404 );
                                $wgOut->showErrorPage( 'nosuchspecialpage', 'nospecialpagetext' );
                        }
                        wfProfileOut( __METHOD__ );
                        return false;
                }

                # Check for redirect
                if ( !$including ) {
                        $redirect = $page->getRedirect( $par );
                        if ( $redirect ) {
                                $query = $page->getRedirectQuery();
                                $url = $redirect->getFullUrl( $query );
                                $wgOut->redirect( $url );
                                wfProfileOut( __METHOD__ );
                                return $redirect;
                        }
                }

                # Redirect to canonical alias for GET commands
                # Not for POST, we'd lose the post data, so it's best to just distribute 
                # the request. Such POST requests are possible for old extensions that 
                # generate self-links without being aware that their default name has 
                # changed.
                if ( !$including && $name != $page->getLocalName() && !$wgRequest->wasPosted() ) {
                        $query = $_GET;
                        unset( $query['title'] );
                        $query = wfArrayToCGI( $query );
                        $title = $page->getTitle( $par );
                        $url = $title->getFullUrl( $query );
                        $wgOut->redirect( $url );
                        wfProfileOut( __METHOD__ );
                        return $redirect;
                }

                if ( $including && !$page->includable() ) {
                        wfProfileOut( __METHOD__ );
                        return false;
                } elseif ( !$including ) {
                        $wgTitle = $page->getTitle();
                }
                $page->including( $including );

                // Execute special page
                $profName = 'Special:' . $page->getName();
                wfProfileIn( $profName );
                $page->execute( $par );
                wfProfileOut( $profName );
                wfProfileOut( __METHOD__ );
                return true;
        }

        /**
         * Just like executePath() except it returns the HTML instead of outputting it
         * Returns false if there was no such special page, or a title object if it was
         * a redirect.
         * @static
         */
        static function capturePath( &$title ) {
                global $wgOut, $wgTitle;

                $oldTitle = $wgTitle;
                $oldOut = $wgOut;
                $wgOut = new OutputPage;

                $ret = SpecialPage::executePath( $title, true );
                if ( $ret === true ) {
                        $ret = $wgOut->getHTML();
                }
                $wgTitle = $oldTitle;
                $wgOut = $oldOut;
                return $ret;
        }

        /**
         * Get the local name for a specified canonical name
         *
         * @param $name
         * @param mixed $subpage Boolean false, or string
         *
         * @return string
         */
        static function getLocalNameFor( $name, $subpage = false ) {
                global $wgContLang;
                $aliases = $wgContLang->getSpecialPageAliases();
                if ( isset( $aliases[$name][0] ) ) {
                        $name = $aliases[$name][0];
                }
                if ( $subpage !== false && !is_null( $subpage ) ) {
                        $name = "$name/$subpage";
                }
                return $name;
        }

        /**
         * Get a localised Title object for a specified special page name
         */
        static function getTitleFor( $name, $subpage = false ) {
                $name = self::getLocalNameFor( $name, $subpage );
                if ( $name ) {
                        return Title::makeTitle( NS_SPECIAL, $name );
                } else {
                        throw new MWException( "Invalid special page name \"$name\"" );
                }
        }

        /**
         * Get a localised Title object for a page name with a possibly unvalidated subpage
         */
        static function getSafeTitleFor( $name, $subpage = false ) {
                $name = self::getLocalNameFor( $name, $subpage );
                if ( $name ) {
                        return Title::makeTitleSafe( NS_SPECIAL, $name );
                } else {
                        return null;
                }
        }

        /**
         * Get a title for a given alias
         * @return Title or null if there is no such alias
         */
        static function getTitleForAlias( $alias ) {
                $name = self::resolveAlias( $alias );
                if ( $name ) {
                        return self::getTitleFor( $name );
                } else {
                        return null;
                }
        }

        /**
         * Default constructor for special pages
         * Derivative classes should call this from their constructor
         *     Note that if the user does not have the required level, an error message will
         *     be displayed by the default execute() method, without the global function ever
         *     being called.
         *
         *     If you override execute(), you can recover the default behaviour with userCanExecute()
         *     and displayRestrictionError()
         *
         * @param string $name Name of the special page, as seen in links and URLs
         * @param string $restriction User right required, e.g. "block" or "delete"
         * @param boolean $listed Whether the page is listed in Special:Specialpages
         * @param string $function Function called by execute(). By default it is constructed from $name
         * @param string $file File which is included by execute(). It is also constructed from $name by default
         */
        function SpecialPage( $name = '', $restriction = '', $listed = true, $function = false, $file = 'default', $includable = false ) {
                $this->mName = $name;
                $this->mRestriction = $restriction;
                $this->mListed = $listed;
                $this->mIncludable = $includable;
                if ( $function == false ) {
                        $this->mFunction = 'wfSpecial'.$name;
                } else {
                        $this->mFunction = $function;
                }
                if ( $file === 'default' ) {
                        $this->mFile = dirname(__FILE__) . "/Special{$name}.php";
                } else {
                        $this->mFile = $file;
                }
        }

        /**#@+
          * Accessor
          *
          * @deprecated
          */
        function getName() { return $this->mName; }
        function getRestriction() { return $this->mRestriction; }
        function getFile() { return $this->mFile; }
        function isListed() { return $this->mListed; }
        /**#@-*/

        /**#@+
          * Accessor and mutator
          */
        function name( $x = NULL ) { return wfSetVar( $this->mName, $x ); }
        function restrictions( $x = NULL) { return wfSetVar( $this->mRestrictions, $x ); }
        function listed( $x = NULL) { return wfSetVar( $this->mListed, $x ); }
        function func( $x = NULL) { return wfSetVar( $this->mFunction, $x ); }
        function file( $x = NULL) { return wfSetVar( $this->mFile, $x ); }
        function includable( $x = NULL ) { return wfSetVar( $this->mIncludable, $x ); }
        function including( $x = NULL ) { return wfSetVar( $this->mIncluding, $x ); }
        /**#@-*/

        /**
         * Get the localised name of the special page
         */
        function getLocalName() {
                if ( !isset( $this->mLocalName ) ) {
                        $this->mLocalName = self::getLocalNameFor( $this->mName );
                }
                return $this->mLocalName;
        }

        /**
         * Can be overridden by subclasses with more complicated permissions
         * schemes.
         *
         * @return bool Should the page be displayed with the restricted-access
         *   pages?
         */
        public function isRestricted() {
                return $this->mRestriction != '';
        }

        /**
         * Checks if the given user (identified by an object) can execute this
         * special page (as defined by $mRestriction).  Can be overridden by sub-
         * classes with more complicated permissions schemes.
         *
         * @param User $user The user to check
         * @return bool Does the user have permission to view the page?
         */
        public function userCanExecute( $user ) {
                return $user->isAllowed( $this->mRestriction );
        }

        /**
         * Output an error message telling the user what access level they have to have
         */
        function displayRestrictionError() {
                global $wgOut;
                $wgOut->permissionRequired( $this->mRestriction );
        }

        /**
         * Sets headers - this should be called from the execute() method of all derived classes!
         */
        function setHeaders() {
                global $wgOut;
                $wgOut->setArticleRelated( false );
                $wgOut->setRobotPolicy( "noindex,nofollow" );
                $wgOut->setPageTitle( $this->getDescription() );
        }

        /**
         * Default execute method
         * Checks user permissions, calls the function given in mFunction
         *
         * This may be overridden by subclasses. 
         */
        function execute( $par ) {
                global $wgUser;

                $this->setHeaders();

                if ( $this->userCanExecute( $wgUser ) ) {
                        $func = $this->mFunction;
                        // only load file if the function does not exist
                        if(!is_callable($func) and $this->mFile) {
                                require_once( $this->mFile );
                        }
                        # FIXME: these hooks are broken for extensions and anything else that subclasses SpecialPage. 
                        if ( wfRunHooks( 'SpecialPageExecuteBeforeHeader', array( &$this, &$par, &$func ) ) )
                                $this->outputHeader();
                        if ( ! wfRunHooks( 'SpecialPageExecuteBeforePage', array( &$this, &$par, &$func ) ) )
                                return;
                        call_user_func( $func, $par, $this );
                        if ( ! wfRunHooks( 'SpecialPageExecuteAfterPage', array( &$this, &$par, &$func ) ) )
                                return;
                } else {
                        $this->displayRestrictionError();
                }
        }

        function outputHeader() {
                global $wgOut, $wgContLang;

                $msg = $wgContLang->lc( $this->name() ) . '-summary';
                $out = wfMsgNoTrans( $msg );
                if ( ! wfEmptyMsg( $msg, $out ) and  $out !== '' and ! $this->including() ) {
                        $wgOut->addWikiText( $out );
                }

        }

        # Returns the name that goes in the <h1> in the special page itself, and also the name that
        # will be listed in Special:Specialpages
        #
        # Derived classes can override this, but usually it is easier to keep the default behaviour.
        # Messages can be added at run-time, see MessageCache.php
        function getDescription() {
                return wfMsg( strtolower( $this->mName ) );
        }

        /**
         * Get a self-referential title object
         */
        function getTitle( $subpage = false) {
                return self::getTitleFor( $this->mName, $subpage );
        }

        /**
         * Set whether this page is listed in Special:Specialpages, at run-time
         */
        function setListed( $listed ) {
                return wfSetVar( $this->mListed, $listed );
        }

        /**
         * If the special page is a redirect, then get the Title object it redirects to. 
         * False otherwise.
         */
        function getRedirect( $subpage ) {
                return false;
        }

        /**
         * Return part of the request string for a special redirect page
         * This allows passing, e.g. action=history to Special:Mypage, etc.
         *
         * @return string
         */
        function getRedirectQuery() {
                global $wgRequest;
                $params = array();
                foreach( $this->mAllowedRedirectParams as $arg ) {
                        if( $val = $wgRequest->getVal( $arg, false ) )
                                $params[] = $arg . '=' . $val;
                }
                
                return count( $params ) ? implode( '&', $params ) : false;
        }
}

/**
 * Shortcut to construct a special page which is unlisted by default
 * @addtogroup SpecialPage
 */
class UnlistedSpecialPage extends SpecialPage
{
        function UnlistedSpecialPage( $name, $restriction = '', $function = false, $file = 'default' ) {
                SpecialPage::SpecialPage( $name, $restriction, false, $function, $file );
        }
}

/**
 * Shortcut to construct an includable special  page
 * @addtogroup SpecialPage
 */
class IncludableSpecialPage extends SpecialPage
{
        function IncludableSpecialPage( $name, $restriction = '', $listed = true, $function = false, $file = 'default' ) {
                SpecialPage::SpecialPage( $name, $restriction, $listed, $function, $file, true );
        }
}

/**
 * Shortcut to construct a special page alias.
 * @addtogroup SpecialPage
 */
class SpecialRedirectToSpecial extends UnlistedSpecialPage {
        var $redirName, $redirSubpage;

        function __construct( $name, $redirName, $redirSubpage = false, $redirectParams = array() ) {
                parent::__construct( $name );
                $this->redirName = $redirName;
                $this->redirSubpage = $redirSubpage;
                $this->mAllowedRedirectParams = $redirectParams;
        }

        function getRedirect( $subpage ) {
                if ( $this->redirSubpage === false ) {
                        return SpecialPage::getTitleFor( $this->redirName, $subpage );
                } else {
                        return SpecialPage::getTitleFor( $this->redirName, $this->redirSubpage );
                }
        }
}

/** SpecialMypage, SpecialMytalk and SpecialMycontributions special pages
 * are used to get user independant links pointing to the user page, talk
 * page and list of contributions.
 * This can let us cache a single copy of any generated content for all
 * users.
 */

/**
 * Shortcut to construct a special page pointing to current user user's page.
 * @addtogroup SpecialPage
 */
class SpecialMypage extends UnlistedSpecialPage {
        function __construct() {
                parent::__construct( 'Mypage' );
                $this->mAllowedRedirectParams = array( 'action' , 'preload' , 'editintro', 'section' );
        }

        function getRedirect( $subpage ) {
                global $wgUser;
                if ( strval( $subpage ) !== '' ) {
                        return Title::makeTitle( NS_USER, $wgUser->getName() . '/' . $subpage );
                } else {
                        return Title::makeTitle( NS_USER, $wgUser->getName() );
                }
        }
}

/**
 * Shortcut to construct a special page pointing to current user talk page.
 * @addtogroup SpecialPage
 */
class SpecialMytalk extends UnlistedSpecialPage {
        function __construct() {
                parent::__construct( 'Mytalk' );
                $this->mAllowedRedirectParams = array( 'action' , 'preload' , 'editintro', 'section' );
        }

        function getRedirect( $subpage ) {
                global $wgUser;
                if ( strval( $subpage ) !== '' ) {
                        return Title::makeTitle( NS_USER_TALK, $wgUser->getName() . '/' . $subpage );
                } else {
                        return Title::makeTitle( NS_USER_TALK, $wgUser->getName() );
                }
        }
}

/**
 * Shortcut to construct a special page pointing to current user contributions.
 * @addtogroup SpecialPage
 */
class SpecialMycontributions extends UnlistedSpecialPage {
        function __construct() {
                parent::__construct(  'Mycontributions' );
        }

        function getRedirect( $subpage ) {
                global $wgUser;
                return SpecialPage::getTitleFor( 'Contributions', $wgUser->getName() );
        }
}