* (bug 13815) In the comment for page moves, use the colon-separator message instead...

[mediawiki.git] / includes / Title.php

<?php
/**
 * See title.txt
 * @file
 */

/** */
if ( !class_exists( 'UtfNormal' ) ) {
        require_once( dirname(__FILE__) . '/normal/UtfNormal.php' );
}

define ( 'GAID_FOR_UPDATE', 1 );

# Title::newFromTitle maintains a cache to avoid
# expensive re-normalization of commonly used titles.
# On a batch operation this can become a memory leak
# if not bounded. After hitting this many titles,
# reset the cache.
define( 'MW_TITLECACHE_MAX', 1000 );

# Constants for pr_cascade bitfield
define( 'CASCADE', 1 );

/**
 * Title class
 * - Represents a title, which may contain an interwiki designation or namespace
 * - Can fetch various kinds of data from the database, albeit inefficiently.
 *
 */
class Title {
        /**
         * Static cache variables
         */
        static private $titleCache=array();
        static private $interwikiCache=array();


        /**
         * All member variables should be considered private
         * Please use the accessor functions
         */

        /**#@+
         * @private
         */

        var $mTextform;                 # Text form (spaces not underscores) of the main part
        var $mUrlform;                  # URL-encoded form of the main part
        var $mDbkeyform;                # Main part with underscores
        var $mUserCaseDBKey;        # DB key with the initial letter in the case specified by the user
        var $mNamespace;                # Namespace index, i.e. one of the NS_xxxx constants
        var $mInterwiki;                # Interwiki prefix (or null string)
        var $mFragment;                 # Title fragment (i.e. the bit after the #)
        var $mArticleID;                # Article ID, fetched from the link cache on demand
        var $mLatestID;                 # ID of most recent revision
        var $mRestrictions;             # Array of groups allowed to edit this article
        var $mCascadeRestriction;       # Cascade restrictions on this page to included templates and images?
        var $mRestrictionsExpiry;       # When do the restrictions on this page expire?
        var $mHasCascadingRestrictions; # Are cascading restrictions in effect on this page?
        var $mCascadeRestrictionSources;# Where are the cascading restrictions coming from on this page?
        var $mRestrictionsLoaded;       # Boolean for initialisation on demand
        var $mPrefixedText;             # Text form including namespace/interwiki, initialised on demand
        var $mDefaultNamespace;         # Namespace index when there is no namespace
                                        # Zero except in {{transclusion}} tags
        var $mWatched;                  # Is $wgUser watching this page? NULL if unfilled, accessed through userIsWatching()
        var $mLength;              # The page length, 0 for special pages
        var $mRedirect;            # Is the article at this title a redirect?
        /**#@-*/


        /**
         * Constructor
         * @private
         */
        /* private */ function __construct() {
                $this->mInterwiki = $this->mUrlform =
                $this->mTextform = $this->mDbkeyform = '';
                $this->mArticleID = -1;
                $this->mNamespace = NS_MAIN;
                $this->mRestrictionsLoaded = false;
                $this->mRestrictions = array();
                # Dont change the following, NS_MAIN is hardcoded in several place
                # See bug #696
                $this->mDefaultNamespace = NS_MAIN;
                $this->mWatched = NULL;
                $this->mLatestID = false;
                $this->mOldRestrictions = false;
                $this->mLength = -1;
                $this->mRedirect = NULL;
        }

        /**
         * Create a new Title from a prefixed DB key
         * @param string $key The database key, which has underscores
         *      instead of spaces, possibly including namespace and
         *      interwiki prefixes
         * @return Title the new object, or NULL on an error
         */
        public static function newFromDBkey( $key ) {
                $t = new Title();
                $t->mDbkeyform = $key;
                if( $t->secureAndSplit() )
                        return $t;
                else
                        return NULL;
        }

        /**
         * Create a new Title from text, such as what one would
         * find in a link. Decodes any HTML entities in the text.
         *
         * @param string $text the link text; spaces, prefixes,
         *      and an initial ':' indicating the main namespace
         *      are accepted
         * @param int $defaultNamespace the namespace to use if
         *      none is specified by a prefix
         * @return Title the new object, or NULL on an error
         */
        public static function newFromText( $text, $defaultNamespace = NS_MAIN ) {
                if( is_object( $text ) ) {
                        throw new MWException( 'Title::newFromText given an object' );
                }

                /**
                 * Wiki pages often contain multiple links to the same page.
                 * Title normalization and parsing can become expensive on
                 * pages with many links, so we can save a little time by
                 * caching them.
                 *
                 * In theory these are value objects and won't get changed...
                 */
                if( $defaultNamespace == NS_MAIN && isset( Title::$titleCache[$text] ) ) {
                        return Title::$titleCache[$text];
                }

                /**
                 * Convert things like &eacute; &#257; or &#x3017; into real text...
                 */
                $filteredText = Sanitizer::decodeCharReferences( $text );

                $t = new Title();
                $t->mDbkeyform = str_replace( ' ', '_', $filteredText );
                $t->mDefaultNamespace = $defaultNamespace;

                static $cachedcount = 0 ;
                if( $t->secureAndSplit() ) {
                        if( $defaultNamespace == NS_MAIN ) {
                                if( $cachedcount >= MW_TITLECACHE_MAX ) {
                                        # Avoid memory leaks on mass operations...
                                        Title::$titleCache = array();
                                        $cachedcount=0;
                                }
                                $cachedcount++;
                                Title::$titleCache[$text] =& $t;
                        }
                        return $t;
                } else {
                        $ret = NULL;
                        return $ret;
                }
        }

        /**
         * Create a new Title from URL-encoded text. Ensures that
         * the given title's length does not exceed the maximum.
         * @param string $url the title, as might be taken from a URL
         * @return Title the new object, or NULL on an error
         */
        public static function newFromURL( $url ) {
                global $wgLegalTitleChars;
                $t = new Title();

                # For compatibility with old buggy URLs. "+" is usually not valid in titles,
                # but some URLs used it as a space replacement and they still come
                # from some external search tools.
                if ( strpos( $wgLegalTitleChars, '+' ) === false ) {
                        $url = str_replace( '+', ' ', $url );
                }

                $t->mDbkeyform = str_replace( ' ', '_', $url );
                if( $t->secureAndSplit() ) {
                        return $t;
                } else {
                        return NULL;
                }
        }

        /**
         * Create a new Title from an article ID
         *
         * @todo This is inefficiently implemented, the page row is requested
         *       but not used for anything else
         *
         * @param int $id the page_id corresponding to the Title to create
         * @param int $flags, use GAID_FOR_UPDATE to use master
         * @return Title the new object, or NULL on an error
         */
        public static function newFromID( $id, $flags = 0 ) {
                $fname = 'Title::newFromID';
                $db = ($flags & GAID_FOR_UPDATE) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
                $row = $db->selectRow( 'page', array( 'page_namespace', 'page_title' ),
                        array( 'page_id' => $id ), $fname );
                if ( $row !== false ) {
                        $title = Title::makeTitle( $row->page_namespace, $row->page_title );
                } else {
                        $title = NULL;
                }
                return $title;
        }

        /**
         * Make an array of titles from an array of IDs
         */
        public static function newFromIDs( $ids ) {
                if ( !count( $ids ) ) {
                        return array();
                }
                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( 'page', array( 'page_namespace', 'page_title' ),
                        'page_id IN (' . $dbr->makeList( $ids ) . ')', __METHOD__ );

                $titles = array();
                while ( $row = $dbr->fetchObject( $res ) ) {
                        $titles[] = Title::makeTitle( $row->page_namespace, $row->page_title );
                }
                return $titles;
        }

        /**
         * Make a Title object from a DB row
         * @param Row $row (needs at least page_title,page_namespace)
         */
        public static function newFromRow( $row ) {
                $t = self::makeTitle( $row->page_namespace, $row->page_title );

                $t->mArticleID = isset($row->page_id) ? intval($row->page_id) : -1;
                $t->mLength = isset($row->page_len) ? intval($row->page_len) : -1;
                $t->mRedirect = isset($row->page_is_redirect) ? (bool)$row->page_is_redirect : NULL;
                $t->mLatestID = isset($row->page_latest) ? $row->page_latest : false;

                return $t;
        }

        /**
         * Create a new Title from a namespace index and a DB key.
         * It's assumed that $ns and $title are *valid*, for instance when
         * they came directly from the database or a special page name.
         * For convenience, spaces are converted to underscores so that
         * eg user_text fields can be used directly.
         *
         * @param int $ns the namespace of the article
         * @param string $title the unprefixed database key form
         * @return Title the new object
         */
        public static function &makeTitle( $ns, $title ) {
                $t = new Title();
                $t->mInterwiki = '';
                $t->mFragment = '';
                $t->mNamespace = $ns = intval( $ns );
                $t->mDbkeyform = str_replace( ' ', '_', $title );
                $t->mArticleID = ( $ns >= 0 ) ? -1 : 0;
                $t->mUrlform = wfUrlencode( $t->mDbkeyform );
                $t->mTextform = str_replace( '_', ' ', $title );
                return $t;
        }

        /**
         * Create a new Title from a namespace index and a DB key.
         * The parameters will be checked for validity, which is a bit slower
         * than makeTitle() but safer for user-provided data.
         *
         * @param int $ns the namespace of the article
         * @param string $title the database key form
         * @return Title the new object, or NULL on an error
         */
        public static function makeTitleSafe( $ns, $title ) {
                $t = new Title();
                $t->mDbkeyform = Title::makeName( $ns, $title );
                if( $t->secureAndSplit() ) {
                        return $t;
                } else {
                        return NULL;
                }
        }

        /**
         * Create a new Title for the Main Page
         * @return Title the new object
         */
        public static function newMainPage() {
                $title = Title::newFromText( wfMsgForContent( 'mainpage' ) );
                // Don't give fatal errors if the message is broken
                if ( !$title ) {
                        $title = Title::newFromText( 'Main Page' );
                }
                return $title;
        }

        /**
         * Extract a redirect destination from a string and return the
         * Title, or null if the text doesn't contain a valid redirect
         *
         * @param string $text Text with possible redirect
         * @return Title
         */
        public static function newFromRedirect( $text ) {
                $redir = MagicWord::get( 'redirect' );
                if( $redir->matchStart( trim($text) ) ) {
                        // Extract the first link and see if it's usable
                        $m = array();
                        if( preg_match( '!\[{2}(.*?)(?:\|.*?)?\]{2}!', $text, $m ) ) {
                                // Strip preceding colon used to "escape" categories, etc.
                                // and URL-decode links
                                if( strpos( $m[1], '%' ) !== false ) {
                                        // Match behavior of inline link parsing here;
                                        // don't interpret + as " " most of the time!
                                        // It might be safe to just use rawurldecode instead, though.
                                        $m[1] = urldecode( ltrim( $m[1], ':' ) );
                                }
                                $title = Title::newFromText( $m[1] );
                                // Redirects to Special:Userlogout are not permitted
                                if( $title instanceof Title && !$title->isSpecial( 'Userlogout' ) )
                                        return $title;
                        }
                }
                return null;
        }

#----------------------------------------------------------------------------
#       Static functions
#----------------------------------------------------------------------------

        /**
         * Get the prefixed DB key associated with an ID
         * @param int $id the page_id of the article
         * @return Title an object representing the article, or NULL
         *      if no such article was found
         * @static
         * @access public
         */
        function nameOf( $id ) {
                $fname = 'Title::nameOf';
                $dbr = wfGetDB( DB_SLAVE );

                $s = $dbr->selectRow( 'page', array( 'page_namespace','page_title' ),  array( 'page_id' => $id ), $fname );
                if ( $s === false ) { return NULL; }

                $n = Title::makeName( $s->page_namespace, $s->page_title );
                return $n;
        }

        /**
         * Get a regex character class describing the legal characters in a link
         * @return string the list of characters, not delimited
         */
        public static function legalChars() {
                global $wgLegalTitleChars;
                return $wgLegalTitleChars;
        }

        /**
         * Get a string representation of a title suitable for
         * including in a search index
         *
         * @param int $ns a namespace index
         * @param string $title text-form main part
         * @return string a stripped-down title string ready for the
         *      search index
         */
        public static function indexTitle( $ns, $title ) {
                global $wgContLang;

                $lc = SearchEngine::legalSearchChars() . '&#;';
                $t = $wgContLang->stripForSearch( $title );
                $t = preg_replace( "/[^{$lc}]+/", ' ', $t );
                $t = $wgContLang->lc( $t );

                # Handle 's, s'
                $t = preg_replace( "/([{$lc}]+)'s( |$)/", "\\1 \\1's ", $t );
                $t = preg_replace( "/([{$lc}]+)s'( |$)/", "\\1s ", $t );

                $t = preg_replace( "/\\s+/", ' ', $t );

                if ( $ns == NS_IMAGE ) {
                        $t = preg_replace( "/ (png|gif|jpg|jpeg|ogg)$/", "", $t );
                }
                return trim( $t );
        }

        /*
         * Make a prefixed DB key from a DB key and a namespace index
         * @param int $ns numerical representation of the namespace
         * @param string $title the DB key form the title
         * @return string the prefixed form of the title
         */
        public static function makeName( $ns, $title ) {
                global $wgContLang;

                $n = $wgContLang->getNsText( $ns );
                return $n == '' ? $title : "$n:$title";
        }

        /**
         * Returns the URL associated with an interwiki prefix
         * @param string $key the interwiki prefix (e.g. "MeatBall")
         * @return the associated URL, containing "$1", which should be
         *      replaced by an article title
         * @static (arguably)
         */
        public function getInterwikiLink( $key )  {
                global $wgMemc, $wgInterwikiExpiry;
                global $wgInterwikiCache, $wgContLang;
                $fname = 'Title::getInterwikiLink';

                $key = $wgContLang->lc( $key );

                $k = wfMemcKey( 'interwiki', $key );
                if( array_key_exists( $k, Title::$interwikiCache ) ) {
                        return Title::$interwikiCache[$k]->iw_url;
                }

                if ($wgInterwikiCache) {
                        return Title::getInterwikiCached( $key );
                }

                $s = $wgMemc->get( $k );
                # Ignore old keys with no iw_local
                if( $s && isset( $s->iw_local ) && isset($s->iw_trans)) {
                        Title::$interwikiCache[$k] = $s;
                        return $s->iw_url;
                }

                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( 'interwiki',
                        array( 'iw_url', 'iw_local', 'iw_trans' ),
                        array( 'iw_prefix' => $key ), $fname );
                if( !$res ) {
                        return '';
                }

                $s = $dbr->fetchObject( $res );
                if( !$s ) {
                        # Cache non-existence: create a blank object and save it to memcached
                        $s = (object)false;
                        $s->iw_url = '';
                        $s->iw_local = 0;
                        $s->iw_trans = 0;
                }
                $wgMemc->set( $k, $s, $wgInterwikiExpiry );
                Title::$interwikiCache[$k] = $s;

                return $s->iw_url;
        }

        /**
         * Fetch interwiki prefix data from local cache in constant database
         *
         * More logic is explained in DefaultSettings
         *
         * @return string URL of interwiki site
         */
        public static function getInterwikiCached( $key ) {
                global $wgInterwikiCache, $wgInterwikiScopes, $wgInterwikiFallbackSite;
                static $db, $site;

                if (!$db)
                        $db=dba_open($wgInterwikiCache,'r','cdb');
                /* Resolve site name */
                if ($wgInterwikiScopes>=3 and !$site) {
                        $site = dba_fetch('__sites:' . wfWikiID(), $db);
                        if ($site=="")
                                $site = $wgInterwikiFallbackSite;
                }
                $value = dba_fetch( wfMemcKey( $key ), $db);
                if ($value=='' and $wgInterwikiScopes>=3) {
                        /* try site-level */
                        $value = dba_fetch("_{$site}:{$key}", $db);
                }
                if ($value=='' and $wgInterwikiScopes>=2) {
                        /* try globals */
                        $value = dba_fetch("__global:{$key}", $db);
                }
                if ($value=='undef')
                        $value='';
                $s = (object)false;
                $s->iw_url = '';
                $s->iw_local = 0;
                $s->iw_trans = 0;
                if ($value!='') {
                        list($local,$url)=explode(' ',$value,2);
                        $s->iw_url=$url;
                        $s->iw_local=(int)$local;
                }
                Title::$interwikiCache[wfMemcKey( 'interwiki', $key )] = $s;
                return $s->iw_url;
        }
        /**
         * Determine whether the object refers to a page within
         * this project.
         *
         * @return bool TRUE if this is an in-project interwiki link
         *      or a wikilink, FALSE otherwise
         */
        public function isLocal() {
                if ( $this->mInterwiki != '' ) {
                        # Make sure key is loaded into cache
                        $this->getInterwikiLink( $this->mInterwiki );
                        $k = wfMemcKey( 'interwiki', $this->mInterwiki );
                        return (bool)(Title::$interwikiCache[$k]->iw_local);
                } else {
                        return true;
                }
        }

        /**
         * Determine whether the object refers to a page within
         * this project and is transcludable.
         *
         * @return bool TRUE if this is transcludable
         */
        public function isTrans() {
                if ($this->mInterwiki == '')
                        return false;
                # Make sure key is loaded into cache
                $this->getInterwikiLink( $this->mInterwiki );
                $k = wfMemcKey( 'interwiki', $this->mInterwiki );
                return (bool)(Title::$interwikiCache[$k]->iw_trans);
        }

        /**
         * Escape a text fragment, say from a link, for a URL
         */
        static function escapeFragmentForURL( $fragment ) {
                $fragment = str_replace( ' ', '_', $fragment );
                $fragment = urlencode( Sanitizer::decodeCharReferences( $fragment ) );
                $replaceArray = array(
                        '%3A' => ':',
                        '%' => '.'
                );
                return strtr( $fragment, $replaceArray );
        }

#----------------------------------------------------------------------------
#       Other stuff
#----------------------------------------------------------------------------

        /** Simple accessors */
        /**
         * Get the text form (spaces not underscores) of the main part
         * @return string
         */
        public function getText() { return $this->mTextform; }
        /**
         * Get the URL-encoded form of the main part
         * @return string
         */
        public function getPartialURL() { return $this->mUrlform; }
        /**
         * Get the main part with underscores
         * @return string
         */
        public function getDBkey() { return $this->mDbkeyform; }
        /**
         * Get the namespace index, i.e. one of the NS_xxxx constants
         * @return int
         */
        public function getNamespace() { return $this->mNamespace; }
        /**
         * Get the namespace text
         * @return string
         */
        public function getNsText() {
                global $wgContLang, $wgCanonicalNamespaceNames;

                if ( '' != $this->mInterwiki ) {
                        // This probably shouldn't even happen. ohh man, oh yuck.
                        // But for interwiki transclusion it sometimes does.
                        // Shit. Shit shit shit.
                        //
                        // Use the canonical namespaces if possible to try to
                        // resolve a foreign namespace.
                        if( isset( $wgCanonicalNamespaceNames[$this->mNamespace] ) ) {
                                return $wgCanonicalNamespaceNames[$this->mNamespace];
                        }
                }
                return $wgContLang->getNsText( $this->mNamespace );
        }
        /**
         * Get the DB key with the initial letter case as specified by the user
         */
        function getUserCaseDBKey() {
                return $this->mUserCaseDBKey;
        }
        /**
         * Get the namespace text of the subject (rather than talk) page
         * @return string
         */
        public function getSubjectNsText() {
                global $wgContLang;
                return $wgContLang->getNsText( MWNamespace::getSubject( $this->mNamespace ) );
        }

        /**
         * Get the namespace text of the talk page
         * @return string
         */
        public function getTalkNsText() {
                global $wgContLang;
                return( $wgContLang->getNsText( MWNamespace::getTalk( $this->mNamespace ) ) );
        }

        /**
         * Could this title have a corresponding talk page?
         * @return bool
         */
        public function canTalk() {
                return( MWNamespace::canTalk( $this->mNamespace ) );
        }

        /**
         * Get the interwiki prefix (or null string)
         * @return string
         */
        public function getInterwiki() { return $this->mInterwiki; }
        /**
         * Get the Title fragment (i.e. the bit after the #) in text form
         * @return string
         */
        public function getFragment() { return $this->mFragment; }
        /**
         * Get the fragment in URL form, including the "#" character if there is one
         * @return string
         */
        public function getFragmentForURL() {
                if ( $this->mFragment == '' ) {
                        return '';
                } else {
                        return '#' . Title::escapeFragmentForURL( $this->mFragment );
                }
        }
        /**
         * Get the default namespace index, for when there is no namespace
         * @return int
         */
        public function getDefaultNamespace() { return $this->mDefaultNamespace; }

        /**
         * Get title for search index
         * @return string a stripped-down title string ready for the
         *      search index
         */
        public function getIndexTitle() {
                return Title::indexTitle( $this->mNamespace, $this->mTextform );
        }

        /**
         * Get the prefixed database key form
         * @return string the prefixed title, with underscores and
         *      any interwiki and namespace prefixes
         */
        public function getPrefixedDBkey() {
                $s = $this->prefix( $this->mDbkeyform );
                $s = str_replace( ' ', '_', $s );
                return $s;
        }

        /**
         * Get the prefixed title with spaces.
         * This is the form usually used for display
         * @return string the prefixed title, with spaces
         */
        public function getPrefixedText() {
                if ( empty( $this->mPrefixedText ) ) { // FIXME: bad usage of empty() ?
                        $s = $this->prefix( $this->mTextform );
                        $s = str_replace( '_', ' ', $s );
                        $this->mPrefixedText = $s;
                }
                return $this->mPrefixedText;
        }

        /**
         * Get the prefixed title with spaces, plus any fragment
         * (part beginning with '#')
         * @return string the prefixed title, with spaces and
         *      the fragment, including '#'
         */
        public function getFullText() {
                $text = $this->getPrefixedText();
                if( '' != $this->mFragment ) {
                        $text .= '#' . $this->mFragment;
                }
                return $text;
        }

        /**
         * Get the base name, i.e. the leftmost parts before the /
         * @return string Base name
         */
        public function getBaseText() {
                if( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
                        return $this->getText();
                }

                $parts = explode( '/', $this->getText() );
                # Don't discard the real title if there's no subpage involved
                if( count( $parts ) > 1 )
                        unset( $parts[ count( $parts ) - 1 ] );
                return implode( '/', $parts );
        }

        /**
         * Get the lowest-level subpage name, i.e. the rightmost part after /
         * @return string Subpage name
         */
        public function getSubpageText() {
                if( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
                        return( $this->mTextform );
                }
                $parts = explode( '/', $this->mTextform );
                return( $parts[ count( $parts ) - 1 ] );
        }

        /**
         * Get a URL-encoded form of the subpage text
         * @return string URL-encoded subpage name
         */
        public function getSubpageUrlForm() {
                $text = $this->getSubpageText();
                $text = wfUrlencode( str_replace( ' ', '_', $text ) );
                $text = str_replace( '%28', '(', str_replace( '%29', ')', $text ) ); # Clean up the URL; per below, this might not be safe
                return( $text );
        }

        /**
         * Get a URL-encoded title (not an actual URL) including interwiki
         * @return string the URL-encoded form
         */
        public function getPrefixedURL() {
                $s = $this->prefix( $this->mDbkeyform );
                $s = str_replace( ' ', '_', $s );

                $s = wfUrlencode ( $s ) ;

                # Cleaning up URL to make it look nice -- is this safe?
                $s = str_replace( '%28', '(', $s );
                $s = str_replace( '%29', ')', $s );

                return $s;
        }

        /**
         * Get a real URL referring to this title, with interwiki link and
         * fragment
         *
         * @param string $query an optional query string, not used
         *      for interwiki links
         * @param string $variant language variant of url (for sr, zh..)
         * @return string the URL
         */
        public function getFullURL( $query = '', $variant = false ) {
                global $wgContLang, $wgServer, $wgRequest;

                if ( '' == $this->mInterwiki ) {
                        $url = $this->getLocalUrl( $query, $variant );

                        // Ugly quick hack to avoid duplicate prefixes (bug 4571 etc)
                        // Correct fix would be to move the prepending elsewhere.
                        if ($wgRequest->getVal('action') != 'render') {
                                $url = $wgServer . $url;
                        }
                } else {
                        $baseUrl = $this->getInterwikiLink( $this->mInterwiki );

                        $namespace = wfUrlencode( $this->getNsText() );
                        if ( '' != $namespace ) {
                                # Can this actually happen? Interwikis shouldn't be parsed.
                                # Yes! It can in interwiki transclusion. But... it probably shouldn't.
                                $namespace .= ':';
                        }
                        $url = str_replace( '$1', $namespace . $this->mUrlform, $baseUrl );
                        $url = wfAppendQuery( $url, $query );
                }

                # Finally, add the fragment.
                $url .= $this->getFragmentForURL();

                wfRunHooks( 'GetFullURL', array( &$this, &$url, $query ) );
                return $url;
        }

        /**
         * Get a URL with no fragment or server name.  If this page is generated
         * with action=render, $wgServer is prepended.
         * @param string $query an optional query string; if not specified,
         *      $wgArticlePath will be used.
         * @param string $variant language variant of url (for sr, zh..)
         * @return string the URL
         */
        public function getLocalURL( $query = '', $variant = false ) {
                global $wgArticlePath, $wgScript, $wgServer, $wgRequest;
                global $wgVariantArticlePath, $wgContLang, $wgUser;

                // internal links should point to same variant as current page (only anonymous users)
                if($variant == false && $wgContLang->hasVariants() && !$wgUser->isLoggedIn()){
                        $pref = $wgContLang->getPreferredVariant(false);
                        if($pref != $wgContLang->getCode())
                                $variant = $pref;
                }

                if ( $this->isExternal() ) {
                        $url = $this->getFullURL();
                        if ( $query ) {
                                // This is currently only used for edit section links in the
                                // context of interwiki transclusion. In theory we should
                                // append the query to the end of any existing query string,
                                // but interwiki transclusion is already broken in that case.
                                $url .= "?$query";
                        }
                } else {
                        $dbkey = wfUrlencode( $this->getPrefixedDBkey() );
                        if ( $query == '' ) {
                                if( $variant != false && $wgContLang->hasVariants() ) {
                                        if( $wgVariantArticlePath == false ) {
                                                $variantArticlePath =  "$wgScript?title=$1&variant=$2"; // default
                                        } else {
                                                $variantArticlePath = $wgVariantArticlePath;
                                        }
                                        $url = str_replace( '$2', urlencode( $variant ), $variantArticlePath );
                                        $url = str_replace( '$1', $dbkey, $url  );
                                } else {
                                        $url = str_replace( '$1', $dbkey, $wgArticlePath );
                                }
                        } else {
                                global $wgActionPaths;
                                $url = false;
                                $matches = array();
                                if( !empty( $wgActionPaths ) &&
                                        preg_match( '/^(.*&|)action=([^&]*)(&(.*)|)$/', $query, $matches ) )
                                {
                                        $action = urldecode( $matches[2] );
                                        if( isset( $wgActionPaths[$action] ) ) {
                                                $query = $matches[1];
                                                if( isset( $matches[4] ) ) $query .= $matches[4];
                                                $url = str_replace( '$1', $dbkey, $wgActionPaths[$action] );
                                                if( $query != '' ) $url .= '?' . $query;
                                        }
                                }
                                if ( $url === false ) {
                                        if ( $query == '-' ) {
                                                $query = '';
                                        }
                                        $url = "{$wgScript}?title={$dbkey}&{$query}";
                                }
                        }

                        // FIXME: this causes breakage in various places when we
                        // actually expected a local URL and end up with dupe prefixes.
                        if ($wgRequest->getVal('action') == 'render') {
                                $url = $wgServer . $url;
                        }
                }
                wfRunHooks( 'GetLocalURL', array( &$this, &$url, $query ) );
                return $url;
        }

        /**
         * Get an HTML-escaped version of the URL form, suitable for
         * using in a link, without a server name or fragment
         * @param string $query an optional query string
         * @return string the URL
         */
        public function escapeLocalURL( $query = '' ) {
                return htmlspecialchars( $this->getLocalURL( $query ) );
        }

        /**
         * Get an HTML-escaped version of the URL form, suitable for
         * using in a link, including the server name and fragment
         *
         * @return string the URL
         * @param string $query an optional query string
         */
        public function escapeFullURL( $query = '' ) {
                return htmlspecialchars( $this->getFullURL( $query ) );
        }

        /**
         * Get the URL form for an internal link.
         * - Used in various Squid-related code, in case we have a different
         * internal hostname for the server from the exposed one.
         *
         * @param string $query an optional query string
         * @param string $variant language variant of url (for sr, zh..)
         * @return string the URL
         */
        public function getInternalURL( $query = '', $variant = false ) {
                global $wgInternalServer;
                $url = $wgInternalServer . $this->getLocalURL( $query, $variant );
                wfRunHooks( 'GetInternalURL', array( &$this, &$url, $query ) );
                return $url;
        }

        /**
         * Get the edit URL for this Title
         * @return string the URL, or a null string if this is an
         *      interwiki link
         */
        public function getEditURL() {
                if ( '' != $this->mInterwiki ) { return ''; }
                $s = $this->getLocalURL( 'action=edit' );

                return $s;
        }

        /**
         * Get the HTML-escaped displayable text form.
         * Used for the title field in <a> tags.
         * @return string the text, including any prefixes
         */
        public function getEscapedText() {
                return htmlspecialchars( $this->getPrefixedText() );
        }

        /**
         * Is this Title interwiki?
         * @return boolean
         */
        public function isExternal() { return ( '' != $this->mInterwiki ); }

        /**
         * Is this page "semi-protected" - the *only* protection is autoconfirm?
         *
         * @param string Action to check (default: edit)
         * @return bool
         */
        public function isSemiProtected( $action = 'edit' ) {
                if( $this->exists() ) {
                        $restrictions = $this->getRestrictions( $action );
                        if( count( $restrictions ) > 0 ) {
                                foreach( $restrictions as $restriction ) {
                                        if( strtolower( $restriction ) != 'autoconfirmed' )
                                                return false;
                                }
                        } else {
                                # Not protected
                                return false;
                        }
                        return true;
                } else {
                        # If it doesn't exist, it can't be protected
                        return false;
                }
        }

        /**
         * Does the title correspond to a protected article?
         * @param string $what the action the page is protected from,
         * by default checks move and edit
         * @return boolean
         */
        public function isProtected( $action = '' ) {
                global $wgRestrictionLevels, $wgRestrictionTypes;

                # Special pages have inherent protection
                if( $this->getNamespace() == NS_SPECIAL )
                        return true;

                # Check regular protection levels
                foreach( $wgRestrictionTypes as $type ){
                        if( $action == $type || $action == '' ) {
                                $r = $this->getRestrictions( $type );
                                foreach( $wgRestrictionLevels as $level ) {
                                        if( in_array( $level, $r ) && $level != '' ) {
                                                return true;
                                        }
                                }
                        }
                }

                return false;
        }

        /**
         * Is $wgUser watching this page?
         * @return boolean
         */
        public function userIsWatching() {
                global $wgUser;

                if ( is_null( $this->mWatched ) ) {
                        if ( NS_SPECIAL == $this->mNamespace || !$wgUser->isLoggedIn()) {
                                $this->mWatched = false;
                        } else {
                                $this->mWatched = $wgUser->isWatched( $this );
                        }
                }
                return $this->mWatched;
        }

        /**
         * Can $wgUser perform $action on this page?
         * This skips potentially expensive cascading permission checks.
         *
         * Suitable for use for nonessential UI controls in common cases, but
         * _not_ for functional access control.
         *
         * May provide false positives, but should never provide a false negative.
         *
         * @param string $action action that permission needs to be checked for
         * @return boolean
         */
        public function quickUserCan( $action ) {
                return $this->userCan( $action, false );
        }

        /**
         * Determines if $wgUser is unable to edit this page because it has been protected
         * by $wgNamespaceProtection.
         *
         * @return boolean
         */
        public function isNamespaceProtected() {
                global $wgNamespaceProtection, $wgUser;
                if( isset( $wgNamespaceProtection[ $this->mNamespace ] ) ) {
                        foreach( (array)$wgNamespaceProtection[ $this->mNamespace ] as $right ) {
                                if( $right != '' && !$wgUser->isAllowed( $right ) )
                                        return true;
                        }
                }
                return false;
        }

        /**
         * Can $wgUser perform $action on this page?
         * @param string $action action that permission needs to be checked for
         * @param bool $doExpensiveQueries Set this to false to avoid doing unnecessary queries.
         * @return boolean
         */
        public function userCan( $action, $doExpensiveQueries = true ) {
                global $wgUser;
                return ( $this->getUserPermissionsErrorsInternal( $action, $wgUser, $doExpensiveQueries ) === array());
        }

        /**
         * Can $user perform $action on this page?
         *
         * FIXME: This *does not* check throttles (User::pingLimiter()).
         *
         * @param string $action action that permission needs to be checked for
         * @param User $user user to check
         * @param bool $doExpensiveQueries Set this to false to avoid doing unnecessary queries.
         * @param array $ignoreErrors Set this to a list of message keys whose corresponding errors may be ignored.
         * @return array Array of arrays of the arguments to wfMsg to explain permissions problems.
         */
        public function getUserPermissionsErrors( $action, $user, $doExpensiveQueries = true, $ignoreErrors = array() ) {
                if( !StubObject::isRealObject( $user ) ) {
                        //Since StubObject is always used on globals, we can unstub $wgUser here and set $user = $wgUser
                        global $wgUser;
                        $wgUser->_unstub( '', 5 );
                        $user = $wgUser;
                }
                $errors = $this->getUserPermissionsErrorsInternal( $action, $user, $doExpensiveQueries );

                global $wgContLang;
                global $wgLang;
                global $wgEmailConfirmToEdit;

                if ( $wgEmailConfirmToEdit && !$user->isEmailConfirmed() && $action != 'createaccount' ) {
                        $errors[] = array( 'confirmedittext' );
                }

                if ( $user->isBlockedFrom( $this ) && $action != 'createaccount' ) {
                        $block = $user->mBlock;

                        // This is from OutputPage::blockedPage
                        // Copied at r23888 by werdna

                        $id = $user->blockedBy();
                        $reason = $user->blockedFor();
                        if( $reason == '' ) {
                                $reason = wfMsg( 'blockednoreason' );
                        }
                        $ip = wfGetIP();

                        if ( is_numeric( $id ) ) {
                                $name = User::whoIs( $id );
                        } else {
                                $name = $id;
                        }

                        $link = '[[' . $wgContLang->getNsText( NS_USER ) . ":{$name}|{$name}]]";
                        $blockid = $block->mId;
                        $blockExpiry = $user->mBlock->mExpiry;
                        $blockTimestamp = $wgLang->timeanddate( wfTimestamp( TS_MW, $user->mBlock->mTimestamp ), true );

                        if ( $blockExpiry == 'infinity' ) {
                                // Entry in database (table ipblocks) is 'infinity' but 'ipboptions' uses 'infinite' or 'indefinite'
                                $scBlockExpiryOptions = wfMsg( 'ipboptions' );

                                foreach ( explode( ',', $scBlockExpiryOptions ) as $option ) {
                                        if ( strpos( $option, ':' ) == false )
                                                continue;

                                        list ($show, $value) = explode( ":", $option );

                                        if ( $value == 'infinite' || $value == 'indefinite' ) {
                                                $blockExpiry = $show;
                                                break;
                                        }
                                }
                        } else {
                                $blockExpiry = $wgLang->timeanddate( wfTimestamp( TS_MW, $blockExpiry ), true );
                        }

                        $intended = $user->mBlock->mAddress;

                        $errors[] = array( ($block->mAuto ? 'autoblockedtext' : 'blockedtext'), $link, $reason, $ip, $name, 
                                $blockid, $blockExpiry, $intended, $blockTimestamp );
                }
                
                // Remove the errors being ignored.
                
                foreach( $errors as $index => $error ) {
                        $error_key = is_array($error) ? $error[0] : $error;
                        
                        if (in_array( $error_key, $ignoreErrors )) {
                                unset($errors[$index]);
                        }
                }

                return $errors;
        }

        /**
         * Can $user perform $action on this page? This is an internal function,
         * which checks ONLY that previously checked by userCan (i.e. it leaves out
         * checks on wfReadOnly() and blocks)
         *
         * @param string $action action that permission needs to be checked for
         * @param User $user user to check
         * @param bool $doExpensiveQueries Set this to false to avoid doing unnecessary queries.
         * @return array Array of arrays of the arguments to wfMsg to explain permissions problems.
         */
        private function getUserPermissionsErrorsInternal( $action, $user, $doExpensiveQueries = true ) {
                wfProfileIn( __METHOD__ );

                $errors = array();

                // Use getUserPermissionsErrors instead
                if ( !wfRunHooks( 'userCan', array( &$this, &$user, $action, &$result ) ) ) {
                        wfProfileOut( __METHOD__ );
                        return $result ? array() : array( array( 'badaccess-group0' ) );
                }

                if (!wfRunHooks( 'getUserPermissionsErrors', array( &$this, &$user, $action, &$result ) ) ) {
                        if ($result != array() && is_array($result) && !is_array($result[0]))
                                $errors[] = $result; # A single array representing an error
                        else if (is_array($result) && is_array($result[0]))
                                $errors = array_merge( $errors, $result ); # A nested array representing multiple errors
                        else if ($result != '' && $result != null && $result !== true && $result !== false)
                                $errors[] = array($result); # A string representing a message-id
                        else if ($result === false )
                                $errors[] = array('badaccess-group0'); # a generic "We don't want them to do that"
                }
                if ($doExpensiveQueries && !wfRunHooks( 'getUserPermissionsErrorsExpensive', array( &$this, &$user, $action, &$result ) ) ) {
                        if ($result != array() && is_array($result) && !is_array($result[0]))
                                $errors[] = $result; # A single array representing an error
                        else if (is_array($result) && is_array($result[0]))
                                $errors = array_merge( $errors, $result ); # A nested array representing multiple errors
                        else if ($result != '' && $result != null && $result !== true && $result !== false)
                                $errors[] = array($result); # A string representing a message-id
                        else if ($result === false )
                                $errors[] = array('badaccess-group0'); # a generic "We don't want them to do that"
                }
                
                $specialOKActions = array( 'createaccount', 'execute' );
                if( NS_SPECIAL == $this->mNamespace && !in_array( $action, $specialOKActions) ) {
                        $errors[] = array('ns-specialprotected');
                }

                if ( $this->isNamespaceProtected() ) {
                        $ns = $this->getNamespace() == NS_MAIN
                                ? wfMsg( 'nstab-main' )
                                : $this->getNsText();
                        $errors[] = (NS_MEDIAWIKI == $this->mNamespace
                                ? array('protectedinterface')
                                : array( 'namespaceprotected',  $ns ) );
                }

                if( $this->mDbkeyform == '_' ) {
                        # FIXME: Is this necessary? Shouldn't be allowed anyway...
                        $errors[] = array('badaccess-group0');
                }

                # protect css/js subpages of user pages
                # XXX: this might be better using restrictions
                # XXX: Find a way to work around the php bug that prevents using $this->userCanEditCssJsSubpage() from working
                if( $this->isCssJsSubpage()
                        && !$user->isAllowed('editusercssjs')
                        && !preg_match('/^'.preg_quote($user->getName(), '/').'\//', $this->mTextform) ) {
                        $errors[] = array('customcssjsprotected');
                }

                if ( $doExpensiveQueries && !$this->isCssJsSubpage() ) {
                        # We /could/ use the protection level on the source page, but it's fairly ugly
                        #  as we have to establish a precedence hierarchy for pages included by multiple
                        #  cascade-protected pages. So just restrict it to people with 'protect' permission,
                        #  as they could remove the protection anyway.
                        list( $cascadingSources, $restrictions ) = $this->getCascadeProtectionSources();
                        # Cascading protection depends on more than this page...
                        # Several cascading protected pages may include this page...
                        # Check each cascading level
                        # This is only for protection restrictions, not for all actions
                        if( $cascadingSources > 0 && isset($restrictions[$action]) ) {
                                foreach( $restrictions[$action] as $right ) {
                                        $right = ( $right == 'sysop' ) ? 'protect' : $right;
                                        if( '' != $right && !$user->isAllowed( $right ) ) {
                                                $pages = '';
                                                foreach( $cascadingSources as $page )
                                                        $pages .= '* [[:' . $page->getPrefixedText() . "]]\n";
                                                $errors[] = array( 'cascadeprotected', count( $cascadingSources ), $pages );
                                        }
                                }
                        }
                }

                foreach( $this->getRestrictions($action) as $right ) {
                        // Backwards compatibility, rewrite sysop -> protect
                        if ( $right == 'sysop' ) {
                                $right = 'protect';
                        }
                        if( '' != $right && !$user->isAllowed( $right ) ) {
                                //Users with 'editprotected' permission can edit protected pages
                                if( $action=='edit' && $user->isAllowed( 'editprotected' ) ) {
                                        //Users with 'editprotected' permission cannot edit protected pages
                                        //with cascading option turned on.
                                        if($this->mCascadeRestriction) {
                                                $errors[] = array( 'protectedpagetext', $right );
                                        } else {
                                                //Nothing, user can edit!
                                        }
                                } else {
                                        $errors[] = array( 'protectedpagetext', $right );
                                }
                        }
                }

                if ($action == 'protect') {
                        if ($this->getUserPermissionsErrors('edit', $user) != array()) {
                                $errors[] = array( 'protect-cantedit' ); // If they can't edit, they shouldn't protect.
                        }
                }

                if ($action == 'create') {
                        $title_protection = $this->getTitleProtection();

                        if (is_array($title_protection)) {
                                extract($title_protection);

                                if ($pt_create_perm == 'sysop')
                                        $pt_create_perm = 'protect';

                                if ($pt_create_perm == '' || !$user->isAllowed($pt_create_perm)) {
                                        $errors[] = array ( 'titleprotected', User::whoIs($pt_user), $pt_reason );
                                }
                        }

                        if( (  $this->isTalkPage() && !$user->isAllowed( 'createtalk' ) ) ||
                                ( !$this->isTalkPage() && !$user->isAllowed( 'createpage' ) ) ) {
                                $errors[] = $user->isAnon() ? array ('nocreatetext') : array ('nocreate-loggedin');
                        }
                } elseif( $action == 'move' && !( $this->isMovable() && $user->isAllowed( 'move' ) ) ) {
                        $errors[] = $user->isAnon() ? array ( 'movenologintext' ) : array ('movenotallowed');
                } elseif ( !$user->isAllowed( $action ) ) {
                        $return = null;
                        $groups = array();
                        global $wgGroupPermissions;
                        foreach( $wgGroupPermissions as $key => $value ) {
                                if( isset( $value[$action] ) && $value[$action] == true ) {
                                        $groupName = User::getGroupName( $key );
                                        $groupPage = User::getGroupPage( $key );
                                        if( $groupPage ) {
                                                $groups[] = '[['.$groupPage->getPrefixedText().'|'.$groupName.']]';
                                        } else {
                                                $groups[] = $groupName;
                                        }
                                }
                        }
                        $n = count( $groups );
                        $groups = implode( ', ', $groups );
                        switch( $n ) {
                                case 0:
                                case 1:
                                case 2:
                                        $return = array( "badaccess-group$n", $groups );
                                        break;
                                default:
                                        $return = array( 'badaccess-groups', $groups );
                        }
                        $errors[] = $return;
                }

                wfProfileOut( __METHOD__ );
                return $errors;
        }

        /**
         * Is this title subject to title protection?
         * @return mixed An associative array representing any existent title
         *   protection, or false if there's none.
         */
        private function getTitleProtection() {
                // Can't protect pages in special namespaces
                if ( $this->getNamespace() < 0 ) {
                        return false;
                }

                $dbr = wfGetDB( DB_SLAVE );
                $res = $dbr->select( 'protected_titles', '*',
                        array ('pt_namespace' => $this->getNamespace(), 'pt_title' => $this->getDBkey()) );

                if ($row = $dbr->fetchRow( $res )) {
                        return $row;
                } else {
                        return false;
                }
        }

        public function updateTitleProtection( $create_perm, $reason, $expiry ) {
                global $wgGroupPermissions,$wgUser,$wgContLang;

                if ($create_perm == implode(',',$this->getRestrictions('create'))
                        && $expiry == $this->mRestrictionsExpiry) {
                        // No change
                        return true;
                }

                list ($namespace, $title) = array( $this->getNamespace(), $this->getDBkey() );

                $dbw = wfGetDB( DB_MASTER );

                $encodedExpiry = Block::encodeExpiry($expiry, $dbw );

                $expiry_description = '';
                if ( $encodedExpiry != 'infinity' ) {
                        $expiry_description = ' (' . wfMsgForContent( 'protect-expiring', $wgContLang->timeanddate( $expiry ) ).')';
                }

                # Update protection table
                if ($create_perm != '' ) {
                        $dbw->replace( 'protected_titles', array(array('pt_namespace', 'pt_title')),
                                array( 'pt_namespace' => $namespace, 'pt_title' => $title
                                        , 'pt_create_perm' => $create_perm
                                        , 'pt_timestamp' => Block::encodeExpiry(wfTimestampNow(), $dbw)
                                        , 'pt_expiry' => $encodedExpiry
                                        , 'pt_user' => $wgUser->getId(), 'pt_reason' => $reason ), __METHOD__  );
                } else {
                        $dbw->delete( 'protected_titles', array( 'pt_namespace' => $namespace,
                                'pt_title' => $title ), __METHOD__ );
                }
                # Update the protection log
                $log = new LogPage( 'protect' );

                if( $create_perm ) {
                        $log->addEntry( $this->mRestrictions['create'] ? 'modify' : 'protect', $this, trim( $reason . " [create=$create_perm] $expiry_description" ) );
                } else {
                        $log->addEntry( 'unprotect', $this, $reason );
                }

                return true;
        }

        /**
         * Remove any title protection (due to page existing
         */
        public function deleteTitleProtection() {
                $dbw = wfGetDB( DB_MASTER );

                $dbw->delete( 'protected_titles',
                        array ('pt_namespace' => $this->getNamespace(), 'pt_title' => $this->getDBkey()), __METHOD__ );
        }

        /**
         * Can $wgUser edit this page?
         * @return boolean
         * @deprecated use userCan('edit')
         */
        public function userCanEdit( $doExpensiveQueries = true ) {
                return $this->userCan( 'edit', $doExpensiveQueries );
        }

        /**
         * Can $wgUser create this page?
         * @return boolean
         * @deprecated use userCan('create')
         */
        public function userCanCreate( $doExpensiveQueries = true ) {
                return $this->userCan( 'create', $doExpensiveQueries );
        }

        /**
         * Can $wgUser move this page?
         * @return boolean
         * @deprecated use userCan('move')
         */
        public function userCanMove( $doExpensiveQueries = true ) {
                return $this->userCan( 'move', $doExpensiveQueries );
        }

        /**
         * Would anybody with sufficient privileges be able to move this page?
         * Some pages just aren't movable.
         *
         * @return boolean
         */
        public function isMovable() {
                return MWNamespace::isMovable( $this->getNamespace() )
                        && $this->getInterwiki() == '';
        }

        /**
         * Can $wgUser read this page?
         * @return boolean
         * @todo fold these checks into userCan()
         */
        public function userCanRead() {
                global $wgUser, $wgGroupPermissions;

                $result = null;
                wfRunHooks( 'userCan', array( &$this, &$wgUser, 'read', &$result ) );
                if ( $result !== null ) {
                        return $result;
                }

                # Shortcut for public wikis, allows skipping quite a bit of code
                if ($wgGroupPermissions['*']['read'])
                        return true;

                if( $wgUser->isAllowed( 'read' ) ) {
                        return true;
                } else {
                        global $wgWhitelistRead;

                        /**
                         * Always grant access to the login page.
                         * Even anons need to be able to log in.
                        */
                        if( $this->isSpecial( 'Userlogin' ) || $this->isSpecial( 'Resetpass' ) ) {
                                return true;
                        }

                        /**
                         * Bail out if there isn't whitelist
                         */
                        if( !is_array($wgWhitelistRead) ) {
                                return false;
                        }

                        /**
                         * Check for explicit whitelisting
                         */
                        $name = $this->getPrefixedText();
                        $dbName = $this->getPrefixedDBKey();
                        // Check with and without underscores
                        if( in_array($name,$wgWhitelistRead,true) || in_array($dbName,$wgWhitelistRead,true) )
                                return true;

                        /**
                         * Old settings might have the title prefixed with
                         * a colon for main-namespace pages
                         */
                        if( $this->getNamespace() == NS_MAIN ) {
                                if( in_array( ':' . $name, $wgWhitelistRead ) )
                                        return true;
                        }

                        /**
                         * If it's a special page, ditch the subpage bit
                         * and check again
                         */
                        if( $this->getNamespace() == NS_SPECIAL ) {
                                $name = $this->getDBkey();
                                list( $name, /* $subpage */) = SpecialPage::resolveAliasWithSubpage( $name );
                                if ( $name === false ) {
                                        # Invalid special page, but we show standard login required message
                                        return false;
                                }

                                $pure = SpecialPage::getTitleFor( $name )->getPrefixedText();
                                if( in_array( $pure, $wgWhitelistRead, true ) )
                                        return true;
                        }

                }
                return false;
        }

        /**
         * Is this a talk page of some sort?
         * @return bool
         */
        public function isTalkPage() {
                return MWNamespace::isTalk( $this->getNamespace() );
        }

        /**
         * Is this a subpage?
         * @return bool
         */
        public function isSubpage() {
                return MWNamespace::hasSubpages( $this->mNamespace )
                        ? strpos( $this->getText(), '/' ) !== false
                        : false;
        }

        /**
         * Does this have subpages?  (Warning, usually requires an extra DB query.)
         * @return bool
         */
        public function hasSubpages() {
                if( !MWNamespace::hasSubpages( $this->mNamespace ) ) {
                        # Duh
                        return false;
                }

                # We dynamically add a member variable for the purpose of this method
                # alone to cache the result.  There's no point in having it hanging
                # around uninitialized in every Title object; therefore we only add it
                # if needed and don't declare it statically.
                if( isset( $this->mHasSubpages ) ) {
                        return $this->mHasSubpages;
                }

                $db = wfGetDB( DB_SLAVE );
                return $this->mHasSubpages = (bool)$db->selectField( 'page', '1',
                        "page_namespace = {$this->mNamespace} AND page_title LIKE '"
                        . $db->escapeLike( $this->mDbkeyform ) . "/%'",
                        __METHOD__
                );
        }

        /**
         * Could this page contain custom CSS or JavaScript, based
         * on the title?
         *
         * @return bool
         */
        public function isCssOrJsPage() {
                return $this->mNamespace == NS_MEDIAWIKI
                        && preg_match( '!\.(?:css|js)$!u', $this->mTextform ) > 0;
        }

        /**
         * Is this a .css or .js subpage of a user page?
         * @return bool
         */
        public function isCssJsSubpage() {
                return ( NS_USER == $this->mNamespace and preg_match("/\\/.*\\.(?:css|js)$/", $this->mTextform ) );
        }
        /**
         * Is this a *valid* .css or .js subpage of a user page?
         * Check that the corresponding skin exists
         */
        public function isValidCssJsSubpage() {
                if ( $this->isCssJsSubpage() ) {
                        $skinNames = Skin::getSkinNames();
                        return array_key_exists( $this->getSkinFromCssJsSubpage(), $skinNames );
                } else {
                        return false;
                }
        }
        /**
         * Trim down a .css or .js subpage title to get the corresponding skin name
         */
        public function getSkinFromCssJsSubpage() {
                $subpage = explode( '/', $this->mTextform );
                $subpage = $subpage[ count( $subpage ) - 1 ];
                return( str_replace( array( '.css', '.js' ), array( '', '' ), $subpage ) );
        }
        /**
         * Is this a .css subpage of a user page?
         * @return bool
         */
        public function isCssSubpage() {
                return ( NS_USER == $this->mNamespace && preg_match("/\\/.*\\.css$/", $this->mTextform ) );
        }
        /**
         * Is this a .js subpage of a user page?
         * @return bool
         */
        public function isJsSubpage() {
                return ( NS_USER == $this->mNamespace && preg_match("/\\/.*\\.js$/", $this->mTextform ) );
        }
        /**
         * Protect css/js subpages of user pages: can $wgUser edit
         * this page?
         *
         * @return boolean
         * @todo XXX: this might be better using restrictions
         */
        public function userCanEditCssJsSubpage() {
                global $wgUser;
                return ( $wgUser->isAllowed('editusercssjs') || preg_match('/^'.preg_quote($wgUser->getName(), '/').'\//', $this->mTextform) );
        }

        /**
         * Cascading protection: Return true if cascading restrictions apply to this page, false if not.
         *
         * @return bool If the page is subject to cascading restrictions.
         */
        public function isCascadeProtected() {
                list( $sources, /* $restrictions */ ) = $this->getCascadeProtectionSources( false );
                return ( $sources > 0 );
        }

        /**
         * Cascading protection: Get the source of any cascading restrictions on this page.
         *
         * @param $get_pages bool Whether or not to retrieve the actual pages that the restrictions have come from.
         * @return array( mixed title array, restriction array)
         * Array of the Title objects of the pages from which cascading restrictions have come, false for none, or true if such restrictions exist, but $get_pages was not set.
         * The restriction array is an array of each type, each of which contains an array of unique groups
         */
        public function getCascadeProtectionSources( $get_pages = true ) {
                global $wgRestrictionTypes;

                # Define our dimension of restrictions types
                $pagerestrictions = array();
                foreach( $wgRestrictionTypes as $action )
                        $pagerestrictions[$action] = array();

                if ( isset( $this->mCascadeSources ) && $get_pages ) {
                        return array( $this->mCascadeSources, $this->mCascadingRestrictions );
                } else if ( isset( $this->mHasCascadingRestrictions ) && !$get_pages ) {
                        return array( $this->mHasCascadingRestrictions, $pagerestrictions );
                }

                wfProfileIn( __METHOD__ );

                $dbr = wfGetDb( DB_SLAVE );

                if ( $this->getNamespace() == NS_IMAGE ) {
                        $tables = array ('imagelinks', 'page_restrictions');
                        $where_clauses = array(
                                'il_to' => $this->getDBkey(),
                                'il_from=pr_page',
                                'pr_cascade' => 1 );
                } else {
                        $tables = array ('templatelinks', 'page_restrictions');
                        $where_clauses = array(
                                'tl_namespace' => $this->getNamespace(),
                                'tl_title' => $this->getDBkey(),
                                'tl_from=pr_page',
                                'pr_cascade' => 1 );
                }

                if ( $get_pages ) {
                        $cols = array('pr_page', 'page_namespace', 'page_title', 'pr_expiry', 'pr_type', 'pr_level' );
                        $where_clauses[] = 'page_id=pr_page';
                        $tables[] = 'page';
                } else {
                        $cols = array( 'pr_expiry' );
                }

                $res = $dbr->select( $tables, $cols, $where_clauses, __METHOD__ );

                $sources = $get_pages ? array() : false;
                $now = wfTimestampNow();
                $purgeExpired = false;

                while( $row = $dbr->fetchObject( $res ) ) {
                        $expiry = Block::decodeExpiry( $row->pr_expiry );
                        if( $expiry > $now ) {
                                if ($get_pages) {
                                        $page_id = $row->pr_page;
                                        $page_ns = $row->page_namespace;
                                        $page_title = $row->page_title;
                                        $sources[$page_id] = Title::makeTitle($page_ns, $page_title);
                                        # Add groups needed for each restriction type if its not already there
                                        # Make sure this restriction type still exists
                                        if ( isset($pagerestrictions[$row->pr_type]) && !in_array($row->pr_level, $pagerestrictions[$row->pr_type]) ) {
                                                $pagerestrictions[$row->pr_type][]=$row->pr_level;
                                        }
                                } else {
                                        $sources = true;
                                }
                        } else {
                                // Trigger lazy purge of expired restrictions from the db
                                $purgeExpired = true;
                        }
                }
                if( $purgeExpired ) {
                        Title::purgeExpiredRestrictions();
                }

                wfProfileOut( __METHOD__ );

                if ( $get_pages ) {
                        $this->mCascadeSources = $sources;
                        $this->mCascadingRestrictions = $pagerestrictions;
                } else {
                        $this->mHasCascadingRestrictions = $sources;
                }

                return array( $sources, $pagerestrictions );
        }

        function areRestrictionsCascading() {
                if (!$this->mRestrictionsLoaded) {
                        $this->loadRestrictions();
                }

                return $this->mCascadeRestriction;
        }

        /**
         * Loads a string into mRestrictions array
         * @param resource $res restrictions as an SQL result.
         */
        private function loadRestrictionsFromRow( $res, $oldFashionedRestrictions = NULL ) {
                global $wgRestrictionTypes;
                $dbr = wfGetDB( DB_SLAVE );

                foreach( $wgRestrictionTypes as $type ){
                        $this->mRestrictions[$type] = array();
                }

                $this->mCascadeRestriction = false;
                $this->mRestrictionsExpiry = Block::decodeExpiry('');

                # Backwards-compatibility: also load the restrictions from the page record (old format).

                if ( $oldFashionedRestrictions === NULL ) {
                        $oldFashionedRestrictions = $dbr->selectField( 'page', 'page_restrictions', 
                                array( 'page_id' => $this->getArticleId() ), __METHOD__ );
                }

                if ($oldFashionedRestrictions != '') {

                        foreach( explode( ':', trim( $oldFashionedRestrictions ) ) as $restrict ) {
                                $temp = explode( '=', trim( $restrict ) );
                                if(count($temp) == 1) {
                                        // old old format should be treated as edit/move restriction
                                        $this->mRestrictions['edit'] = explode( ',', trim( $temp[0] ) );
                                        $this->mRestrictions['move'] = explode( ',', trim( $temp[0] ) );
                                } else {
                                        $this->mRestrictions[$temp[0]] = explode( ',', trim( $temp[1] ) );
                                }
                        }

                        $this->mOldRestrictions = true;

                }

                if( $dbr->numRows( $res ) ) {
                        # Current system - load second to make them override.
                        $now = wfTimestampNow();
                        $purgeExpired = false;

                        while ($row = $dbr->fetchObject( $res ) ) {
                                # Cycle through all the restrictions.

                                // Don't take care of restrictions types that aren't in $wgRestrictionTypes
                                if( !in_array( $row->pr_type, $wgRestrictionTypes ) )
                                        continue;

                                // This code should be refactored, now that it's being used more generally,
                                // But I don't really see any harm in leaving it in Block for now -werdna
                                $expiry = Block::decodeExpiry( $row->pr_expiry );

                                // Only apply the restrictions if they haven't expired!
                                if ( !$expiry || $expiry > $now ) {
                                        $this->mRestrictionsExpiry = $expiry;
                                        $this->mRestrictions[$row->pr_type] = explode( ',', trim( $row->pr_level ) );

                                        $this->mCascadeRestriction |= $row->pr_cascade;
                                } else {
                                        // Trigger a lazy purge of expired restrictions
                                        $purgeExpired = true;
                                }
                        }

                        if( $purgeExpired ) {
                                Title::purgeExpiredRestrictions();
                        }
                }

                $this->mRestrictionsLoaded = true;
        }

        public function loadRestrictions( $oldFashionedRestrictions = NULL ) {
                if( !$this->mRestrictionsLoaded ) {
                        if ($this->exists()) {
                                $dbr = wfGetDB( DB_SLAVE );

                                $res = $dbr->select( 'page_restrictions', '*',
                                        array ( 'pr_page' => $this->getArticleId() ), __METHOD__ );

                                $this->loadRestrictionsFromRow( $res, $oldFashionedRestrictions );
                        } else {
                                $title_protection = $this->getTitleProtection();

                                if (is_array($title_protection)) {
                                        extract($title_protection);

                                        $now = wfTimestampNow();
                                        $expiry = Block::decodeExpiry($pt_expiry);

                                        if (!$expiry || $expiry > $now) {
                                                // Apply the restrictions
                                                $this->mRestrictionsExpiry = $expiry;
                                                $this->mRestrictions['create'] = explode(',', trim($pt_create_perm) );
                                        } else { // Get rid of the old restrictions
                                                Title::purgeExpiredRestrictions();
                                        }
                                } else {
                                        $this->mRestrictionsExpiry = Block::decodeExpiry('');
                                }
                                $this->mRestrictionsLoaded = true;
                        }
                }
        }

        /**
         * Purge expired restrictions from the page_restrictions table
         */
        static function purgeExpiredRestrictions() {
                $dbw = wfGetDB( DB_MASTER );
                $dbw->delete( 'page_restrictions',
                        array( 'pr_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ),
                        __METHOD__ );

                $dbw->delete( 'protected_titles',
                        array( 'pt_expiry < ' . $dbw->addQuotes( $dbw->timestamp() ) ),
                        __METHOD__ );
        }

        /**
         * Accessor/initialisation for mRestrictions
         *
         * @param string $action action that permission needs to be checked for
         * @return array the array of groups allowed to edit this article
         */
        public function getRestrictions( $action ) {
                if( !$this->mRestrictionsLoaded ) {
                        $this->loadRestrictions();
                }
                return isset( $this->mRestrictions[$action] )
                                ? $this->mRestrictions[$action]
                                : array();
        }

        /**
         * Is there a version of this page in the deletion archive?
         * @return int the number of archived revisions
         */
        public function isDeleted() {
                $fname = 'Title::isDeleted';
                if ( $this->getNamespace() < 0 ) {
                        $n = 0;
                } else {
                        $dbr = wfGetDB( DB_SLAVE );
                        $n = $dbr->selectField( 'archive', 'COUNT(*)', array( 'ar_namespace' => $this->getNamespace(),
                                'ar_title' => $this->getDBkey() ), $fname );
                        if( $this->getNamespace() == NS_IMAGE ) {
                                $n += $dbr->selectField( 'filearchive', 'COUNT(*)',
                                        array( 'fa_name' => $this->getDBkey() ), $fname );
                        }
                }
                return (int)$n;
        }

        /**
         * Get the article ID for this Title from the link cache,
         * adding it if necessary
         * @param int $flags a bit field; may be GAID_FOR_UPDATE to select
         *      for update
         * @return int the ID
         */
        public function getArticleID( $flags = 0 ) {
                $linkCache = LinkCache::singleton();
                if ( $flags & GAID_FOR_UPDATE ) {
                        $oldUpdate = $linkCache->forUpdate( true );
                        $this->mArticleID = $linkCache->addLinkObj( $this );
                        $linkCache->forUpdate( $oldUpdate );
                } else {
                        if ( -1 == $this->mArticleID ) {
                                $this->mArticleID = $linkCache->addLinkObj( $this );
                        }
                }
                return $this->mArticleID;
        }

        /**
         * Is this an article that is a redirect page?
         * Uses link cache, adding it if necessary
         * @param int $flags a bit field; may be GAID_FOR_UPDATE to select for update
         * @return bool
         */
        public function isRedirect( $flags = 0 ) {
                if( !is_null($this->mRedirect) )
                        return $this->mRedirect;
                # Zero for special pages.
                # Also, calling getArticleID() loads the field from cache!
                if( !$this->getArticleID($flags) || $this->getNamespace() == NS_SPECIAL ) {
                        return false;
                }
                $linkCache = LinkCache::singleton();
                $this->mRedirect = (bool)$linkCache->getGoodLinkFieldObj( $this, 'redirect' );

                return $this->mRedirect;
        }

        /**
         * What is the length of this page?
         * Uses link cache, adding it if necessary
         * @param int $flags a bit field; may be GAID_FOR_UPDATE to select for update
         * @return bool
         */
        public function getLength( $flags = 0 ) {
                if( $this->mLength != -1 )
                        return $this->mLength;
                # Zero for special pages.
                # Also, calling getArticleID() loads the field from cache!
                if( !$this->getArticleID($flags) || $this->getNamespace() == NS_SPECIAL ) {
                        return 0;
                }
                $linkCache = LinkCache::singleton();
                $this->mLength = intval( $linkCache->getGoodLinkFieldObj( $this, 'length' ) );

                return $this->mLength;
        }

        /**
         * What is the page_latest field for this page?
         * @param int $flags a bit field; may be GAID_FOR_UPDATE to select for update
         * @return int
         */
        public function getLatestRevID( $flags = 0 ) {
                if ($this->mLatestID !== false)
                        return $this->mLatestID;

                $db = ($flags & GAID_FOR_UPDATE) ? wfGetDB(DB_MASTER) : wfGetDB(DB_SLAVE);
                return $this->mLatestID = $db->selectField( 'revision',
                        "max(rev_id)",
                        array('rev_page' => $this->getArticleID($flags)),
                        'Title::getLatestRevID' );
        }

        /**
         * This clears some fields in this object, and clears any associated
         * keys in the "bad links" section of the link cache.
         *
         * - This is called from Article::insertNewArticle() to allow
         * loading of the new page_id. It's also called from
         * Article::doDeleteArticle()
         *
         * @param int $newid the new Article ID
         */
        public function resetArticleID( $newid ) {
                $linkCache = LinkCache::singleton();
                $linkCache->clearBadLink( $this->getPrefixedDBkey() );

                if ( 0 == $newid ) { $this->mArticleID = -1; }
                else { $this->mArticleID = $newid; }
                $this->mRestrictionsLoaded = false;
                $this->mRestrictions = array();
        }

        /**
         * Updates page_touched for this page; called from LinksUpdate.php
         * @return bool true if the update succeded
         */
        public function invalidateCache() {
                global $wgUseFileCache;

                if ( wfReadOnly() ) {
                        return;
                }

                $dbw = wfGetDB( DB_MASTER );
                $success = $dbw->update( 'page',
                        array( /* SET */
                                'page_touched' => $dbw->timestamp()
                        ), array( /* WHERE */
                                'page_namespace' => $this->getNamespace() ,
                                'page_title' => $this->getDBkey()
                        ), 'Title::invalidateCache'
                );

                if ($wgUseFileCache) {
                        $cache = new HTMLFileCache($this);
                        @unlink($cache->fileCacheName());
                }

                return $success;
        }

        /**
         * Prefix some arbitrary text with the namespace or interwiki prefix
         * of this object
         *
         * @param string $name the text
         * @return string the prefixed text
         * @private
         */
        /* private */ function prefix( $name ) {
                $p = '';
                if ( '' != $this->mInterwiki ) {
                        $p = $this->mInterwiki . ':';
                }
                if ( 0 != $this->mNamespace ) {
                        $p .= $this->getNsText() . ':';
                }
                return $p . $name;
        }

        /**
         * Secure and split - main initialisation function for this object
         *
         * Assumes that mDbkeyform has been set, and is urldecoded
         * and uses underscores, but not otherwise munged.  This function
         * removes illegal characters, splits off the interwiki and
         * namespace prefixes, sets the other forms, and canonicalizes
         * everything.
         * @return bool true on success
         */
        private function secureAndSplit() {
                global $wgContLang, $wgLocalInterwiki, $wgCapitalLinks;

                # Initialisation
                static $rxTc = false;
                if( !$rxTc ) {
                        # Matching titles will be held as illegal.
                        $rxTc = '/' .
                                # Any character not allowed is forbidden...
                                '[^' . Title::legalChars() . ']' .
                                # URL percent encoding sequences interfere with the ability
                                # to round-trip titles -- you can't link to them consistently.
                                '|%[0-9A-Fa-f]{2}' .
                                # XML/HTML character references produce similar issues.
                                '|&[A-Za-z0-9\x80-\xff]+;' .
                                '|&#[0-9]+;' .
                                '|&#x[0-9A-Fa-f]+;' .
                                '/S';
                }

                $this->mInterwiki = $this->mFragment = '';
                $this->mNamespace = $this->mDefaultNamespace; # Usually NS_MAIN

                $dbkey = $this->mDbkeyform;

                # Strip Unicode bidi override characters.
                # Sometimes they slip into cut-n-pasted page titles, where the
                # override chars get included in list displays.
                $dbkey = str_replace( "\xE2\x80\x8E", '', $dbkey ); // 200E LEFT-TO-RIGHT MARK
                $dbkey = str_replace( "\xE2\x80\x8F", '', $dbkey ); // 200F RIGHT-TO-LEFT MARK

                # Clean up whitespace
                #
                $dbkey = preg_replace( '/[ _]+/', '_', $dbkey );
                $dbkey = trim( $dbkey, '_' );

                if ( '' == $dbkey ) {
                        return false;
                }

                if( false !== strpos( $dbkey, UTF8_REPLACEMENT ) ) {
                        # Contained illegal UTF-8 sequences or forbidden Unicode chars.
                        return false;
                }

                $this->mDbkeyform = $dbkey;

                # Initial colon indicates main namespace rather than specified default
                # but should not create invalid {ns,title} pairs such as {0,Project:Foo}
                if ( ':' == $dbkey{0} ) {
                        $this->mNamespace = NS_MAIN;
                        $dbkey = substr( $dbkey, 1 ); # remove the colon but continue processing
                        $dbkey = trim( $dbkey, '_' ); # remove any subsequent whitespace
                }

                # Namespace or interwiki prefix
                $firstPass = true;
                do {
                        $m = array();
                        if ( preg_match( "/^(.+?)_*:_*(.*)$/S", $dbkey, $m ) ) {
                                $p = $m[1];
                                if ( $ns = $wgContLang->getNsIndex( $p )) {
                                        # Ordinary namespace
                                        $dbkey = $m[2];
                                        $this->mNamespace = $ns;
                                } elseif( $this->getInterwikiLink( $p ) ) {
                                        if( !$firstPass ) {
                                                # Can't make a local interwiki link to an interwiki link.
                                                # That's just crazy!
                                                return false;
                                        }

                                        # Interwiki link
                                        $dbkey = $m[2];
                                        $this->mInterwiki = $wgContLang->lc( $p );

                                        # Redundant interwiki prefix to the local wiki
                                        if ( 0 == strcasecmp( $this->mInterwiki, $wgLocalInterwiki ) ) {
                                                if( $dbkey == '' ) {
                                                        # Can't have an empty self-link
                                                        return false;
                                                }
                                                $this->mInterwiki = '';
                                                $firstPass = false;
                                                # Do another namespace split...
                                                continue;
                                        }

                                        # If there's an initial colon after the interwiki, that also
                                        # resets the default namespace
                                        if ( $dbkey !== '' && $dbkey[0] == ':' ) {
                                                $this->mNamespace = NS_MAIN;
                                                $dbkey = substr( $dbkey, 1 );
                                        }
                                }
                                # If there's no recognized interwiki or namespace,
                                # then let the colon expression be part of the title.
                        }
                        break;
                } while( true );

                # We already know that some pages won't be in the database!
                #
                if ( '' != $this->mInterwiki || NS_SPECIAL == $this->mNamespace ) {
                        $this->mArticleID = 0;
                }
                $fragment = strstr( $dbkey, '#' );
                if ( false !== $fragment ) {
                        $this->setFragment( $fragment );
                        $dbkey = substr( $dbkey, 0, strlen( $dbkey ) - strlen( $fragment ) );
                        # remove whitespace again: prevents "Foo_bar_#"
                        # becoming "Foo_bar_"
                        $dbkey = preg_replace( '/_*$/', '', $dbkey );
                }

                # Reject illegal characters.
                #
                if( preg_match( $rxTc, $dbkey ) ) {
                        return false;
                }

                /**
                 * Pages with "/./" or "/../" appearing in the URLs will
                 * often be unreachable due to the way web browsers deal
                 * with 'relative' URLs. Forbid them explicitly.
                 */
                if ( strpos( $dbkey, '.' ) !== false &&
                     ( $dbkey === '.' || $dbkey === '..' ||
                       strpos( $dbkey, './' ) === 0  ||
                       strpos( $dbkey, '../' ) === 0 ||
                       strpos( $dbkey, '/./' ) !== false ||
                       strpos( $dbkey, '/../' ) !== false  ||
                       substr( $dbkey, -2 ) == '/.' ||
                       substr( $dbkey, -3 ) == '/..' ) )
                {
                        return false;
                }

                /**
                 * Magic tilde sequences? Nu-uh!
                 */
                if( strpos( $dbkey, '~~~' ) !== false ) {
                        return false;
                }

                /**
                 * Limit the size of titles to 255 bytes.
                 * This is typically the size of the underlying database field.
                 * We make an exception for special pages, which don't need to be stored
                 * in the database, and may edge over 255 bytes due to subpage syntax
                 * for long titles, e.g. [[Special:Block/Long name]]
                 */
                if ( ( $this->mNamespace != NS_SPECIAL && strlen( $dbkey ) > 255 ) ||
                  strlen( $dbkey ) > 512 )
                {
                        return false;
                }

                /**
                 * Normally, all wiki links are forced to have
                 * an initial capital letter so [[foo]] and [[Foo]]
                 * point to the same place.
                 *
                 * Don't force it for interwikis, since the other
                 * site might be case-sensitive.
                 */
                $this->mUserCaseDBKey = $dbkey;
                if( $wgCapitalLinks && $this->mInterwiki == '') {
                        $dbkey = $wgContLang->ucfirst( $dbkey );
                }

                /**
                 * Can't make a link to a namespace alone...
                 * "empty" local links can only be self-links
                 * with a fragment identifier.
                 */
                if( $dbkey == '' &&
                        $this->mInterwiki == '' &&
                        $this->mNamespace != NS_MAIN ) {
                        return false;
                }
                // Allow IPv6 usernames to start with '::' by canonicalizing IPv6 titles.
                // IP names are not allowed for accounts, and can only be referring to
                // edits from the IP. Given '::' abbreviations and caps/lowercaps,
                // there are numerous ways to present the same IP. Having sp:contribs scan
                // them all is silly and having some show the edits and others not is
                // inconsistent. Same for talk/userpages. Keep them normalized instead.
                $dbkey = ($this->mNamespace == NS_USER || $this->mNamespace == NS_USER_TALK) ?
                        IP::sanitizeIP( $dbkey ) : $dbkey;
                // Any remaining initial :s are illegal.
                if ( $dbkey !== '' && ':' == $dbkey{0} ) {
                        return false;
                }

                # Fill fields
                $this->mDbkeyform = $dbkey;
                $this->mUrlform = wfUrlencode( $dbkey );

                $this->mTextform = str_replace( '_', ' ', $dbkey );

                return true;
        }

        /**
         * Set the fragment for this title
         * This is kind of bad, since except for this rarely-used function, Title objects
         * are immutable. The reason this is here is because it's better than setting the
         * members directly, which is what Linker::formatComment was doing previously.
         *
         * @param string $fragment text
         * @todo clarify whether access is supposed to be public (was marked as "kind of public")
         */
        public function setFragment( $fragment ) {
                $this->mFragment = str_replace( '_', ' ', substr( $fragment, 1 ) );
        }

        /**
         * Get a Title object associated with the talk page of this article
         * @return Title the object for the talk page
         */
        public function getTalkPage() {
                return Title::makeTitle( MWNamespace::getTalk( $this->getNamespace() ), $this->getDBkey() );
        }

        /**
         * Get a title object associated with the subject page of this
         * talk page
         *
         * @return Title the object for the subject page
         */
        public function getSubjectPage() {
                return Title::makeTitle( MWNamespace::getSubject( $this->getNamespace() ), $this->getDBkey() );
        }

        /**
         * Get an array of Title objects linking to this Title
         * Also stores the IDs in the link cache.
         *
         * WARNING: do not use this function on arbitrary user-supplied titles!
         * On heavily-used templates it will max out the memory.
         *
         * @param string $options may be FOR UPDATE
         * @return array the Title objects linking here
         */
        public function getLinksTo( $options = '', $table = 'pagelinks', $prefix = 'pl' ) {
                $linkCache = LinkCache::singleton();

                if ( $options ) {
                        $db = wfGetDB( DB_MASTER );
                } else {
                        $db = wfGetDB( DB_SLAVE );
                }

                $res = $db->select( array( 'page', $table ),
                        array( 'page_namespace', 'page_title', 'page_id', 'page_len', 'page_is_redirect' ),
                        array(
                                "{$prefix}_from=page_id",
                                "{$prefix}_namespace" => $this->getNamespace(),
                                "{$prefix}_title"     => $this->getDBkey() ),
                        'Title::getLinksTo',
                        $options );

                $retVal = array();
                if ( $db->numRows( $res ) ) {
                        while ( $row = $db->fetchObject( $res ) ) {
                                if ( $titleObj = Title::makeTitle( $row->page_namespace, $row->page_title ) ) {
                                        $linkCache->addGoodLinkObj( $row->page_id, $titleObj, $row->page_len, $row->page_is_redirect );
                                        $retVal[] = $titleObj;
                                }
                        }
                }
                $db->freeResult( $res );
                return $retVal;
        }

        /**
         * Get an array of Title objects using this Title as a template
         * Also stores the IDs in the link cache.
         *
         * WARNING: do not use this function on arbitrary user-supplied titles!
         * On heavily-used templates it will max out the memory.
         *
         * @param string $options may be FOR UPDATE
         * @return array the Title objects linking here
         */
        public function getTemplateLinksTo( $options = '' ) {
                return $this->getLinksTo( $options, 'templatelinks', 'tl' );
        }

        /**
         * Get an array of Title objects referring to non-existent articles linked from this page
         *
         * @todo check if needed (used only in SpecialBrokenRedirects.php, and should use redirect table in this case)
         * @param string $options may be FOR UPDATE
         * @return array the Title objects
         */
        public function getBrokenLinksFrom( $options = '' ) {
                if ( $this->getArticleId() == 0 ) {
                        # All links from article ID 0 are false positives
                        return array();
                }

                if ( $options ) {
                        $db = wfGetDB( DB_MASTER );
                } else {
                        $db = wfGetDB( DB_SLAVE );
                }

                $res = $db->safeQuery(
                          "SELECT pl_namespace, pl_title
                             FROM !
                        LEFT JOIN !
                               ON pl_namespace=page_namespace
                              AND pl_title=page_title
                            WHERE pl_from=?
                              AND page_namespace IS NULL
                                  !",
                        $db->tableName( 'pagelinks' ),
                        $db->tableName( 'page' ),
                        $this->getArticleId(),
                        $options );

                $retVal = array();
                if ( $db->numRows( $res ) ) {
                        while ( $row = $db->fetchObject( $res ) ) {
                                $retVal[] = Title::makeTitle( $row->pl_namespace, $row->pl_title );
                        }
                }
                $db->freeResult( $res );
                return $retVal;
        }


        /**
         * Get a list of URLs to purge from the Squid cache when this
         * page changes
         *
         * @return array the URLs
         */
        public function getSquidURLs() {
                global $wgContLang;

                $urls = array(
                        $this->getInternalURL(),
                        $this->getInternalURL( 'action=history' )
                );

                // purge variant urls as well
                if($wgContLang->hasVariants()){
                        $variants = $wgContLang->getVariants();
                        foreach($variants as $vCode){
                                if($vCode==$wgContLang->getCode()) continue; // we don't want default variant
                                $urls[] = $this->getInternalURL('',$vCode);
                        }
                }

                return $urls;
        }

        public function purgeSquid() {
                global $wgUseSquid;
                if ( $wgUseSquid ) {
                        $urls = $this->getSquidURLs();
                        $u = new SquidUpdate( $urls );
                        $u->doUpdate();
                }
        }

        /**
         * Move this page without authentication
         * @param Title &$nt the new page Title
         */
        public function moveNoAuth( &$nt ) {
                return $this->moveTo( $nt, false );
        }

        /**
         * Check whether a given move operation would be valid.
         * Returns true if ok, or a getUserPermissionsErrors()-like array otherwise
         * @param Title &$nt the new title
         * @param bool $auth indicates whether $wgUser's permissions
         *      should be checked
         * @param string $reason is the log summary of the move, used for spam checking
         * @return mixed True on success, getUserPermissionsErrors()-like array on failure
         */
        public function isValidMoveOperation( &$nt, $auth = true, $reason = '' ) {
                $errors = array();      
                if( !$nt ) {
                        // Normally we'd add this to $errors, but we'll get
                        // lots of syntax errors if $nt is not an object
                        return array(array('badtitletext'));
                }
                if( $this->equals( $nt ) ) {
                        $errors[] = array('selfmove');
                }
                if( !$this->isMovable() || !$nt->isMovable() ) {
                        $errors[] = array('immobile_namespace');
                }

                $oldid = $this->getArticleID();
                $newid = $nt->getArticleID();

                if ( strlen( $nt->getDBkey() ) < 1 ) {
                        $errors[] = array('articleexists');
                }
                if ( ( '' == $this->getDBkey() ) ||
                         ( !$oldid ) ||
                     ( '' == $nt->getDBkey() ) ) {
                        $errors[] = array('badarticleerror');
                }

                // Image-specific checks
                if( $this->getNamespace() == NS_IMAGE ) {
                        $file = wfLocalFile( $this );
                        if( $file->exists() ) {
                                if( $nt->getNamespace() != NS_IMAGE ) {
                                        $errors[] = array('imagenocrossnamespace');
                                }
                                if( $nt->getText() != wfStripIllegalFilenameChars( $nt->getText() ) ) {
                                        $errors[] = array('imageinvalidfilename');
                                }
                                if( !File::checkExtensionCompatibility( $file, $nt->getDbKey() ) ) {
                                        $errors[] = array('imagetypemismatch');
                                }
                        }
                }

                if ( $auth ) {
                        global $wgUser;
                        $errors = array_merge($errors, 
                                        $this->getUserPermissionsErrors('move', $wgUser),
                                        $this->getUserPermissionsErrors('edit', $wgUser),
                                        $nt->getUserPermissionsErrors('move', $wgUser),
                                        $nt->getUserPermissionsErrors('edit', $wgUser));
                }

                global $wgUser;
                $err = null;
                if( !wfRunHooks( 'AbortMove', array( $this, $nt, $wgUser, &$err, $reason ) ) ) {
                        $errors[] = array('hookaborted', $err);
                }

                # The move is allowed only if (1) the target doesn't exist, or
                # (2) the target is a redirect to the source, and has no history
                # (so we can undo bad moves right after they're done).

                if ( 0 != $newid ) { # Target exists; check for validity
                        if ( ! $this->isValidMoveTarget( $nt ) ) {
                                $errors[] = array('articleexists');
                        }
                } else {
                        $tp = $nt->getTitleProtection();
                        $right = ( $tp['pt_create_perm'] == 'sysop' ) ? 'protect' : $tp['pt_create_perm'];
                        if ( $tp and !$wgUser->isAllowed( $right ) ) {
                                $errors[] = array('cantmove-titleprotected');
                        }
                }
                if(empty($errors))
                        return true;
                return $errors;
        }

        /**
         * Move a title to a new location
         * @param Title &$nt the new title
         * @param bool $auth indicates whether $wgUser's permissions
         *      should be checked
         * @param string $reason The reason for the move
         * @param bool $createRedirect Whether to create a redirect from the old title to the new title.
         *  Ignored if the user doesn't have the suppressredirect right.
         * @return mixed true on success, getUserPermissionsErrors()-like array on failure
         */
        public function moveTo( &$nt, $auth = true, $reason = '', $createRedirect = true ) {
                $err = $this->isValidMoveOperation( $nt, $auth, $reason );
                if( is_array( $err ) ) {
                        return $err;
                }

                $pageid = $this->getArticleID();
                if( $nt->exists() ) {
                        $err = $this->moveOverExistingRedirect( $nt, $reason, $createRedirect );
                        $pageCountChange = ($createRedirect ? 0 : -1);
                } else { # Target didn't exist, do normal move.
                        $err = $this->moveToNewTitle( $nt, $reason, $createRedirect );
                        $pageCountChange = ($createRedirect ? 1 : 0);
                }

                if( is_array( $err ) ) {
                        return $err;
                }
                $redirid = $this->getArticleID();

                // Category memberships include a sort key which may be customized.
                // If it's left as the default (the page title), we need to update
                // the sort key to match the new title.
                //
                // Be careful to avoid resetting cl_timestamp, which may disturb
                // time-based lists on some sites.
                //
                // Warning -- if the sort key is *explicitly* set to the old title,
                // we can't actually distinguish it from a default here, and it'll
                // be set to the new title even though it really shouldn't.
                // It'll get corrected on the next edit, but resetting cl_timestamp.
                $dbw = wfGetDB( DB_MASTER );
                $dbw->update( 'categorylinks',
                        array(
                                'cl_sortkey' => $nt->getPrefixedText(),
                                'cl_timestamp=cl_timestamp' ),
                        array(
                                'cl_from' => $pageid,
                                'cl_sortkey' => $this->getPrefixedText() ),
                        __METHOD__ );

                # Update watchlists

                $oldnamespace = $this->getNamespace() & ~1;
                $newnamespace = $nt->getNamespace() & ~1;
                $oldtitle = $this->getDBkey();
                $newtitle = $nt->getDBkey();

                if( $oldnamespace != $newnamespace || $oldtitle != $newtitle ) {
                        WatchedItem::duplicateEntries( $this, $nt );
                }

                # Update search engine
                $u = new SearchUpdate( $pageid, $nt->getPrefixedDBkey() );
                $u->doUpdate();
                $u = new SearchUpdate( $redirid, $this->getPrefixedDBkey(), '' );
                $u->doUpdate();

                # Update site_stats
                if( $this->isContentPage() && !$nt->isContentPage() ) {
                        # No longer a content page
                        # Not viewed, edited, removing
                        $u = new SiteStatsUpdate( 0, 1, -1, $pageCountChange );
                } elseif( !$this->isContentPage() && $nt->isContentPage() ) {
                        # Now a content page
                        # Not viewed, edited, adding
                        $u = new SiteStatsUpdate( 0, 1, +1, $pageCountChange );
                } elseif( $pageCountChange ) {
                        # Redirect added
                        $u = new SiteStatsUpdate( 0, 0, 0, 1 );
                } else {
                        # Nothing special
                        $u = false;
                }
                if( $u )
                        $u->doUpdate();
                # Update message cache for interface messages
                if( $nt->getNamespace() == NS_MEDIAWIKI ) {
                        global $wgMessageCache;
                        $oldarticle = new Article( $this );
                        $wgMessageCache->replace( $this->getDBkey(), $oldarticle->getContent() );
                        $newarticle = new Article( $nt );
                        $wgMessageCache->replace( $nt->getDBkey(), $newarticle->getContent() );
                }

                global $wgUser;
                wfRunHooks( 'TitleMoveComplete', array( &$this, &$nt, &$wgUser, $pageid, $redirid ) );
                return true;
        }

        /**
         * Move page to a title which is at present a redirect to the
         * source page
         *
         * @param Title &$nt the page to move to, which should currently
         *      be a redirect
         * @param string $reason The reason for the move
         * @param bool $createRedirect Whether to leave a redirect at the old title.
         *  Ignored if the user doesn't have the suppressredirect right
         */
        private function moveOverExistingRedirect( &$nt, $reason = '', $createRedirect = true ) {
                global $wgUseSquid, $wgUser;
                $fname = 'Title::moveOverExistingRedirect';
                $comment = wfMsgForContent( '1movedto2_redir', $this->getPrefixedText(), $nt->getPrefixedText() );

                if ( $reason ) {
                        $comment .= ": $reason";
                }

                $now = wfTimestampNow();
                $newid = $nt->getArticleID();
                $oldid = $this->getArticleID();

                $dbw = wfGetDB( DB_MASTER );
                $dbw->begin();

                # Delete the old redirect. We don't save it to history since
                # by definition if we've got here it's rather uninteresting.
                # We have to remove it so that the next step doesn't trigger
                # a conflict on the unique namespace+title index...
                $dbw->delete( 'page', array( 'page_id' => $newid ), $fname );
                if ( !$dbw->cascadingDeletes() ) {
                        $dbw->delete( 'revision', array( 'rev_page' => $newid ), __METHOD__ );
                        global $wgUseTrackbacks;
                        if ($wgUseTrackbacks)
                                $dbw->delete( 'trackbacks', array( 'tb_page' => $newid ), __METHOD__ );
                        $dbw->delete( 'pagelinks', array( 'pl_from' => $newid ), __METHOD__ );
                        $dbw->delete( 'imagelinks', array( 'il_from' => $newid ), __METHOD__ );
                        $dbw->delete( 'categorylinks', array( 'cl_from' => $newid ), __METHOD__ );
                        $dbw->delete( 'templatelinks', array( 'tl_from' => $newid ), __METHOD__ );
                        $dbw->delete( 'externallinks', array( 'el_from' => $newid ), __METHOD__ );
                        $dbw->delete( 'langlinks', array( 'll_from' => $newid ), __METHOD__ );
                        $dbw->delete( 'redirect', array( 'rd_from' => $newid ), __METHOD__ );
                }

                # Save a null revision in the page's history notifying of the move
                $nullRevision = Revision::newNullRevision( $dbw, $oldid, $comment, true );
                $nullRevId = $nullRevision->insertOn( $dbw );
                
                $article = new Article( $this );
                wfRunHooks( 'NewRevisionFromEditComplete', array($article, $nullRevision, false) );

                # Change the name of the target page:
                $dbw->update( 'page',
                        /* SET */ array(
                                'page_touched'   => $dbw->timestamp($now),
                                'page_namespace' => $nt->getNamespace(),
                                'page_title'     => $nt->getDBkey(),
                                'page_latest'    => $nullRevId,
                        ),
                        /* WHERE */ array( 'page_id' => $oldid ),
                        $fname
                );
                $nt->resetArticleID( $oldid );

                # Recreate the redirect, this time in the other direction.
                if( $createRedirect || !$wgUser->isAllowed('suppressredirect') ) {
                        $mwRedir = MagicWord::get( 'redirect' );
                        $redirectText = $mwRedir->getSynonym( 0 ) . ' [[' . $nt->getPrefixedText() . "]]\n";
                        $redirectArticle = new Article( $this );
                        $newid = $redirectArticle->insertOn( $dbw );
                        $redirectRevision = new Revision( array(
                                'page'    => $newid,
                                'comment' => $comment,
                                'text'    => $redirectText ) );
                        $redirectRevision->insertOn( $dbw );
                        $redirectArticle->updateRevisionOn( $dbw, $redirectRevision, 0 );
                        
                        wfRunHooks( 'NewRevisionFromEditComplete', array($redirectArticle, $redirectRevision, false) );

                        # Now, we record the link from the redirect to the new title.
                        # It should have no other outgoing links...
                        $dbw->delete( 'pagelinks', array( 'pl_from' => $newid ), $fname );
                        $dbw->insert( 'pagelinks',
                                array(
                                        'pl_from'      => $newid,
                                        'pl_namespace' => $nt->getNamespace(),
                                        'pl_title'     => $nt->getDBkey() ),
                                $fname );
                } else {
                        $this->resetArticleID( 0 );
                }
                
                # Move an image if this is a file
                if( $this->getNamespace() == NS_IMAGE ) {
                        $file = wfLocalFile( $this );
                        if( $file->exists() ) {
                                $status = $file->move( $nt );
                                if( !$status->isOk() ) {
                                        $dbw->rollback();
                                        return $status->getErrorsArray();
                                }
                        }
                }
                $dbw->commit();

                # Log the move
                $log = new LogPage( 'move' );
                $log->addEntry( 'move_redir', $this, $reason, array( 1 => $nt->getPrefixedText() ) );

                # Purge squid
                if ( $wgUseSquid ) {
                        $urls = array_merge( $nt->getSquidURLs(), $this->getSquidURLs() );
                        $u = new SquidUpdate( $urls );
                        $u->doUpdate();
                }
                
        }

        /**
         * Move page to non-existing title.
         * @param Title &$nt the new Title
         * @param string $reason The reason for the move
         * @param bool $createRedirect Whether to create a redirect from the old title to the new title
         *  Ignored if the user doesn't have the suppressredirect right
         */
        private function moveToNewTitle( &$nt, $reason = '', $createRedirect = true ) {
                global $wgUseSquid, $wgUser;
                $fname = 'MovePageForm::moveToNewTitle';
                $comment = wfMsgForContent( '1movedto2', $this->getPrefixedText(), $nt->getPrefixedText() );
                if ( $reason ) {
                        $comment .= wfMsgExt( 'colon-separator',
                                array( 'escapenoentities', 'content' ) );
                        $comment .= $reason;
                }

                $newid = $nt->getArticleID();
                $oldid = $this->getArticleID();
                
                $dbw = wfGetDB( DB_MASTER );
                $dbw->begin();
                $now = $dbw->timestamp();

                # Save a null revision in the page's history notifying of the move
                $nullRevision = Revision::newNullRevision( $dbw, $oldid, $comment, true );
                $nullRevId = $nullRevision->insertOn( $dbw );
                
                $article = new Article( $this );
                wfRunHooks( 'NewRevisionFromEditComplete', array($article, $nullRevision, false) );

                # Rename page entry
                $dbw->update( 'page',
                        /* SET */ array(
                                'page_touched'   => $now,
                                'page_namespace' => $nt->getNamespace(),
                                'page_title'     => $nt->getDBkey(),
                                'page_latest'    => $nullRevId,
                        ),
                        /* WHERE */ array( 'page_id' => $oldid ),
                        $fname
                );
                $nt->resetArticleID( $oldid );

                if( $createRedirect || !$wgUser->isAllowed('suppressredirect') ) {
                        # Insert redirect
                        $mwRedir = MagicWord::get( 'redirect' );
                        $redirectText = $mwRedir->getSynonym( 0 ) . ' [[' . $nt->getPrefixedText() . "]]\n";
                        $redirectArticle = new Article( $this );
                        $newid = $redirectArticle->insertOn( $dbw );
                        $redirectRevision = new Revision( array(
                                'page'    => $newid,
                                'comment' => $comment,
                                'text'    => $redirectText ) );
                        $redirectRevision->insertOn( $dbw );
                        $redirectArticle->updateRevisionOn( $dbw, $redirectRevision, 0 );
                        
                        wfRunHooks( 'NewRevisionFromEditComplete', array($redirectArticle, $redirectRevision, false) );

                        # Record the just-created redirect's linking to the page
                        $dbw->insert( 'pagelinks',
                                array(
                                        'pl_from'      => $newid,
                                        'pl_namespace' => $nt->getNamespace(),
                                        'pl_title'     => $nt->getDBkey() ),
                                $fname );
                } else {
                        $this->resetArticleID( 0 );
                }
                
                # Move an image if this is a file
                if( $this->getNamespace() == NS_IMAGE ) {
                        $file = wfLocalFile( $this );
                        if( $file->exists() ) {
                                $status = $file->move( $nt );
                                if( !$status->isOk() ) {
                                        $dbw->rollback();
                                        return $status->getErrorsArray();
                                }
                        }
                }
                $dbw->commit();

                # Log the move
                $log = new LogPage( 'move' );
                $log->addEntry( 'move', $this, $reason, array( 1 => $nt->getPrefixedText()) );

                # Purge caches as per article creation
                Article::onArticleCreate( $nt );

                # Purge old title from squid
                # The new title, and links to the new title, are purged in Article::onArticleCreate()
                $this->purgeSquid();
                
        }

        /**
         * Checks if $this can be moved to a given Title
         * - Selects for update, so don't call it unless you mean business
         *
         * @param Title &$nt the new title to check
         */
        public function isValidMoveTarget( $nt ) {

                $fname = 'Title::isValidMoveTarget';
                $dbw = wfGetDB( DB_MASTER );

                # Is it an existsing file?
                if( $nt->getNamespace() == NS_IMAGE ) {
                        $file = wfLocalFile( $nt );
                        if( $file->exists() ) {
                                wfDebug( __METHOD__ . ": file exists\n" );
                                return false;
                        }
                }

                # Is it a redirect?
                $id  = $nt->getArticleID();
                $obj = $dbw->selectRow( array( 'page', 'revision', 'text'),
                        array( 'page_is_redirect','old_text','old_flags' ),
                        array( 'page_id' => $id, 'page_latest=rev_id', 'rev_text_id=old_id' ),
                        $fname, 'FOR UPDATE' );

                if ( !$obj || 0 == $obj->page_is_redirect ) {
                        # Not a redirect
                        wfDebug( __METHOD__ . ": not a redirect\n" );
                        return false;
                }
                $text = Revision::getRevisionText( $obj );

                # Does the redirect point to the source?
                # Or is it a broken self-redirect, usually caused by namespace collisions?
                $m = array();
                if ( preg_match( "/\\[\\[\\s*([^\\]\\|]*)]]/", $text, $m ) ) {
                        $redirTitle = Title::newFromText( $m[1] );
                        if( !is_object( $redirTitle ) ||
                                ( $redirTitle->getPrefixedDBkey() != $this->getPrefixedDBkey() &&
                                $redirTitle->getPrefixedDBkey() != $nt->getPrefixedDBkey() ) ) {
                                wfDebug( __METHOD__ . ": redirect points to other page\n" );
                                return false;
                        }
                } else {
                        # Fail safe
                        wfDebug( __METHOD__ . ": failsafe\n" );
                        return false;
                }

                # Does the article have a history?
                $row = $dbw->selectRow( array( 'page', 'revision'),
                        array( 'rev_id' ),
                        array( 'page_namespace' => $nt->getNamespace(),
                                'page_title' => $nt->getDBkey(),
                                'page_id=rev_page AND page_latest != rev_id'
                        ), $fname, 'FOR UPDATE'
                );

                # Return true if there was no history
                return $row === false;
        }

        /**
         * Can this title be added to a user's watchlist?
         *
         * @return bool
         */
        public function isWatchable() {
                return !$this->isExternal()
                        && MWNamespace::isWatchable( $this->getNamespace() );
        }

        /**
         * Get categories to which this Title belongs and return an array of
         * categories' names.
         *
         * @return array an array of parents in the form:
         *      $parent => $currentarticle
         */
        public function getParentCategories() {
                global $wgContLang;

                $titlekey = $this->getArticleId();
                $dbr = wfGetDB( DB_SLAVE );
                $categorylinks = $dbr->tableName( 'categorylinks' );

                # NEW SQL
                $sql = "SELECT * FROM $categorylinks"
                     ." WHERE cl_from='$titlekey'"
                         ." AND cl_from <> '0'"
                         ." ORDER BY cl_sortkey";

                $res = $dbr->query( $sql );

                if( $dbr->numRows( $res ) > 0 ) {
                        while( $x = $dbr->fetchObject( $res ) )
                                //$data[] = Title::newFromText($wgContLang->getNSText ( NS_CATEGORY ).':'.$x->cl_to);
                                $data[$wgContLang->getNSText( NS_CATEGORY ).':'.$x->cl_to] = $this->getFullText();
                        $dbr->freeResult( $res );
                } else {
                        $data = array();
                }
                return $data;
        }

        /**
         * Get a tree of parent categories
         * @param array $children an array with the children in the keys, to check for circular refs
         * @return array
         */
        public function getParentCategoryTree( $children = array() ) {
                $stack = array();
                $parents = $this->getParentCategories();

                if( $parents ) {
                        foreach( $parents as $parent => $current ) {
                                if ( array_key_exists( $parent, $children ) ) {
                                        # Circular reference
                                        $stack[$parent] = array();
                                } else {
                                        $nt = Title::newFromText($parent);
                                        if ( $nt ) {
                                                $stack[$parent] = $nt->getParentCategoryTree( $children + array($parent => 1) );
                                        }
                                }
                        }
                        return $stack;
                } else {
                        return array();
                }
        }


        /**
         * Get an associative array for selecting this title from
         * the "page" table
         *
         * @return array
         */
        public function pageCond() {
                return array( 'page_namespace' => $this->mNamespace, 'page_title' => $this->mDbkeyform );
        }

        /**
         * Get the revision ID of the previous revision
         *
         * @param integer $revision  Revision ID. Get the revision that was before this one.
         * @param integer $flags, GAID_FOR_UPDATE
         * @return integer $oldrevision|false
         */
        public function getPreviousRevisionID( $revision, $flags=0 ) {
                $db = ($flags & GAID_FOR_UPDATE) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
                return $db->selectField( 'revision', 'rev_id',
                        array(
                                'rev_page' => $this->getArticleId($flags),
                                'rev_id < ' . intval( $revision )
                        ),
                        __METHOD__,
                        array( 'ORDER BY' => 'rev_id DESC' )
                );
        }

        /**
         * Get the revision ID of the next revision
         *
         * @param integer $revision  Revision ID. Get the revision that was after this one.
         * @param integer $flags, GAID_FOR_UPDATE
         * @return integer $oldrevision|false
         */
        public function getNextRevisionID( $revision, $flags=0 ) {
                $db = ($flags & GAID_FOR_UPDATE) ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
                return $db->selectField( 'revision', 'rev_id',
                        array(
                                'rev_page' => $this->getArticleId($flags),
                                'rev_id > ' . intval( $revision )
                        ),
                        __METHOD__,
                        array( 'ORDER BY' => 'rev_id' )
                );
        }

        /**
         * Get the number of revisions between the given revision IDs.
         * Used for diffs and other things that really need it.
         *
         * @param integer $old  Revision ID.
         * @param integer $new  Revision ID.
         * @return integer  Number of revisions between these IDs.
         */
        public function countRevisionsBetween( $old, $new ) {
                $dbr = wfGetDB( DB_SLAVE );
                return $dbr->selectField( 'revision', 'count(*)',
                        'rev_page = ' . intval( $this->getArticleId() ) .
                        ' AND rev_id > ' . intval( $old ) .
                        ' AND rev_id < ' . intval( $new ),
                        __METHOD__,
                        array( 'USE INDEX' => 'PRIMARY' ) );
        }

        /**
         * Compare with another title.
         *
         * @param Title $title
         * @return bool
         */
        public function equals( $title ) {
                // Note: === is necessary for proper matching of number-like titles.
                return $this->getInterwiki() === $title->getInterwiki()
                        && $this->getNamespace() == $title->getNamespace()
                        && $this->getDBkey() === $title->getDBkey();
        }

        /**
         * Callback for usort() to do title sorts by (namespace, title)
         */
        static function compare( $a, $b ) {
                if( $a->getNamespace() == $b->getNamespace() ) {
                        return strcmp( $a->getText(), $b->getText() );
                } else {
                        return $a->getNamespace() - $b->getNamespace();
                }
        }

        /**
         * Return a string representation of this title
         *
         * @return string
         */
        public function __toString() {
                return $this->getPrefixedText();
        }

        /**
         * Check if page exists
         * @return bool
         */
        public function exists() {
                return $this->getArticleId() != 0;
        }

        /**
         * Do we know that this title definitely exists, or should we otherwise
         * consider that it exists?
         *
         * @return bool
         */
        public function isAlwaysKnown() {
                // If the page is form Mediawiki:message/lang, calling wfMsgWeirdKey causes
                // the full l10n of that language to be loaded. That takes much memory and
                // isn't needed. So we strip the language part away.
                // Also, extension messages which are not loaded, are shown as red, because
                // we don't call MessageCache::loadAllMessages.
                list( $basename, /* rest */ ) = explode( '/', $this->mDbkeyform, 2 );
                return $this->isExternal()
                        || ( $this->mNamespace == NS_MAIN && $this->mDbkeyform == '' )
                        || ( $this->mNamespace == NS_MEDIAWIKI && wfMsgWeirdKey( $basename ) );
        }

        /**
         * Update page_touched timestamps and send squid purge messages for
         * pages linking to this title. May be sent to the job queue depending
         * on the number of links. Typically called on create and delete.
         */
        public function touchLinks() {
                $u = new HTMLCacheUpdate( $this, 'pagelinks' );
                $u->doUpdate();

                if ( $this->getNamespace() == NS_CATEGORY ) {
                        $u = new HTMLCacheUpdate( $this, 'categorylinks' );
                        $u->doUpdate();
                }
        }

        /**
         * Get the last touched timestamp
         */
        public function getTouched() {
                $dbr = wfGetDB( DB_SLAVE );
                $touched = $dbr->selectField( 'page', 'page_touched',
                        array(
                                'page_namespace' => $this->getNamespace(),
                                'page_title' => $this->getDBkey()
                        ), __METHOD__
                );
                return $touched;
        }

        public function trackbackURL() {
                global $wgTitle, $wgScriptPath, $wgServer;

                return "$wgServer$wgScriptPath/trackback.php?article="
                        . htmlspecialchars(urlencode($wgTitle->getPrefixedDBkey()));
        }

        public function trackbackRDF() {
                $url = htmlspecialchars($this->getFullURL());
                $title = htmlspecialchars($this->getText());
                $tburl = $this->trackbackURL();

                // Autodiscovery RDF is placed in comments so HTML validator
                // won't barf. This is a rather icky workaround, but seems
                // frequently used by this kind of RDF thingy.
                //
                // Spec: http://www.sixapart.com/pronet/docs/trackback_spec
                return "<!--
<rdf:RDF xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"
         xmlns:dc=\"http://purl.org/dc/elements/1.1/\"
         xmlns:trackback=\"http://madskills.com/public/xml/rss/module/trackback/\">
<rdf:Description
   rdf:about=\"$url\"
   dc:identifier=\"$url\"
   dc:title=\"$title\"
   trackback:ping=\"$tburl\" />
</rdf:RDF>
-->";
        }

        /**
         * Generate strings used for xml 'id' names in monobook tabs
         * @return string
         */
        public function getNamespaceKey() {
                global $wgContLang;
                switch ($this->getNamespace()) {
                        case NS_MAIN:
                        case NS_TALK:
                                return 'nstab-main';
                        case NS_USER:
                        case NS_USER_TALK:
                                return 'nstab-user';
                        case NS_MEDIA:
                                return 'nstab-media';
                        case NS_SPECIAL:
                                return 'nstab-special';
                        case NS_PROJECT:
                        case NS_PROJECT_TALK:
                                return 'nstab-project';
                        case NS_IMAGE:
                        case NS_IMAGE_TALK:
                                return 'nstab-image';
                        case NS_MEDIAWIKI:
                        case NS_MEDIAWIKI_TALK:
                                return 'nstab-mediawiki';
                        case NS_TEMPLATE:
                        case NS_TEMPLATE_TALK:
                                return 'nstab-template';
                        case NS_HELP:
                        case NS_HELP_TALK:
                                return 'nstab-help';
                        case NS_CATEGORY:
                        case NS_CATEGORY_TALK:
                                return 'nstab-category';
                        default:
                                return 'nstab-' . $wgContLang->lc( $this->getSubjectNsText() );
                }
        }

        /**
         * Returns true if this title resolves to the named special page
         * @param string $name The special page name
         */
        public function isSpecial( $name ) {
                if ( $this->getNamespace() == NS_SPECIAL ) {
                        list( $thisName, /* $subpage */ ) = SpecialPage::resolveAliasWithSubpage( $this->getDBkey() );
                        if ( $name == $thisName ) {
                                return true;
                        }
                }
                return false;
        }

        /**
         * If the Title refers to a special page alias which is not the local default,
         * returns a new Title which points to the local default. Otherwise, returns $this.
         */
        public function fixSpecialName() {
                if ( $this->getNamespace() == NS_SPECIAL ) {
                        $canonicalName = SpecialPage::resolveAlias( $this->mDbkeyform );
                        if ( $canonicalName ) {
                                $localName = SpecialPage::getLocalNameFor( $canonicalName );
                                if ( $localName != $this->mDbkeyform ) {
                                        return Title::makeTitle( NS_SPECIAL, $localName );
                                }
                        }
                }
                return $this;
        }

        /**
         * Is this Title in a namespace which contains content?
         * In other words, is this a content page, for the purposes of calculating
         * statistics, etc?
         *
         * @return bool
         */
        public function isContentPage() {
                return MWNamespace::isContent( $this->getNamespace() );
        }

        public function getRedirectsHere( $ns = null ) {
                $redirs = array();
                
                $dbr = wfGetDB( DB_SLAVE );     
                $where = array(
                        'rd_namespace' => $this->getNamespace(),
                        'rd_title' => $this->getDBkey(),
                        'rd_from = page_id'
                );
                if ( !is_null($ns) ) $where['page_namespace'] = $ns;
                
                $result = $dbr->select(
                        array( 'redirect', 'page' ),
                        array( 'page_namespace', 'page_title' ),
                        $where,
                        __METHOD__
                );


                while( $row = $dbr->fetchObject( $result ) ) {
                        $redirs[] = self::newFromRow( $row );
                }
                return $redirs;
        }
}