Category.php

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<?php
class Category {
        private $mName = null;
        private $mID = null;
        private $mTitle = null;
        private $mPages = null, $mSubcats = null, $mFiles = null;

        private function __construct() { }

        protected function initialize() {
                if ( $this->mName === null && $this->mID === null ) {
                        throw new MWException( __METHOD__ . ' has both names and IDs null' );
                } elseif ( $this->mID === null ) {
                        $where = array( 'cat_title' => $this->mName );
                } elseif ( $this->mName === null ) {
                        $where = array( 'cat_id' => $this->mID );
                } else {
                        # Already initialized
                        return true;
                }

                wfProfileIn( __METHOD__ );

                $dbr = wfGetDB( DB_SLAVE );
                $row = $dbr->selectRow(
                        'category',
                        array( 'cat_id', 'cat_title', 'cat_pages', 'cat_subcats', 'cat_files' ),
                        $where,
                        __METHOD__
                );

                wfProfileOut( __METHOD__ );

                if ( !$row ) {
                        # Okay, there were no contents.  Nothing to initialize.
                        if ( $this->mTitle ) {
                                # If there is a title object but no record in the category table, treat this as an empty category
                                $this->mID      = false;
                                $this->mName    = $this->mTitle->getDBkey();
                                $this->mPages   = 0;
                                $this->mSubcats = 0;
                                $this->mFiles   = 0;

                                return true;
                        } else {
                                return false; # Fail
                        }
                }

                $this->mID      = $row->cat_id;
                $this->mName    = $row->cat_title;
                $this->mPages   = $row->cat_pages;
                $this->mSubcats = $row->cat_subcats;
                $this->mFiles   = $row->cat_files;

                # (bug 13683) If the count is negative, then 1) it's obviously wrong
                # and should not be kept, and 2) we *probably* don't have to scan many
                # rows to obtain the correct figure, so let's risk a one-time recount.
                if ( $this->mPages < 0 || $this->mSubcats < 0 || $this->mFiles < 0 ) {
                        $this->refreshCounts();
                }

                return true;
        }

        public static function newFromName( $name ) {
                $cat = new self();
                $title = Title::makeTitleSafe( NS_CATEGORY, $name );

                if ( !is_object( $title ) ) {
                        return false;
                }

                $cat->mTitle = $title;
                $cat->mName = $title->getDBkey();

                return $cat;
        }

        public static function newFromTitle( $title ) {
                $cat = new self();

                $cat->mTitle = $title;
                $cat->mName = $title->getDBkey();

                return $cat;
        }

        public static function newFromID( $id ) {
                $cat = new self();
                $cat->mID = intval( $id );
                return $cat;
        }

        public static function newFromRow( $row, $title = null ) {
                $cat = new self();
                $cat->mTitle = $title;

                # NOTE: the row often results from a LEFT JOIN on categorylinks. This may result in
                #       all the cat_xxx fields being null, if the category page exists, but nothing
                #       was ever added to the category. This case should be treated linke an empty
                #       category, if possible.

                if ( $row->cat_title === null ) {
                        if ( $title === null ) {
                                # the name is probably somewhere in the row, for example as page_title,
                                # but we can't know that here...
                                return false;
                        } else {
                                $cat->mName = $title->getDBkey(); # if we have a title object, fetch the category name from there
                        }

                        $cat->mID =   false;
                        $cat->mSubcats = 0;
                        $cat->mPages   = 0;
                        $cat->mFiles   = 0;
                } else {
                        $cat->mName    = $row->cat_title;
                        $cat->mID      = $row->cat_id;
                        $cat->mSubcats = $row->cat_subcats;
                        $cat->mPages   = $row->cat_pages;
                        $cat->mFiles   = $row->cat_files;
                }

                return $cat;
        }

        public function getName() {
                return $this->getX( 'mName' );
        }

        public function getID() {
                return $this->getX( 'mID' );
        }

        public function getPageCount() {
                return $this->getX( 'mPages' );
        }

        public function getSubcatCount() {
                return $this->getX( 'mSubcats' );
        }

        public function getFileCount() {
                return $this->getX( 'mFiles' );
        }

        public function getTitle() {
                if ( $this->mTitle ) {
                        return $this->mTitle;
                }

                if ( !$this->initialize() ) {
                        return false;
                }

                $this->mTitle = Title::makeTitleSafe( NS_CATEGORY, $this->mName );
                return $this->mTitle;
        }

        public function getMembers( $limit = false, $offset = '' ) {
                wfProfileIn( __METHOD__ );

                $dbr = wfGetDB( DB_SLAVE );

                $conds = array( 'cl_to' => $this->getName(), 'cl_from = page_id' );
                $options = array( 'ORDER BY' => 'cl_sortkey' );

                if ( $limit ) {
                        $options['LIMIT'] = $limit;
                }

                if ( $offset !== '' ) {
                        $conds[] = 'cl_sortkey > ' . $dbr->addQuotes( $offset );
                }

                $result = TitleArray::newFromResult(
                        $dbr->select(
                                array( 'page', 'categorylinks' ),
                                array( 'page_id', 'page_namespace', 'page_title', 'page_len',
                                        'page_is_redirect', 'page_latest' ),
                                $conds,
                                __METHOD__,
                                $options
                        )
                );

                wfProfileOut( __METHOD__ );

                return $result;
        }

        private function getX( $key ) {
                if ( !$this->initialize() ) {
                        return false;
                }
                return $this->{$key};
        }

        public function refreshCounts() {
                if ( wfReadOnly() ) {
                        return false;
                }

                # Note, we must use names for this, since categorylinks does.
                if ( $this->mName === null ) {
                        if ( !$this->initialize() ) {
                                return false;
                        }
                }

                wfProfileIn( __METHOD__ );

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

                # Insert the row if it doesn't exist yet (e.g., this is being run via
                # update.php from a pre-1.16 schema).  TODO: This will cause lots and
                # lots of gaps on some non-MySQL DBMSes if you run populateCategory.php
                # repeatedly.  Plus it's an extra query that's unneeded almost all the
                # time.  This should be rewritten somehow, probably.
                $seqVal = $dbw->nextSequenceValue( 'category_cat_id_seq' );
                $dbw->insert(
                        'category',
                        array(
                                'cat_id' => $seqVal,
                                'cat_title' => $this->mName
                        ),
                        __METHOD__,
                        'IGNORE'
                );

                $cond1 = $dbw->conditional( array( 'page_namespace' => NS_CATEGORY ), 1, 'NULL' );
                $cond2 = $dbw->conditional( array( 'page_namespace' => NS_FILE ), 1, 'NULL' );
                $result = $dbw->selectRow(
                        array( 'categorylinks', 'page' ),
                        array( 'pages' => 'COUNT(*)',
                                'subcats' => "COUNT($cond1)",
                                'files' => "COUNT($cond2)"
                        ),
                        array( 'cl_to' => $this->mName, 'page_id = cl_from' ),
                        __METHOD__,
                        'LOCK IN SHARE MODE'
                );
                $ret = $dbw->update(
                        'category',
                        array(
                                'cat_pages' => $result->pages,
                                'cat_subcats' => $result->subcats,
                                'cat_files' => $result->files
                        ),
                        array( 'cat_title' => $this->mName ),
                        __METHOD__
                );
                $dbw->commit( __METHOD__ );

                wfProfileOut( __METHOD__ );

                # Now we should update our local counts.
                $this->mPages   = $result->pages;
                $this->mSubcats = $result->subcats;
                $this->mFiles   = $result->files;

                return $ret;
        }
}