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[mediawiki.git] / includes / db / DatabaseUtility.php

<?php
/**
 * Utility class.
 * @ingroup Database
 */
class DBObject {
        public $mData;

        function __construct( $data ) {
                $this->mData = $data;
        }

        /**
         * @return bool
         */
        function isLOB() {
                return false;
        }

        function data() {
                return $this->mData;
        }
}

/**
 * Utility class
 * @ingroup Database
 *
 * This allows us to distinguish a blob from a normal string and an array of strings
 */
class Blob {
        private $mData;

        function __construct( $data ) {
                $this->mData = $data;
        }

        function fetch() {
                return $this->mData;
        }
}

/**
 * Base for all database-specific classes representing information about database fields
 * @ingroup Database
 */
interface Field {
        /**
         * Field name
         * @return string
         */
        function name();

        /**
         * Name of table this field belongs to
         * @return string
         */
        function tableName();

        /**
         * Database type
         * @return string
         */
        function type();

        /**
         * Whether this field can store NULL values
         * @return bool
         */
        function isNullable();
}

/**
 * Result wrapper for grabbing data queried by someone else
 * @ingroup Database
 */
class ResultWrapper implements Iterator {
        var $db, $result, $pos = 0, $currentRow = null;

        /**
         * Create a new result object from a result resource and a Database object
         *
         * @param DatabaseBase $database
         * @param resource $result
         */
        function __construct( $database, $result ) {
                $this->db = $database;

                if ( $result instanceof ResultWrapper ) {
                        $this->result = $result->result;
                } else {
                        $this->result = $result;
                }
        }

        /**
         * Get the number of rows in a result object
         *
         * @return integer
         */
        function numRows() {
                return $this->db->numRows( $this );
        }

        /**
         * Fetch the next row from the given result object, in object form.
         * Fields can be retrieved with $row->fieldname, with fields acting like
         * member variables.
         *
         * @return object
         * @throws DBUnexpectedError Thrown if the database returns an error
         */
        function fetchObject() {
                return $this->db->fetchObject( $this );
        }

        /**
         * Fetch the next row from the given result object, in associative array
         * form.  Fields are retrieved with $row['fieldname'].
         *
         * @return Array
         * @throws DBUnexpectedError Thrown if the database returns an error
         */
        function fetchRow() {
                return $this->db->fetchRow( $this );
        }

        /**
         * Free a result object
         */
        function free() {
                $this->db->freeResult( $this );
                unset( $this->result );
                unset( $this->db );
        }

        /**
         * Change the position of the cursor in a result object.
         * See mysql_data_seek()
         *
         * @param $row integer
         */
        function seek( $row ) {
                $this->db->dataSeek( $this, $row );
        }

        /*********************
         * Iterator functions
         * Note that using these in combination with the non-iterator functions
         * above may cause rows to be skipped or repeated.
         */

        function rewind() {
                if ( $this->numRows() ) {
                        $this->db->dataSeek( $this, 0 );
                }
                $this->pos = 0;
                $this->currentRow = null;
        }

        /**
         * @return int
         */
        function current() {
                if ( is_null( $this->currentRow ) ) {
                        $this->next();
                }
                return $this->currentRow;
        }

        /**
         * @return int
         */
        function key() {
                return $this->pos;
        }

        /**
         * @return int
         */
        function next() {
                $this->pos++;
                $this->currentRow = $this->fetchObject();
                return $this->currentRow;
        }

        /**
         * @return bool
         */
        function valid() {
                return $this->current() !== false;
        }
}

/**
 * Overloads the relevant methods of the real ResultsWrapper so it
 * doesn't go anywhere near an actual database.
 */
class FakeResultWrapper extends ResultWrapper {
        var $result     = array();
        var $db         = null; // And it's going to stay that way :D
        var $pos        = 0;
        var $currentRow = null;

        function __construct( $array ) {
                $this->result = $array;
        }

        /**
         * @return int
         */
        function numRows() {
                return count( $this->result );
        }

        function fetchRow() {
                if ( $this->pos < count( $this->result ) ) {
                        $this->currentRow = $this->result[$this->pos];
                } else {
                        $this->currentRow = false;
                }
                $this->pos++;
                return $this->currentRow;
        }

        function seek( $row ) {
                $this->pos = $row;
        }

        function free() {}

        // Callers want to be able to access fields with $this->fieldName
        function fetchObject() {
                $this->fetchRow();
                if ( $this->currentRow ) {
                        return (object)$this->currentRow;
                } else {
                        return false;
                }
        }

        function rewind() {
                $this->pos = 0;
                $this->currentRow = null;
        }

        function next() {
                return $this->fetchObject();
        }
}

/**
 * Used by DatabaseBase::buildLike() to represent characters that have special meaning in SQL LIKE clauses
 * and thus need no escaping. Don't instantiate it manually, use DatabaseBase::anyChar() and anyString() instead.
 */
class LikeMatch {
        private $str;

        /**
         * Store a string into a LikeMatch marker object.
         *
         * @param String $s
         */
        public function __construct( $s ) {
                $this->str = $s;
        }

        /**
         * Return the original stored string.
         *
         * @return String
         */
        public function toString() {
                return $this->str;
        }
}

/**
 * An object representing a master or slave position in a replicated setup.
 */
interface DBMasterPos {
}