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diff --git a/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/EntityStore/DataItemHandler.php b/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/EntityStore/DataItemHandler.php
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+<?php
+
+namespace SMW\SQLStore\EntityStore;
+
+use SMW\SQLStore\SQLStore;
+use SMWDataItem as DataItem;
+
+/**
+ * Classes extending this represent all store layout that is known about a certain dataitem
+ *
+ * @license GNU GPL v2+
+ * @since 1.8
+ *
+ * @author Nischay Nahata
+ */
+abstract class DataItemHandler {
+
+	/**
+	 * @var SQLStore
+	*/
+	protected $store;
+
+	/**
+	 * @var integer
+	*/
+	protected $fieldTypeFeatures = false;
+
+	/**
+	 * @var null|string
+	*/
+	private $dbType;
+
+	/**
+	 * @since 1.8
+	 *
+	 * @param SQLStore $store
+	 */
+	public function __construct( SQLStore $store ) {
+		$this->store = $store;
+	}
+
+	/**
+	 * @since 3.0
+	 *
+	 * @param integer $fieldTypeFeatures
+	 */
+	public function setFieldTypeFeatures( $fieldTypeFeatures ) {
+		$this->fieldTypeFeatures = $fieldTypeFeatures;
+	}
+
+	/**
+	 * @since 3.0
+	 *
+	 * @param integer $feature
+	 *
+	 * @return boolean
+	 */
+	public function isEnabledFeature( $feature ) {
+		return ( (int)$this->fieldTypeFeatures & $feature ) != 0;
+	}
+
+	/**
+	 * @since 3.0
+	 *
+	 * @param boolean
+	 */
+	public function isDbType( $dbType ) {
+
+		if ( $this->dbType === null ) {
+			$this->dbType = $this->store->getConnection( 'mw.db' )->getType();
+		}
+
+		return $this->dbType === $dbType;
+	}
+
+	/**
+	 * Return array of fields for a DI type.
+	 *
+	 * Tables declare value columns ("object fields") by specifying their
+	 * name and type. Types are given using letters:
+	 * - t for strings of the same maximal length as MediaWiki title names,
+	 * - l for arbitrarily long strings; searching/sorting with such data
+	 *   may be limited for performance reasons,
+	 * - w for strings as used in MediaWiki for encoding interwiki prefixes
+	 * - n for namespace numbers (or other similar integers)
+	 * - f for floating point numbers of double precision
+	 * - p for a reference to an SMW ID as stored in the SMW IDs table;
+	 *   this corresponds to a data entry of ID "tnwt".
+	 *
+	 * @since 1.8
+	 * @return array
+	 */
+	abstract public function getTableFields();
+
+	/**
+	 * Return an array with all the field names and types that need to be
+	 * retrieved from the database in order to create a dataitem using
+	 * dataItemFromDBKeys(). The result format is the same as for
+	 * getTableFields(), but usually with fewer field names.
+	 *
+	 * @note In the future, we will most likely use a method that return
+	 * only a single field name. Currently, we still need an array for
+	 * concepts.
+	 *
+	 * @since 1.8
+	 * @return array
+	 */
+	abstract public function getFetchFields();
+
+	/**
+	 * Return an array of additional indexes that should be provided for
+	 * the table using this DI handler. By default, SMWSQLStore3 will
+	 * already create indexes for all standard select operations, based
+	 * on the indexfield provided by getIndexField(). Hence, most handlers
+	 * do not need to define any indexes.
+	 *
+	 * @since 1.8
+	 * @return array
+	 */
+	public function getTableIndexes() {
+		return [];
+	}
+
+	/**
+	 * Provides a possibility to return a specific index hint for a domain.
+	 *
+	 * @since 3.0
+	 *
+	 * @param string $key
+	 *
+	 * @return string
+	 */
+	public function getIndexHint( $key ) {
+		return '';
+	}
+
+	/**
+	 * Return an array of fields=>values to conditions (WHERE part) in SQL
+	 * queries for the given DataItem. This method can return fewer
+	 * fields than getInstertValues as long as they are enough to identify
+	 * an item for search.
+	 *
+	 * @since 1.8
+	 * @param DataItem $dataItem
+	 * @return array
+	 */
+	abstract public function getWhereConds( DataItem $dataItem );
+
+	/**
+	 * Return an array of fields=>values that is to be inserted when
+	 * writing the given DataItem to the database. Values should be set
+	 * for all columns, even if NULL. This array is used to perform all
+	 * insert operations into the DB.
+	 *
+	 * @since 1.8
+	 * @param DataItem $dataItem
+	 * @return array
+	 */
+	abstract public function getInsertValues( DataItem $dataItem );
+
+	/**
+	 * Return the field used to select this type of DataItem. In
+	 * particular, this identifies the column that is used to sort values
+	 * of this kind. Every type of data returns a non-empty string here.
+	 *
+	 * @since 1.8
+	 * @return string
+	 */
+	abstract public function getIndexField();
+
+	/**
+	 * Return the label field for this type of DataItem. This should be
+	 * a string column in the database table that can be used for selecting
+	 * values using criteria such as "starts with". The return value can be
+	 * empty if this is not supported. This is preferred for DataItem
+	 * classes that do not have an obvious canonical string writing anyway.
+	 *
+	 * The return value can be a column name or the empty string (if the
+	 * give type of DataItem does not have a label field).
+	 *
+	 * @since 1.8
+	 * @return string
+	 */
+	abstract public function getLabelField();
+
+	/**
+	 * Returns the expected sort field.
+	 *
+	 * @since 3.0
+	 *
+	 * @return string
+	 */
+	public function getSortField() {
+		return '';
+	}
+
+	/**
+	 * Create a dataitem from an array of DB keys or a single DB key
+	 * string. May throw an DataItemException if the given DB keys
+	 * cannot be converted back into a dataitem. Each implementation
+	 * of this method must otherwise run without errors for both array
+	 * and string inputs.
+	 *
+	 * @since 1.8
+	 * @param array|string $dbkeys
+	 * @throws DataItemException
+	 * @return DataItem
+	 */
+	abstract public function dataItemFromDBKeys( $dbkeys );
+
+}