MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / includes / libs / rdbms / database / resultwrapper / ResultWrapper.php

diff --git a/includes/libs/rdbms/database/resultwrapper/ResultWrapper.php b/includes/libs/rdbms/database/resultwrapper/ResultWrapper.php
new file mode 100644 (file)
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+++ b/includes/libs/rdbms/database/resultwrapper/ResultWrapper.php
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+<?php
+
+namespace Wikimedia\Rdbms;
+
+use stdClass;
+use RuntimeException;
+
+/**
+ * Result wrapper for grabbing data queried from an IDatabase object
+ *
+ * Note that using the Iterator methods in combination with the non-Iterator
+ * DB result iteration functions may cause rows to be skipped or repeated.
+ *
+ * By default, this will use the iteration methods of the IDatabase handle if provided.
+ * Subclasses can override methods to make it solely work on the result resource instead.
+ * If no database is provided, and the subclass does not override the DB iteration methods,
+ * then a RuntimeException will be thrown when iteration is attempted.
+ *
+ * The result resource field should not be accessed from non-Database related classes.
+ * It is database class specific and is stored here to associate iterators with queries.
+ *
+ * @ingroup Database
+ */
+class ResultWrapper implements IResultWrapper {
+       /** @var resource|array|null Optional underlying result handle for subclass usage */
+       public $result;
+
+       /** @var IDatabase|null */
+       protected $db;
+
+       /** @var int */
+       protected $pos = 0;
+       /** @var stdClass|null */
+       protected $currentRow = null;
+
+       /**
+        * Create a row iterator from a result resource and an optional Database object
+        *
+        * Only Database-related classes should construct ResultWrapper. Other code may
+        * use the FakeResultWrapper subclass for convenience or compatibility shims, however.
+        *
+        * @param IDatabase|null $db Optional database handle
+        * @param ResultWrapper|array|resource $result Optional underlying result handle
+        */
+       public function __construct( IDatabase $db = null, $result ) {
+               $this->db = $db;
+               if ( $result instanceof ResultWrapper ) {
+                       $this->result = $result->result;
+               } else {
+                       $this->result = $result;
+               }
+       }
+
+       public function numRows() {
+               return $this->getDB()->numRows( $this );
+       }
+
+       public function fetchObject() {
+               return $this->getDB()->fetchObject( $this );
+       }
+
+       public function fetchRow() {
+               return $this->getDB()->fetchRow( $this );
+       }
+
+       public function seek( $row ) {
+               $this->getDB()->dataSeek( $this, $row );
+       }
+
+       public function free() {
+               if ( $this->db ) {
+                       $this->db->freeResult( $this );
+                       $this->db = null;
+               }
+               $this->result = null;
+       }
+
+       /**
+        * @return IDatabase
+        * @throws RuntimeException
+        */
+       private function getDB() {
+               if ( !$this->db ) {
+                       throw new RuntimeException( static::class . ' needs a DB handle for iteration.' );
+               }
+
+               return $this->db;
+       }
+
+       function rewind() {
+               if ( $this->numRows() ) {
+                       $this->getDB()->dataSeek( $this, 0 );
+               }
+               $this->pos = 0;
+               $this->currentRow = null;
+       }
+
+       function current() {
+               if ( is_null( $this->currentRow ) ) {
+                       $this->next();
+               }
+
+               return $this->currentRow;
+       }
+
+       function key() {
+               return $this->pos;
+       }
+
+       function next() {
+               $this->pos++;
+               $this->currentRow = $this->fetchObject();
+
+               return $this->currentRow;
+       }
+
+       function valid() {
+               return $this->current() !== false;
+       }
+}
+
+class_alias( ResultWrapper::class, 'ResultWrapper' );