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vendor/yiisoft/yii2/db/BatchQueryResult.php

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+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\db;
+
+use yii\base\BaseObject;
+
+/**
+ * BatchQueryResult represents a batch query from which you can retrieve data in batches.
+ *
+ * You usually do not instantiate BatchQueryResult directly. Instead, you obtain it by
+ * calling [[Query::batch()]] or [[Query::each()]]. Because BatchQueryResult implements the [[\Iterator]] interface,
+ * you can iterate it to obtain a batch of data in each iteration. For example,
+ *
+ * ```php
+ * $query = (new Query)->from('user');
+ * foreach ($query->batch() as $i => $users) {
+ *     // $users represents the rows in the $i-th batch
+ * }
+ * foreach ($query->each() as $user) {
+ * }
+ * ```
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class BatchQueryResult extends BaseObject implements \Iterator
+{
+    /**
+     * @var Connection the DB connection to be used when performing batch query.
+     * If null, the "db" application component will be used.
+     */
+    public $db;
+    /**
+     * @var Query the query object associated with this batch query.
+     * Do not modify this property directly unless after [[reset()]] is called explicitly.
+     */
+    public $query;
+    /**
+     * @var int the number of rows to be returned in each batch.
+     */
+    public $batchSize = 100;
+    /**
+     * @var bool whether to return a single row during each iteration.
+     * If false, a whole batch of rows will be returned in each iteration.
+     */
+    public $each = false;
+
+    /**
+     * @var DataReader the data reader associated with this batch query.
+     */
+    private $_dataReader;
+    /**
+     * @var array the data retrieved in the current batch
+     */
+    private $_batch;
+    /**
+     * @var mixed the value for the current iteration
+     */
+    private $_value;
+    /**
+     * @var string|int the key for the current iteration
+     */
+    private $_key;
+
+
+    /**
+     * Destructor.
+     */
+    public function __destruct()
+    {
+        // make sure cursor is closed
+        $this->reset();
+    }
+
+    /**
+     * Resets the batch query.
+     * This method will clean up the existing batch query so that a new batch query can be performed.
+     */
+    public function reset()
+    {
+        if ($this->_dataReader !== null) {
+            $this->_dataReader->close();
+        }
+        $this->_dataReader = null;
+        $this->_batch = null;
+        $this->_value = null;
+        $this->_key = null;
+    }
+
+    /**
+     * Resets the iterator to the initial state.
+     * This method is required by the interface [[\Iterator]].
+     */
+    public function rewind()
+    {
+        $this->reset();
+        $this->next();
+    }
+
+    /**
+     * Moves the internal pointer to the next dataset.
+     * This method is required by the interface [[\Iterator]].
+     */
+    public function next()
+    {
+        if ($this->_batch === null || !$this->each || $this->each && next($this->_batch) === false) {
+            $this->_batch = $this->fetchData();
+            reset($this->_batch);
+        }
+
+        if ($this->each) {
+            $this->_value = current($this->_batch);
+            if ($this->query->indexBy !== null) {
+                $this->_key = key($this->_batch);
+            } elseif (key($this->_batch) !== null) {
+                $this->_key = $this->_key === null ? 0 : $this->_key + 1;
+            } else {
+                $this->_key = null;
+            }
+        } else {
+            $this->_value = $this->_batch;
+            $this->_key = $this->_key === null ? 0 : $this->_key + 1;
+        }
+    }
+
+    /**
+     * Fetches the next batch of data.
+     * @return array the data fetched
+     */
+    protected function fetchData()
+    {
+        if ($this->_dataReader === null) {
+            $this->_dataReader = $this->query->createCommand($this->db)->query();
+        }
+
+        $rows = [];
+        $count = 0;
+        while ($count++ < $this->batchSize && ($row = $this->_dataReader->read())) {
+            $rows[] = $row;
+        }
+
+        return $this->query->populate($rows);
+    }
+
+    /**
+     * Returns the index of the current dataset.
+     * This method is required by the interface [[\Iterator]].
+     * @return int the index of the current row.
+     */
+    public function key()
+    {
+        return $this->_key;
+    }
+
+    /**
+     * Returns the current dataset.
+     * This method is required by the interface [[\Iterator]].
+     * @return mixed the current dataset.
+     */
+    public function current()
+    {
+        return $this->_value;
+    }
+
+    /**
+     * Returns whether there is a valid dataset at the current position.
+     * This method is required by the interface [[\Iterator]].
+     * @return bool whether there is a valid dataset at the current position.
+     */
+    public function valid()
+    {
+        return !empty($this->_batch);
+    }
+}