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lib/pkp/classes/db/DAOResultIterator.php

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+<?php
+
+/**
+ * @file classes/db/DAOResultIterator.php
+ *
+ * Copyright (c) 2014-2021 Simon Fraser University
+ * Copyright (c) 2000-2021 John Willinsky
+ * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
+ *
+ * @class DAOResultIterator
+ *
+ * @ingroup db
+ *
+ * @brief Wrapper around a DAOResultFactory providing a proper PHP Iterator implementation
+ */
+
+namespace PKP\db;
+
+/**
+ * @template T of \PKP\core\DataObject
+ * @implements \Iterator<int,T>
+ */
+class DAOResultIterator implements \Iterator, \Countable
+{
+    /** @var DAOResultFactory<T> */
+    public $_resultFactory;
+
+    /** @var T Current return value data object. */
+    public $_current = null;
+
+    /** @var int $_i 0-based index of current data object. */
+    public $_i = 0;
+
+    /**
+     * Create an Iterator for the specified DAOResultFactory.
+     * @param DAOResultFactory<T> $resultFactory
+     */
+    public function __construct($resultFactory)
+    {
+        $this->_resultFactory = $resultFactory;
+        $this->_current = $this->_resultFactory->next();
+    }
+
+    /**
+     * @copydoc \Iterator::current
+     */
+    public function current(): mixed
+    {
+        return $this->_current;
+    }
+
+    /**
+     * Return the 0-based index for the current object.
+     * Note that this is NOT the DataObject's ID -- for that, call
+     * getId() on the current element.
+     *
+     * @return int|null
+     */
+    public function key(): mixed
+    {
+        if (!$this->_current) {
+            return null;
+        }
+        return $this->_i;
+    }
+
+    /**
+     * @copydoc \Iterator::next()
+     */
+    public function next(): void
+    {
+        $this->_current = $this->_resultFactory->next();
+        $this->_i++;
+    }
+
+    /**
+     * Rewind the DAOResultFactory to the beginning. WARNING that this
+     * operation is not arbitrarily supported -- it can only be called
+     * before the first call to `next()`.
+     */
+    public function rewind(): void
+    {
+        if ($this->_i != 0) {
+            throw new \Exception('DAOResultIterator currently does not support rewind() once iteration has started.');
+        }
+    }
+
+    /**
+     * @copydoc \Iterator::valid()
+     */
+    public function valid(): bool
+    {
+        return ($this->_current !== null);
+    }
+
+    /**
+     * @copydoc \Countable::count()
+     */
+    public function count(): int
+    {
+        return $this->_resultFactory->getCount();
+    }
+}
+
+if (!PKP_STRICT_MODE) {
+    class_alias('\PKP\db\DAOResultIterator', '\DAOResultIterator');
+}