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    <h3>Editing: CachingIterator.php</h3>
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/**
 * This file is part of the Nette Framework (https://nette.org)
 * Copyright (c) 2004 David Grudl (https://davidgrudl.com)
 */

declare(strict_types=1);

namespace Nette\Iterators;

use Nette;


/**
 * Smarter caching iterator.
 *
 * @property-read bool $first
 * @property-read bool $last
 * @property-read bool $empty
 * @property-read bool $odd
 * @property-read bool $even
 * @property-read int $counter
 * @property-read mixed $nextKey
 * @property-read mixed $nextValue
 */
class CachingIterator extends \CachingIterator implements \Countable
{
	use Nette\SmartObject;

	/** @var int */
	private $counter = 0;


	public function __construct($iterator)
	{
		if (is_array($iterator) || $iterator instanceof \stdClass) {
			$iterator = new \ArrayIterator($iterator);

		} elseif ($iterator instanceof \IteratorAggregate) {
			do {
				$iterator = $iterator-&gt;getIterator();
			} while ($iterator instanceof \IteratorAggregate);

			assert($iterator instanceof \Iterator);

		} elseif ($iterator instanceof \Iterator) {
		} elseif ($iterator instanceof \Traversable) {
			$iterator = new \IteratorIterator($iterator);
		} else {
			throw new Nette\InvalidArgumentException(sprintf('Invalid argument passed to %s; array or Traversable expected, %s given.', self::class, is_object($iterator) ? get_class($iterator) : gettype($iterator)));
		}

		parent::__construct($iterator, 0);
	}


	/**
	 * Is the current element the first one?
	 */
	public function isFirst(?int $gridWidth = null): bool
	{
		return $this-&gt;counter === 1 || ($gridWidth &amp;&amp; $this-&gt;counter !== 0 &amp;&amp; (($this-&gt;counter - 1) % $gridWidth) === 0);
	}


	/**
	 * Is the current element the last one?
	 */
	public function isLast(?int $gridWidth = null): bool
	{
		return !$this-&gt;hasNext() || ($gridWidth &amp;&amp; ($this-&gt;counter % $gridWidth) === 0);
	}


	/**
	 * Is the iterator empty?
	 */
	public function isEmpty(): bool
	{
		return $this-&gt;counter === 0;
	}


	/**
	 * Is the counter odd?
	 */
	public function isOdd(): bool
	{
		return $this-&gt;counter % 2 === 1;
	}


	/**
	 * Is the counter even?
	 */
	public function isEven(): bool
	{
		return $this-&gt;counter % 2 === 0;
	}


	/**
	 * Returns the counter.
	 */
	public function getCounter(): int
	{
		return $this-&gt;counter;
	}


	/**
	 * Returns the count of elements.
	 */
	public function count(): int
	{
		$inner = $this-&gt;getInnerIterator();
		if ($inner instanceof \Countable) {
			return $inner-&gt;count();

		} else {
			throw new Nette\NotSupportedException('Iterator is not countable.');
		}
	}


	/**
	 * Forwards to the next element.
	 */
	public function next(): void
	{
		parent::next();
		if (parent::valid()) {
			$this-&gt;counter++;
		}
	}


	/**
	 * Rewinds the Iterator.
	 */
	public function rewind(): void
	{
		parent::rewind();
		$this-&gt;counter = parent::valid() ? 1 : 0;
	}


	/**
	 * Returns the next key.
	 * @return mixed
	 */
	public function getNextKey()
	{
		return $this-&gt;getInnerIterator()-&gt;key();
	}


	/**
	 * Returns the next element.
	 * @return mixed
	 */
	public function getNextValue()
	{
		return $this-&gt;getInnerIterator()-&gt;current();
	}
}
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