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<?php
/**
* This file is part of the ramsey/collection library
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*
* @copyright Copyright (c) Ben Ramsey <ben@benramsey.com>
* @license http://opensource.org/licenses/MIT MIT
*/
declare(strict_types=1);
namespace Ramsey\Collection;
use Ramsey\Collection\Exception\InvalidArgumentException;
use Ramsey\Collection\Exception\NoSuchElementException;
/**
* This class provides a basic implementation of `DoubleEndedQueueInterface`, to
* minimize the effort required to implement this interface.
*
* @template T
* @template-extends Queue<T>
* @template-implements DoubleEndedQueueInterface<T>
*/
class DoubleEndedQueue extends Queue implements DoubleEndedQueueInterface
{
/**
* Index of the last element in the queue.
*
* @var int
*/
private $tail = -1;
/**
* @inheritDoc
*/
public function offsetSet($offset, $value): void
{
if ($this->checkType($this->getType(), $value) === false) {
throw new InvalidArgumentException(
'Value must be of type ' . $this->getType() . '; value is '
. $this->toolValueToString($value)
);
}
$this->tail++;
$this->data[$this->tail] = $value;
}
/**
* @inheritDoc
*/
public function addFirst($element): bool
{
if ($this->checkType($this->getType(), $element) === false) {
throw new InvalidArgumentException(
'Value must be of type ' . $this->getType() . '; value is '
. $this->toolValueToString($element)
);
}
$this->index--;
$this->data[$this->index] = $element;
return true;
}
/**
* @inheritDoc
*/
public function addLast($element): bool
{
return $this->add($element);
}
/**
* @inheritDoc
*/
public function offerFirst($element): bool
{
try {
return $this->addFirst($element);
} catch (InvalidArgumentException $e) {
return false;
}
}
/**
* @inheritDoc
*/
public function offerLast($element): bool
{
return $this->offer($element);
}
/**
* @inheritDoc
*/
public function removeFirst()
{
return $this->remove();
}
/**
* @inheritDoc
*/
public function removeLast()
{
$tail = $this->pollLast();
if ($tail === null) {
throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
}
return $tail;
}
/**
* @inheritDoc
*/
public function pollFirst()
{
return $this->poll();
}
/**
* @inheritDoc
*/
public function pollLast()
{
if ($this->count() === 0) {
return null;
}
$tail = $this[$this->tail];
unset($this[$this->tail]);
$this->tail--;
return $tail;
}
/**
* @inheritDoc
*/
public function firstElement()
{
return $this->element();
}
/**
* @inheritDoc
*/
public function lastElement()
{
if ($this->count() === 0) {
throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
}
return $this->data[$this->tail];
}
/**
* @inheritDoc
*/
public function peekFirst()
{
return $this->peek();
}
/**
* @inheritDoc
*/
public function peekLast()
{
if ($this->count() === 0) {
return null;
}
return $this->data[$this->tail];
}
}
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