289 lines
7.7 KiB
PHP
289 lines
7.7 KiB
PHP
<?php
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/**
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* This file is part of the ramsey/collection library
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*
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* @copyright Copyright (c) Ben Ramsey <ben@benramsey.com>
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* @license http://opensource.org/licenses/MIT MIT
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*/
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declare(strict_types=1);
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namespace Ramsey\Collection;
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use Ramsey\Collection\Exception\InvalidArgumentException;
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use Ramsey\Collection\Exception\NoSuchElementException;
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/**
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* This class provides a basic implementation of `DoubleEndedQueueInterface`, to
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* minimize the effort required to implement this interface.
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*/
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class DoubleEndedQueue extends Queue implements DoubleEndedQueueInterface
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{
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/**
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* Index of the last element in the queue.
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*
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* @var int
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*/
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private $tail = -1;
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/**
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* Sets the given value to the given offset in the queue.
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*
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* Since arbitrary offsets may not be manipulated in a queue, this method
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* serves only to fulfill the `ArrayAccess` interface requirements. It is
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* invoked by other operations when adding values to the queue.
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*
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* @link http://php.net/manual/en/arrayaccess.offsetset.php ArrayAccess::offsetSet()
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*
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* @param mixed|null $offset The offset is ignored and is treated as `null`.
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* @param mixed $value The value to set at the given offset.
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*
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* @throws InvalidArgumentException when the value does not match the
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* specified type for this queue.
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*/
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public function offsetSet($offset, $value): void
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{
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if ($this->checkType($this->getType(), $value) === false) {
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throw new InvalidArgumentException(
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'Value must be of type ' . $this->getType() . '; value is '
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. $this->toolValueToString($value)
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);
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}
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$this->tail++;
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$this->data[$this->tail] = $value;
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}
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/**
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* Ensures that the specified element is inserted at the front of this queue.
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*
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* @see self::offerFirst()
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*
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* @param mixed $element The element to add to this queue.
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*
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* @return bool `true` if this queue changed as a result of the call.
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*
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* @throws InvalidArgumentException when the value does not match the
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* specified type for this queue.
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*/
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public function addFirst($element): bool
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{
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if ($this->checkType($this->getType(), $element) === false) {
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throw new InvalidArgumentException(
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'Value must be of type ' . $this->getType() . '; value is '
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. $this->toolValueToString($element)
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);
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}
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$this->index--;
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$this->data[$this->index] = $element;
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return true;
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}
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/**
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* Ensures that the specified element in inserted at the end of this queue.
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*
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* @see Queue::add()
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*
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* @param mixed $element The element to add to this queue.
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*
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* @return bool `true` if this queue changed as a result of the call.
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*
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* @throws InvalidArgumentException when the value does not match the
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* specified type for this queue.
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*/
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public function addLast($element): bool
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{
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return $this->add($element);
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}
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/**
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* Inserts the specified element at the front this queue.
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*
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* @see self::addFirst()
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*
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* @param mixed $element The element to add to this queue.
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*
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* @return bool `true` if the element was added to this queue, else `false`.
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*/
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public function offerFirst($element): bool
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{
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try {
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return $this->addFirst($element);
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} catch (InvalidArgumentException $e) {
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return false;
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}
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}
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/**
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* Inserts the specified element at the end this queue.
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*
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* @see self::addLast()
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* @see Queue::offer()
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*
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* @param mixed $element The element to add to this queue.
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*
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* @return bool `true` if the element was added to this queue, else `false`.
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*/
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public function offerLast($element): bool
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{
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return $this->offer($element);
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}
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/**
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* Retrieves and removes the head of this queue.
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*
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* This method differs from `pollFirst()` only in that it throws an
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* exception if this queue is empty.
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*
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* @see self::pollFirst()
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* @see Queue::remove()
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*
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* @return mixed the head of this queue.
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*
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* @throws NoSuchElementException if this queue is empty.
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*/
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public function removeFirst()
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{
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return $this->remove();
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}
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/**
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* Retrieves and removes the tail of this queue.
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*
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* This method differs from `pollLast()` only in that it throws an exception
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* if this queue is empty.
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*
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* @see self::pollLast()
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*
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* @return mixed the tail of this queue.
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*
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* @throws NoSuchElementException if this queue is empty.
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*/
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public function removeLast()
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{
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if ($this->count() === 0) {
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throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
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}
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$tail = $this[$this->tail];
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unset($this[$this->tail]);
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$this->tail--;
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return $tail;
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}
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/**
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* Retrieves and removes the head of this queue, or returns `null` if this
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* queue is empty.
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*
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* @see self::removeFirst()
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*
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* @return mixed|null the head of this queue, or `null` if this queue is empty.
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*/
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public function pollFirst()
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{
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return $this->poll();
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}
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/**
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* Retrieves and removes the tail of this queue, or returns `null` if this
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* queue is empty.
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*
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* @see self::removeLast()
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*
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* @return mixed|null the tail of this queue, or `null` if this queue is empty.
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*/
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public function pollLast()
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{
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if ($this->count() === 0) {
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return null;
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}
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$tail = $this[$this->tail];
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unset($this[$this->tail]);
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$this->tail--;
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return $tail;
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}
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/**
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* Retrieves, but does not remove, the head of this queue.
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*
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* This method differs from `peekFirst()` only in that it throws an
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* exception if this queue is empty.
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*
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* @see self::peekFirst()
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* @see Queue::element()
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*
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* @return mixed the head of this queue.
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*
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* @throws NoSuchElementException if this queue is empty.
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*/
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public function firstElement()
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{
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return $this->element();
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}
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/**
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* Retrieves, but does not remove, the tail of this queue.
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*
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* This method differs from `peekLast()` only in that it throws an exception
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* if this queue is empty.
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*
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* @see self::peekLast()
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*
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* @return mixed the tail of this queue.
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*
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* @throws NoSuchElementException if this queue is empty.
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*/
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public function lastElement()
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{
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if ($this->count() === 0) {
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throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
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}
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return $this->data[$this->tail];
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}
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/**
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* Retrieves, but does not remove, the head of this queue, or returns `null`
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* if this queue is empty.
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*
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* @see self::firstElement()
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* @see Queue::peek()
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*
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* @return mixed|null the head of this queue, or `null` if this queue is empty.
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*/
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public function peekFirst()
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{
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return $this->peek();
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}
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/**
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* Retrieves, but does not remove, the tail of this queue, or returns `null`
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* if this queue is empty.
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*
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* @see self::lastElement()
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*
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* @return mixed|null the tail of this queue, or `null` if this queue is empty
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*/
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public function peekLast()
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{
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if ($this->count() === 0) {
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return null;
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}
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return $this->data[$this->tail];
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}
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}
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