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<?php
namespace Ds;
use Error;
use OutOfBoundsException;
/**
* A “first in, first out” or “FIFO” collection that only allows access to the
* value at the front of the queue and iterates in that order, destructively.
*
* @package Ds
*
* @template TValue
* @implements Collection<int, TValue>
* @implements \ArrayAccess<int, TValue>
* @template-use Traits\GenericCollection<int, TValue>
*/
final class Queue implements Collection, \ArrayAccess
{
use Traits\GenericCollection;
/**
* @var Deque internal deque to store values.
*
* @psalm-var Deque<TValue>
*/
private $deque;
/**
* Creates an instance using the values of an array or Traversable object.
*
* @param iterable<mixed> $values
*
* @psalm-param iterable<TValue> $values
*/
public function __construct(iterable $values = [])
{
$this->deque = new Deque($values);
}
/**
* Ensures that enough memory is allocated for a specified capacity. This
* potentially reduces the number of reallocations as the size increases.
*
* @param int $capacity The number of values for which capacity should be
* allocated. Capacity will stay the same if this value
* is less than or equal to the current capacity.
*/
public function allocate(int $capacity)
{
$this->deque->allocate($capacity);
}
/**
* Returns the current capacity of the queue.
*/
public function capacity(): int
{
return $this->deque->capacity();
}
/**
* @inheritDoc
*/
public function clear()
{
$this->deque->clear();
}
/**
* @inheritDoc
*/
public function copy(): self
{
return new self($this->deque);
}
/**
* @inheritDoc
*/
public function count(): int
{
return count($this->deque);
}
/**
* Returns the value at the front of the queue without removing it.
*
* @return mixed
*
* @psalm-return TValue
*/
public function peek()
{
return $this->deque->first();
}
/**
* Returns and removes the value at the front of the Queue.
*
* @return mixed
*
* @psalm-return TValue
*/
public function pop()
{
return $this->deque->shift();
}
/**
* Pushes zero or more values into the back of the queue.
*
* @param mixed ...$values
*
* @psalm-param TValue ...$values
*/
public function push(...$values)
{
$this->deque->push(...$values);
}
/**
* @inheritDoc
*/
public function toArray(): array
{
return $this->deque->toArray();
}
/**
* Get iterator
*/
#[\ReturnTypeWillChange]
public function getIterator()
{
while ( ! $this->isEmpty()) {
yield $this->pop();
}
}
/**
* @inheritdoc
*
* @throws OutOfBoundsException
*/
#[\ReturnTypeWillChange]
public function offsetSet($offset, $value)
{
if ($offset === null) {
$this->push($value);
} else {
throw new Error();
}
}
/**
* @inheritdoc
*
* @throws Error
*/
#[\ReturnTypeWillChange]
public function offsetGet($offset)
{
throw new Error();
}
/**
* @inheritdoc
*
* @throws Error
*/
#[\ReturnTypeWillChange]
public function offsetUnset($offset)
{
throw new Error();
}
/**
* @inheritdoc
*
* @throws Error
*/
#[\ReturnTypeWillChange]
public function offsetExists($offset)
{
throw new Error();
}
/**
* Ensures that the internal sequence will be cloned too.
*/
public function __clone()
{
$this->deque = clone $this->deque;
}
}
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