SplQueue Class Reference

Inheritance diagram for SplQueue:

Collaboration diagram for SplQueue:

Public Member Functions
	bottom ()
	count ()
	current ()
	dequeue ()
	enqueue ($data)
	getIteratorMode ()
	isEmpty ()
	key ()
	next ()
	offsetExists ($offset)
	offsetGet ($offset)
	offsetSet ($offset, $value)
	offsetUnset ($offset)
	pop ()
	push ($data)
	rewind ()
	setIteratorMode ($mode)
	shift ()
	top ()
	unshift ($data)
	valid ()

Public Attributes
const	IT_MODE_DELETE = 0x00000001
const	IT_MODE_FIFO = 0x00000000
const	IT_MODE_KEEP = 0x00000000
const	IT_MODE_LIFO = 0x00000002

Protected Attributes
	$_it_mode = parent::IT_MODE_FIFO
	$_it_pos = 0
	$_llist = array()

Detailed Description

Implementation of a Queue through a DoublyLinkedList.

As SplQueue extends SplDoublyLinkedList, unshift() and pop() are still available even though they don't make much sense for a queue. For convenience, two aliases are available:

• enqueue() is an alias of push()
• dequeue() is an alias of shift()

Since

PHP 5.3

The SplQueue class provides the main functionalities of a queue implemented using a doubly linked list (DLL).

Definition at line 25 of file splqueue.inc.

Member Function Documentation

SplDoublyLinkedList::bottom ( )

inherited

Returns

the element at the end of the DLL.

Definition at line 97 of file spldoublylinkedlist.inc.

    {
        return reset($this->_llist);
    }

SplDoublyLinkedList::count ( )

inherited

Returns

number elements in the DLL.

Implements Countable.

Definition at line 104 of file spldoublylinkedlist.inc.

Referenced by SplDoublyLinkedList\isEmpty(), SplDoublyLinkedList\offsetGet(), SplDoublyLinkedList\offsetSet(), SplDoublyLinkedList\offsetUnset(), SplDoublyLinkedList\pop(), SplDoublyLinkedList\rewind(), and SplDoublyLinkedList\shift().

    {
        return count($this->_llist);
    }

SplDoublyLinkedList::current ( )

inherited

Returns

current object

Implements Iterator.

Definition at line 170 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\$_it_pos.

    {
        return $this->_llist[$this->_it_pos];
    }

SplQueue::dequeue

(

)

Returns

the first element of the queue.

Note

dequeue is an alias of push()

See Also

splDoublyLinkedList::push()

Definition at line 55 of file splqueue.inc.

    {
        return parent::shift();
    }

SplQueue::enqueue

(

$data

)

Pushes an element at the end of the queue.

Parameters

$data

variable to add to the queue.

Note

enqueue is an alias of shift()

See Also

splDoublyLinkedList::shift()

Definition at line 65 of file splqueue.inc.

    {
        return parent::push($data);
    }

SplDoublyLinkedList::getIteratorMode ( )

inherited

Returns

the current iteration mode

See Also

setIteratorMode

Definition at line 138 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\$_it_mode.

    {
        return $this->_it_mode;
    }

SplDoublyLinkedList::isEmpty ( )

inherited

Returns

whether the DLL is empty.

Definition at line 111 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\count().

    {
        return ($this->count() == 0);
    }

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SplDoublyLinkedList::key ( )

inherited

Returns

current key

Implements Iterator.

Definition at line 163 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\$_it_pos.

    {
        return $this->_it_pos;
    }

SplDoublyLinkedList::next ( )

inherited

Forward to next element.

Implements Iterator.

Definition at line 177 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\pop(), and SplDoublyLinkedList\shift().

    {
        if ($this->_it_mode & self::IT_MODE_LIFO) {
            if ($this->_it_mode & self::IT_MODE_DELETE) {
                $this->pop();
            }
            $this->_it_pos--;
        } else {
            if ($this->_it_mode & self::IT_MODE_DELETE) {
                $this->shift();
            } else {
                $this->_it_pos++;
            }
        }
    }

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SplDoublyLinkedList::offsetExists (   $offset )

inherited

Returns

whether a certain offset exists in the DLL

Parameters

$offset

The offset

Exceptions

OutOfRangeException

If the offset is either invalid or out of range.

Implements ArrayAccess.

Definition at line 199 of file spldoublylinkedlist.inc.

    {
        if (!is_numeric($offset)) {
            throw new OutOfRangeException("Offset invalid or out of range");
        } else {
            return array_key_exists($offset, $this->_llist);
        }
    }

SplDoublyLinkedList::offsetGet (   $offset )

inherited

Returns

the data at a certain offset in the DLL

Parameters

$offset

The offset

Exceptions

OutOfRangeException

If the offset is either invalid or out of range.

Implements ArrayAccess.

Definition at line 214 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\count().

    {
        if ($this->_it_mode & self::IT_MODE_LIFO) {
            $realOffset = count($this->_llist)-$offset;
        } else {
            $realOffset = $offset;
        }

        if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
            throw new OutOfRangeException("Offset invalid or out of range");
        } else {
            return $this->_llist[$realOffset];
        }
    }

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SplDoublyLinkedList::offsetSet (   $offset,   $value  )

inherited

Defines the data at a certain offset in the DLL.

Parameters

$offset	The offset
$value	New value

Exceptions

OutOfRangeException

If the offset is either invalid or out of range.

Implements ArrayAccess.

Definition at line 236 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\count(), and SplDoublyLinkedList\push().

    {
        if ($offset === null) {
            return $this->push($value);
        }

        if ($this->_it_mode & self::IT_MODE_LIFO) {
            $realOffset = count($this->_llist)-$offset;
        } else {
            $realOffset = $offset;
        }

        if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
            throw new OutOfRangeException("Offset invalid or out of range");
        } else {
            $this->_llist[$realOffset] = $value;
        }
    }

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SplDoublyLinkedList::offsetUnset (   $offset )

inherited

Unsets the element at a certain offset in the DLL.

Parameters

$offset

The offset

Exceptions

OutOfRangeException

If the offset is either invalid or out of range.

Implements ArrayAccess.

Definition at line 261 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\count().

    {
        if ($this->_it_mode & self::IT_MODE_LIFO) {
            $realOffset = count($this->_llist)-$offset;
        } else {
            $realOffset = $offset;
        }

        if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
            throw new OutOfRangeException("Offset invalid or out of range");
        } else {
            array_splice($this->_llist, $realOffset, 1);
        }
    }

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SplDoublyLinkedList::pop ( )

inherited

Returns

the element popped from the end of the DLL.

Exceptions

RuntimeException

If the datastructure is empty.

Definition at line 51 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\count().

Referenced by SplDoublyLinkedList\next().

    {
        if (count($this->_llist) == 0) {
            throw new RuntimeException("Can't pop from an empty datastructure");
        }
        return array_pop($this->_llist);
    }

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SplDoublyLinkedList::push (   $data )

inherited

Pushes an element to the end of the DLL.

Parameters

$data

variable to add to the DLL.

Definition at line 73 of file spldoublylinkedlist.inc.

Referenced by SplDoublyLinkedList\offsetSet().

    {
        array_push($this->_llist, $data);
        return true;
    }

SplDoublyLinkedList::rewind ( )

inherited

Rewind to top iterator as set in constructor.

Implements Iterator.

Definition at line 145 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\count().

    {
        if ($this->_it_mode & self::IT_MODE_LIFO) {
            $this->_it_pos = count($this->_llist)-1;
        } else {
            $this->_it_pos = 0;
        }
    }

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SplQueue::setIteratorMode

(

$mode

)

Changes the iteration mode.

There are two orthogonal sets of modes that can be set:

• The behavior of the iterator (either one or the other)
  • SplDoublyLnkedList::IT_MODE_DELETE (Elements are deleted by the iterator)
  • SplDoublyLnkedList::IT_MODE_KEEP (Elements are traversed by the iterator)

The default mode is 0 : SplDoublyLnkedList::IT_MODE_LIFO | SplDoublyLnkedList::IT_MODE_KEEP

Note

The iteration's direction is not modifiable for queue instances

Parameters

$mode

New mode of iteration

Exceptions

RuntimeException

If the new mode affects the iteration's direction.

Definition at line 42 of file splqueue.inc.

    {
        if ($mode & parent::IT_MODE_LIFO === parent::IT_MODE_LIFO) {
            throw new RuntimeException("Iterators' LIFO/FIFO modes for SplStack/SplQueue objects are frozen");
        }

        $this->_it_mode = $mode;
    }

SplDoublyLinkedList::shift ( )

inherited

Returns

the element shifted from the beginning of the DLL.

Exceptions

RuntimeException

If the datastructure is empty.

Definition at line 62 of file spldoublylinkedlist.inc.

References SplDoublyLinkedList\count().

Referenced by SplDoublyLinkedList\next().

    {
        if (count($this->_llist) == 0) {
            throw new RuntimeException("Can't shift from an empty datastructure");
        }
        return array_shift($this->_llist);
    }

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SplDoublyLinkedList::top ( )

inherited

Returns

the element at the beginning of the DLL.

Definition at line 90 of file spldoublylinkedlist.inc.

    {
        return end($this->_llist);
    }

SplDoublyLinkedList::unshift (   $data )

inherited

Adds an element to the beginning of the DLL.

Parameters

$data

variable to add to the DLL.

Definition at line 82 of file spldoublylinkedlist.inc.

    {
        array_unshift($this->_llist, $data);
        return true;
    }

SplDoublyLinkedList::valid ( )

inherited

Returns

whether iterator is valid

Implements Iterator.

Definition at line 156 of file spldoublylinkedlist.inc.

    {
        return array_key_exists($this->_it_pos, $this->_llist);
    }

Member Data Documentation

SplQueue::$_it_mode = parent::IT_MODE_FIFO

protected

Definition at line 27 of file splqueue.inc.

SplDoublyLinkedList::$_it_pos = 0

protectedinherited

Definition at line 26 of file spldoublylinkedlist.inc.

Referenced by SplDoublyLinkedList\current(), and SplDoublyLinkedList\key().

SplDoublyLinkedList::$_llist = array()

protectedinherited

Definition at line 24 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_DELETE = 0x00000001

inherited

Iterator mode.

See Also

setIteratorMode

Definition at line 46 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_FIFO = 0x00000000

inherited

Iterator mode.

See Also

setIteratorMode

Definition at line 36 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_KEEP = 0x00000000

inherited

Iterator mode.

See Also

setIteratorMode

Definition at line 41 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_LIFO = 0x00000002

inherited

Iterator mode.

See Also

setIteratorMode

Definition at line 31 of file spldoublylinkedlist.inc.

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The documentation for this class was generated from the following file:

• splqueue.inc