SplDoublyLinkedList Class Reference

Inheritance diagram for SplDoublyLinkedList:

Collaboration diagram for SplDoublyLinkedList:

Public Member Functions
	bottom ()
	count ()
	current ()
	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 = 0
	$_it_pos = 0
	$_llist = array()

Detailed Description

Doubly Linked List.

Since

PHP 5.3

The SplDoublyLinkedList class provides the main functionalities of a doubly linked list (DLL).

Note

The following userland implementation of Iterator is a bit different from the internal one. Internally, iterators generated by nested foreachs are independent, while they share the same traverse pointer in userland.

Definition at line 22 of file spldoublylinkedlist.inc.

Member Function Documentation

SplDoublyLinkedList::bottom

(

)

Returns

the element at the end of the DLL.

Definition at line 97 of file spldoublylinkedlist.inc.

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

SplDoublyLinkedList::count

(

)

Returns

number elements in the DLL.

Implements Countable.

Definition at line 104 of file spldoublylinkedlist.inc.

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

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

SplDoublyLinkedList::current

(

)

Returns

current object

Implements Iterator.

Definition at line 170 of file spldoublylinkedlist.inc.

References $_it_pos.

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

SplDoublyLinkedList::getIteratorMode

(

)

Returns

the current iteration mode

See Also

setIteratorMode

Definition at line 138 of file spldoublylinkedlist.inc.

References $_it_mode.

    {
        return $this->_it_mode;
    }

SplDoublyLinkedList::isEmpty

(

)

Returns

whether the DLL is empty.

Definition at line 111 of file spldoublylinkedlist.inc.

References count().

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

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SplDoublyLinkedList::key

(

)

Returns

current key

Implements Iterator.

Definition at line 163 of file spldoublylinkedlist.inc.

References $_it_pos.

    {
        return $this->_it_pos;
    }

SplDoublyLinkedList::next

(

)

Forward to next element.

Implements Iterator.

Definition at line 177 of file spldoublylinkedlist.inc.

References pop(), and 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

)

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

)

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 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
	)

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 count(), and 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

)

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 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

(

)

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 count().

Referenced by 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

)

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 offsetSet().

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

SplDoublyLinkedList::rewind

(

)

Rewind to top iterator as set in constructor.

Implements Iterator.

Definition at line 145 of file spldoublylinkedlist.inc.

References 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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SplDoublyLinkedList::setIteratorMode

(

$mode

)

Changes the iteration mode.

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

• The direction of the iteration (either one or the other)
  • SplDoublyLnkedList::IT_MODE_LIFO (Stack style)
  • SplDoublyLnkedList::IT_MODE_FIFO (Queue style)
• 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_FIFO | SplDoublyLnkedList::IT_MODE_KEEP

Parameters

$mode

new mode of iteration

Definition at line 130 of file spldoublylinkedlist.inc.

    {
        $this->_it_mode = $mode;
    }

SplDoublyLinkedList::shift

(

)

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 count().

Referenced by 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

(

)

Returns

the element at the beginning of the DLL.

Definition at line 90 of file spldoublylinkedlist.inc.

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

SplDoublyLinkedList::unshift

(

$data

)

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

(

)

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

SplDoublyLinkedList::$_it_mode = 0

protected

Definition at line 25 of file spldoublylinkedlist.inc.

Referenced by getIteratorMode().

SplDoublyLinkedList::$_it_pos = 0

protected

Definition at line 26 of file spldoublylinkedlist.inc.

Referenced by current(), and key().

SplDoublyLinkedList::$_llist = array()

protected

Definition at line 24 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_DELETE = 0x00000001

Iterator mode.

See Also

setIteratorMode

Definition at line 46 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_FIFO = 0x00000000

Iterator mode.

See Also

setIteratorMode

Definition at line 36 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_KEEP = 0x00000000

Iterator mode.

See Also

setIteratorMode

Definition at line 41 of file spldoublylinkedlist.inc.

const SplDoublyLinkedList::IT_MODE_LIFO = 0x00000002

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:

• spldoublylinkedlist.inc