spldoublylinkedlist.inc

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<?php
class SplDoublyLinkedList implements Iterator, ArrayAccess, Countable
{
    protected $_llist   = array();
    protected $_it_mode = 0;
    protected $_it_pos  = 0;

    const IT_MODE_LIFO     = 0x00000002;

    const IT_MODE_FIFO     = 0x00000000;

    const IT_MODE_KEEP     = 0x00000000;

    const IT_MODE_DELETE   = 0x00000001;

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

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

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

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

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

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

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

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

    public function setIteratorMode($mode)
    {
        $this->_it_mode = $mode;
    }

    public function getIteratorMode()
    {
        return $this->_it_mode;
    }

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

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

    public function key()
    {
        return $this->_it_pos;
    }

    public function current()
    {
        return $this->_llist[$this->_it_pos];
    }

    public function next()
    {
        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++;
            }
        }
    }

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

    public function offsetGet($offset)
    {
        if ($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];
        }
    }

    public function offsetSet($offset, $value)
    {
        if ($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;
        }
    }

    public function offsetUnset($offset)
    {
        if ($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);
        }
    }
}

?>