php简单堆栈操作

        class Stackeob implements IteratorAggregate
        {
                private $data;
                private $count;
                public function __construct($data=null)
                {
                        $this->count = 0;
                        $this->data = array();
                        if(!is_null($data))
                                $this->copyData($data);
                }
                public function push($data)
                {
                        ++$this->count;
                        array_push($this->data,$data);
                }
                public function pop()
                {
                        if(!$this->count)
                                return false;
                        $this->count--;
                        return array_pop($this->data);
                }
                public function peek()
                {
                        if(!$this->count)
                                return false;
                        return $this->data[$this->count()-1];
                }
                public function contains($item)
                {
                        return array_search($item,$this->data,true)!==false;
                }
                public function clean()
                {
                        $this->count = 0;
                        $this->data = array();
                }
                public function count()
                {
                        return $this->count;
                }
                public function copyData($data)
                {
                        if(is_array($data))
                        {
                                $this->clean();
                                foreach ($data as $value)
                                {
                                        $this->push($value);
                                }
                        }
                        elseif (!is_null($data))
                                exit('不是数组的其它格式');
                }
                public function toArray()
                {
                        return $this->data;
                }
                public function getIterator()
                {
                        return new StackIterator($this->data);
                }
        }
        
        /*StackIterator实现了Iterator接口 提供一个统一的迭代方法*/
        class StackIterator implements Iterator
        {
                /*
                        abstract public mixed current ( void )
                        abstract public scalar key ( void )
                        abstract public void next ( void )
                        abstract public void rewind ( void )
                        abstract public boolean valid ( void )
                */
                private $data;
                private $index;
                public function __construct(&$data)
                {
                        $this->data = $data;
                        $this->index= 0;
                }
                public function current()
                {
                        return $this->data[$this->index];
                }
                public function key()
                {
                        return $this->index;
                }
                public function next()
                {
                        $this->index++;
                }
                public function rewind()
                {
                        $this->index = 0;
                }
                public function valid()
                {
                        return $this->current()!==false;
                }
        }
        
        /*
        $a = array('a','b','c','d','e');   
        $b = new Stackeob($a); //实例化栈   
        $b->push('test'); //压入数据   
        echo $b->pop(); //弹出数据,后进先出 弹出test   
        //遍历栈内容   
        foreach ($b as $key=>$val)   
        {   
            echo $key;   
            echo $val;   
        }
        */