php迭代器

<?php
class myIterator implements Iterator
{
    public $position = 0 ;
    public $arr = array('one','two','three','four','five','six');
 
    public function __construct()
    {
        $this->position = 0;
    }
 
    public function rewind()
    {
        var_dump(__METHOD__);
        $this->position = 0 ;
    }
 
    public function current()
    {
        var_dump(__METHOD__);
        return $this->arr[$this->position] ;
    }
 
    public function key()
    {
        var_dump(__METHOD__);
        return $this->position;
    }
 
    public function next()
    {
        var_dump(__METHOD__);
        ++$this->position;
    }
    public function valid()
    {
        var_dump(__METHOD__);
        return isset($this->arr[$this->position]);
    }
}
 
$it = new myIterator;
foreach($it as $key=>$value)
{
    var_dump($key,$value);
    echo "</br>";
}

string(18) "myIterator::rewind" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(0) string(3) "one" 
string(16) "myIterator::next" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(1) string(3) "two" 
string(16) "myIterator::next" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(2) string(5) "three" 
string(16) "myIterator::next" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(3) string(4) "four" 
string(16) "myIterator::next" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(4) string(4) "five" 
string(16) "myIterator::next" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(5) string(3) "six" 
string(16) "myIterator::next" string(17) "myIterator::valid"