实现Iterator接口

使对象可以像数组一样进行foreach循环，要求属性必须是私有。

 

 

<?php
class MyIterator implements Iterator
{
     private $var = array();

     public function __construct($array)
     {
         if (is_array($array)) {
            $this->var = $array;
         }
     }

     public function rewind() {
         echo "rewinding\n";
        reset($this->var);
     }

     public function current() {
        $var = current($this->var);
         echo "current: $var\n";
         return $var;
     }

     public function key() {
        $var = key($this->var);
         echo "key: $var\n";
         return $var;
     }

     public function next() {
        $var = next($this->var);
         echo "next: $var\n";
         return $var;
     }

     public function valid() {
        $var = $this->current() !== false;
         echo "valid: {$var}\n";
         return $var;
     }
}

$values = array(1,2,3);
$it = new MyIterator($values);

foreach ($it as $a => $b) {
     print "$a: $b\n";
}

/*          
输出：
rewinding
current: 1
valid: 1
current: 1
key: 0
0: 1
next: 2
current: 2
valid: 1
current: 2
key: 1
1: 2
next: 3
current: 3
valid: 1
current: 3
key: 2
2: 3
next:
current:
valid:

*/
?>

 

 

 

迭代器有一个简单的和经常被看到的接口

 

<?php
   function Iterator($array) // Constructor. Takes array to be traversed as a parameter. 构造函数。
使需要遍历的数组作为一个参数
   function reset() // Sets internal pointer to the first element 设置内部指针指向第一个元素
   function end() // Sets internal pointer to the last element 设置内部指针指向最后一个元素
   function seek($position) // Sets internal pointer to desired position 设置内部指针指向一个指定的元素
   function next() // Returns next element in the iteration 返回后一个元素
   function previous() // Returns previous element in the iteration 返回前一个元素
 ?>