PHP design pattern iterator pattern_php example

Traversing the internal elements of an aggregate object without exposing the internal representation of the object without knowing the internal implementation is the definition of the PHP iterator pattern.

Applicable scenarios:
Access the contents of an aggregate object without exposing its internal representation
Supports multiple traversals of aggregate objects
Provide a unified interface for traversing different aggregate structures

Iterator pattern example:

<&#63;php
class ConcreteIterator implements Iterator{
 private $position = 0;
 private $arr;
 function __construct(array $arr){
 $this->arr = $arr;
 }

 function rewind(){
 $this->position = 0;
 }

 function current(){
 return $this->arr[$this->position];
 }

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

 function next(){
 ++$this->position;
 }

 function valid(){
 return isset($this->arr[$this->position]);
 }
}

$arr = array('xiao hong','xiao ming','xiaohua');
$concreteIterator = new ConcreteIterator($arr);
foreach ($concreteIterator as $key => $value) {
 echo $key."=>".$value."\n";
}

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