<?php

/**
 * Description of IteratorDemo
 * 迭代器模式
 * @author jm
 */
class IteratorDemo
{
    //put your code here
    public static function main()
    {
        $string = ["AA","BB","CC","DD","EE","FF"];
        $collection = new MyCollection($string);
        $it = $collection->iterator();
        while ($it->hasNext()){
            print_r("下一个是：".$it->next()."\n");
        }
    }
}
//集合接口
interface ICollection{
    public function iterator();
    public function get($i);
    public function size();
}

//迭代器接口
interface IIterator{
    public function previous();
    public function next();
    public function hasNext();
    public function first();
}

//实现集合
class MyCollection implements ICollection{
    private $_string = ["A","B","C","D","E","F"];
    public function __construct($data)
    {
        $this->_string = $data;
    }

    /**
     * 
     * @return \MyIterator
     */
    public function iterator(){
        return new MyIterator($this);
    }
    public function get($i){
        return $this->_string[$i];
    }
    public function size(){
        return count($this->_string);
    }
}
//实现迭代器
class MyIterator implements IIterator{
    /**
     *
     * @var MyCollection 
     */
    private $_collection = null;
    private $_position = -1;
    public function __construct($collection)
    {
        $this->_collection = $collection;
    }
    
    public function previous()
    {
        if($this->_position > 0){
            $this->_position--;
        }
        return $this->_collection->get($this->_position);
    }
    
    public function next()
    {
        if ($this->_position < ($this->_collection->size()-1)) {
            $this->_position++;
        }
        return $this->_collection->get($this->_position);
    }
    public function hasNext()
    {
        if ($this->_position < ($this->_collection->size()-1)) {
            return true;
        }
        return false;
    }
    public function first()
    {
        $this->_position = 0;
        return $this->_collection->get($this->_position);
    }
}

IteratorDemo::main();