■ArrayAccess

以下のインターフェイスを実装することにより、配列のようにオブジェクトへアクセスができる。但し、ビルトインインターフェイスであり、以下のコードは記述する必要はない。

<?php
interface ArrayAccess {
    function offsetSet($offset, $value);
    function offsetGet($offset);
    function offsetUnset($offset);
    function offsetExists($offset);
}
?>

offfsetSet

配列に値をセットする

offsetGet

配列から値を得る

offsetUnset

配列から値を削除する

offsetExists

配列に要素が存在するか判定する

<?php
class MyArray implements ArrayAccess {
    protected $array();
    public function offsetSet($offset, $value){
        if(!is_int($offset)){
            throw new Exception();
        }
        $this->array[$offset] = $value;
    }
    public function offsetGet($offset){
        return $this->array[$offset];
    }
    public function offsetUnset($offset){
        unset($this->array[$offset]);
    }
    public function offsetExists($offset){
        return array_key_exists($this->array, $offset);
    }
}

$obj = new MyArray();
$obj[1] = 2;
$obj['a'] = 1;//throws exception
?>

■Iterator

<?php
interface Iterator {
    function current();
    function next();
    function rewind();
    function key();
    function valid();
}
?>

<?php
class MyData implements Iterator {
    private $myData = array(
        "Mike",
        "Jack",
        "Emily",
        "Naomi"
    );
    private $current = 0;
    public function current(){
        return $this->myData[$this->current];
    }
    public function next(){
        $this->current++;
    }
    public function rewind(){
        $this->current = 0;
    }
    public function key(){
        return $this->current;
    }
    public function valid(){
        return isset($this->myData[$this->current]);
    }
}

$data = new MyData();
foreach($data as $key => $value){
    print("{$key} : {$value}");
}
?>

■SeekableIterator

<?php
interface SeekableIterator {
    function current();
    function next();
    function rewind();
    function key();
    function valid();
    function seek($index);
}
?>

■Recursive Iteration

<?php
RecursiveIteratorIterator   implements OuterIterator, Traversable, Iterator {
    public function current(void);
    public function getDepth(void);
    public function getSubIterator(void);
    public function key(void);
    public function next(void);
    public function rewind(void);
    public function valid(void);
}
?>

<?php
class Company_Iterator extends RecursiveIteratorIterator {
    public function beginChildren(){
        if($this->getDepth() >= 3){
            print(str_repeat("t", $this->getDepth() - 1));
            print('<ul>');
        }
    }
    public function endChildren(){
        if($this->getDepth() >= 3){
            print(str_repeat("t", $this->getDepth() - 1));
            print('</ul>');
        }
    }
}
class RecursiveArrayObject extends ArrayObject {
    function getIterator(){
        return new RecursiveArrayIterator($this);
    }
}
$company = array(
    array("Acme Anvil Co."),
    array(
        array(
            "Human Resources",
            array(
                'Nick',
                'Jack',
                'Mike'
            )
        ),
        array(
            "Accounting",
            array(
                'John',
                'Emily',
                'Naomi'
            )
        )
    )
);

$it = new Company_Iterator(new RecursiveArrayObject($company));
foreach($it as $item){
    print(str_replace("t", $it->getDepth()));
    switch($it->getDepth()){
        case 1:
            print("<h1>Company: {$item}</h1>" . PHP_EOL);
            break;
        case 2:
            print("<h2>Department: {$item}</h2>" . PHP_EOL);
            break;
        default:
            print("<li>{$item}</li>" . PHP_EOL);
    }
}
/*
	<h1>Company: Acme Anvil Co.</h1>
		<h2>Department: Human Resources</h2>
		<ul>
			<li>Nick</li>
			<li>Jack</li>
			<li>Mike</li>

		</ul>
		<h2>Department: Accounting</h2>
		<ul>
			<li>John</li>
			<li>Emily</li>
			<li>Naomi</li>
		</ul>
*/
?>

■Recursive Iteration

<?php
class NumberFilter extends FilterIterator {
    const FILTER_EVEN = 1;
    const FILTER_ODD = 2;
    private $_type;
    public function __construct($iterator, $odd_or_even = self::FILTER_EVEN){
        $this->_type = $odd_or_even;
        parent::__construct($iterator);
    }
    public function accept(){
        if($this->_type === self::FILTER_EVEN){
            return ($this->current() % 2 == 0);
        }
        else{
            return ($this->current() % 2 == 1);
        }
    }
}

$numbers = new ArrayObject(range(0, 10));
$number_it = new ArrayIterator($numbers);

$it = new NumberFilter($numbers_it, NumberFilter::FILTER_ODD)

foreach($it as $number){
    print("{$number}" . PHP_EOL);
}
?>