Interator

Пример реализации интератора range

<?php
 
class RangeIterator implements Iterator {
    protected $start;
    protected $end;
    protected $step;
 
    protected $key;
    protected $value;
 
    public function __construct($start, $end, $step = 1) {
        $this->start = $start;
        $this->end   = $end;
        $this->step  = $step;
    }
 
    public function rewind() {
        $this->key   = 0;
        $this->value = $this->start;
    }
 
    public function valid() {
        return $this->value < $this->end;
    }
 
    public function next() {
        $this->value += $this->step;
        $this->key   += 1;
    }
 
    public function current() {
        return $this->value;
    }
 
    public function key() {
        return $this->key;
    }
}
 
$interator = new RangeIterator(0, 11);
 
foreach($interator as $item){
 
	echo (string) $item . "\n";
 
}

Вывод

php ./interator.php
0
1
2
3
4
5
6
7
8
9
10

Пример интератора (перебор данных файла) (к сожалению не рабочий и в таком случае нада использовать генератор)

class FileIterator implements Iterator {
    protected $f;
    public function __construct($file) {
        $this->f = fopen($file, 'r');
        if (!$this->f) throw new Exception();
    }
    public function current() {
        return fgets($this->f);
    }
    public function key() {
        return ftell($this->f);
    }
    public function next() {
    }
    public function rewind() {
        fseek($this->f, 0);
    }
    public function valid() {
        return !feof($this->f);
    }
}
 
$file = new FileIterator($path);
 
foreach($file as $line_nunmber => $line_value){
    // do it
}