immutable.php

См. документацию.

<?php
 
namespace Bitrix\Mail\Collection;
use Bitrix\Mail\Item\Base as Item;

abstract class Immutable implements \Iterator, \Countable
{
    protected $position = 0;

    protected $items = array();
 
    protected function appendItem(Item $item, $throwException = true)
    {
        if ($this->ensureItem($item, $throwException)) {
            $this->items[] = $item;
            return true;
        }
        return false;
    }
 
    protected function appendCollection(Immutable $collection, $throwException = true)
    {
        foreach ($collection as $item) {
            $this->appendItem($item, $throwException);
        }
    }
 
    public function ensureItem(Item $item, $throwException = true)
    {
        if ($throwException) {
            // TODO: unsupported item special exception
            throw new \Bitrix\Main\SystemException('unsupported item');
        }
        return false;
    }
 
    abstract public function createItem(array $array);
 
    public function __construct(array $data = [])
    {
        foreach ($data as $item) {
            $this->appendItem($item);
        }
    }

    public static function fromArray(array $array)
    {
        $collection = new static();
        foreach ($array as $row) {
            if ($item = $collection->createItem($row)) {
                $collection->appendItem($item);
            }
        }
        return $collection;
    }
 
    public function getFirst(&$position)
    {
        $position = 0;
        return $this->getNext($position);
    }
 
    public function getNext(&$position)
    {
        return isset($this->items[$position]) ? $this->items[$position++] : null;
    }

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

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

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

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

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

    public function count()
    {
        return count($this->items);
    }
}