collection.php

<?php
 
namespace Bitrix\Calendar\Core\Base;
 
use Countable;
use IteratorAggregate;
use ArrayIterator;
 
abstract class Collection implements IteratorAggregate, Countable
{
    protected array $collection = [];
    protected ?\Generator $generator = null;
 
    public function __construct(array $collection = [])
    {
        $this->collection = $collection;
    }
 
    public function getIterator(): ArrayIterator
    {
        return new ArrayIterator($this->collection);
    }
 
    public function count(): int
    {
        return count($this->collection);
    }
 
    public function add($item): Collection
    {
        $this->collection[] = $item;
 
        if ($this->generator)
        {
            $this->generator->send($item);
        }
 
        return $this;
    }
 
    public function addItems(array $items): Collection
    {
 
        $this->collection = array_merge($this->collection, $items);
 
        return $this;
    }
 
    public function remove($key): Collection
    {
        unset($this->collection[$key]);
 
        return $this;
    }
 
    public function getCollection(): array
    {
        return $this->collection;
    }
 
    public function fetch()
    {
        if ($this->generator === null)
        {
            $this->generator = $this->fetchGenerator();
        }
 
        $item = $this->generator->current();
        $this->generator->next();
 
        return $item;
    }
 
    protected function fetchGenerator(): ?\Generator
    {
        if (empty($this->collection))
        {
            return null;
        }
 
        foreach ($this->collection as $key => $item)
        {
            yield $key => $item;
        }
    }
 
    public function rewindGenerator(): void
    {
        if (!$this->generator->valid())
        {
            $this->generator->rewind();
        }
    }
}