创建PHP迭代器CsvFileIterator

<?php

namespace lib;

use Iterator;

class CsvFileIterator implements Iterator
{
    private $handler;
    private int $index = 0;

    public function __construct($filepath)
    {
        $this->handler = fopen($filepath, 'r');
    }

    public function __destruct()
    {
        fclose($this->handler);
    }

    public function current(): mixed
    {
        return fgetcsv($this->handler, 2048);
    }

    public function rewind(): void
    {
        fseek($this->handler, 0);
        $this->index = 0;
    }

    public function key(): int
    {
        return $this->index;
    }

    public function next(): void
    {
        $this->index++;
    }

    public function valid(): bool
    {
        return !feof($this->handler);
    }
}

$csv_items = new CsvFileIterator("../public/data.csv");
foreach ($csv_items as $key => $csv_item) {
    var_dump($key, $csv_item);
}