A forward or reverse array iterator, with a test (PHP).

ReverseArrayIterator.php

<?php
/**
 * A forward or reverse array iterator, with a test (PHP).
 *
 * @copyright Nick Freear, 12-July-2021.
 *
 * @see https://doc.wikimedia.org/mediawiki-core/master/php/ReverseArrayIterator_8php_source.html
 * @see https://github.com/wikimedia/mediawiki/blob/master/includes/libs/ReverseArrayIterator.php
 */

class ReverseArrayIterator implements Iterator, Countable {
    protected $array;

    protected $isReverse;
    protected $idx;

    public function __construct( array $array = [], bool $isReverse = true ) {
        if ( is_array( $array ) ) {
            $this->array = $array;
        } elseif ( is_object( $array ) ) {
            $this->array = get_object_vars( $array );
        } else {
            throw new InvalidArgumentException( __METHOD__ . ' requires an array or object' );
        }

        $this->isReverse = $isReverse;

        $this->rewind();
    }

    public function current() {
        return current( $this->array );
    }

    public function key(): int | string | null {
        return key( $this->array );
    }

    public function next(): void {
        if ($this->isReverse) {
            prev( $this->array );
        } else {
            next( $this->array );
        }

        $this->idx++;
    }

    public function rewind(): void {
        if ($this->isReverse) {
            end( $this->array );
        } else {
            reset( $this->array );
        }

        $this->idx = 0;
    }

    public function valid(): bool {
        return key( $this->array ) !== null;
    }

    public function count(): int {
        return count( $this->array );
    }

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

/**
 * ----------------------------------------------------------
 * TEST.
 */

$lastArg = $argv[ $argc - 1 ];
$isReverse = $lastArg === '--reverse';

$programmingLangArray = [ 'Ada', 'Basic', 'C++', 'Delphi', 'E', 'Fortran', 'Go', 'Haskell', 'Javascript' ];
// $programmingLangArray = ["PHP", "C++", "C#", "Python", "Java"];
// $fruitArray = [ 'Apples', 'Bananas', 'Cherries', 'Durian', ];

$arrayIterator = new ReverseArrayIterator($programmingLangArray, $isReverse);

while( $arrayIterator->valid() )
{
    echo ($arrayIterator->index() + 1) . '. ' . $arrayIterator->current() . PHP_EOL;
    $arrayIterator->next();
}

// End.