demo.php

<?php

$a = 'foo';
dump($a); // "foo"

snapshot($a);

$a = 'bar';
dump($a); // "bar"

restore($a);
dump($a); // "foo"

helpers.php

<?php

function snapshot(&$variable)
{
	return Snapshots::instance()->snapshot($variable);
}

function restore(&$variable) {
	return Snapshots::instance()->restore($variable);
}

Snapshots.php

<?php

use Illuminate\Support\Collection;

class Snapshots
{
	protected static ?self $instance = null;
	
	public static function instance(): self
	{
		return static::$instance ??= new self();
	}
	
	public function __construct(
		public Collection $cache = new Collection()
	) {
	}
	
	public function &snapshot(&$variable)
	{
		$snapshot = $variable;
		
		$this->cache[] = function(&$restoring) use (&$variable, $snapshot) {
			if ($this->match($variable, $restoring)) {
				$variable = $snapshot;
				return true;
			}
			return false;
		};
		
		return $variable;
	}
	
	public function &restore(&$variable)
	{
		$this->cache = $this->cache->reject(function($matcher) use (&$variable) {
			return $matcher($variable);
		});
		
		return $variable;
	}
	
	protected function match(&$a, &$b): bool
	{
		if ($a !== $b) {
			return false;
		}
		
		return match(true) {
			is_object($a) => true,
			is_scalar($a) && $this->areLinked($a, $b) => true,
			is_array($a) && $this->areLinked($a, $b) => true,
			default => false,
		};
	}
	
	protected function areLinked(&$a, &$b): bool
	{
		$backup = $a;
		
		try {
			$a = new stdClass();
			return $b === $a;
		} finally {
			$a = $backup;
		}
	}
}