class ProfilerExtension

class ProfilerExtension extends AbstractExtension {
    private $actives = [];
    public function __construct(Profile $profile) {
        $this->actives[] = $profile;
    }
    
    /**
     * @return void
     */
    public function enter(Profile $profile) {
        $this->actives[0]
            ->addProfile($profile);
        array_unshift($this->actives, $profile);
    }
    
    /**
     * @return void
     */
    public function leave(Profile $profile) {
        $profile->leave();
        array_shift($this->actives);
        if (1 === \count($this->actives)) {
            $this->actives[0]
                ->leave();
        }
    }
    public function getNodeVisitors() : array {
        return [
            new ProfilerNodeVisitor(static::class),
        ];
    }

}