Chain of Responsibility Pattern Example

AbstractStep.php

<?php

abstract class AbstractStep
{
    protected $successor;

    protected $shouldPassToSuccessor = true;

    public static function registerSteps(array $steps): AbstractStep
    {
        $firstStep = $nextStep = array_shift($steps);

        foreach ($steps as $step) {
            $nextStep = $nextStep->next($step);
        }

        return $firstStep;
    }

    public function next(AbstractStep $step): AbstractStep
    {
        $this->successor = $step;
        return $step;
    }

    public function handle($data)
    {
        $data = $this->process($data);
        if ($this->shouldPassToSuccessor && $this->successor) {
            $data = $this->successor->handle($data);
        }
        return $data;
    }

    abstract protected function process($data);
}

Example.php

<?php

return AbstractStep::registerSteps([
    new Step1,
    new Step2,
    new Step3,
])->handle($data);

Step1.php

<?php

class Step1 extends AbstractStep
{
    protected function process($data)
    {
        $this->shouldPassToSuccessor = $this->check($data);
        return $data;
    }

    private function check($data)
    {
        // return true or false;
    }
}