Explain about blade directives used with hasRole as a parameter?

I'm given with a task of adding new features in a built-in application and I end up with a piece of code. I have no idea how its working. On AppServiceProvider.php

 Blade::directive('hasRole', function ($expression) {
            $exp=explode(",",$expression);
            return "<?php if(Auth::user()->hasPermission($exp[0],$exp[1])): ?>";
        });

On blades:

@hasRole('travel_calendar','view')
        <button class="btn btn-space btn-default btn-big tactive" id="travel_menu_cal" ><i class="icon mdi mdi-calendar"></i> Calendar</button>
        @endHasRole

What does the view does in this code too. Someone place explain me the code.

via Chebli Mohamed