// ============================================================
// simulate.pp : Propagation patterns for bus route simulation.
// Written by Ali Ozmez for COM3360 project.
// Last update on Tue Nov 28 21:51:23 1995.
// ============================================================


// Following PP does a unit time long (1 min) simulation.
*operation* void simulate()
  *traverse*
    *from* BusRoute *to* Bus
  *carry*
    *in* BusRoute *busRoute = (@ this @)
    *along* *from* BusRoute *to* Bus
  *wrapper* Bus
    (@
     StopId *stopId = this->get_currentStop();
     if (stopId != NULL) {
       // waiting at a stop
       this->drop_passengers(stopId);
       this->load_passengers( busRoute->find_stop(stopId) );
       this->set_currentStop(NULL);   // prepare to move
     }	
     else {
       // moving along the route
       int prevPos = this->get_loc();
       int nextPos = (prevPos + this->get_spd()) % busRoute->get_len();
       BusStop *stop = busRoute->any_stop_around(prevPos, nextPos);
       if (stop == NULL)
	 this->proceed_to(nextPos);
       else if (this->have_stop_request( stop->get_id() )) {
	 this->proceed_to( stop->get_loc() );
	 this->set_currentStop( stop->get_id() );   // stop here
       }
       else {
	 int have_room = this->get_cap() - this->count_passengers(); 
	 if ( have_room && stop->anybody_waiting() ) {
	   this->proceed_to( stop->get_loc() );
	   this->set_currentStop( stop->get_id() );   // stop here
	 }
	 else
	   this->proceed_to(nextPos);
       }
     }
    @)

// PP to drop the passengers who want to get off at the current stop.
*operation* void drop_passengers(StopId *iStopId)
  *traverse*
    *from* Bus *to* Person
  *carry*
    *out* Person_List *newPasList = (@ new Person_List() @)
    *along* *from* Bus *to* Person
  *wrapper* Person
    (@
     if (!iStopId->g_equal( this->get_destination() )) 
       newPasList->append(this);
     @)
  *wrapper* Bus *suffix*
    (@ this->set_passengers(newPasList); @)

// PP to load some (or all) of the people waiting at the stop.
*operation* void load_passengers(BusStop *iStop)
  *traverse*
    *from* Bus *to* Person_List
  *carry*
    *in* Person_List *newPasList
    *along* *from* Bus *to* Person_List
  *wrapper* Bus
    (@
     int allowance = this->get_cap() - this->count_passengers();
     newPasList = iStop->give_passengers(allowance);
     @)
  *wrapper* Person_List
    (@ this->concatenate(newPasList); @)

// PP to find the stop from its id. 
*operation* BusStop *find_stop(StopId *iStopId) *init* (@ NULL @)
  *traverse*
    *from* BusRoute *to* BusStop
  *wrapper* BusStop
    (@
     if (iStopId->g_equal( this->get_id() ))
       return_val = this;
     @)
  *wrapper* ~> BusStop_List, BusStop
    (@ if (return_val) return; @)

// PP to count the passengers travelling on a bus.
*operation* int count_passengers()
  *traverse*
    *from* Bus *to* Person_List
  *wrapper* Person_List
    (@ return_val = this->list_length(); @)

// PP to transfer people from a stop (to a bus).
*operation* Person_List *give_passengers(int allowance)
  *init* (@ new Person_List() @)
  *traverse*
    *from* BusStop *to* Person
  *carry*
    *out* Person_List *newWaitList = (@ new Person_List() @)
    *along* *from* BusStop *to* Person
  *wrapper* Person
    (@ 
     if (return_val->list_length() < allowance)
       return_val->append(this);
     else
       newWaitList->append(this);
     @)
  *wrapper* BusStop *suffix*
    (@ this->set_waitingList(newWaitList); @)

// PP to search for a stop in the given interval of route.
*operation* BusStop *any_stop_around(int prevPos, int nextPos)
  *init* (@ NULL @)
  *traverse*
    *from* BusRoute *to* BusStop
  *wrapper* BusStop
    (@ 
     int stopLoc = this->get_loc();
     if (prevPos < nextPos) {
       if ((stopLoc > prevPos) && (stopLoc <= nextPos))
         return_val = this;
     }
     else if ((stopLoc > prevPos) || (stopLoc <= nextPos))
       return_val = this;
     @)
  *wrapper* ~> BusStop_List, BusStop
    (@ if (return_val) return; @)

// PP to move the bus to its new position.
*operation* void proceed_to(int newPos)
  *traverse*
    *from* Bus *to* RouteLoc
  *wrapper* RouteLoc
    (@ this->get_v()->set_val(newPos); @)

// PP to see if there is any passenger who wants to get off at
// the specified stop.
*operation* int have_stop_request(StopId *iStopId) *init* (@ 0 @)
  *traverse*
    *from* Bus *to* Person
  *wrapper* Person
    (@
     if (iStopId->g_equal( this->get_destination() ))
       return_val = 1;
     @)
  *wrapper* ~> Person_List, Person
    (@ if (return_val) return; @)

// PP to see if anybody waiting at the specified stop.
*operation* int anybody_waiting() *init* (@ 0 @)
  *traverse*
    *from* BusStop *to* Person_List
   *wrapper* Person_List
     (@ return_val = this->empty(); @)

// PP to get the get the length of a BusRoute object as an int.
*operation* int get_len()
  *traverse*
    *from* BusRoute *to* RouteLen
   *wrapper* RouteLen
     (@ return_val = this->get_v()->get_val(); @)

// PP to get the get the position of a Bus or BusStop object as an int.
*operation* int get_loc()
  *traverse*
    *from* {Bus, BusStop} *to* RouteLoc
   *wrapper* RouteLoc
     (@ return_val = this->get_v()->get_val(); @)

// PP to get the get the capacity of a Bus object as an int.
*operation* int get_cap()
  *traverse*
    *from* Bus *to* BusCapac
   *wrapper* BusCapac
     (@ return_val = this->get_v()->get_val(); @)

// PP to get the get the speed of a Bus object as an int.
*operation* int get_spd()
  *traverse*
    *from* Bus *to* BusSpeed
   *wrapper* BusSpeed
     (@ return_val = this->get_v()->get_val(); @)