void advance_trains(struct station *kipling, struct train **first)
{
// Advance every train on the track (if it can be advanced)
// PRE: *first != NULL and there is more than one train on the track
// POST: the trains' positions will be incremented
assert(*first);
assert((*first)->next);
struct train *curr = *first;
struct train *prev = NULL;
while(curr)
{
if(curr->pos >= MAX_POS + 1)
{
// delete the train when it gets to position 83
prev->next = NULL;
free(curr);
return;
}
else
{
// otherwise, the train is on the track and we should advance it
int num_pass = 0;
struct station *curr_station = get_station_at_pos(curr->pos, kipling);
if(curr_station)
{
num_pass = num_passengers(curr_station->passengers);
}
advance_train(curr, num_pass);
prev = curr;
curr = curr->next;
}
}
}
static void advance_train_test() {
// absent
check_expect_train(__LINE__, advance_train(make_train_none(), 3.0),
make_train_none());
// borders
check_expect_train(__LINE__, advance_train(make_train_at(0.0), 0.0),
make_train_at(0.0));
check_expect_train(__LINE__, advance_train(make_train_at(10.0), 0.0),
make_train_at(10.0));
check_expect_train(__LINE__, advance_train(make_train_at(1.0), -1.0),
make_train_at(0.0));
check_expect_train(__LINE__, advance_train(make_train_at(9.0), 1.0),
make_train_at(10.0));
// interior (both before and after advance)
check_expect_train(__LINE__, advance_train(make_train_at(1.0), 0.0),
make_train_at(1.0));
check_expect_train(__LINE__, advance_train(make_train_at(5.5), 1.5),
make_train_at(7.0));
check_expect_train(__LINE__, advance_train(make_train_at(4.5), -1.0),
make_train_at(3.5));
// leaving the section
check_expect_train(__LINE__, advance_train(make_train_at(9.0), 1.1),
make_train_none());
check_expect_train(__LINE__, advance_train(make_train_at(1.0), -1.1),
make_train_none());
// entering the section
check_expect_train(__LINE__, advance_train(make_train_at(-0.1), 0.1),
make_train_at(0.0));
check_expect_train(__LINE__, advance_train(make_train_at(10.1), -0.1),
make_train_at(10.0));
}