package body QueuesGeneric is

procedure makeEmpty (Q : in out queue ) is

begin

Q.tail := 0;

end makeEmpty;

procedure Enqueue (Q : in out Queue; E : in Element) is

begin

if Q.tail = q.capacity then

raise QueueFull;

else

Q.tail := q.tail + 1;

Q.store (Q.tail) := E;

end if;

end Enqueue;

procedure Dequeue (Q : in out Queue) is

begin

if q.tail = 0 then

raise QueueEmpty;

else

Q.store(1..Q.tail-1) := Q.store (2..Q.tail); -- slice

Q.tail := Q.tail - 1;

end if;

end Dequeue;

function first (Q : in Queue) return Element is

begin

if q.tail = 0 then

raise QueueEmpty;

else

return Q.Store(1);

end if;

end first;

function isEmpty (Q: in Queue) return boolean is

begin

return Q.tail = 0;

end IsEmpty;

function isFull (Q : in Queue) return Boolean is

begin

return Q.tail = Q.capacity;

end isFull;

end QueuesGeneric;