generic -- specification

type element is private;

package queuesgeneric is

-- type definition

type queue (capacity: positive) is limited private;

-- exported exceptions

QueueFull : exception;

QueueEmpty : exception;

-- constructors

procedure MakeEmpty (Q : in out queue);

-- pre: Q is defined

-- post: Q is empty

procedure Enqueue (Q: in out Queue; E : in element);

-- pre: Q and E are defined

-- post: Q is returned with E as the top element

-- raises: QueueFull if Q already contains Capacity Elements

procedure dequeue (Q: in out Queue);

-- pre: Q is defined

-- post: Q is returned with the top Element discarded

-- raises QueueEmpty if Q contains no elemelnts

-- selector

function first (Q : in Queue) return Element;

-- pre: Q is defined

-- post: The first element of Q is returned

-- raises: QueueEmpty if Q contains no elements

-- inquiry operations

Function isEmpty (Q : in Queue) return Boolean;

-- pre: Q is defined

-- post: returns True if Q is empty, False otherwise

Function isFull (Q: in Queue) return boolean;

-- pre: Q is defined

-- post: returns True if Q is full, False otherwise

Private

Type List is Array (positive Range <> ) of element;

Type Queue (Capacity : positive) is record

tail : natural := 0;

store : List (1..Capacity);

End record;

End QueuesGeneric;