Data commit

Task/Queue-Definition/Elisa/queue-definition-1.elisa

@@ -0,0 +1,23 @@
+component GenericQueue ( Queue, Element );
+ type Queue;
+      Queue (MaxLength = integer) -> Queue;
+      Length( Queue )           -> integer;
+      Empty ( Queue )           -> boolean;
+      Full ( Queue )            -> boolean;
+      Push ( Queue, Element)    -> nothing;
+      Pull ( Queue )            -> Element;
+begin
+      Queue (MaxLength) = Queue:[ MaxLength; length:=0; list=alist(Element) ];
+      Length ( queue ) = queue.length;
+      Empty ( queue ) = (queue.length <= 0);
+      Full ( queue ) = (queue.length >= queue.MaxLength);
+
+      Push ( queue, element ) =
+                   [ exception (Full(queue), "Queue Overflow");
+                     queue.length:= queue.length + 1;
+                     add (queue.list, element)];
+      Pull ( queue ) =
+                   [ exception (Empty(queue), "Queue Underflow");
+                     queue.length:= queue.length - 1;
+                     remove(first(queue.list))];
+end component GenericQueue;

Task/Queue-Definition/Elisa/queue-definition-2.elisa

@@ -0,0 +1,29 @@
+use GenericQueue (QueueofPersons, Person);
+type Person = text;
+Q = QueueofPersons(25);
+
+Push (Q, "Peter");
+Push (Q, "Alice");
+Push (Q, "Edward");
+Q?
+QueueofPersons:[MaxLength = 25;
+                length = 3;
+                list = { "Peter",
+                         "Alice",
+                         "Edward"}]
+Pull (Q)?
+"Peter"
+
+Pull (Q)?
+"Alice"
+
+Pull (Q)?
+"Edward"
+
+Q?
+QueueofPersons:[MaxLength = 25;
+                length = 0;
+                list = { }]
+
+Pull (Q)?
+***** Exception: Queue Underflow