Data commit

Task/Stack/Ada/stack-2.ada

@@ -0,0 +1,42 @@
+with Ada.Unchecked_Deallocation;
+
+package body Generic_Stack is
+
+   ------------
+   -- Create --
+   ------------
+
+   function Create return Stack is
+   begin
+      return (null);
+   end Create;
+
+   ----------
+   -- Push --
+   ----------
+
+   procedure Push(Item : Element_Type; Onto : in out Stack) is
+      Temp : Stack := new Node;
+   begin
+      Temp.Element := Item;
+      Temp.Next := Onto;
+      Onto := Temp;
+   end Push;
+
+   ---------
+   -- Pop --
+   ---------
+
+   procedure Pop(Item : out Element_Type; From : in out Stack) is
+      procedure Free is new Ada.Unchecked_Deallocation(Node, Stack);
+      Temp : Stack := From;
+   begin
+      if Temp = null then
+         raise Stack_Empty_Error;
+      end if;
+      Item := Temp.Element;
+      From := Temp.Next;
+      Free(Temp);
+   end Pop;
+
+end Generic_Stack;