Initial commitHEADmain

1 files changed, 31 insertions, 0 deletions

diff --git a/stack/src/stack.adb b/stack/src/stack.adb
new file mode 100644
index 0000000..4dc8fb1
--- /dev/null
+++ b/stack/src/stack.adb
@@ -0,0 +1,31 @@
+with Ada.Unchecked_Deallocation;
+
+package body Stack is
+   procedure Free is new Ada.Unchecked_Deallocation (Node, Node_Access);
+
+   procedure Push (S : in out Stack; Val : T) is
+      New_Top : Node_Access := new Node;
+   begin
+      New_Top.Val := Val;
+      New_Top.Bottom := S.Top;
+      S.Top := New_Top;
+   end Push;
+
+   function Pop (S : in out Stack; Val : out T) return Boolean is
+      Old_Top : Node_Access := S.Top;
+   begin
+      if Old_Top /= null then
+         Val := Old_Top.Val;
+         S.Top := Old_Top.Bottom;
+         Free (Old_Top);
+         return True;
+      else
+         return False;
+      end if;
+   end Pop;
+
+   function Empty (S : Stack) return Boolean is
+   begin
+      return S.Top = null;
+   end Empty;
+end Stack;