Data commit

Task/Stack/Component-Pascal/stack.pas

@@ -0,0 +1,110 @@
+MODULE Stacks;
+IMPORT StdLog;
+
+TYPE
+	(* some pointers to records *)
+	Object* = POINTER TO ABSTRACT RECORD END;
+	
+	Integer = POINTER TO RECORD (Object)
+		i: INTEGER
+	END;
+	
+	Point = POINTER TO RECORD (Object)
+		x,y: REAL
+	END;
+
+	Node = POINTER TO LIMITED RECORD
+		next- : Node;
+		data-: ANYPTR;
+	END;
+
+	(* Stack *)
+	Stack* = POINTER TO RECORD
+		top- : Node;
+	END;
+	
+	PROCEDURE (dn: Object) Show*, NEW, ABSTRACT;
+	
+	PROCEDURE (i: Integer) Show*;
+	BEGIN
+		StdLog.String("Integer(");StdLog.Int(i.i);StdLog.String(");");StdLog.Ln
+	END Show;
+	
+	PROCEDURE (p: Point) Show*;
+	BEGIN
+		StdLog.String("Point(");StdLog.Real(p.x);StdLog.Char(',');
+		StdLog.Real(p.y);StdLog.String(");");StdLog.Ln
+	END Show;
+	
+	PROCEDURE (s: Stack) Init, NEW;
+	BEGIN
+		s.top := NIL;
+	END Init;
+	
+	PROCEDURE (s: Stack) Push*(data: ANYPTR), NEW;
+	VAR
+		n: Node;
+	BEGIN
+		NEW(n);n.next := NIL;n.data := data;
+		IF s.top = NIL THEN
+			s.top := n
+		ELSE
+			n.next := s.top;
+			s.top := n
+		END
+	END Push;
+	
+	PROCEDURE (s: Stack) Pop*(): ANYPTR, NEW;
+	VAR
+		x: ANYPTR;
+	BEGIN
+		IF s.top # NIL THEN
+			x := s.top.data;
+			s.top := s.top.next
+		ELSE
+			x := NIL
+		END;
+		RETURN x
+	END Pop;
+	
+	PROCEDURE (s: Stack) Empty*(): BOOLEAN, NEW;
+	BEGIN
+		RETURN s.top = NIL
+	END Empty;
+	
+	PROCEDURE NewStack*(): Stack;
+	VAR
+		s: Stack;
+	BEGIN
+		NEW(s);s.Init;
+		RETURN s
+	END NewStack;
+	
+	PROCEDURE NewInteger*(data: INTEGER): Integer;
+	VAR
+		i: Integer;
+	BEGIN
+		NEW(i);i.i := data;
+		RETURN i
+	END NewInteger;
+	
+	PROCEDURE NewPoint*(x,y: REAL): Point;
+	VAR
+		p: Point;
+	BEGIN
+		NEW(p);p.x := x;p.y := y;
+		RETURN p
+	END NewPoint;
+	
+	PROCEDURE TestStack*;
+	VAR
+		s: Stack;
+	BEGIN
+		s := NewStack();
+		s.Push(NewInteger(1));
+		s.Push(NewPoint(2.0,3.4));
+		s.Pop()(Object).Show();
+		s.Pop()(Object).Show();
+	END TestStack;
+	
+END Stacks.