Ada Programming: STACK Data Structure and Tagged Types, Slides of Programming Languages

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package STACK is

procedure PUSH (x : INTEGER);

function POP return INTEGER;

end STACK;

package body STACK is MAX: constant := 100; S : array (1..MAX) of INTEGER; TOP : INTEGER range 0..MAX;

procedure PUSH (x : INTEGER) is begin TOP := TOP + 1; S(TOP) := x; end PUSH;

function POP return integer is TOP := TOP - 1; return S(TOP + 1); end POP; begin TOP := 0; end STACK; Docsity.com

package STACKS is

type STACK is private; procedure PUSH (s : in out STACK; i : in integer);

procedure POP (s : in out STACK; o : out integer);

private MAX: constant := 100; type STACK is record ST : array (1..MAX) of INTEGER; TOP : INTEGER range 0..MAX := 0; end record;

end STACKS;

Procedure not a function?

package body STACKS is procedure PUSH (S: in out STACK; i : in INTEGER) is begin S.TOP := S.TOP + 1; S.ST(S.TOP) := i; end PUSH;

procedure POP (S: in out STACK; o : out INTEGER) is begin o := S.ST(S.TOP); S.TOP := S.TOP - 1; end POP;

end STACK;

package STACKS is

overFlow, underFlow : exception; type STACK is private; procedure PUSH (s : in out STACK; i : in integer); procedure POP (s : in out STACK; o : out integer);

private MAX: constant := 100; type STACK is record ST : array (1..MAX) of INTEGER; TOP : INTEGER range 0..MAX := 0; end record;

end STACKS;

package body STACKS is procedure PUSH (S: in out STACK; i : in INTEGER) is begin if S.TOP = MAX then raise overFlow; end if; S.TOP := S.TOP + 1; S.ST(S.TOP) := i; end PUSH;

procedure POP (S: in out STACK; o : out INTEGER) is begin if S.TOP = 0 then raise underFlow; end if; o := S.ST(S.TOP); S.TOP := S.TOP - 1; end POP;

end STACK;

Object Orientation – The Ada

Way

• Ada provides tools and constructs for

extending types through inheritance

• In many object oriented languages the

concept of a class is overloaded

• It is both the unit of encapsulation and a type

definition

• Ada separates these two concepts
  • Packages are used for encapsulation
  • Tagged types are used to define extensible

types

Tagged Type

type Person is tagged record

Name : String(1..20); Age : Natural;

end record;

• Such a type definition can be performed in a package
• Immediately following the type definition must be the procedures and functions comprising the primitive operations defined for this type
• Primitive operations must have one of its parameters be of the tagged type, or for functions the return value can be an instance of the tagged type - This allows you to overload functions based upon their return type - Note that C++ and Java do not allow you to overload, based upon the return type of a function Docsity.com

Generics

• Allow parameterization of subprograms

and packages with parameters which can

be types and subprograms as well as

values and objects

generic

MAX : positive;

type item is private;

package STACK is

procedure PUSH (x : item);

function POP return item;

end STACK;

Generics

declare package myStack is new STACK(100, integer); use myStack;

begin

… push (i); …

O := pop; …

end;

Concurrency

• The support for concurrency in Ada is provided

by Tasking

• It initiates several parallel activities which

cooperate as needed

• Syntax is similar to packages

Concurrency

procedure COOKING is

begin

cookMeat; cookRice; cookPudding;

end COOKING;

Concurrency

procedure COOKING is task cookMeat; task body cookMeat is begin -- follow instructions for cooking meat end cookMeat;

task cookRice; task body cookRice is begin -- follow instructions for cooking rice end cookRice;

begin cookPudding; end COOKING;