Stack
Stack
You are encouraged to solve this task according to the task description, using any language you may know.
You are encouraged to solve this task according to the task description, using any language you may know.
Ada
This is a generic stack implementation.
generic type Element_Type is private; package Generic_Stack is type Stack is private; procedure Push (Item : Element_Type; Onto : in out Stack); procedure Pop (Item : out Element_Type; From : in out Stack); function Create return Stack; Stack_Empty_Error : exception; private type Node; type Stack is access Node; type Node is record Element : Element_Type; Next : Stack := null; end record; end Generic_Stack;
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;
C++
Library: STL
#include <stack>
#include <deque> template <class T, class Sequence = deque<T> > class stack { friend bool operator== (const stack&, const stack&); friend bool operator< (const stack&, const stack&); public: typedef typename Sequence::value_type value_type; typedef typename Sequence::size_type size_type; typedef Sequence container_type; typedef typename Sequence::reference reference; typedef typename Sequence::const_reference const_reference; protected: Sequence seq; public: stack() : seq() {} explicit stack(const Sequence& s0) : seq(s0) {} bool empty() const { return seq.empty(); } size_type size() const { return seq.size(); } reference top() { return seq.back(); } const_reference top() const { return seq.back(); } void push(const value_type& x) { seq.push_back(x); } void pop() { seq.pop_back(); } };
template <class T, class Sequence> bool operator==(const stack<T,Sequence>& x, const stack<T,Sequence>& y) { return x.seq == y.seq; } template <class T, class Sequence> bool operator<(const stack<T,Sequence>& x, const stack<T,Sequence>& y) { return x.seq < y.seq; }
template <class T, class Sequence> bool operator!=(const stack<T,Sequence>& x, const stack<T,Sequence>& y) { return !(x == y); } template <class T, class Sequence> bool operator>(const stack<T,Sequence>& x, const stack<T,Sequence>& y) { return y < x; } template <class T, class Sequence> bool operator<=(const stack<T,Sequence>& x, const stack<T,Sequence>& y) { return !(y < x); } template <class T, class Sequence> bool operator>=(const stack<T,Sequence>& x, const stack<T,Sequence>& y) { return !(x < y); }
Java
public class Stack { private Node first = null; public boolean isEmpty { return (first == null); } public Object Pop() { if (first == null) throw new Exception("Can't Pop from an empty Stack."); else { Object temp = first.Value; first = first.Next; return temp; } } public void Push(Object o) { first = new Node(o, first); } class Node { public Node Next; public Object Value; public Node(Object value) { this(value, null); } public Node(Object value, Node next) { Next = next; Value = value; } } }
Compiler: JDK 1.5 with Generics
public class Stack<T> { private Node first = null; public boolean isEmpty { return (first == null); } public T Pop() { if (first == null) throw new Exception("Can't Pop from an empty Stack."); else { T temp = first.Value; first = first.Next; return temp; } } public void Push(T o) { first = new Node(o, first); } class Node { public Node Next; public T Value; public Node(T value) { this(value, null); } public Node(T value, Node next) { Next = next; Value = value; } } }
C#
public class Stack { private Node first = null; public bool Empty { get { return (first == null); } } public object Pop() { if (first == null) throw new Exception("Can't Pop from an empty Stack."); else { object temp = first.Value; first = first.Next; return temp; } } public void Push(object o) { first = new Node(o, first); } class Node { public Node Next; public object Value; public Node(object value): this(value, null) {} public Node(object value, Node next) { Next = next; Value = value; } } }