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///a stack template class.
#include <iostream>
#pragma once
#include <string>
using namespace std;
class EmptyStack
////Exception class used by Pop and Top when stack is empty
{
//return (topPtr==NULL);
};
class FullStack
{
//return false;
};
//defenition of the node
template <class T>
struct nodeType
{
T info;
nodeType <T> * link;
};
template <class T>
class StackADT{
public:
StackADT();
/*Function: Constructor
Precondition: None;
Postcondition : stackADT is initialized, maxsize is set to 250, top is set to -1, items array is initialized with the size set to maxsize
*/
StackADT(int max);
/*Function: Constructor
Precondition: None;
Postcondition : stackADT is initialized, maxsize is set to max, top is set to -1, items array is initialized with the size set to maxsize
*/
bool isEmpty() const;
/*Function: Determines whether the stack is empty
Precondition: Stack has been initialized;
Postcondition : Returns True if stack is empty, False if stack is not empty
*/
bool isFull();
/*Function: Determines whether the stack is full
Precondition: Stack has been initialized;
Postcondition : Returns True if stack is full, False if stack is not full
*/
void Push(T newItem);
/*Function: Adds new item T to the top of the stack
Precondition: Stack has been initialized;
Postcondition :if stack is full, exception "The stack is full" is thrown, else the new item T is added to the stack
*/
void Pop();
/*Function: removes top item from stack
Precondition: Stack has been initialized;
Postcondition :if stack is empty, exception "The stack is empty is thrown, else the top element is removed
*/
T Top() ;
/*Function: returns a copy of the top item on the stack
Precondition: Stack has been initialized;
Postcondition :if stack is empty, exception "The stack is Empty" is thrown, else the top element is returned
*/
~StackADT();
/*Function: Destructor
Precondition: Stack has been initialized;
Postcondition :if stack is empty, exception 10 is thrown, else the top element is returned
*/
private:
nodeType <T> * topPtr;// Pointer to a stack
};
//Implementatation, because the class is a template class, contains the implementation of the class memeber for the stack class
template<class T> StackADT<T>::StackADT()//default constructor
{
topPtr= NULL;
}
template<class T> StackADT<T>::~StackADT()
// Post: Stack is empty; all items have been deallocated.
{
NodeType* tempPtr;
while (topPtr != NULL)
{
tempPtr = topPtr;
topPtr = topPtr->next;
delete tempPtr;
}
}
template <class T> bool StackADT <T>:: isEmpty () const
// Returns true if there are no elements on the stack and false otherwise.
{
return (topPtr == NULL);
}
template <class T> void StackADT <T>::Pop()
// Removes top item from stack
// Pre: Stack has been initialized.
// Post: If stack is empty, EmptyStack exception is thrown;
// else, top element has been removed.
{
if (IsEmpty())
throw EmptyStack();
else
{
NodeType* tempPtr;
tempPtr = topPtr;
topPtr = topPtr->next;
delete tempPtr;
}
}
template <class T> void StackADT <T>::Push(T newItem)
// Adds newItem to the top of the stack.
// Pre: Stack has been initialized.
// Post: If stack is full, FullStack exception is thrown;
// else, newItem is at the top of the stack.
{
if (isFull())
throw FullStack();
else
{
NodeType* location;
location = new NodeType;
location->info = newItem;
location->next = topPtr;
topPtr = location;
}
}
template <class T> bool StackADT <T>:: isFull ()
// Returns true if there is no room for another NodeType object
// on the free store and false otherwise.
{
NodeType* location;
try
{
location = new NodeType;
delete location;
return false;
}
catch(std::bad_alloc exception)
{
return true;
}
}
template <class T> T StackADT <T> :: Top ()
// Returns a copy of the top item in the stack.
// Pre: Stack has been initialized.
// Post: If stack is empty. EmptyStack exception is thrown;
// else, a copy of the top element is returned.
{
if (IsEmpty())
throw EmptyStack();
else
return topPtr->info;
}
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