// *********************************************************
// Header file StackA.h for the ADT stack.
// Array-based implementation.
// *********************************************************
#include "Object.h"
#include "StackException.h"
const int MAX_STACK = 100;

class Stack
{
public:
// constructors and destructor:
   Stack();  // default constructor
   // copy constructor is supplied by the compiler
   ~Stack();

// stack operations:
   bool isEmpty() const;
   // Determines whether a stack is empty.
   // Precondition: None.
   // Postcondition: Returns true if the stack is empty;
   // otherwise returns false.
 
   void push(Object* newItem) throw(StackException);
   // Adds an item to the top of a stack.
   // Precondition: newItem is the item to be added.
   // Postcondition: If the insertion is successful, newItem
   // is on the top of the stack.
   // Exception: Throws StackException if the item cannot 
   // be placed on the stack.

   Object* pop() throw(StackException);
   // Retrieves and removes the top of a stack.
   // Precondition: None.
   // Postcondition: If the stack is not empty, the item 
   // that was added most recently is removed. However, if 
   // the stack is empty, deletion is impossible.
   // Exception: Throws StackException if the stack is empty.

   void popAll();
   // Removes all the items from the stack.
   // Precondition: None.
   // Postcondition: Stack is empty. Calls delete on all objects on the stack.

   const Object* peek() const throw(StackException);
   // Retrieves the top of a stack.
   // Precondition: None.
   // Postcondition: If the stack is not empty, stackTop
   // contains the item that was added most recently.
   // However, if the stack is empty, the operation fails
   // and stackTop is unchanged. The stack is unchanged.
   // Exception: Throws StackException if the stack is empty.

private:
   Object*       items[MAX_STACK];  // array of stack items
   int           top;               // index to top of stack
};  // end class
// End of header file.