#ifndef _APSTACK_H

#define _APSTACK_H



// uncomment line below if bool not built-in type

// #include "bool.h"



// *******************************************************************

//  Last Revised: September 1, 1997

//

// APCS stack class

// *******************************************************************



#include "apvector.h"                  // used for stack implementation



template <class itemType>

class apstack

{

  public:

    

  // constructors/destructor



    apstack( );                            // construct empty stack

    apstack( const apstack & s );          // copy constructor

    ~apstack( );                           // destructor



  // assignment



    const apstack & operator = ( const apstack & rhs );



  // accessors



    const itemType & top( )      const;   // return top element (NO pop)

    bool             isEmpty( )  const;   // return true if empty, else false

    int              length( )   const;   // return number of elements in stack



  // modifiers



    void push( const itemType & item );   // push item onto top of stack

    void pop( );                          // pop top element

    void pop( itemType & item );          // combines pop and top

    void makeEmpty( );                    // make stack empty (no elements)



  private:



    int myTop;                            // index of top element

    apvector<itemType> myElements;        // storage for stack

};



  // **********************************************************************

  //

  // Specifications for stack functions

  //

  // Any violation of a function's precondition will result in an error message

  // followed by a call to abort.

  //

  //

  // constructors/destructor

  //

  //  apstack( )

  //    postcondition: the stack is empty

  //

  //  apstack( const apstack & s )

  //    postcondition: stack is a copy of s

  //

  //  ~apstack( )

  //    postcondition: stack is destroyed

  //

  // assignment

  //

  //  const apstack & operator = ( const apstack & rhs )

  //    postcondition: normal assignment via copying has been performed

  //

  // accessors

  //

  //  const itemType & top( ) const

  //    precondition: stack is [e1, e2, ... en] with n >= 1

  //    postcondition: returns en

  //

  //  bool isEmpty( ) const

  //     postcondition: returns true if stack is empty, false otherwise

  //

  //  int length( ) const

  //     postcondition: returns # of elements currently in stack

  //

  // modifiers

  //

  //  void push( const itemType & item )

  //     precondition: stack is [e1, e2...en] with  n >= 0

  //     postcondition: stack is [e1, e2, ... en, item]

  //

  //  void pop( )

  //     precondition: stack is [e1, e2, ... en] with n >= 1

  //     postcondition: stack is [e1, e2, ... e(n-1)]

  //

  //

  //  void pop(itemType & item )

  //     precondition: stack is [e1,e2,...en] with n >= 1

  //     postcondition: stack is [e1,e2,...e(n-1)] and item == en

  //

  //  void makeEmpty( )

  //     postcondition:  stack is empty

  //

  //  Examples of variable definition 

  //

  //    apstack<int> istack;                    // creates empty stack of integers

  //    apstack<double> dstack;                 // creates empty stack of doubles

  //



#include "apstack.cpp"



#endif