StackInterface.h(textbook)

/** @file StackInterface.h */
#ifndef _STACK_INTERFACE
#define _STACK_INTERFACE
template<class ItemType>
class StackInterface
{
public:
/** Sees whether this stack is empty.
@return True if the stack is empty, or false if not. */
virtual bool isEmpty() const = 0;
/** Adds a new entry to the top of this stack.
@post If the operation was successful, newEntry is at the top of the stack.
@param newEntry The object to be added as a new entry.
@return True if the addition is successful or false if not. */
virtual bool push(const ItemType& newEntry) = 0;
/** Removes the top of this stack.
@post If the operation was successful, the top of the stack
has been removed.
@return True if the removal is successful or false if not. */
virtual bool pop() = 0;
/** Returns the top of this stack.
@pre The stack is not empty.
@post The top of the stack has been returned, and
the stack is unchanged.
@return The top of the stack. */
virtual ItemType peek() const = 0;
}; // end StackInterface
#endif