/*-------------------------------------------------------------------*/
/* stack.c (Version 6: Generic ADTs)                                 */
/*-------------------------------------------------------------------*/

#include "stack.h"
#include <stdlib.h>
#include <assert.h>

struct Stack
{
   void **ppvArray;
   int iTop;
   int iMaxSize;
};

struct Stack *Stack_new(int iMaxSize)
/* Return the address of a new Stack that is able to store iMaxSize 
   items, each of type double. */
{
   struct Stack *psStack;
   assert(iMaxSize > 0);
   psStack = (struct Stack*)malloc(sizeof(struct Stack));
   assert(psStack != NULL);
   psStack->ppvArray = (void**)calloc(iMaxSize, sizeof(void*));
   assert(psStack->ppvArray != NULL);
   psStack->iTop = 0;
   psStack->iMaxSize = iMaxSize;
   return psStack;
}

void Stack_free(struct Stack *psStack)
/* Free *psStack. */
{
   assert(psStack != NULL);
   free(psStack->ppvArray);
   free(psStack);
}

void Stack_push(struct Stack *psStack, void *pvItem)
/* Push pvItem onto *psStack. */
{
   assert(psStack != NULL);
   assert(psStack->iTop < psStack->iMaxSize);
   (psStack->ppvArray)[psStack->iTop] = pvItem;
   ++(psStack->iTop);
}

void *Stack_pop(struct Stack *psStack)
/* Pop *psStack, and return the popped item. */
{
   assert(psStack != NULL);
   assert(psStack->iTop > 0);
   --(psStack->iTop);
   return (psStack->ppvArray)[psStack->iTop];
}

int Stack_empty(struct Stack *psStack)
/* Return 1 (TRUE) iff *psStack is empty. */
{
   assert(psStack != NULL);
   return psStack->iTop == 0;
}

int Stack_full(struct Stack *psStack)
/* Return 1 (TRUE) iff *psStack is full. */
{
   assert(psStack != NULL);
   return psStack->iTop == psStack->iMaxSize;
}