/* 
   +----------------------------------------------+
   | DPL Programming Language v1.1                |
   +----------------------------------------------+
   | The DPL langauge was developed for a school  |
   | project at ThunderRidge High School.         |
   |                                              |
   | Development of the language after its        |
   | completion is reserved to Brian Rosner.      |
   +----------------------------------------------+
   | Author: Brian Rosner <br@brosner.com>        |
   +----------------------------------------------+
*/
 
#include <stdio.h>
#include <string.h>
 
#include "dpl.h"
#include "stack.h"
 
void stackInit(Stack *stack) {
  stack->size = 0;
  stack->head = NULL;
  stack->tail = NULL;
}
 
void stackDestroy(Stack *stack) {
}
 
int stackPush(Stack *stack, void *data, int size) {
  StackElement *element;
 
  /* allocate memory for element */
  element = (StackElement *) malloc(sizeof(StackElement));
 
  if(element == NULL) {
    return FAILURE;
  }
 
  /* allocate memory for data and store it */
  element->data = (void *) malloc(size);
  memcpy(element->data, data, size);
 
  if(stackSize(stack) == 0) {
    stack->tail = element;
  }
 
  element->next = stack->head;
  stack->head = element;
 
  /* adjust stack size */
  stackSize(stack)++;
 
  return SUCCESS;
}
 
int stackPop(Stack *stack, void **data) {
  StackElement *element;
 
  /* dont allow removal from empty list */
  if(stackSize(stack) == 0) {
    return FAILURE;
  }
 
  *data = stack->head->data;
  element = stack->head;
  stack->head = stack->head->next;
 
  if(stackSize(stack) == 1) {
    stack->tail = NULL;
  }
 
  /* free memory */
  free(element);
 
  /* adjust stack size */
  stackSize(stack)--;
 
  return SUCCESS;
}