#include <stdlib.h>

#include "vec.h"

/* The full definition of the struct, private to this file*/
struct vector
{
  int* data;
  int max;
  int size;
};

/* Constructor */
struct vector* vector_create(int init_size)
{
  struct vector* v = malloc(sizeof(struct vector));
  /* Make sure to ALWAYS give every piece of allocted memory a known starting value */
  v->data = calloc(init_size, sizeof(int)); /* calloc clears to zeores */
  v->max = init_size;
  v->size = 0;
  return v;
}

/* Member function (method) */
void vector_push_back(struct vector* me, int val)
{
  /* Make sure to ALWAYS notice if parameters have insane values */
  if ( me->size >= me->max)
    abort();
  me->data[me->size++] = val;
}

/* A private helper function, static makes it local to this compilation unit */
static int* index_ref(struct vector* me, int index)
{
  return &me->data[index];
}

/* Member function (method) */
int vector_at(struct vector* me, int index)
{
  /* Make sure to ALWAYS notice if parameters have insane values */
  if ( index < 0 || index >= me->size)
    abort();
  return *index_ref(me, index);
}

/* Destructor */
void vector_delete(struct vector* me)
{
  free(me->data);
  free(me);
}