generic-stack.c

/************************************************************************
 * 
 * File name:		generic-stack.c
 * Description:		Generic Stack's Implementation
 * Author:		dennis_fan(dennis_fan@outlook.com), 2013/2/26
 * Version:		1.0
 *************************************************************************/

#include "generic-stack.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MIN_STACK_SIZE (4)

/* Create a new stack */
Stack 
stack_create(int elemsize, PfCbFree freefn)
{
	Stack stk;
	
	stk = malloc(sizeof(struct StackRecord));
	
	if ( stk == NULL) {
		fprintf(stderr, "Out of memory\n");
		exit(1);
	}
	
	stk->array = malloc(elemsize * MIN_STACK_SIZE);
	if (stk->array == NULL) {
		fprintf(stderr, "Out of memory\n");
		exit(1);
	}
	stk->elemsize = elemsize;
	stk->loglength = 0; 
	stk->alloclength = MIN_STACK_SIZE;
}

/* Dispose the stack*/
void 
stack_dispose(Stack stk)
{
	stack_make_empty(stk);
	free(stk->array);
	free(stk);
}

/* Make the given stack empty*/
void 
stack_make_empty(Stack stk)
{
	if ( stk->freefn ) {
		int i;
		for ( i = 0; i < stk->loglength; ++i) {
			stk->freefn((char *)stk->array + 
				    i * stk->elemsize);
		}
	}
	stk->loglength = 0;
}

/* Return true if the stack is empty*/
int 
stack_is_empty(Stack stk)
{
	return stk->loglength == 0;
}

static void 
stack_grow(Stack stk)
{
	stk->alloclength *= 2;
	stk->array = realloc(stk->array, 
	                     stk->alloclength * stk->elemsize);
}

/* Insert a new element onto stack */
void 
stack_push(Stack stk, ElementAddr elemaddr)
{
	ElementAddr target;
	if ( stk->loglength == stk->alloclength )
		stack_grow(stk);
	target = (char *)stk->array + stk->loglength * stk->elemsize;
	memcpy(target, elemaddr, stk->elemsize);
	stk->loglength++;	
}

/* Delete the top element off the stack */
void 
stack_pop(Stack stk)
{
	ElementAddr target;
	if ( stack_is_empty(stk) ) {
		fprintf(stderr, "Empty stack\n");
		exit(1);
	}
	if ( stk->freefn ) {
		target = (char *)stk->array + 
                         (stk->loglength-1) * stk->elemsize;
		stk->freefn(target);
	}
	stk->loglength--;
}

/* Fetch the top element from the stack */
void 
stack_top(Stack stk, ElementAddr elemaddr)
{
	void *target = (char *)stk->array + 
                       (stk->loglength-1) * stk->elemsize;
	memcpy(elemaddr, target, stk->elemsize);
}

/* Fetch & Delete the top element from the stack */
void 
stack_top_and_pop(Stack stk, ElementAddr elemaddr)
{
	ElementAddr target;
	if ( stack_is_empty(stk) ) {
		fprintf(stderr, "Empty stack\n");
		exit(1);
	}
	target = (char *)stk->array + 
                 (stk->loglength-1) * stk->elemsize;
	memcpy(elemaddr, target, stk->elemsize);
	stk->loglength--;
}