Deque Implementation in C

deque.h

#ifndef DEQUE_H
# define DEQUE_H
# include "stdlib.h"
# include "stdio.h"

typedef struct	s_deque
{
	struct	s_deque_node	*head;
	struct	s_deque_node	*tail;
	int	len;

}	t_deque;

typedef	struct	s_deque_node
{
	struct	s_deque_node	*prev;
	struct	s_deque_node	*next;
	void	*content;

}	t_deque_node;

t_deque	*deque_init(void);
void	deque_push_front(t_deque *__, void *_);
void	deque_push_back(t_deque *__, void *_);
void	*deque_pop_front(t_deque *_);
void	*deque_pop_back(t_deque *_);
int	deque_is_empty(t_deque *_);
int	deque_len(t_deque *_);

void	deque_print(t_deque *_);

#endif

deque_pop.c

#include "deque.h"

void	*deque_pop_back(t_deque* dq)
{
	if (deque_is_empty(dq))
	{
		return (NULL);
	}

	t_deque_node	*temp;
	void		*cont;

	temp = dq->tail;
	dq->tail = temp->prev;
	if (!dq->tail)
	{
		dq->head = NULL;
	}
	else
	{
		dq->tail->next = NULL;
	}
	cont = temp->content;
	free(temp);
	dq->len--;
	return (cont);
}

void	*deque_pop_front(t_deque *dq)
{
	if (deque_is_empty(dq))
	{
		return (NULL);
	}

	t_deque_node	*temp;
	void		*cont;

	temp = dq->head;
	dq->head = temp->next;
	if (!dq->head)
	{
		dq->tail = NULL;
	}
	else
	{
		dq->head->prev = NULL;
	}
	cont = temp->content;
	free(temp);
	dq->len--;
	return (cont);
}

deque_push.c

#include "deque.h"

void	deque_push_back(t_deque *dq, void *content)
{
	t_deque_node	*node;

	node = malloc(sizeof(t_deque_node));
	if (!node)
		return ;
	node->content = content;
	node->prev = dq->tail;
	node->next = NULL;
	if (deque_is_empty(dq))
	{
		dq->head = node;
	}
	else
	{
		dq->tail->next = node;
	}
	dq->tail = node;
	dq->len++;
}

void	deque_push_front(t_deque *dq, void *content)
{
	t_deque_node	*node;

	node = malloc(sizeof(t_deque_node));
	if (!node)
		return ;
	node->content = content;
	node->next = dq->head;
	node->prev = NULL;
	if (deque_is_empty(dq))
	{
		dq->tail = node;
	}
	else
	{
		dq->head->prev = node;
	}
	dq->head = node;
	dq->len++;
}

deque_util.c

#include "deque.h"

t_deque	*deque_init(void)
{
	t_deque	*dq;

	dq = malloc(sizeof(t_deque));
	if (!dq)
		return (NULL);
	dq->head = NULL;
	dq->tail = NULL;
	dq->len = 0;
	return (dq);
}

int	deque_is_empty(t_deque *dq)
{
	return (!dq->head || !dq->tail);
}

int	deque_len(t_deque *dq)
{
	return (dq->len);
}

///	need alt_printf

void	deque_print(t_deque *dq)
{
	t_deque_node	*node;

	node = dq->head;
	while (node)
	{
		printf("%d ", *(int*) node->content);
		node = node->next;
	}
	printf("end\n");
}

test.c

#include "deque.h"

int	main()
{
	t_deque	*e;

	e = deque_init();
	int	n1 = 2;
	deque_push_back(e, &n1);
	int	n2 = 4;
	deque_push_back(e, &n2);
	int	n3 = 8;
	deque_push_back(e, &n3);

	printf("\n");
	deque_print(e);

	printf("head: %i \n", *(int*) (e->head->content));
	printf("tail: %i \n", *(int*) (e->tail->content));
	printf("len: %i \n", e->len);
	printf("\n");

	deque_print(e);

	printf("popped: %i \n", *(int*)deque_pop_back(e));
	printf("head: %i \n", *(int*) (e->head->content));
	printf("tail: %i \n", *(int*) (e->tail->content));
	printf("len: %i \n", e->len);
	printf("\n");

	deque_print(e);

	printf("popped: %i \n", *(int*)deque_pop_back(e));
	printf("head: %i \n", *(int*) (e->head->content));
	printf("tail: %i \n", *(int*) (e->tail->content));
	printf("len: %i \n", e->len);
	printf("\n");
	
	deque_print(e);
	printf("\n");

	return (0);
}