list.h

#ifndef __LIBDS_LIST_H__
#define __LIBDS_LIST_H__

/* A C implementation of a doubly-linked list. Contains void pointer values.
   Can be used as a LIFO stack of FIFO queue. */

#define FRONT 0
#define BACK 1

struct linked_node{
	void* data;
	struct linked_node* next;
	struct linked_node* prev;
};

typedef struct linked_node* lnode_p;

struct list{
	int length;
	lnode_p first;
	lnode_p last;
	void (*destructor)(void*);
};

typedef struct list * list_p;

struct list_iter{
	lnode_p current;
	char started;
};

typedef struct list_iter * list_iter_p;

/* Create a linked_list object. This pointer is created on the heap and must be
   cleared with a call to destroy_list to avoid memory leaks */
list_p create_list();

/* Create a list_iter object for the linked_list list. The flag init can be 
   either FRONT or BACK and indicates whether to start the iterator from the first
   or last item in the list */
list_iter_p list_iterator(list_p list, char init);

/* Add an item with the given value and size to the back of the list. 
   The data is copied by value, so the original pointer must be freed if it
   was allocated on the heap. */
void list_add(list_p list, void* data, int size);

/* Gets the data stored in the first item of the list or NULL if the list is empty */
void* list_first(list_p list);
/* Gets the data stored in the last item of the list or NULL if the list is empty */
void* list_last(list_p list);
/* Returns 1 (true) if the list is empty */
int list_empty(list_p list);

/* Removes the last item in the list (LIFO order) and returns the data stored 
   there. The data returned must be freed later in order to remain memory safe. */
void* list_pop(list_p list);
/* Removes the first item in the list (FIFO order) and returns the data stored 
   there. The data return must be freed later in order to remain memory safe. */
void* list_poll(list_p list);
/* Convenience function for completely destroying an item in the list. If the end
   flag is FRONT, an item will be polled from the front of the list and its data
   freed. If the end flag is set to BACK, an item will be popped off the end of 
   the list and the data freed. */
void list_remove(list_p list, char end);

/* Completely free the data associated with the list. */
void destroy_list(list_p list);

/* Return the data held by the current item pointed to by the iterator */
void* list_current(list_iter_p list);
/* Advances the iterator to the next item in the list and returns the data 
   stored there. */
void* list_next(list_iter_p list);
/* Advances the iterator to the previous item in the list and returns the data 
   stored there. */
void* list_prev(list_iter_p list);
/* Add an item with the given value and size after the node 'before' */
void list_insert(list_p list, lnode_p before, void *data, int size);
/* Remove an arbitrary node from the list and return it's value */
void* list_pluck(list_p list, lnode_p removed);

#endif