| /* llist.c - Linked list functions |
| * |
| * Linked list structures have a next pointer as their first element. |
| */ |
| |
| #include "toys.h" |
| |
| // Callback function to free data pointer of double_list or arg_list |
| |
| void llist_free_arg(void *node) |
| { |
| struct arg_list *d = node; |
| |
| free(d->arg); |
| free(d); |
| } |
| |
| void llist_free_double(void *node) |
| { |
| struct double_list *d = node; |
| |
| free(d->data); |
| free(d); |
| } |
| |
| // Call a function (such as free()) on each element of a linked list. |
| void llist_traverse(void *list, void (*using)(void *node)) |
| { |
| void *old = list; |
| |
| while (list) { |
| void *pop = llist_pop(&list); |
| using(pop); |
| |
| // End doubly linked list too. |
| if (old == list) break; |
| } |
| } |
| |
| // Return the first item from the list, advancing the list (which must be called |
| // as &list) |
| void *llist_pop(void *list) |
| { |
| // I'd use a void ** for the argument, and even accept the typecast in all |
| // callers as documentation you need the &, except the stupid compiler |
| // would then scream about type-punned pointers. Screw it. |
| void **llist = (void **)list; |
| void **next = (void **)*llist; |
| *llist = *next; |
| |
| return (void *)next; |
| } |
| |
| void *dlist_pop(void *list) |
| { |
| struct double_list **pdlist = (struct double_list **)list, *dlist = *pdlist; |
| |
| if (dlist->next == dlist) *pdlist = 0; |
| else { |
| dlist->next->prev = dlist->prev; |
| dlist->prev->next = *pdlist = dlist->next; |
| } |
| |
| return dlist; |
| } |
| |
| void dlist_add_nomalloc(struct double_list **list, struct double_list *new) |
| { |
| if (*list) { |
| new->next = *list; |
| new->prev = (*list)->prev; |
| (*list)->prev->next = new; |
| (*list)->prev = new; |
| } else *list = new->next = new->prev = new; |
| } |
| |
| |
| // Add an entry to the end of a doubly linked list |
| struct double_list *dlist_add(struct double_list **list, char *data) |
| { |
| struct double_list *new = xmalloc(sizeof(struct double_list)); |
| |
| new->data = data; |
| dlist_add_nomalloc(list, new); |
| |
| return new; |
| } |