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/* 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;
}
// Terminate circular list for traversal in either direction. Returns end *.
void *dlist_terminate(void *list)
{
struct double_list *end = list;
if (!list) return 0;
end = end->prev;
end->next->prev = 0;
end->next = 0;
return end;
}
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