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#include "c.h"
static List freenodes; /* free list nodes */
/* append - append x to list, return new list */
List append(void *x, List list) {
List new;
if ((new = freenodes) != NULL)
freenodes = freenodes->link;
else
NEW(new, PERM);
if (list) {
new->link = list->link;
list->link = new;
} else
new->link = new;
new->x = x;
return new;
}
/* length - # elements in list */
int length(List list) {
int n = 0;
if (list) {
List lp = list;
do
n++;
while ((lp = lp->link) != list);
}
return n;
}
/* ltov - convert list to an NULL-terminated vector allocated in arena */
void *ltov(List *list, unsigned arena) {
int i = 0;
void **array = newarray(length(*list) + 1, sizeof array[0], arena);
if (*list) {
List lp = *list;
do {
lp = lp->link;
array[i++] = lp->x;
} while (lp != *list);
#ifndef PURIFY
lp = (*list)->link;
(*list)->link = freenodes;
freenodes = lp;
#endif
}
*list = NULL;
array[i] = NULL;
return array;
}
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