LXR toybox/lib/llist.c

   1/* llist.c - Linked list functions
   2 *
   3 * Linked list structures have a next pointer as their first element.
   4 */
   5
   6#include "toys.h"
   7
   8// Callback function to free data pointer of double_list or arg_list
   9
  10void llist_free_arg(void *node)
  11{
  12  struct arg_list *d = node;
  13
  14  free(d->arg);
  15  free(d);
  16}
  17
  18void llist_free_double(void *node)
  19{
  20  struct double_list *d = node;
  21
  22  free(d->data);
  23  free(d);
  24}
  25
  26// Call a function (such as free()) on each element of a linked list.
  27void llist_traverse(void *list, void (*using)(void *node))
  28{
  29  void *old = list;
  30
  31  while (list) {
  32    void *pop = llist_pop(&list);
  33    using(pop);
  34
  35    // End doubly linked list too.
  36    if (old == list) break;
  37  }
  38}
  39
  40// Return the first item from the list, advancing the list (which must be called
  41// as &list)
  42void *llist_pop(void *list)
  43{
  44  void **llist = list, **next;
  45
  46  if (!list || !*llist) return 0;
  47  next = (void **)*llist;
  48  *llist = *next;
  49
  50  return next;
  51}
  52
  53// Remove first item from &list and return it
  54void *dlist_pop(void *list)
  55{
  56  struct double_list **pdlist = (struct double_list **)list, *dlist = *pdlist;
  57
  58  if (!dlist) return 0;
  59  if (dlist->next == dlist) *pdlist = 0;
  60  else {
  61    if (dlist->next) dlist->next->prev = dlist->prev;
  62    if (dlist->prev) dlist->prev->next = dlist->next;
  63    *pdlist = dlist->next;
  64  }
  65
  66  return dlist;
  67}
  68
  69// remove last item from &list and return it (stack pop)
  70void *dlist_lpop(void *list)
  71{
  72  struct double_list *dl = *(struct double_list **)list;
  73  void *v = 0;
  74
  75  if (dl) {
  76    dl = dl->prev;
  77    v = dlist_pop(&dl);
  78    if (!dl) *(void **)list = 0;
  79  }
  80
  81  return v;
  82}
  83
  84// Append to list in-order (*list unchanged unless empty, ->prev is new node)
  85void dlist_add_nomalloc(struct double_list **list, struct double_list *new)
  86{
  87  if (*list) {
  88    new->next = *list;
  89    new->prev = (*list)->prev;
  90    (*list)->prev->next = new;
  91    (*list)->prev = new;
  92  } else *list = new->next = new->prev = new;
  93}
  94
  95// Add an entry to the end of a doubly linked list
  96struct double_list *dlist_add(struct double_list **list, char *data)
  97{
  98  struct double_list *new = xmalloc(sizeof(struct double_list));
  99
 100  new->data = data;
 101  dlist_add_nomalloc(list, new);
 102
 103  return new;
 104}
 105
 106// Terminate circular list for traversal in either direction. Returns end *.
 107void *dlist_terminate(void *list)
 108{
 109  struct double_list *end = list;
 110
 111  if (!end || !end->prev) return 0;
 112
 113  end = end->prev;
 114  end->next->prev = 0;
 115  end->next = 0;
 116
 117  return end;
 118}
 119
 120// Find num in cache
 121struct num_cache *get_num_cache(struct num_cache *cache, long long num)
 122{
 123  while (cache) {
 124    if (num==cache->num) return cache;
 125    cache = cache->next;
 126  }
 127
 128  return 0;
 129}
 130
 131// Uniquely add num+data to cache. Updates *cache, returns pointer to existing
 132// entry if it was already there.
 133struct num_cache *add_num_cache(struct num_cache **cache, long long num,
 134  void *data, int len)
 135{
 136  struct num_cache *old = get_num_cache(*cache, num);
 137
 138  if (old) return old;
 139
 140  old = xzalloc(sizeof(struct num_cache)+len);
 141  old->next = *cache;
 142  old->num = num;
 143  memcpy(old->data, data, len);
 144  *cache = old;
 145
 146  return 0;
 147}
 148