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      1 /* Copyright (c) 2013, Ben Noordhuis <info (at) bnoordhuis.nl>
      2  *
      3  * Permission to use, copy, modify, and/or distribute this software for any
      4  * purpose with or without fee is hereby granted, provided that the above
      5  * copyright notice and this permission notice appear in all copies.
      6  *
      7  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      8  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
      9  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
     10  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     11  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     12  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
     13  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     14  */
     15 
     16 #ifndef QUEUE_H_
     17 #define QUEUE_H_
     18 
     19 #include <stddef.h>
     20 
     21 #define uv__queue_data(pointer, type, field)                                  \
     22   ((type*) ((char*) (pointer) - offsetof(type, field)))
     23 
     24 #define uv__queue_foreach(q, h)                                               \
     25   for ((q) = (h)->next; (q) != (h); (q) = (q)->next)
     26 
     27 static inline void uv__queue_init(struct uv__queue* q) {
     28   q->next = q;
     29   q->prev = q;
     30 }
     31 
     32 static inline int uv__queue_empty(const struct uv__queue* q) {
     33   return q == q->next;
     34 }
     35 
     36 static inline struct uv__queue* uv__queue_head(const struct uv__queue* q) {
     37   return q->next;
     38 }
     39 
     40 static inline struct uv__queue* uv__queue_next(const struct uv__queue* q) {
     41   return q->next;
     42 }
     43 
     44 static inline void uv__queue_add(struct uv__queue* h, struct uv__queue* n) {
     45   h->prev->next = n->next;
     46   n->next->prev = h->prev;
     47   h->prev = n->prev;
     48   h->prev->next = h;
     49 }
     50 
     51 static inline void uv__queue_split(struct uv__queue* h,
     52                                    struct uv__queue* q,
     53                                    struct uv__queue* n) {
     54   n->prev = h->prev;
     55   n->prev->next = n;
     56   n->next = q;
     57   h->prev = q->prev;
     58   h->prev->next = h;
     59   q->prev = n;
     60 }
     61 
     62 static inline void uv__queue_move(struct uv__queue* h, struct uv__queue* n) {
     63   if (uv__queue_empty(h))
     64     uv__queue_init(n);
     65   else
     66     uv__queue_split(h, h->next, n);
     67 }
     68 
     69 static inline void uv__queue_insert_head(struct uv__queue* h,
     70                                          struct uv__queue* q) {
     71   q->next = h->next;
     72   q->prev = h;
     73   q->next->prev = q;
     74   h->next = q;
     75 }
     76 
     77 static inline void uv__queue_insert_tail(struct uv__queue* h,
     78                                          struct uv__queue* q) {
     79   q->next = h;
     80   q->prev = h->prev;
     81   q->prev->next = q;
     82   h->prev = q;
     83 }
     84 
     85 static inline void uv__queue_remove(struct uv__queue* q) {
     86   q->prev->next = q->next;
     87   q->next->prev = q->prev;
     88 }
     89 
     90 #endif /* QUEUE_H_ */
     91