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26 * \brief Doubly-linked list abstract container type.
28 * Each doubly-linked list has a sentinal head and tail node. These nodes
29 * contain no data. The head sentinal can be identified by its \c prev
30 * pointer being \c NULL. The tail sentinal can be identified by its
31 * \c next pointer being \c NULL.
33 * A list is empty if either the head sentinal's \c next pointer points to the
34 * tail sentinal or the tail sentinal's \c prev poiner points to the head
37 * Instead of tracking two separate \c node structures and a \c list structure
38 * that points to them, the sentinal nodes are in a single structure. Noting
39 * that each sentinal node always has one \c NULL pointer, the \c NULL
40 * pointers occupy the same memory location. In the \c list structure
41 * contains a the following:
43 * - A \c head pointer that represents the \c next pointer of the
45 * - A \c tail pointer that represents the \c prev pointer of the head
46 * sentinal node and the \c next pointer of the tail sentinal node. This
47 * pointer is \b always \c NULL.
48 * - A \c tail_prev pointer that represents the \c prev pointer of the
51 * Therefore, if \c head->next is \c NULL or \c tail_prev->prev is \c NULL,
54 * To anyone familiar with "exec lists" on the Amiga, this structure should
55 * be immediately recognizable. See the following link for the original Amiga
56 * operating system documentation on the subject.
58 * http://www.natami.net/dev/Libraries_Manual_guide/node02D7.html
60 * \author Ian Romanick <ian.d.romanick@intel.com>
64 #ifndef LIST_CONTAINER_H
65 #define LIST_CONTAINER_H
79 struct exec_node
*next
;
80 struct exec_node
*prev
;
83 /* Callers of this talloc-based new need not call delete. It's
84 * easier to just talloc_free 'ctx' (or any of its ancestors). */
85 static void* operator new(size_t size
, void *ctx
)
89 node
= talloc_size(ctx
, size
);
95 /* If the user *does* call delete, that's OK, we will just
96 * talloc_free in that case. */
97 static void operator delete(void *node
)
102 exec_node() : next(NULL
), prev(NULL
)
107 const exec_node
*get_next() const
112 exec_node
*get_next()
117 const exec_node
*get_prev() const
122 exec_node
*get_prev()
136 * Link a node with itself
138 * This creates a sort of degenerate list that is occasionally useful.
147 * Insert a node in the list after the current node
149 void insert_after(exec_node
*after
)
151 after
->next
= this->next
;
154 this->next
->prev
= after
;
158 * Insert a node in the list before the current node
160 void insert_before(exec_node
*before
)
163 before
->prev
= this->prev
;
165 this->prev
->next
= before
;
170 * Is this the sentinal at the tail of the list?
172 bool is_tail_sentinal() const
174 return this->next
== NULL
;
178 * Is this the sentinal at the head of the list?
180 bool is_head_sentinal() const
182 return this->prev
== NULL
;
189 /* This macro will not work correctly if `t' uses virtual inheritance. If you
190 * are using virtual inheritance, you deserve a slow and painful death. Enjoy!
192 #define exec_list_offsetof(t, f, p) \
193 (((char *) &((t *) p)->f) - ((char *) p))
195 #define exec_list_offsetof(t, f, p) offsetof(t, f)
199 * Get a pointer to the structure containing an exec_node
201 * Given a pointer to an \c exec_node embedded in a structure, get a pointer to
202 * the containing structure.
204 * \param type Base type of the structure containing the node
205 * \param node Pointer to the \c exec_node
206 * \param field Name of the field in \c type that is the embedded \c exec_node
208 #define exec_node_data(type, node, field) \
209 ((type *) (((char *) node) - exec_list_offsetof(type, field, node)))
225 bool has_next() const
231 class exec_list_iterator
: public iterator
{
233 exec_list_iterator(exec_node
*n
) : node(n
), _next(n
->next
)
254 bool has_next() const
256 return _next
!= NULL
;
264 #define foreach_iter(iter_type, iter, container) \
265 for (iter_type iter = (container) . iterator(); iter.has_next(); iter.next())
270 struct exec_node
*head
;
271 struct exec_node
*tail
;
272 struct exec_node
*tail_pred
;
282 head
= (exec_node
*) & tail
;
284 tail_pred
= (exec_node
*) & head
;
287 bool is_empty() const
289 /* There are three ways to test whether a list is empty or not.
291 * - Check to see if the \c head points to the \c tail.
292 * - Check to see if the \c tail_pred points to the \c head.
293 * - Check to see if the \c head is the sentinal node by test whether its
294 * \c next pointer is \c NULL.
296 * The first two methods tend to generate better code on modern systems
297 * because they save a pointer dereference.
299 return head
== (exec_node
*) &tail
;
302 const exec_node
*get_head() const
304 return !is_empty() ? head
: NULL
;
307 exec_node
*get_head()
309 return !is_empty() ? head
: NULL
;
312 const exec_node
*get_tail() const
314 return !is_empty() ? tail_pred
: NULL
;
317 exec_node
*get_tail()
319 return !is_empty() ? tail_pred
: NULL
;
322 void push_head(exec_node
*n
)
325 n
->prev
= (exec_node
*) &head
;
331 void push_tail(exec_node
*n
)
333 n
->next
= (exec_node
*) &tail
;
340 void push_degenerate_list_at_head(exec_node
*n
)
342 assert(n
->prev
->next
== n
);
344 n
->prev
->next
= head
;
345 head
->prev
= n
->prev
;
346 n
->prev
= (exec_node
*) &head
;
351 * Move all of the nodes from this list to the target list
353 void move_nodes_to(exec_list
*target
)
356 target
->make_empty();
360 target
->tail_pred
= tail_pred
;
362 target
->head
->prev
= (exec_node
*) &target
->head
;
363 target
->tail_pred
->next
= (exec_node
*) &target
->tail
;
369 exec_list_iterator
iterator()
371 return exec_list_iterator(head
);
374 exec_list_iterator
iterator() const
376 return exec_list_iterator((exec_node
*) head
);
381 #define foreach_list(__node, __list) \
382 for (exec_node * __node = (__list)->head \
383 ; (__node)->next != NULL \
384 ; (__node) = (__node)->next)
386 #define foreach_list_const(__node, __list) \
387 for (const exec_node * __node = (__list)->head \
388 ; (__node)->next != NULL \
389 ; (__node) = (__node)->next)
391 #define foreach_list_typed(__type, __node, __field, __list) \
392 for (__type * __node = \
393 exec_node_data(__type, (__list)->head, __field); \
394 (__node)->__field.next != NULL; \
395 (__node) = exec_node_data(__type, (__node)->__field.next, __field))
397 #define foreach_list_typed_const(__type, __node, __field, __list) \
398 for (const __type * __node = \
399 exec_node_data(__type, (__list)->head, __field); \
400 (__node)->__field.next != NULL; \
401 (__node) = exec_node_data(__type, (__node)->__field.next, __field))
403 #endif /* LIST_CONTAINER_H */