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26 * \brief Doubly-linked list abstract container type.
28 * Each doubly-linked list has a sentinel head and tail node. These nodes
29 * contain no data. The head sentinel can be identified by its \c prev
30 * pointer being \c NULL. The tail sentinel can be identified by its
31 * \c next pointer being \c NULL.
33 * A list is empty if either the head sentinel's \c next pointer points to the
34 * tail sentinel or the tail sentinel'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 sentinel nodes are in a single structure. Noting
39 * that each sentinel 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 * sentinel node and the \c next pointer of the tail sentinel 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
75 struct exec_node *next;
76 struct exec_node *prev;
79 /* Callers of this ralloc-based new need not call delete. It's
80 * easier to just ralloc_free 'ctx' (or any of its ancestors). */
81 static void* operator new(size_t size, void *ctx)
85 node = ralloc_size(ctx, size);
91 /* If the user *does* call delete, that's OK, we will just
92 * ralloc_free in that case. */
93 static void operator delete(void *node)
98 exec_node() : next(NULL), prev(NULL)
103 const exec_node *get_next() const
108 exec_node *get_next()
113 const exec_node *get_prev() const
118 exec_node *get_prev()
132 * Link a node with itself
134 * This creates a sort of degenerate list that is occasionally useful.
143 * Insert a node in the list after the current node
145 void insert_after(exec_node *after)
147 after->next = this->next;
150 this->next->prev = after;
154 * Insert a node in the list before the current node
156 void insert_before(exec_node *before)
159 before->prev = this->prev;
161 this->prev->next = before;
166 * Insert another list in the list before the current node
168 void insert_before(struct exec_list *before);
171 * Replace the current node with the given node.
173 void replace_with(exec_node *replacement)
175 replacement->prev = this->prev;
176 replacement->next = this->next;
178 this->prev->next = replacement;
179 this->next->prev = replacement;
183 * Is this the sentinel at the tail of the list?
185 bool is_tail_sentinel() const
187 return this->next == NULL;
191 * Is this the sentinel at the head of the list?
193 bool is_head_sentinel() const
195 return this->prev == NULL;
202 /* This macro will not work correctly if `t' uses virtual inheritance. If you
203 * are using virtual inheritance, you deserve a slow and painful death. Enjoy!
205 #define exec_list_offsetof(t, f, p) \
206 (((char *) &((t *) p)->f) - ((char *) p))
208 #define exec_list_offsetof(t, f, p) offsetof(t, f)
212 * Get a pointer to the structure containing an exec_node
214 * Given a pointer to an \c exec_node embedded in a structure, get a pointer to
215 * the containing structure.
217 * \param type Base type of the structure containing the node
218 * \param node Pointer to the \c exec_node
219 * \param field Name of the field in \c type that is the embedded \c exec_node
221 #define exec_node_data(type, node, field) \
222 ((type *) (((char *) node) - exec_list_offsetof(type, field, node)))
238 bool has_next() const
244 class exec_list_iterator : public iterator {
246 exec_list_iterator(exec_node *n) : node(n), _next(n->next)
267 bool has_next() const
269 return _next != NULL;
277 #define foreach_iter(iter_type, iter, container) \
278 for (iter_type iter = (container) . iterator(); iter.has_next(); iter.next())
283 struct exec_node *head;
284 struct exec_node *tail;
285 struct exec_node *tail_pred;
288 /* Callers of this ralloc-based new need not call delete. It's
289 * easier to just ralloc_free 'ctx' (or any of its ancestors). */
290 static void* operator new(size_t size, void *ctx)
294 node = ralloc_size(ctx, size);
295 assert(node != NULL);
300 /* If the user *does* call delete, that's OK, we will just
301 * ralloc_free in that case. */
302 static void operator delete(void *node)
314 head = (exec_node *) & tail;
316 tail_pred = (exec_node *) & head;
319 bool is_empty() const
321 /* There are three ways to test whether a list is empty or not.
323 * - Check to see if the \c head points to the \c tail.
324 * - Check to see if the \c tail_pred points to the \c head.
325 * - Check to see if the \c head is the sentinel node by test whether its
326 * \c next pointer is \c NULL.
328 * The first two methods tend to generate better code on modern systems
329 * because they save a pointer dereference.
331 return head == (exec_node *) &tail;
334 const exec_node *get_head() const
336 return !is_empty() ? head : NULL;
339 exec_node *get_head()
341 return !is_empty() ? head : NULL;
344 const exec_node *get_tail() const
346 return !is_empty() ? tail_pred : NULL;
349 exec_node *get_tail()
351 return !is_empty() ? tail_pred : NULL;
354 void push_head(exec_node *n)
357 n->prev = (exec_node *) &head;
363 void push_tail(exec_node *n)
365 n->next = (exec_node *) &tail;
372 void push_degenerate_list_at_head(exec_node *n)
374 assert(n->prev->next == n);
376 n->prev->next = head;
377 head->prev = n->prev;
378 n->prev = (exec_node *) &head;
383 * Remove the first node from a list and return it
386 * The first node in the list or \c NULL if the list is empty.
388 * \sa exec_list::get_head
390 exec_node *pop_head()
392 exec_node *const n = this->get_head();
400 * Move all of the nodes from this list to the target list
402 void move_nodes_to(exec_list *target)
405 target->make_empty();
409 target->tail_pred = tail_pred;
411 target->head->prev = (exec_node *) &target->head;
412 target->tail_pred->next = (exec_node *) &target->tail;
419 * Append all nodes from the source list to the target list
422 append_list(exec_list *source)
424 if (source->is_empty())
427 /* Link the first node of the source with the last node of the target list.
429 this->tail_pred->next = source->head;
430 source->head->prev = this->tail_pred;
432 /* Make the tail of the source list be the tail of the target list.
434 this->tail_pred = source->tail_pred;
435 this->tail_pred->next = (exec_node *) &this->tail;
437 /* Make the source list empty for good measure.
439 source->make_empty();
442 exec_list_iterator iterator()
444 return exec_list_iterator(head);
447 exec_list_iterator iterator() const
449 return exec_list_iterator((exec_node *) head);
456 inline void exec_node::insert_before(exec_list *before)
458 if (before->is_empty())
461 before->tail_pred->next = this;
462 before->head->prev = this->prev;
464 this->prev->next = before->head;
465 this->prev = before->tail_pred;
467 before->make_empty();
472 * This version is safe even if the current node is removed.
474 #define foreach_list_safe(__node, __list) \
475 for (exec_node * __node = (__list)->head, * __next = __node->next \
477 ; __node = __next, __next = __next->next)
479 #define foreach_list(__node, __list) \
480 for (exec_node * __node = (__list)->head \
481 ; (__node)->next != NULL \
482 ; (__node) = (__node)->next)
484 #define foreach_list_const(__node, __list) \
485 for (const exec_node * __node = (__list)->head \
486 ; (__node)->next != NULL \
487 ; (__node) = (__node)->next)
489 #define foreach_list_typed(__type, __node, __field, __list) \
490 for (__type * __node = \
491 exec_node_data(__type, (__list)->head, __field); \
492 (__node)->__field.next != NULL; \
493 (__node) = exec_node_data(__type, (__node)->__field.next, __field))
495 #define foreach_list_typed_const(__type, __node, __field, __list) \
496 for (const __type * __node = \
497 exec_node_data(__type, (__list)->head, __field); \
498 (__node)->__field.next != NULL; \
499 (__node) = exec_node_data(__type, (__node)->__field.next, __field))
501 #endif /* LIST_CONTAINER_H */