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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
73 struct exec_node
*next
;
74 struct exec_node
*prev
;
77 exec_node() : next(NULL
), prev(NULL
)
82 const exec_node
*get_next() const
92 const exec_node
*get_prev() const
111 * Link a node with itself
113 * This creates a sort of degenerate list that is occasionally useful.
122 * Insert a node in the list after the current node
124 void insert_after(exec_node
*after
)
126 after
->next
= this->next
;
129 this->next
->prev
= after
;
133 * Insert a node in the list before the current node
135 void insert_before(exec_node
*before
)
138 before
->prev
= this->prev
;
140 this->prev
->next
= before
;
148 /* This macro will not work correctly if `t' uses virtual inheritance. If you
149 * are using virtual inheritance, you deserve a slow and painful death. Enjoy!
151 #define exec_list_offsetof(t, f, p) \
152 (((char *) &((t *) p)->f) - ((char *) p))
154 #define exec_list_offsetof(t, f, p) offsetof(t, f)
158 * Get a pointer to the structure containing an exec_node
160 * Given a pointer to an \c exec_node embedded in a structure, get a pointer to
161 * the containing structure.
163 * \param type Base type of the structure containing the node
164 * \param node Pointer to the \c exec_node
165 * \param field Name of the field in \c type that is the embedded \c exec_node
167 #define exec_node_data(type, node, field) \
168 ((type *) (((char *) node) - exec_list_offsetof(type, field, node)))
184 bool has_next() const
190 class exec_list_iterator
: public iterator
{
192 exec_list_iterator(exec_node
*n
) : node(n
), _next(n
->next
)
213 bool has_next() const
215 return _next
!= NULL
;
223 #define foreach_iter(iter_type, iter, container) \
224 for (iter_type iter = (container) . iterator(); iter.has_next(); iter.next())
229 struct exec_node
*head
;
230 struct exec_node
*tail
;
231 struct exec_node
*tail_pred
;
241 head
= (exec_node
*) & tail
;
243 tail_pred
= (exec_node
*) & head
;
246 bool is_empty() const
248 /* There are three ways to test whether a list is empty or not.
250 * - Check to see if the \c head points to the \c tail.
251 * - Check to see if the \c tail_pred points to the \c head.
252 * - Check to see if the \c head is the sentinal node by test whether its
253 * \c next pointer is \c NULL.
255 * The first two methods tend to generate better code on modern systems
256 * because they save a pointer dereference.
258 return head
== (exec_node
*) &tail
;
261 const exec_node
*get_head() const
263 return !is_empty() ? head
: NULL
;
266 exec_node
*get_head()
268 return !is_empty() ? head
: NULL
;
271 const exec_node
*get_tail() const
273 return !is_empty() ? tail_pred
: NULL
;
276 exec_node
*get_tail()
278 return !is_empty() ? tail_pred
: NULL
;
281 void push_head(exec_node
*n
)
284 n
->prev
= (exec_node
*) &head
;
290 void push_tail(exec_node
*n
)
292 n
->next
= (exec_node
*) &tail
;
299 void push_degenerate_list_at_head(exec_node
*n
)
301 assert(n
->prev
->next
== n
);
303 n
->prev
->next
= head
;
304 head
->prev
= n
->prev
;
305 n
->prev
= (exec_node
*) &head
;
310 * Move all of the nodes from this list to the target list
312 void move_nodes_to(exec_list
*target
)
315 target
->make_empty();
319 target
->tail_pred
= tail_pred
;
321 target
->head
->prev
= (exec_node
*) &target
->head
;
322 target
->tail_pred
->next
= (exec_node
*) &target
->tail
;
328 exec_list_iterator
iterator()
330 return exec_list_iterator(head
);
333 exec_list_iterator
iterator() const
335 return exec_list_iterator((exec_node
*) head
);
340 #define foreach_list(__node, __list) \
341 for (exec_node * __node = (__list)->head \
342 ; (__node)->next != NULL \
343 ; (__node) = (__node)->next)
345 #define foreach_list_const(__node, __list) \
346 for (const exec_node * __node = (__list)->head \
347 ; (__node)->next != NULL \
348 ; (__node) = (__node)->next)
350 #endif /* LIST_CONTAINER_H */