nwrap: Fix resolving hostnames with a trailing dot.
[sfrench/samba-autobuild/.git] / lib / util / rbtree.c
1 /*
2   Red Black Trees
3   (C) 1999  Andrea Arcangeli <andrea@suse.de>
4   (C) 2002  David Woodhouse <dwmw2@infradead.org>
5   
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 2 of the License, or
9   (at your option) any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; if not, write to the Free Software
18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19
20   linux/lib/rbtree.c
21 */
22
23 #include "includes.h"
24 #include "rbtree.h"
25
26 #define RB_RED          0
27 #define RB_BLACK        1
28
29 #define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
30 #define rb_color(r)   ((r)->rb_parent_color & 1)
31 #define rb_is_red(r)   (!rb_color(r))
32 #define rb_is_black(r) rb_color(r)
33 #define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
34 #define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
35
36 static void rb_set_parent(struct rb_node *rb, struct rb_node *p)
37 {
38         rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
39 }
40 static void rb_set_color(struct rb_node *rb, int color)
41 {
42         rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
43 }
44
45 #define RB_EMPTY_ROOT(root)     ((root)->rb_node == NULL)
46 #define RB_EMPTY_NODE(node)     (rb_parent(node) == node)
47 #define RB_CLEAR_NODE(node)     (rb_set_parent(node, node))
48
49 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
50 {
51         struct rb_node *right = node->rb_right;
52         struct rb_node *parent = rb_parent(node);
53
54         if ((node->rb_right = right->rb_left))
55                 rb_set_parent(right->rb_left, node);
56         right->rb_left = node;
57
58         rb_set_parent(right, parent);
59
60         if (parent)
61         {
62                 if (node == parent->rb_left)
63                         parent->rb_left = right;
64                 else
65                         parent->rb_right = right;
66         }
67         else
68                 root->rb_node = right;
69         rb_set_parent(node, right);
70 }
71
72 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
73 {
74         struct rb_node *left = node->rb_left;
75         struct rb_node *parent = rb_parent(node);
76
77         if ((node->rb_left = left->rb_right))
78                 rb_set_parent(left->rb_right, node);
79         left->rb_right = node;
80
81         rb_set_parent(left, parent);
82
83         if (parent)
84         {
85                 if (node == parent->rb_right)
86                         parent->rb_right = left;
87                 else
88                         parent->rb_left = left;
89         }
90         else
91                 root->rb_node = left;
92         rb_set_parent(node, left);
93 }
94
95 void rb_insert_color(struct rb_node *node, struct rb_root *root)
96 {
97         struct rb_node *parent, *gparent;
98
99         while ((parent = rb_parent(node)) && rb_is_red(parent))
100         {
101                 gparent = rb_parent(parent);
102
103                 if (parent == gparent->rb_left)
104                 {
105                         {
106                                 register struct rb_node *uncle = gparent->rb_right;
107                                 if (uncle && rb_is_red(uncle))
108                                 {
109                                         rb_set_black(uncle);
110                                         rb_set_black(parent);
111                                         rb_set_red(gparent);
112                                         node = gparent;
113                                         continue;
114                                 }
115                         }
116
117                         if (parent->rb_right == node)
118                         {
119                                 register struct rb_node *tmp;
120                                 __rb_rotate_left(parent, root);
121                                 tmp = parent;
122                                 parent = node;
123                                 node = tmp;
124                         }
125
126                         rb_set_black(parent);
127                         rb_set_red(gparent);
128                         __rb_rotate_right(gparent, root);
129                 } else {
130                         {
131                                 register struct rb_node *uncle = gparent->rb_left;
132                                 if (uncle && rb_is_red(uncle))
133                                 {
134                                         rb_set_black(uncle);
135                                         rb_set_black(parent);
136                                         rb_set_red(gparent);
137                                         node = gparent;
138                                         continue;
139                                 }
140                         }
141
142                         if (parent->rb_left == node)
143                         {
144                                 register struct rb_node *tmp;
145                                 __rb_rotate_right(parent, root);
146                                 tmp = parent;
147                                 parent = node;
148                                 node = tmp;
149                         }
150
151                         rb_set_black(parent);
152                         rb_set_red(gparent);
153                         __rb_rotate_left(gparent, root);
154                 }
155         }
156
157         rb_set_black(root->rb_node);
158 }
159
160 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
161                              struct rb_root *root)
162 {
163         struct rb_node *other;
164
165         while ((!node || rb_is_black(node)) && node != root->rb_node)
166         {
167                 if (parent->rb_left == node)
168                 {
169                         other = parent->rb_right;
170                         if (rb_is_red(other))
171                         {
172                                 rb_set_black(other);
173                                 rb_set_red(parent);
174                                 __rb_rotate_left(parent, root);
175                                 other = parent->rb_right;
176                         }
177                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
178                             (!other->rb_right || rb_is_black(other->rb_right)))
179                         {
180                                 rb_set_red(other);
181                                 node = parent;
182                                 parent = rb_parent(node);
183                         }
184                         else
185                         {
186                                 if (!other->rb_right || rb_is_black(other->rb_right))
187                                 {
188                                         struct rb_node *o_left;
189                                         if ((o_left = other->rb_left))
190                                                 rb_set_black(o_left);
191                                         rb_set_red(other);
192                                         __rb_rotate_right(other, root);
193                                         other = parent->rb_right;
194                                 }
195                                 rb_set_color(other, rb_color(parent));
196                                 rb_set_black(parent);
197                                 if (other->rb_right)
198                                         rb_set_black(other->rb_right);
199                                 __rb_rotate_left(parent, root);
200                                 node = root->rb_node;
201                                 break;
202                         }
203                 }
204                 else
205                 {
206                         other = parent->rb_left;
207                         if (rb_is_red(other))
208                         {
209                                 rb_set_black(other);
210                                 rb_set_red(parent);
211                                 __rb_rotate_right(parent, root);
212                                 other = parent->rb_left;
213                         }
214                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
215                             (!other->rb_right || rb_is_black(other->rb_right)))
216                         {
217                                 rb_set_red(other);
218                                 node = parent;
219                                 parent = rb_parent(node);
220                         }
221                         else
222                         {
223                                 if (!other->rb_left || rb_is_black(other->rb_left))
224                                 {
225                                         register struct rb_node *o_right;
226                                         if ((o_right = other->rb_right))
227                                                 rb_set_black(o_right);
228                                         rb_set_red(other);
229                                         __rb_rotate_left(other, root);
230                                         other = parent->rb_left;
231                                 }
232                                 rb_set_color(other, rb_color(parent));
233                                 rb_set_black(parent);
234                                 if (other->rb_left)
235                                         rb_set_black(other->rb_left);
236                                 __rb_rotate_right(parent, root);
237                                 node = root->rb_node;
238                                 break;
239                         }
240                 }
241         }
242         if (node)
243                 rb_set_black(node);
244 }
245
246 void rb_erase(struct rb_node *node, struct rb_root *root)
247 {
248         struct rb_node *child, *parent;
249         int color;
250
251         if (!node->rb_left)
252                 child = node->rb_right;
253         else if (!node->rb_right)
254                 child = node->rb_left;
255         else
256         {
257                 struct rb_node *old = node, *left;
258
259                 node = node->rb_right;
260                 while ((left = node->rb_left) != NULL)
261                         node = left;
262                 child = node->rb_right;
263                 parent = rb_parent(node);
264                 color = rb_color(node);
265
266                 if (child)
267                         rb_set_parent(child, parent);
268                 if (parent == old) {
269                         parent->rb_right = child;
270                         parent = node;
271                 } else
272                         parent->rb_left = child;
273
274                 node->rb_parent_color = old->rb_parent_color;
275                 node->rb_right = old->rb_right;
276                 node->rb_left = old->rb_left;
277
278                 if (rb_parent(old))
279                 {
280                         if (rb_parent(old)->rb_left == old)
281                                 rb_parent(old)->rb_left = node;
282                         else
283                                 rb_parent(old)->rb_right = node;
284                 } else
285                         root->rb_node = node;
286
287                 rb_set_parent(old->rb_left, node);
288                 if (old->rb_right)
289                         rb_set_parent(old->rb_right, node);
290                 goto color;
291         }
292
293         parent = rb_parent(node);
294         color = rb_color(node);
295
296         if (child)
297                 rb_set_parent(child, parent);
298         if (parent)
299         {
300                 if (parent->rb_left == node)
301                         parent->rb_left = child;
302                 else
303                         parent->rb_right = child;
304         }
305         else
306                 root->rb_node = child;
307
308  color:
309         if (color == RB_BLACK)
310                 __rb_erase_color(child, parent, root);
311 }
312
313 /*
314  * This function returns the first node (in sort order) of the tree.
315  */
316 struct rb_node *rb_first(struct rb_root *root)
317 {
318         struct rb_node  *n;
319
320         n = root->rb_node;
321         if (!n)
322                 return NULL;
323         while (n->rb_left)
324                 n = n->rb_left;
325         return n;
326 }
327
328 struct rb_node *rb_last(struct rb_root *root)
329 {
330         struct rb_node  *n;
331
332         n = root->rb_node;
333         if (!n)
334                 return NULL;
335         while (n->rb_right)
336                 n = n->rb_right;
337         return n;
338 }
339
340 struct rb_node *rb_next(struct rb_node *node)
341 {
342         struct rb_node *parent;
343
344         if (rb_parent(node) == node)
345                 return NULL;
346
347         /* If we have a right-hand child, go down and then left as far
348            as we can. */
349         if (node->rb_right) {
350                 node = node->rb_right; 
351                 while (node->rb_left)
352                         node=node->rb_left;
353                 return node;
354         }
355
356         /* No right-hand children.  Everything down and left is
357            smaller than us, so any 'next' node must be in the general
358            direction of our parent. Go up the tree; any time the
359            ancestor is a right-hand child of its parent, keep going
360            up. First time it's a left-hand child of its parent, said
361            parent is our 'next' node. */
362         while ((parent = rb_parent(node)) && node == parent->rb_right)
363                 node = parent;
364
365         return parent;
366 }
367
368 struct rb_node *rb_prev(struct rb_node *node)
369 {
370         struct rb_node *parent;
371
372         if (rb_parent(node) == node)
373                 return NULL;
374
375         /* If we have a left-hand child, go down and then right as far
376            as we can. */
377         if (node->rb_left) {
378                 node = node->rb_left; 
379                 while (node->rb_right)
380                         node=node->rb_right;
381                 return node;
382         }
383
384         /* No left-hand children. Go up till we find an ancestor which
385            is a right-hand child of its parent */
386         while ((parent = rb_parent(node)) && node == parent->rb_left)
387                 node = parent;
388
389         return parent;
390 }
391
392 void rb_replace_node(struct rb_node *victim, struct rb_node *new_node,
393                      struct rb_root *root)
394 {
395         struct rb_node *parent = rb_parent(victim);
396
397         /* Set the surrounding nodes to point to the replacement */
398         if (parent) {
399                 if (victim == parent->rb_left)
400                         parent->rb_left = new_node;
401                 else
402                         parent->rb_right = new_node;
403         } else {
404                 root->rb_node = new_node;
405         }
406         if (victim->rb_left)
407                 rb_set_parent(victim->rb_left, new_node);
408         if (victim->rb_right)
409                 rb_set_parent(victim->rb_right, new_node);
410
411         /* Copy the pointers/colour from the victim to the replacement */
412         *new_node = *victim;
413 }
414
415 void rb_link_node(struct rb_node * node, struct rb_node * parent,
416                   struct rb_node ** rb_link)
417 {
418         node->rb_parent_color = (unsigned long )parent;
419         node->rb_left = node->rb_right = NULL;
420
421         *rb_link = node;
422 }