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9a0882ef | 1 | // Splay tree utilities -*- C++ -*- |
a945c346 | 2 | // Copyright (C) 2020-2024 Free Software Foundation, Inc. |
9a0882ef RS |
3 | // |
4 | // This file is part of GCC. | |
5 | // | |
6 | // GCC is free software; you can redistribute it and/or modify it under | |
7 | // the terms of the GNU General Public License as published by the Free | |
8 | // Software Foundation; either version 3, or (at your option) any later | |
9 | // version. | |
10 | // | |
11 | // GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | // WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | // for more details. | |
15 | // | |
16 | // You should have received a copy of the GNU General Public License | |
17 | // along with GCC; see the file COPYING3. If not see | |
18 | // <http://www.gnu.org/licenses/>. | |
19 | ||
20 | // INDEX is either 0 or 1. If it is 0, return NODE's left child, | |
21 | // otherwise return NODE's right child. | |
22 | template<typename Accessors> | |
23 | inline typename base_splay_tree<Accessors>::node_type | |
24 | base_splay_tree<Accessors>::get_child (node_type node, unsigned int index) | |
25 | { | |
26 | return Accessors::child (node, index); | |
27 | } | |
28 | ||
29 | // INDEX is either 0 or 1. If it is 0, change NODE's left child to CHILD, | |
30 | // otherwise change NODE's right child to CHILD. If CHILD has a parent | |
31 | // field, record that its parent is now NODE. | |
32 | template<typename Accessors> | |
33 | inline void | |
34 | base_splay_tree<Accessors>::set_child (node_type node, unsigned int index, | |
35 | node_type child) | |
36 | { | |
37 | Accessors::child (node, index) = child; | |
38 | if (child) | |
39 | set_parent (child, node); | |
40 | } | |
41 | ||
42 | // Rotate the tree to promote child number INDEX of NODE, so that that | |
43 | // child becomes a parent of NODE. Return the promoted node. | |
44 | // | |
45 | // The caller has the responsibility of assigning a correct parent | |
46 | // to the returned node. | |
47 | template<typename Accessors> | |
48 | inline typename base_splay_tree<Accessors>::node_type | |
49 | base_splay_tree<Accessors>::promote_child (node_type node, unsigned int index) | |
50 | { | |
51 | node_type promoted = get_child (node, index); | |
52 | set_child (node, index, get_child (promoted, 1 - index)); | |
53 | set_child (promoted, 1 - index, node); | |
54 | return promoted; | |
55 | } | |
56 | ||
57 | // Treat child number INDEX of NODE as being CHILD and rotate the tree | |
58 | // so that CHILD becomes a parent of NODE. | |
59 | // | |
60 | // The caller has the responsibility of assigning a correct parent to CHILD. | |
61 | template<typename Accessors> | |
62 | inline void | |
63 | base_splay_tree<Accessors>::promote_child (node_type node, unsigned int index, | |
64 | node_type child) | |
65 | { | |
66 | set_child (node, index, get_child (child, 1 - index)); | |
67 | set_child (child, 1 - index, node); | |
68 | } | |
69 | ||
70 | // Print NODE to PP, using PRINTER (PP, N) to print the contents of node N. | |
71 | // Prefix each new line with INDENT_STRING. CODE is 'T' if NODE is the root | |
72 | // node, 'L' if NODE is the left child of its parent, or 'R' if NODE is the | |
73 | // right child of its parent. | |
74 | template<typename Accessors> | |
75 | template<typename Printer> | |
76 | void | |
77 | base_splay_tree<Accessors>::print (pretty_printer *pp, node_type node, | |
78 | Printer printer, char code, | |
79 | vec<char> &indent_string) | |
80 | { | |
81 | // In the comments below, PREFIX refers to the incoming contents | |
82 | // of INDENT_STRING. | |
83 | node_type left = get_child (node, 0); | |
84 | node_type right = get_child (node, 1); | |
85 | ||
86 | auto orig_indent_len = indent_string.length (); | |
87 | indent_string.safe_grow (orig_indent_len + 3); | |
88 | char *extra_indent = indent_string.address () + orig_indent_len; | |
89 | ||
90 | // Print [T], [L], or [R]. | |
91 | extra_indent[0] = '['; | |
92 | extra_indent[1] = code; | |
93 | extra_indent[2] = ']'; | |
94 | pp_append_text (pp, extra_indent, indent_string.end ()); | |
95 | pp_space (pp); | |
96 | ||
97 | // Print the node itself, using PREFIX + " | " or PREFIX + " " to indent | |
98 | // new lines under the "[_]" that we just printed. | |
99 | extra_indent[0] = ' '; | |
100 | extra_indent[1] = (left || right ? '|' : ' '); | |
101 | extra_indent[2] = ' '; | |
102 | { | |
103 | pretty_printer sub_pp; | |
104 | printer (&sub_pp, node); | |
105 | const char *text = pp_formatted_text (&sub_pp); | |
106 | while (const char *end = strchr (text, '\n')) | |
107 | { | |
108 | pp_append_text (pp, text, end); | |
109 | pp_newline_and_indent (pp, 0); | |
110 | pp_append_text (pp, indent_string.begin (), indent_string.end ()); | |
111 | text = end + 1; | |
112 | } | |
113 | pp_string (pp, text); | |
114 | } | |
115 | ||
116 | if (left) | |
117 | { | |
118 | // Print PREFIX + " +-" for the first line of the left subtree, | |
119 | // to be followed by "[L]". | |
120 | extra_indent[1] = '+'; | |
121 | extra_indent[2] = '-'; | |
122 | pp_newline_and_indent (pp, 0); | |
123 | pp_append_text (pp, indent_string.begin (), indent_string.end ()); | |
124 | ||
125 | // Print the left subtree, using PREFIX + " | " or PREFIX + " " | |
126 | // to indent under the PREFIX + " +-" that we just printed. | |
127 | extra_indent[1] = right ? '|' : ' '; | |
128 | extra_indent[2] = ' '; | |
129 | print (pp, left, printer, 'L', indent_string); | |
130 | extra_indent = indent_string.address () + orig_indent_len; | |
131 | ||
132 | // If LEFT is not a leaf and we also have a right subtree, use a | |
133 | // PREFIX + " |" line to separate them. | |
134 | if (right && (get_child (left, 0) || get_child (left, 1))) | |
135 | { | |
136 | pp_newline_and_indent (pp, 0); | |
137 | pp_append_text (pp, indent_string.begin (), &extra_indent[2]); | |
138 | } | |
139 | } | |
140 | if (right) | |
141 | { | |
142 | // Print PREFIX + " +-" for the first line of the right subtree, | |
143 | // to be followed by "[R]". | |
144 | extra_indent[1] = '+'; | |
145 | extra_indent[2] = '-'; | |
146 | pp_newline_and_indent (pp, 0); | |
147 | pp_append_text (pp, indent_string.begin (), indent_string.end ()); | |
148 | ||
149 | // Print the right subtree, using PREFIX + " " to indent under the | |
150 | // PREFIX + " +-" that we just printed. | |
151 | extra_indent[1] = ' '; | |
152 | extra_indent[2] = ' '; | |
153 | print (pp, right, printer, 'R', indent_string); | |
154 | } | |
155 | indent_string.truncate (orig_indent_len); | |
156 | } | |
157 | ||
158 | // See the comment above the declaration. | |
159 | template<typename Accessors> | |
160 | template<typename Printer> | |
161 | void | |
162 | base_splay_tree<Accessors>::print (pretty_printer *pp, node_type node, | |
163 | Printer printer) | |
164 | { | |
165 | if (!node) | |
166 | { | |
167 | pp_string (pp, "null"); | |
168 | return; | |
169 | } | |
170 | auto_vec<char, 64> indent_string; | |
171 | print (pp, node, printer, 'T', indent_string); | |
172 | } | |
173 | ||
174 | // If N is 1, splay the last (rightmost) node reachable from START | |
175 | // to the position that START current holds and return the splayed node. | |
176 | // START is not itself the last node. | |
177 | // | |
178 | // If N is 0, splay the first (leftmost) node reachable from START | |
179 | // to the position that START current holds and return the splayed node. | |
180 | // START is not itself the first node. | |
181 | // | |
182 | // The caller has the responsibility of updating the parent of the | |
183 | // returned node. | |
184 | template<typename Accessors> | |
185 | template<unsigned int N> | |
186 | typename base_splay_tree<Accessors>::node_type | |
187 | base_splay_tree<Accessors>::splay_limit (node_type start) | |
188 | { | |
189 | // This essentially follows the simpilfied top-down method described | |
190 | // in Sleator and Tarjan's "Self-adjusting Binary Search Trees", but | |
191 | // specialized for the case in which the comparison result is fixed. | |
192 | // The first iteration is peeled to avoid the need for stack temporaries. | |
193 | // | |
194 | // The comments and names reflect the behavior for N == 1, but the | |
195 | // N == 0 case behaves analogously. | |
196 | ||
197 | // Rotate the tree to promote the right child of START to the root. | |
198 | node_type node = promote_child (start, N); | |
199 | if (node_type right = get_child (node, N)) | |
200 | { | |
201 | // Perform the link left step, which for this first iteration | |
202 | // means making NODE the root of the left tree. | |
203 | // | |
204 | // NODE will become left child of the final node. For a right | |
205 | // spine starting at NODE of the form: | |
206 | // | |
207 | // 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> ... -> N | |
208 | // | | | | | | | | | |
209 | // V V V V V V V V | |
210 | // A B C D E F G NL | |
211 | // | |
212 | // the next step is to create a subtree of N whose right spine contains | |
213 | // the odd-numbered nodes, as follows: | |
214 | // | |
215 | // N | |
216 | // | | |
217 | // V | |
218 | // 1 ------> 3 ------> 5 ------> 7 -> .... -> NL | |
219 | // | | | | | |
220 | // V V V V | |
221 | // A 2 -> C 4 -> E 6 -> G | |
222 | // | | | | |
223 | // V V V | |
224 | // B D F | |
225 | // | |
226 | // First record 1 as the left child of the final root (N) and move | |
227 | // on to node 2. | |
228 | node_type final_child = node; | |
229 | node_type new_spine_end = node; | |
230 | node = right; | |
231 | while (node_type right = get_child (node, N)) | |
232 | { | |
233 | // Perform another rotate left step. | |
234 | // | |
235 | // We've built the tree rooted at 1 in the diagram above up to, | |
236 | // but not including, an even-numbered node NODE on the original | |
237 | // right spine. Rotate the tree at NODE to promote the following | |
238 | // odd-numbered node. | |
239 | promote_child (node, N, right); | |
240 | node = right; | |
241 | if (node_type right = get_child (node, N)) | |
242 | { | |
243 | // Perform another link left step. | |
244 | // | |
245 | // Add the promoted odd-numbered node to the right spine of the | |
246 | // tree rooted at 1 and move on to the next even-numbered node. | |
247 | set_child (new_spine_end, N, node); | |
248 | new_spine_end = node; | |
249 | node = right; | |
250 | } | |
251 | } | |
252 | // Perform the assembly step. | |
253 | // | |
254 | // Add NL to the new spine and make N the new root. | |
255 | set_child (new_spine_end, N, get_child (node, 1 - N)); | |
256 | set_child (node, 1 - N, final_child); | |
257 | } | |
258 | return node; | |
259 | } | |
260 | ||
261 | // Remove NODE from its position in the splay tree. If NODE has at least | |
262 | // one child node, return the node that should now hold NODE's position in | |
263 | // the splay tree. If NODE has no children, return null. | |
264 | // | |
265 | // The caller has the responsibility of updating the parent of the | |
266 | // returned node. | |
267 | template<typename Accessors> | |
268 | inline typename base_splay_tree<Accessors>::node_type | |
269 | base_splay_tree<Accessors>::remove_node_internal (node_type node) | |
270 | { | |
271 | node_type left = get_child (node, 0); | |
272 | node_type right = get_child (node, 1); | |
273 | if (!left) | |
274 | return right; | |
275 | ||
276 | if (!right) | |
277 | return left; | |
278 | ||
279 | if (get_child (left, 1)) | |
280 | { | |
281 | left = splay_limit<1> (left); | |
282 | gcc_checking_assert (!get_child (left, 1)); | |
283 | } | |
284 | set_child (left, 1, right); | |
285 | return left; | |
286 | } | |
287 | ||
288 | // See the comment above the declaration. | |
289 | template<typename Accessors> | |
290 | inline void | |
291 | base_splay_tree<Accessors>::insert_child (node_type node, unsigned int index, | |
292 | node_type child) | |
293 | { | |
294 | gcc_checking_assert (!get_child (child, 0) && !get_child (child, 1)); | |
295 | set_child (child, index, get_child (node, index)); | |
296 | set_child (node, index, child); | |
297 | } | |
298 | ||
299 | // Implement splay_next_node if N == 1 and splay_prev_node if N == 0. | |
300 | template<typename Accessors> | |
301 | template<unsigned int N> | |
302 | bool | |
303 | rooted_splay_tree<Accessors>::splay_neighbor () | |
304 | { | |
305 | node_type node = m_root; | |
306 | node_type new_root = get_child (node, N); | |
307 | if (!new_root) | |
308 | return false; | |
309 | ||
310 | if (get_child (new_root, 1 - N)) | |
311 | { | |
312 | // NEW_ROOT is not itself the required node, so splay the required | |
313 | // node into its place. | |
314 | new_root = parent::template splay_limit<1 - N> (new_root); | |
315 | gcc_checking_assert (!get_child (new_root, 1 - N)); | |
316 | set_child (node, N, node_type ()); | |
317 | set_child (new_root, 1 - N, node); | |
318 | } | |
319 | else | |
320 | promote_child (node, N, new_root); | |
321 | set_parent (new_root, node_type ()); | |
322 | m_root = new_root; | |
323 | return true; | |
324 | } | |
325 | ||
326 | // See the comment above the declaration. | |
327 | template<typename Accessors> | |
328 | template<typename Comparator> | |
329 | bool | |
330 | rooted_splay_tree<Accessors>::insert (node_type new_node, Comparator compare) | |
331 | { | |
332 | gcc_checking_assert (!get_child (new_node, 0) && !get_child (new_node, 1)); | |
333 | if (!m_root) | |
334 | { | |
335 | m_root = new_node; | |
336 | return true; | |
337 | } | |
338 | ||
339 | int comparison = lookup (compare); | |
340 | if (comparison == 0) | |
341 | return false; | |
342 | ||
343 | // Insert NEW_NODE before M_ROOT if COMPARISON < 0 and after M_ROOT | |
344 | // otherwise. | |
345 | set_child (new_node, comparison < 0, m_root); | |
346 | set_child (new_node, comparison > 0, get_child (m_root, comparison > 0)); | |
347 | set_child (m_root, comparison > 0, nullptr); | |
348 | m_root = new_node; | |
349 | return true; | |
350 | } | |
351 | ||
352 | // See the comment above the declaration. | |
353 | template<typename Accessors> | |
354 | inline void | |
355 | rooted_splay_tree<Accessors>::insert_max_node (node_type new_node) | |
356 | { | |
357 | gcc_checking_assert (!get_child (new_node, 0) && !get_child (new_node, 1)); | |
358 | set_child (new_node, 0, m_root); | |
359 | m_root = new_node; | |
360 | } | |
361 | ||
362 | // See the comment above the declaration. | |
363 | template<typename Accessors> | |
364 | inline void | |
365 | rooted_splay_tree<Accessors>::splice_next_tree (rooted_splay_tree next_tree) | |
366 | { | |
367 | splay_max_node (); | |
368 | set_child (m_root, 1, next_tree.m_root); | |
369 | } | |
370 | ||
371 | // See the comment above the declaration. | |
372 | template<typename Accessors> | |
373 | inline void | |
374 | rooted_splay_tree<Accessors>::replace_max_node_at_root (node_type new_node) | |
375 | { | |
376 | node_type old_node = m_root; | |
377 | gcc_checking_assert (!get_child (new_node, 0) | |
378 | && !get_child (new_node, 1) | |
379 | && !get_child (old_node, 1)); | |
380 | set_child (new_node, 0, get_child (old_node, 0)); | |
381 | // Clear the links from OLD_NODE. Its parent and right child are | |
382 | // already node_type (). | |
383 | set_child (old_node, 0, node_type ()); | |
384 | m_root = new_node; | |
385 | } | |
386 | ||
387 | // See the comment above the declaration. | |
388 | template<typename Accessors> | |
389 | inline void | |
390 | rooted_splay_tree<Accessors>::remove_root () | |
391 | { | |
392 | node_type node = m_root; | |
393 | m_root = parent::remove_node_internal (node); | |
394 | if (m_root) | |
395 | set_parent (m_root, node_type ()); | |
396 | // Clear the links from NODE. Its parent is already node_type (). | |
397 | set_child (node, 0, node_type ()); | |
398 | set_child (node, 1, node_type ()); | |
399 | } | |
400 | ||
401 | // See the comment above the declaration. | |
402 | template<typename Accessors> | |
403 | inline rooted_splay_tree<Accessors> | |
404 | rooted_splay_tree<Accessors>::split_before_root () | |
405 | { | |
406 | node_type new_root = get_child (m_root, 0); | |
407 | set_child (m_root, 0, node_type ()); | |
408 | set_parent (new_root, node_type ()); | |
409 | return new_root; | |
410 | } | |
411 | ||
412 | // See the comment above the declaration. | |
413 | template<typename Accessors> | |
414 | inline rooted_splay_tree<Accessors> | |
415 | rooted_splay_tree<Accessors>::split_after_root () | |
416 | { | |
417 | node_type new_root = get_child (m_root, 1); | |
418 | set_child (m_root, 1, node_type ()); | |
419 | set_parent (new_root, node_type ()); | |
420 | return new_root; | |
421 | } | |
422 | ||
423 | // See the comment above the declaration. | |
424 | template<typename Accessors> | |
425 | inline bool | |
426 | rooted_splay_tree<Accessors>::splay_prev_node () | |
427 | { | |
428 | return splay_neighbor<0> (); | |
429 | } | |
430 | ||
431 | // See the comment above the declaration. | |
432 | template<typename Accessors> | |
433 | inline bool | |
434 | rooted_splay_tree<Accessors>::splay_next_node () | |
435 | { | |
436 | return splay_neighbor<1> (); | |
437 | } | |
438 | ||
439 | // See the comment above the declaration. | |
440 | template<typename Accessors> | |
441 | inline void | |
442 | rooted_splay_tree<Accessors>::splay_min_node () | |
443 | { | |
444 | if (m_root && get_child (m_root, 0)) | |
445 | { | |
446 | m_root = parent::template splay_limit<0> (m_root); | |
447 | set_parent (m_root, node_type ()); | |
448 | } | |
449 | } | |
450 | ||
451 | // See the comment above the declaration. | |
452 | template<typename Accessors> | |
453 | inline void | |
454 | rooted_splay_tree<Accessors>::splay_max_node () | |
455 | { | |
456 | if (m_root && get_child (m_root, 1)) | |
457 | { | |
458 | m_root = parent::template splay_limit<1> (m_root); | |
459 | set_parent (m_root, node_type ()); | |
460 | } | |
461 | } | |
462 | ||
463 | // See the comment above the declaration. | |
464 | template<typename Accessors> | |
465 | inline typename rooted_splay_tree<Accessors>::node_type | |
466 | rooted_splay_tree<Accessors>::min_node () | |
467 | { | |
468 | splay_min_node (); | |
469 | return m_root; | |
470 | } | |
471 | ||
472 | // See the comment above the declaration. | |
473 | template<typename Accessors> | |
474 | inline typename rooted_splay_tree<Accessors>::node_type | |
475 | rooted_splay_tree<Accessors>::max_node () | |
476 | { | |
477 | splay_max_node (); | |
478 | return m_root; | |
479 | } | |
480 | ||
481 | // See the comment above the declaration. | |
482 | template<typename Accessors> | |
483 | template<typename Comparator> | |
484 | auto | |
485 | rooted_splay_tree<Accessors>::lookup (Comparator compare) | |
486 | -> decltype (compare (m_root)) | |
487 | { | |
488 | // This essentially follows the simpilfied top-down method described | |
489 | // in Sleator and Tarjan's "Self-adjusting Binary Search Trees", but | |
490 | // with the complication that the comparisons are done only once. | |
491 | using result_type = decltype (compare (m_root)); | |
492 | ||
493 | // The roots of the left and right trees. | |
494 | node_type link_left_root = node_type (); | |
495 | node_type link_right_root = node_type (); | |
496 | ||
497 | // Where to add new nodes to the left and right trees. | |
498 | node_type *link_left_ptr = &link_left_root; | |
499 | node_type *link_right_ptr = &link_right_root; | |
500 | ||
501 | // The nodes that contain *LINK_LEFT_PTR and *LINK_RIGHT_PTR, | |
502 | // once they no longer point to the roots above. | |
503 | node_type link_left_parent = node_type (); | |
504 | node_type link_right_parent = node_type (); | |
505 | ||
506 | auto link_left = [&](node_type node) | |
507 | { | |
508 | *link_left_ptr = node; | |
509 | link_left_ptr = &Accessors::child (node, 1); | |
510 | set_parent (node, link_left_parent); | |
511 | link_left_parent = node; | |
512 | }; | |
513 | ||
514 | auto link_right = [&](node_type node) | |
515 | { | |
516 | *link_right_ptr = node; | |
517 | link_right_ptr = &Accessors::child (node, 0); | |
518 | set_parent (node, link_right_parent); | |
519 | link_right_parent = node; | |
520 | }; | |
521 | ||
522 | node_type node = m_root; | |
523 | node_type parent = node_type (); | |
524 | result_type result; | |
525 | result_type old_result = 0; | |
526 | while (1) | |
527 | { | |
528 | // OLD_RESULT is 0 if NODE is the root of the middle tree. | |
529 | // Otherwise, PARENT is the root of the middle tree and OLD_RESULT | |
530 | // is how it compared. | |
531 | // | |
532 | // Results are: | |
533 | // < 0 if we want something smaller. | |
534 | // = 0 if we found the right node. | |
535 | // > 0 if we want something bigger. | |
536 | result = compare (node); | |
537 | if (old_result < 0) | |
538 | { | |
539 | if (result < 0) | |
540 | { | |
541 | // SEARCH < NODE < PARENT | |
542 | // | |
543 | // Promote NODE (rotate right). | |
544 | promote_child (parent, 0, node); | |
545 | node_type next = get_child (node, 0); | |
546 | if (!next) | |
547 | break; | |
548 | ||
549 | link_right (node); | |
550 | ||
551 | // NEXT is now the root of the middle tree. | |
552 | node = next; | |
553 | old_result = 0; | |
554 | continue; | |
555 | } | |
556 | ||
557 | // SEARCH >= NODE, NODE < PARENT | |
558 | link_right (parent); | |
559 | } | |
560 | else if (old_result > 0) | |
561 | { | |
562 | if (result > 0) | |
563 | { | |
564 | // SEARCH > NODE > PARENT | |
565 | // | |
566 | // Promote NODE (rotate left). | |
567 | promote_child (parent, 1, node); | |
568 | node_type next = get_child (node, 1); | |
569 | if (!next) | |
570 | break; | |
571 | ||
572 | link_left (node); | |
573 | ||
574 | // NEXT is now the root of the middle tree. | |
575 | node = next; | |
576 | old_result = 0; | |
577 | continue; | |
578 | } | |
579 | ||
580 | // SEARCH <= NODE, NODE > PARENT | |
581 | link_left (parent); | |
582 | } | |
583 | ||
584 | // Microoptimization to allow NODE to be read even if RESULT == 0. | |
585 | node_type next = get_child (node, result >= 0); | |
586 | if (result == 0 || !next) | |
587 | break; | |
588 | ||
589 | // NODE is now the root of the tree. | |
590 | parent = node; | |
591 | node = next; | |
592 | old_result = result; | |
593 | } | |
594 | ||
595 | node_type new_left = link_left_root; | |
596 | node_type new_right = link_right_root; | |
597 | ||
598 | if (new_left) | |
599 | { | |
600 | node_type old_left = get_child (node, 0); | |
601 | *link_left_ptr = old_left; | |
602 | if (old_left) | |
603 | set_parent (old_left, link_left_parent); | |
604 | set_child (node, 0, new_left); | |
605 | } | |
606 | ||
607 | if (new_right) | |
608 | { | |
609 | node_type old_right = get_child (node, 1); | |
610 | *link_right_ptr = old_right; | |
611 | if (old_right) | |
612 | set_parent (old_right, link_right_parent); | |
613 | set_child (node, 1, new_right); | |
614 | } | |
615 | ||
616 | set_parent (node, node_type ()); | |
617 | m_root = node; | |
618 | return result; | |
619 | } | |
620 | ||
621 | // See the comment above the declaration. | |
622 | template<typename Accessors> | |
623 | template<typename LeftPredicate, typename RightPredicate> | |
624 | int | |
625 | rooted_splay_tree<Accessors>::lookup (LeftPredicate want_something_smaller, | |
626 | RightPredicate want_something_bigger) | |
627 | { | |
628 | // This essentially follows the simpilfied top-down method described | |
629 | // in Sleator and Tarjan's "Self-adjusting Binary Search Trees" | |
630 | // (and follows it more closely than the single-comparator version above). | |
631 | ||
632 | // The roots of the left and right trees. | |
633 | node_type link_left_root = node_type (); | |
634 | node_type link_right_root = node_type (); | |
635 | ||
636 | // Where to add new nodes to the left and right trees. | |
637 | node_type *link_left_ptr = &link_left_root; | |
638 | node_type *link_right_ptr = &link_right_root; | |
639 | ||
640 | // The nodes that contain *LINK_LEFT_PTR and *LINK_RIGHT_PTR, | |
641 | // once they no longer point to the roots above. | |
642 | node_type link_left_parent = node_type (); | |
643 | node_type link_right_parent = node_type (); | |
644 | ||
645 | node_type node = m_root; | |
646 | int result; | |
647 | for (;;) | |
648 | { | |
649 | // NODE is the root of the middle tree. | |
650 | if (want_something_smaller (node)) | |
651 | { | |
652 | result = -1; | |
653 | node_type next = get_child (node, 0); | |
654 | if (!next) | |
655 | break; | |
656 | ||
657 | if (want_something_smaller (next)) | |
658 | { | |
659 | // Promote NODE (rotate right). | |
660 | promote_child (node, 0, next); | |
661 | node = next; | |
662 | next = get_child (node, 0); | |
663 | if (!next) | |
664 | break; | |
665 | } | |
666 | ||
667 | // Add NODE to the right tree (link right). | |
668 | *link_right_ptr = node; | |
669 | link_right_ptr = &Accessors::child (node, 0); | |
670 | set_parent (node, link_right_parent); | |
671 | link_right_parent = node; | |
672 | ||
673 | node = next; | |
674 | } | |
675 | else if (want_something_bigger (node)) | |
676 | { | |
677 | result = 1; | |
678 | node_type next = get_child (node, 1); | |
679 | if (!next) | |
680 | break; | |
681 | ||
682 | if (want_something_bigger (next)) | |
683 | { | |
684 | // Promote NODE (rotate left). | |
685 | promote_child (node, 1, next); | |
686 | node = next; | |
687 | next = get_child (node, 1); | |
688 | if (!next) | |
689 | break; | |
690 | } | |
691 | ||
692 | // Add NODE to the left tree (link left). | |
693 | *link_left_ptr = node; | |
694 | link_left_ptr = &Accessors::child (node, 1); | |
695 | set_parent (node, link_left_parent); | |
696 | link_left_parent = node; | |
697 | ||
698 | node = next; | |
699 | } | |
700 | else | |
701 | { | |
702 | result = 0; | |
703 | break; | |
704 | } | |
705 | } | |
706 | ||
707 | node_type new_left = link_left_root; | |
708 | node_type new_right = link_right_root; | |
709 | ||
710 | if (new_left) | |
711 | { | |
712 | node_type old_left = get_child (node, 0); | |
713 | *link_left_ptr = old_left; | |
714 | if (old_left) | |
715 | set_parent (old_left, link_left_parent); | |
716 | set_child (node, 0, new_left); | |
717 | } | |
718 | ||
719 | if (new_right) | |
720 | { | |
721 | node_type old_right = get_child (node, 1); | |
722 | *link_right_ptr = old_right; | |
723 | if (old_right) | |
724 | set_parent (old_right, link_right_parent); | |
725 | set_child (node, 1, new_right); | |
726 | } | |
727 | ||
728 | set_parent (node, node_type ()); | |
729 | m_root = node; | |
730 | return result; | |
731 | } | |
732 | ||
733 | // See the comment above the declaration. | |
734 | template<typename Accessors> | |
735 | template<typename Printer> | |
736 | inline void | |
737 | rooted_splay_tree<Accessors>::print (pretty_printer *pp, Printer printer) const | |
738 | { | |
739 | print (pp, m_root, printer); | |
740 | } | |
741 | ||
742 | // Return NODE's current parent. | |
743 | template<typename Accessors> | |
744 | inline typename rootless_splay_tree<Accessors>::node_type | |
745 | rootless_splay_tree<Accessors>::get_parent (node_type node) | |
746 | { | |
747 | return Accessors::parent (node); | |
748 | } | |
749 | ||
750 | // CHILD is known to be a child of PARENT. Return which index it has. | |
751 | template<typename Accessors> | |
752 | inline unsigned int | |
753 | rootless_splay_tree<Accessors>::child_index (node_type parent, node_type child) | |
754 | { | |
755 | return get_child (parent, 1) == child; | |
756 | } | |
757 | ||
758 | // If N == 1, implement splay_known_max_node, otherwise implement | |
759 | // splay_known_min_node. | |
760 | template<typename Accessors> | |
761 | template<unsigned int N> | |
762 | inline void | |
763 | rootless_splay_tree<Accessors>::splay_known_limit (node_type node) | |
764 | { | |
765 | node_type child = node; | |
766 | node_type parent = get_parent (child); | |
767 | if (!parent) | |
768 | return; | |
769 | ||
770 | do | |
771 | // At this point, NODE conceptually replaces CHILD as a child of | |
772 | // PARENT, but we haven't yet updated PARENT accordingly. | |
773 | if (node_type grandparent = get_parent (parent)) | |
774 | { | |
775 | node_type greatgrandparent = get_parent (grandparent); | |
776 | promote_child (grandparent, N, parent); | |
777 | promote_child (parent, N, node); | |
778 | child = grandparent; | |
779 | parent = greatgrandparent; | |
780 | } | |
781 | else | |
782 | { | |
783 | promote_child (parent, N, node); | |
784 | break; | |
785 | } | |
786 | while (parent); | |
787 | set_parent (node, node_type ()); | |
788 | } | |
789 | ||
790 | // See the comment above the declaration. | |
791 | template<typename Accessors> | |
792 | typename rootless_splay_tree<Accessors>::node_type | |
793 | rootless_splay_tree<Accessors>::remove_node (node_type node) | |
794 | { | |
795 | node_type replacement = parent::remove_node_internal (node); | |
796 | if (node_type parent = get_parent (node)) | |
797 | set_child (parent, child_index (parent, node), replacement); | |
798 | else if (replacement) | |
799 | set_parent (replacement, node_type ()); | |
800 | // Clear the links from NODE. | |
801 | set_parent (node, node_type ()); | |
802 | set_child (node, 0, node_type ()); | |
803 | set_child (node, 1, node_type ()); | |
804 | return replacement; | |
805 | } | |
806 | ||
807 | // See the comment above the declaration. | |
808 | template<typename Accessors> | |
809 | void | |
810 | rootless_splay_tree<Accessors>::splay (node_type node) | |
811 | { | |
812 | node_type child = node; | |
813 | node_type parent = get_parent (child); | |
814 | if (!parent) | |
815 | return; | |
816 | ||
817 | do | |
818 | { | |
819 | // At this point, NODE conceptually replaces CHILD as a child of | |
820 | // PARENT, but we haven't yet updated PARENT accordingly. | |
821 | unsigned int index = child_index (parent, child); | |
822 | if (node_type grandparent = get_parent (parent)) | |
823 | { | |
824 | node_type greatgrandparent = get_parent (grandparent); | |
825 | unsigned int parent_index = child_index (grandparent, parent); | |
826 | if (index == parent_index) | |
827 | { | |
828 | promote_child (grandparent, parent_index, parent); | |
829 | promote_child (parent, index, node); | |
830 | } | |
831 | else | |
832 | { | |
833 | promote_child (parent, index, node); | |
834 | promote_child (grandparent, parent_index, node); | |
835 | } | |
836 | child = grandparent; | |
837 | parent = greatgrandparent; | |
838 | } | |
839 | else | |
840 | { | |
841 | promote_child (parent, index, node); | |
842 | break; | |
843 | } | |
844 | } | |
845 | while (parent); | |
846 | set_parent (node, node_type ()); | |
847 | } | |
848 | ||
849 | // See the comment above the declaration. | |
850 | template<typename Accessors> | |
851 | inline void | |
852 | rootless_splay_tree<Accessors>::splay_known_min_node (node_type node) | |
853 | { | |
854 | splay_known_limit<0> (node); | |
855 | } | |
856 | ||
857 | // See the comment above the declaration. | |
858 | template<typename Accessors> | |
859 | inline void | |
860 | rootless_splay_tree<Accessors>::splay_known_max_node (node_type node) | |
861 | { | |
862 | splay_known_limit<1> (node); | |
863 | } | |
864 | ||
865 | // See the comment above the declaration. | |
866 | template<typename Accessors> | |
867 | template<typename DefaultResult, typename Predicate> | |
868 | auto | |
869 | rootless_splay_tree<Accessors>:: | |
870 | splay_and_search (node_type node, DefaultResult default_result, | |
871 | Predicate predicate) | |
872 | -> decltype (predicate (node, 0)) | |
873 | { | |
874 | using Result = decltype (predicate (node, 0)); | |
875 | ||
876 | node_type child = node; | |
877 | node_type parent = get_parent (child); | |
878 | if (!parent) | |
879 | return default_result; | |
880 | ||
881 | do | |
882 | { | |
883 | // At this point, NODE conceptually replaces CHILD as a child of | |
884 | // PARENT, but we haven't yet updated PARENT accordingly. | |
885 | unsigned int index = child_index (parent, child); | |
886 | if (Result result = predicate (parent, index)) | |
887 | { | |
888 | set_child (parent, index, node); | |
889 | return result; | |
890 | } | |
891 | if (node_type grandparent = get_parent (parent)) | |
892 | { | |
893 | node_type greatgrandparent = get_parent (grandparent); | |
894 | unsigned int parent_index = child_index (grandparent, parent); | |
895 | if (Result result = predicate (grandparent, parent_index)) | |
896 | { | |
897 | set_child (parent, index, node); | |
898 | return result; | |
899 | } | |
900 | if (index == parent_index) | |
901 | { | |
902 | promote_child (grandparent, parent_index, parent); | |
903 | promote_child (parent, index, node); | |
904 | } | |
905 | else | |
906 | { | |
907 | promote_child (parent, index, node); | |
908 | promote_child (grandparent, parent_index, node); | |
909 | } | |
910 | child = grandparent; | |
911 | parent = greatgrandparent; | |
912 | } | |
913 | else | |
914 | { | |
915 | promote_child (parent, index, node); | |
916 | break; | |
917 | } | |
918 | } | |
919 | while (parent); | |
920 | set_parent (node, node_type ()); | |
921 | return default_result; | |
922 | } | |
923 | ||
924 | // Splay NODE1 looking to see if one of its ancestors is NODE2. If it is, | |
925 | // return -1 if NODE1 comes before NODE2 or 1 if NODE1 comes after NODE2. | |
926 | // Return 0 if NODE2 is not an ancestor of NODE1. | |
927 | template<typename Accessors> | |
928 | int | |
929 | rootless_splay_tree<Accessors>::compare_nodes_one_way (node_type node1, | |
930 | node_type node2) | |
931 | { | |
932 | auto compare = [&](node_type parent, unsigned int index) -> int | |
933 | { | |
934 | if (parent == node2) | |
935 | return index ? 1 : -1; | |
936 | return 0; | |
937 | }; | |
938 | return splay_and_search (node1, 0, compare); | |
939 | } | |
940 | ||
941 | // See the comment above the declaration. | |
942 | template<typename Accessors> | |
943 | int | |
944 | rootless_splay_tree<Accessors>::compare_nodes (node_type node1, | |
945 | node_type node2) | |
946 | { | |
947 | if (node1 == node2) | |
948 | return 0; | |
949 | ||
950 | // Splay NODE1 looking for NODE2. | |
951 | int cmp = compare_nodes_one_way (node1, node2); | |
952 | if (cmp) | |
953 | return cmp; | |
954 | ||
955 | // That failed, but NODE1 is now the root of the tree. Splay NODE2 | |
956 | // to see on which side of NODE1 it falls. | |
957 | cmp = compare_nodes_one_way (node2, node1); | |
958 | gcc_checking_assert (cmp); | |
959 | return -cmp; | |
960 | } |