1 | ///////////////////////////////////////////////////////////////////////////// |
2 | // |
3 | // (C) Copyright Olaf Krzikalla 2004-2006. |
4 | // (C) Copyright Ion Gaztanaga 2006-2014 |
5 | // |
6 | // Distributed under the Boost Software License, Version 1.0. |
7 | // (See accompanying file LICENSE_1_0.txt or copy at |
8 | // http://www.boost.org/LICENSE_1_0.txt) |
9 | // |
10 | // See http://www.boost.org/libs/intrusive for documentation. |
11 | // |
12 | ///////////////////////////////////////////////////////////////////////////// |
13 | |
14 | #ifndef BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP |
15 | #define BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP |
16 | |
17 | #include <cstddef> |
18 | #include <boost/intrusive/detail/config_begin.hpp> |
19 | #include <boost/intrusive/intrusive_fwd.hpp> |
20 | #include <boost/intrusive/detail/common_slist_algorithms.hpp> |
21 | #include <boost/intrusive/detail/algo_type.hpp> |
22 | |
23 | #if defined(BOOST_HAS_PRAGMA_ONCE) |
24 | # pragma once |
25 | #endif |
26 | |
27 | namespace boost { |
28 | namespace intrusive { |
29 | |
30 | //! circular_slist_algorithms provides basic algorithms to manipulate nodes |
31 | //! forming a circular singly linked list. An empty circular list is formed by a node |
32 | //! whose pointer to the next node points to itself. |
33 | //! |
34 | //! circular_slist_algorithms is configured with a NodeTraits class, which encapsulates the |
35 | //! information about the node to be manipulated. NodeTraits must support the |
36 | //! following interface: |
37 | //! |
38 | //! <b>Typedefs</b>: |
39 | //! |
40 | //! <tt>node</tt>: The type of the node that forms the circular list |
41 | //! |
42 | //! <tt>node_ptr</tt>: A pointer to a node |
43 | //! |
44 | //! <tt>const_node_ptr</tt>: A pointer to a const node |
45 | //! |
46 | //! <b>Static functions</b>: |
47 | //! |
48 | //! <tt>static node_ptr get_next(const_node_ptr n);</tt> |
49 | //! |
50 | //! <tt>static void set_next(node_ptr n, node_ptr next);</tt> |
51 | template<class NodeTraits> |
52 | class circular_slist_algorithms |
53 | /// @cond |
54 | : public detail::common_slist_algorithms<NodeTraits> |
55 | /// @endcond |
56 | { |
57 | /// @cond |
58 | typedef detail::common_slist_algorithms<NodeTraits> base_t; |
59 | /// @endcond |
60 | public: |
61 | typedef typename NodeTraits::node node; |
62 | typedef typename NodeTraits::node_ptr node_ptr; |
63 | typedef typename NodeTraits::const_node_ptr const_node_ptr; |
64 | typedef NodeTraits node_traits; |
65 | |
66 | #if defined(BOOST_INTRUSIVE_DOXYGEN_INVOKED) |
67 | |
68 | //! <b>Effects</b>: Constructs an non-used list element, putting the next |
69 | //! pointer to null: |
70 | //! <tt>NodeTraits::get_next(this_node) == node_ptr()</tt> |
71 | //! |
72 | //! <b>Complexity</b>: Constant |
73 | //! |
74 | //! <b>Throws</b>: Nothing. |
75 | static void init(node_ptr this_node); |
76 | |
77 | //! <b>Requires</b>: this_node must be in a circular list or be an empty circular list. |
78 | //! |
79 | //! <b>Effects</b>: Returns true is "this_node" is the only node of a circular list: |
80 | //! or it's a not inserted node: |
81 | //! <tt>return node_ptr() == NodeTraits::get_next(this_node) || NodeTraits::get_next(this_node) == this_node</tt> |
82 | //! |
83 | //! <b>Complexity</b>: Constant |
84 | //! |
85 | //! <b>Throws</b>: Nothing. |
86 | static bool unique(const_node_ptr this_node); |
87 | |
88 | //! <b>Effects</b>: Returns true is "this_node" has the same state as |
89 | //! if it was inited using "init(node_ptr)" |
90 | //! |
91 | //! <b>Complexity</b>: Constant |
92 | //! |
93 | //! <b>Throws</b>: Nothing. |
94 | static bool inited(const_node_ptr this_node); |
95 | |
96 | //! <b>Requires</b>: prev_node must be in a circular list or be an empty circular list. |
97 | //! |
98 | //! <b>Effects</b>: Unlinks the next node of prev_node from the circular list. |
99 | //! |
100 | //! <b>Complexity</b>: Constant |
101 | //! |
102 | //! <b>Throws</b>: Nothing. |
103 | static void unlink_after(node_ptr prev_node); |
104 | |
105 | //! <b>Requires</b>: prev_node and last_node must be in a circular list |
106 | //! or be an empty circular list. |
107 | //! |
108 | //! <b>Effects</b>: Unlinks the range (prev_node, last_node) from the circular list. |
109 | //! |
110 | //! <b>Complexity</b>: Constant |
111 | //! |
112 | //! <b>Throws</b>: Nothing. |
113 | static void unlink_after(node_ptr prev_node, node_ptr last_node); |
114 | |
115 | //! <b>Requires</b>: prev_node must be a node of a circular list. |
116 | //! |
117 | //! <b>Effects</b>: Links this_node after prev_node in the circular list. |
118 | //! |
119 | //! <b>Complexity</b>: Constant |
120 | //! |
121 | //! <b>Throws</b>: Nothing. |
122 | static void link_after(node_ptr prev_node, node_ptr this_node); |
123 | |
124 | //! <b>Requires</b>: b and e must be nodes of the same circular list or an empty range. |
125 | //! and p must be a node of a different circular list. |
126 | //! |
127 | //! <b>Effects</b>: Removes the nodes from (b, e] range from their circular list and inserts |
128 | //! them after p in p's circular list. |
129 | //! |
130 | //! <b>Complexity</b>: Constant |
131 | //! |
132 | //! <b>Throws</b>: Nothing. |
133 | static void transfer_after(node_ptr p, node_ptr b, node_ptr e); |
134 | |
135 | #endif //#if defined(BOOST_INTRUSIVE_DOXYGEN_INVOKED) |
136 | |
137 | //! <b>Effects</b>: Constructs an empty list, making this_node the only |
138 | //! node of the circular list: |
139 | //! <tt>NodeTraits::get_next(this_node) == this_node</tt>. |
140 | //! |
141 | //! <b>Complexity</b>: Constant |
142 | //! |
143 | //! <b>Throws</b>: Nothing. |
144 | static void (const node_ptr &this_node) |
145 | { NodeTraits::set_next(this_node, this_node); } |
146 | |
147 | //! <b>Requires</b>: this_node and prev_init_node must be in the same circular list. |
148 | //! |
149 | //! <b>Effects</b>: Returns the previous node of this_node in the circular list starting. |
150 | //! the search from prev_init_node. The first node checked for equality |
151 | //! is NodeTraits::get_next(prev_init_node). |
152 | //! |
153 | //! <b>Complexity</b>: Linear to the number of elements between prev_init_node and this_node. |
154 | //! |
155 | //! <b>Throws</b>: Nothing. |
156 | static node_ptr get_previous_node(const node_ptr &prev_init_node, const node_ptr &this_node) |
157 | { return base_t::get_previous_node(prev_init_node, this_node); } |
158 | |
159 | //! <b>Requires</b>: this_node must be in a circular list or be an empty circular list. |
160 | //! |
161 | //! <b>Effects</b>: Returns the previous node of this_node in the circular list. |
162 | //! |
163 | //! <b>Complexity</b>: Linear to the number of elements in the circular list. |
164 | //! |
165 | //! <b>Throws</b>: Nothing. |
166 | static node_ptr get_previous_node(const node_ptr & this_node) |
167 | { return base_t::get_previous_node(this_node, this_node); } |
168 | |
169 | //! <b>Requires</b>: this_node must be in a circular list or be an empty circular list. |
170 | //! |
171 | //! <b>Effects</b>: Returns the previous node of the previous node of this_node in the circular list. |
172 | //! |
173 | //! <b>Complexity</b>: Linear to the number of elements in the circular list. |
174 | //! |
175 | //! <b>Throws</b>: Nothing. |
176 | static node_ptr get_previous_previous_node(const node_ptr & this_node) |
177 | { return get_previous_previous_node(this_node, this_node); } |
178 | |
179 | //! <b>Requires</b>: this_node and p must be in the same circular list. |
180 | //! |
181 | //! <b>Effects</b>: Returns the previous node of the previous node of this_node in the |
182 | //! circular list starting. the search from p. The first node checked |
183 | //! for equality is NodeTraits::get_next((NodeTraits::get_next(p)). |
184 | //! |
185 | //! <b>Complexity</b>: Linear to the number of elements in the circular list. |
186 | //! |
187 | //! <b>Throws</b>: Nothing. |
188 | static node_ptr get_previous_previous_node(node_ptr p, const node_ptr & this_node) |
189 | { |
190 | node_ptr p_next = NodeTraits::get_next(p); |
191 | node_ptr p_next_next = NodeTraits::get_next(p_next); |
192 | while (this_node != p_next_next){ |
193 | p = p_next; |
194 | p_next = p_next_next; |
195 | p_next_next = NodeTraits::get_next(p_next); |
196 | } |
197 | return p; |
198 | } |
199 | |
200 | //! <b>Requires</b>: this_node must be in a circular list or be an empty circular list. |
201 | //! |
202 | //! <b>Effects</b>: Returns the number of nodes in a circular list. If the circular list |
203 | //! is empty, returns 1. |
204 | //! |
205 | //! <b>Complexity</b>: Linear |
206 | //! |
207 | //! <b>Throws</b>: Nothing. |
208 | static std::size_t count(const const_node_ptr & this_node) |
209 | { |
210 | std::size_t result = 0; |
211 | const_node_ptr p = this_node; |
212 | do{ |
213 | p = NodeTraits::get_next(p); |
214 | ++result; |
215 | } while (p != this_node); |
216 | return result; |
217 | } |
218 | |
219 | //! <b>Requires</b>: this_node must be in a circular list, be an empty circular list or be inited. |
220 | //! |
221 | //! <b>Effects</b>: Unlinks the node from the circular list. |
222 | //! |
223 | //! <b>Complexity</b>: Linear to the number of elements in the circular list |
224 | //! |
225 | //! <b>Throws</b>: Nothing. |
226 | static void unlink(const node_ptr & this_node) |
227 | { |
228 | if(NodeTraits::get_next(this_node)) |
229 | base_t::unlink_after(get_previous_node(this_node)); |
230 | } |
231 | |
232 | //! <b>Requires</b>: nxt_node must be a node of a circular list. |
233 | //! |
234 | //! <b>Effects</b>: Links this_node before nxt_node in the circular list. |
235 | //! |
236 | //! <b>Complexity</b>: Linear to the number of elements in the circular list. |
237 | //! |
238 | //! <b>Throws</b>: Nothing. |
239 | static void link_before (const node_ptr & nxt_node, const node_ptr & this_node) |
240 | { base_t::link_after(get_previous_node(nxt_node), this_node); } |
241 | |
242 | //! <b>Requires</b>: this_node and other_node must be nodes inserted |
243 | //! in circular lists or be empty circular lists. |
244 | //! |
245 | //! <b>Effects</b>: Swaps the position of the nodes: this_node is inserted in |
246 | //! other_nodes position in the second circular list and the other_node is inserted |
247 | //! in this_node's position in the first circular list. |
248 | //! |
249 | //! <b>Complexity</b>: Linear to number of elements of both lists |
250 | //! |
251 | //! <b>Throws</b>: Nothing. |
252 | static void swap_nodes(const node_ptr & this_node, const node_ptr & other_node) |
253 | { |
254 | if (other_node == this_node) |
255 | return; |
256 | const node_ptr this_next = NodeTraits::get_next(this_node); |
257 | const node_ptr other_next = NodeTraits::get_next(other_node); |
258 | const bool this_null = !this_next; |
259 | const bool other_null = !other_next; |
260 | const bool this_empty = this_next == this_node; |
261 | const bool other_empty = other_next == other_node; |
262 | |
263 | if(!(other_null || other_empty)){ |
264 | NodeTraits::set_next(this_next == other_node ? other_node : get_previous_node(other_node), this_node ); |
265 | } |
266 | if(!(this_null | this_empty)){ |
267 | NodeTraits::set_next(other_next == this_node ? this_node : get_previous_node(this_node), other_node ); |
268 | } |
269 | NodeTraits::set_next(this_node, other_empty ? this_node : (other_next == this_node ? other_node : other_next) ); |
270 | NodeTraits::set_next(other_node, this_empty ? other_node : (this_next == other_node ? this_node : this_next ) ); |
271 | } |
272 | |
273 | //! <b>Effects</b>: Reverses the order of elements in the list. |
274 | //! |
275 | //! <b>Throws</b>: Nothing. |
276 | //! |
277 | //! <b>Complexity</b>: This function is linear to the contained elements. |
278 | static void reverse(const node_ptr & p) |
279 | { |
280 | node_ptr i = NodeTraits::get_next(p), e(p); |
281 | for (;;) { |
282 | node_ptr nxt(NodeTraits::get_next(i)); |
283 | if (nxt == e) |
284 | break; |
285 | base_t::transfer_after(e, i, nxt); |
286 | } |
287 | } |
288 | |
289 | //! <b>Effects</b>: Moves the node p n positions towards the end of the list. |
290 | //! |
291 | //! <b>Returns</b>: The previous node of p after the function if there has been any movement, |
292 | //! Null if n leads to no movement. |
293 | //! |
294 | //! <b>Throws</b>: Nothing. |
295 | //! |
296 | //! <b>Complexity</b>: Linear to the number of elements plus the number moved positions. |
297 | static node_ptr move_backwards(const node_ptr & p, std::size_t n) |
298 | { |
299 | //Null shift, nothing to do |
300 | if(!n) return node_ptr(); |
301 | node_ptr first = NodeTraits::get_next(p); |
302 | |
303 | //count() == 1 or 2, nothing to do |
304 | if(NodeTraits::get_next(first) == p) |
305 | return node_ptr(); |
306 | |
307 | bool end_found = false; |
308 | node_ptr new_last = node_ptr(); |
309 | |
310 | //Now find the new last node according to the shift count. |
311 | //If we find p before finding the new last node |
312 | //unlink p, shortcut the search now that we know the size of the list |
313 | //and continue. |
314 | for(std::size_t i = 1; i <= n; ++i){ |
315 | new_last = first; |
316 | first = NodeTraits::get_next(first); |
317 | if(first == p){ |
318 | //Shortcut the shift with the modulo of the size of the list |
319 | n %= i; |
320 | if(!n) |
321 | return node_ptr(); |
322 | i = 0; |
323 | //Unlink p and continue the new first node search |
324 | first = NodeTraits::get_next(p); |
325 | base_t::unlink_after(new_last); |
326 | end_found = true; |
327 | } |
328 | } |
329 | |
330 | //If the p has not been found in the previous loop, find it |
331 | //starting in the new first node and unlink it |
332 | if(!end_found){ |
333 | base_t::unlink_after(base_t::get_previous_node(first, p)); |
334 | } |
335 | |
336 | //Now link p after the new last node |
337 | base_t::link_after(new_last, p); |
338 | return new_last; |
339 | } |
340 | |
341 | //! <b>Effects</b>: Moves the node p n positions towards the beginning of the list. |
342 | //! |
343 | //! <b>Returns</b>: The previous node of p after the function if there has been any movement, |
344 | //! Null if n leads equals to no movement. |
345 | //! |
346 | //! <b>Throws</b>: Nothing. |
347 | //! |
348 | //! <b>Complexity</b>: Linear to the number of elements plus the number moved positions. |
349 | static node_ptr move_forward(const node_ptr & p, std::size_t n) |
350 | { |
351 | //Null shift, nothing to do |
352 | if(!n) return node_ptr(); |
353 | node_ptr first = node_traits::get_next(p); |
354 | |
355 | //count() == 1 or 2, nothing to do |
356 | if(node_traits::get_next(first) == p) return node_ptr(); |
357 | |
358 | //Iterate until p is found to know where the current last node is. |
359 | //If the shift count is less than the size of the list, we can also obtain |
360 | //the position of the new last node after the shift. |
361 | node_ptr old_last(first), next_to_it, new_last(p); |
362 | std::size_t distance = 1; |
363 | while(p != (next_to_it = node_traits::get_next(old_last))){ |
364 | if(++distance > n) |
365 | new_last = node_traits::get_next(new_last); |
366 | old_last = next_to_it; |
367 | } |
368 | //If the shift was bigger or equal than the size, obtain the equivalent |
369 | //forward shifts and find the new last node. |
370 | if(distance <= n){ |
371 | //Now find the equivalent forward shifts. |
372 | //Shortcut the shift with the modulo of the size of the list |
373 | std::size_t new_before_last_pos = (distance - (n % distance))% distance; |
374 | //If the shift is a multiple of the size there is nothing to do |
375 | if(!new_before_last_pos) return node_ptr(); |
376 | |
377 | for( new_last = p |
378 | ; new_before_last_pos-- |
379 | ; new_last = node_traits::get_next(new_last)){ |
380 | //empty |
381 | } |
382 | } |
383 | |
384 | //Now unlink p and link it after the new last node |
385 | base_t::unlink_after(old_last); |
386 | base_t::link_after(new_last, p); |
387 | return new_last; |
388 | } |
389 | }; |
390 | |
391 | /// @cond |
392 | |
393 | template<class NodeTraits> |
394 | struct get_algo<CircularSListAlgorithms, NodeTraits> |
395 | { |
396 | typedef circular_slist_algorithms<NodeTraits> type; |
397 | }; |
398 | |
399 | /// @endcond |
400 | |
401 | } //namespace intrusive |
402 | } //namespace boost |
403 | |
404 | #include <boost/intrusive/detail/config_end.hpp> |
405 | |
406 | #endif //BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP |
407 | |