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1 | //======================================================================= |
2 | // Copyright (c) Aaron Windsor 2007 | |
3 | // | |
4 | // Distributed under the Boost Software License, Version 1.0. (See | |
5 | // accompanying file LICENSE_1_0.txt or copy at | |
6 | // http://www.boost.org/LICENSE_1_0.txt) | |
7 | //======================================================================= | |
8 | ||
9 | #ifndef __FACE_HANDLES_HPP__ | |
10 | #define __FACE_HANDLES_HPP__ | |
11 | ||
12 | ||
13 | #include <list> | |
14 | #include <boost/graph/graph_traits.hpp> | |
15 | #include <boost/shared_ptr.hpp> | |
16 | ||
17 | ||
18 | // A "face handle" is an optimization meant to serve two purposes in | |
19 | // the implementation of the Boyer-Myrvold planarity test: (1) it holds | |
20 | // the partial planar embedding of a particular vertex as it's being | |
21 | // constructed, and (2) it allows for efficient traversal around the | |
22 | // outer face of the partial embedding at that particular vertex. A face | |
23 | // handle is lightweight, just a shared pointer to the actual implementation, | |
24 | // since it is passed around/copied liberally in the algorithm. It consists | |
25 | // of an "anchor" (the actual vertex it's associated with) as well as a | |
26 | // sequence of edges. The functions first_vertex/second_vertex and | |
27 | // first_edge/second_edge allow fast access to the beginning and end of the | |
28 | // stored sequence, which allows one to traverse the outer face of the partial | |
29 | // planar embedding as it's being created. | |
30 | // | |
31 | // There are some policies below that define the contents of the face handles: | |
32 | // in the case no embedding is needed (for example, if one just wants to use | |
33 | // the Boyer-Myrvold algorithm as a true/false test for planarity, the | |
34 | // no_embedding class can be passed as the StoreEmbedding policy. Otherwise, | |
35 | // either std_list (which uses as std::list) or recursive_lazy_list can be | |
36 | // passed as this policy. recursive_lazy_list has the best theoretical | |
37 | // performance (O(n) for a sequence of interleaved concatenations and reversals | |
38 | // of the underlying list), but I've noticed little difference between std_list | |
39 | // and recursive_lazy_list in my tests, even though using std_list changes | |
40 | // the worst-case complexity of the planarity test to O(n^2) | |
41 | // | |
42 | // Another policy is StoreOldHandlesPolicy, which specifies whether or not | |
43 | // to keep a record of the previous first/second vertex/edge - this is needed | |
44 | // if a Kuratowski subgraph needs to be isolated. | |
45 | ||
46 | ||
47 | namespace boost { namespace graph { namespace detail { | |
48 | ||
49 | ||
50 | //face handle policies | |
51 | ||
52 | //EmbeddingStorage policy | |
53 | struct store_embedding {}; | |
54 | struct recursive_lazy_list : public store_embedding {}; | |
55 | struct std_list : public store_embedding {}; | |
56 | struct no_embedding {}; | |
57 | ||
58 | //StoreOldHandlesPolicy | |
59 | struct store_old_handles {}; | |
60 | struct no_old_handles {}; | |
61 | ||
62 | ||
63 | ||
64 | ||
65 | template<typename DataType> | |
66 | struct lazy_list_node | |
67 | { | |
68 | typedef shared_ptr< lazy_list_node<DataType> > ptr_t; | |
69 | ||
70 | lazy_list_node(const DataType& data) : | |
71 | m_reversed(false), | |
72 | m_data(data), | |
73 | m_has_data(true) | |
74 | {} | |
75 | ||
76 | lazy_list_node(ptr_t left_child, ptr_t right_child) : | |
77 | m_reversed(false), | |
78 | m_has_data(false), | |
79 | m_left_child(left_child), | |
80 | m_right_child(right_child) | |
81 | {} | |
82 | ||
83 | bool m_reversed; | |
84 | DataType m_data; | |
85 | bool m_has_data; | |
86 | shared_ptr<lazy_list_node> m_left_child; | |
87 | shared_ptr<lazy_list_node> m_right_child; | |
88 | }; | |
89 | ||
90 | ||
91 | ||
92 | template <typename StoreOldHandlesPolicy, typename Vertex, typename Edge> | |
93 | struct old_handles_storage; | |
94 | ||
95 | template <typename Vertex, typename Edge> | |
96 | struct old_handles_storage<store_old_handles, Vertex, Edge> | |
97 | { | |
98 | Vertex first_vertex; | |
99 | Vertex second_vertex; | |
100 | Edge first_edge; | |
101 | Edge second_edge; | |
102 | }; | |
103 | ||
104 | template <typename Vertex, typename Edge> | |
105 | struct old_handles_storage<no_old_handles, Vertex, Edge> | |
106 | {}; | |
107 | ||
108 | ||
109 | ||
110 | ||
111 | ||
112 | ||
113 | template <typename StoreEmbeddingPolicy, typename Edge> | |
114 | struct edge_list_storage; | |
115 | ||
116 | ||
117 | ||
118 | ||
119 | ||
120 | template <typename Edge> | |
121 | struct edge_list_storage<no_embedding, Edge> | |
122 | { | |
123 | typedef void type; | |
124 | ||
125 | void push_back(Edge) {} | |
126 | void push_front(Edge) {} | |
127 | void reverse() {} | |
128 | void concat_front(edge_list_storage<no_embedding,Edge>) {} | |
129 | void concat_back(edge_list_storage<no_embedding,Edge>) {} | |
130 | template <typename OutputIterator> | |
131 | void get_list(OutputIterator) {} | |
132 | }; | |
133 | ||
134 | ||
135 | ||
136 | ||
137 | ||
138 | template <typename Edge> | |
139 | struct edge_list_storage<recursive_lazy_list, Edge> | |
140 | { | |
141 | typedef lazy_list_node<Edge> node_type; | |
142 | typedef shared_ptr< node_type > type; | |
143 | type value; | |
144 | ||
145 | void push_back(Edge e) | |
146 | { | |
147 | type new_node(new node_type(e)); | |
148 | value = type(new node_type(value, new_node)); | |
149 | } | |
150 | ||
151 | void push_front(Edge e) | |
152 | { | |
153 | type new_node(new node_type(e)); | |
154 | value = type(new node_type(new_node, value)); | |
155 | } | |
156 | ||
157 | void reverse() | |
158 | { | |
159 | value->m_reversed = !value->m_reversed; | |
160 | } | |
161 | ||
162 | void concat_front(edge_list_storage<recursive_lazy_list, Edge> other) | |
163 | { | |
164 | value = type(new node_type(other.value, value)); | |
165 | } | |
166 | ||
167 | void concat_back(edge_list_storage<recursive_lazy_list, Edge> other) | |
168 | { | |
169 | value = type(new node_type(value, other.value)); | |
170 | } | |
171 | ||
172 | template <typename OutputIterator> | |
173 | void get_list(OutputIterator out) | |
174 | { | |
175 | get_list_helper(out, value); | |
176 | } | |
177 | ||
178 | private: | |
179 | ||
180 | template <typename OutputIterator> | |
181 | void get_list_helper(OutputIterator o_itr, | |
182 | type root, | |
183 | bool flipped = false | |
184 | ) | |
185 | { | |
186 | if (!root) | |
187 | return; | |
188 | ||
189 | if (root->m_has_data) | |
190 | *o_itr = root->m_data; | |
191 | ||
192 | if ((flipped && !root->m_reversed) || | |
193 | (!flipped && root->m_reversed) | |
194 | ) | |
195 | { | |
196 | get_list_helper(o_itr, root->m_right_child, true); | |
197 | get_list_helper(o_itr, root->m_left_child, true); | |
198 | } | |
199 | else | |
200 | { | |
201 | get_list_helper(o_itr, root->m_left_child, false); | |
202 | get_list_helper(o_itr, root->m_right_child, false); | |
203 | } | |
204 | ||
205 | } | |
206 | ||
207 | }; | |
208 | ||
209 | ||
210 | ||
211 | ||
212 | ||
213 | template <typename Edge> | |
214 | struct edge_list_storage<std_list, Edge> | |
215 | { | |
216 | typedef std::list<Edge> type; | |
217 | type value; | |
218 | ||
219 | void push_back(Edge e) | |
220 | { | |
221 | value.push_back(e); | |
222 | } | |
223 | ||
224 | void push_front(Edge e) | |
225 | { | |
226 | value.push_front(e); | |
227 | } | |
228 | ||
229 | void reverse() | |
230 | { | |
231 | value.reverse(); | |
232 | } | |
233 | ||
234 | void concat_front(edge_list_storage<std_list,Edge> other) | |
235 | { | |
236 | value.splice(value.begin(), other.value); | |
237 | } | |
238 | ||
239 | void concat_back(edge_list_storage<std_list, Edge> other) | |
240 | { | |
241 | value.splice(value.end(), other.value); | |
242 | } | |
243 | ||
244 | template <typename OutputIterator> | |
245 | void get_list(OutputIterator out) | |
246 | { | |
247 | std::copy(value.begin(), value.end(), out); | |
248 | } | |
249 | ||
250 | }; | |
251 | ||
252 | ||
253 | ||
254 | ||
255 | ||
256 | ||
257 | ||
258 | template<typename Graph, | |
259 | typename StoreOldHandlesPolicy, | |
260 | typename StoreEmbeddingPolicy | |
261 | > | |
262 | struct face_handle_impl | |
263 | { | |
264 | typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; | |
265 | typedef typename graph_traits<Graph>::edge_descriptor edge_t; | |
266 | typedef typename edge_list_storage<StoreEmbeddingPolicy, edge_t>::type | |
267 | edge_list_storage_t; | |
268 | ||
269 | ||
270 | face_handle_impl() : | |
271 | cached_first_vertex(graph_traits<Graph>::null_vertex()), | |
272 | cached_second_vertex(graph_traits<Graph>::null_vertex()), | |
273 | true_first_vertex(graph_traits<Graph>::null_vertex()), | |
274 | true_second_vertex(graph_traits<Graph>::null_vertex()), | |
275 | anchor(graph_traits<Graph>::null_vertex()) | |
276 | { | |
277 | initialize_old_vertices_dispatch(StoreOldHandlesPolicy()); | |
278 | } | |
279 | ||
280 | void initialize_old_vertices_dispatch(store_old_handles) | |
281 | { | |
282 | old_handles.first_vertex = graph_traits<Graph>::null_vertex(); | |
283 | old_handles.second_vertex = graph_traits<Graph>::null_vertex(); | |
284 | } | |
285 | ||
286 | void initialize_old_vertices_dispatch(no_old_handles) {} | |
287 | ||
288 | vertex_t cached_first_vertex; | |
289 | vertex_t cached_second_vertex; | |
290 | vertex_t true_first_vertex; | |
291 | vertex_t true_second_vertex; | |
292 | vertex_t anchor; | |
293 | edge_t cached_first_edge; | |
294 | edge_t cached_second_edge; | |
295 | ||
296 | edge_list_storage<StoreEmbeddingPolicy, edge_t> edge_list; | |
297 | old_handles_storage<StoreOldHandlesPolicy, vertex_t, edge_t> old_handles; | |
298 | ||
299 | }; | |
300 | ||
301 | ||
302 | ||
303 | ||
304 | ||
305 | ||
306 | ||
307 | ||
308 | ||
309 | ||
310 | ||
311 | template <typename Graph, | |
312 | typename StoreOldHandlesPolicy = store_old_handles, | |
313 | typename StoreEmbeddingPolicy = recursive_lazy_list | |
314 | > | |
315 | class face_handle | |
316 | { | |
317 | public: | |
318 | typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; | |
319 | typedef typename graph_traits<Graph>::edge_descriptor edge_t; | |
320 | typedef face_handle_impl | |
321 | <Graph, StoreOldHandlesPolicy, StoreEmbeddingPolicy> impl_t; | |
322 | typedef face_handle | |
323 | <Graph, StoreOldHandlesPolicy, StoreEmbeddingPolicy> self_t; | |
324 | ||
325 | face_handle(vertex_t anchor = graph_traits<Graph>::null_vertex()) : | |
326 | pimpl(new impl_t()) | |
327 | { | |
328 | pimpl->anchor = anchor; | |
329 | } | |
330 | ||
331 | face_handle(vertex_t anchor, edge_t initial_edge, const Graph& g) : | |
332 | pimpl(new impl_t()) | |
333 | { | |
334 | vertex_t s(source(initial_edge,g)); | |
335 | vertex_t t(target(initial_edge,g)); | |
336 | vertex_t other_vertex = s == anchor ? t : s; | |
337 | pimpl->anchor = anchor; | |
338 | pimpl->cached_first_edge = initial_edge; | |
339 | pimpl->cached_second_edge = initial_edge; | |
340 | pimpl->cached_first_vertex = other_vertex; | |
341 | pimpl->cached_second_vertex = other_vertex; | |
342 | pimpl->true_first_vertex = other_vertex; | |
343 | pimpl->true_second_vertex = other_vertex; | |
344 | ||
345 | pimpl->edge_list.push_back(initial_edge); | |
346 | store_old_face_handles_dispatch(StoreOldHandlesPolicy()); | |
347 | } | |
348 | ||
349 | //default copy construction, assignment okay. | |
350 | ||
351 | void push_first(edge_t e, const Graph& g) | |
352 | { | |
353 | pimpl->edge_list.push_front(e); | |
354 | pimpl->cached_first_vertex = pimpl->true_first_vertex = | |
355 | source(e, g) == pimpl->anchor ? target(e,g) : source(e,g); | |
356 | pimpl->cached_first_edge = e; | |
357 | } | |
358 | ||
359 | void push_second(edge_t e, const Graph& g) | |
360 | { | |
361 | pimpl->edge_list.push_back(e); | |
362 | pimpl->cached_second_vertex = pimpl->true_second_vertex = | |
363 | source(e, g) == pimpl->anchor ? target(e,g) : source(e,g); | |
364 | pimpl->cached_second_edge = e; | |
365 | } | |
366 | ||
367 | inline void store_old_face_handles() | |
368 | { | |
369 | store_old_face_handles_dispatch(StoreOldHandlesPolicy()); | |
370 | } | |
371 | ||
372 | inline vertex_t first_vertex() const | |
373 | { | |
374 | return pimpl->cached_first_vertex; | |
375 | } | |
376 | ||
377 | inline vertex_t second_vertex() const | |
378 | { | |
379 | return pimpl->cached_second_vertex; | |
380 | } | |
381 | ||
382 | inline vertex_t true_first_vertex() const | |
383 | { | |
384 | return pimpl->true_first_vertex; | |
385 | } | |
386 | ||
387 | inline vertex_t true_second_vertex() const | |
388 | { | |
389 | return pimpl->true_second_vertex; | |
390 | } | |
391 | ||
392 | inline vertex_t old_first_vertex() const | |
393 | { | |
394 | return pimpl->old_handles.first_vertex; | |
395 | } | |
396 | ||
397 | inline vertex_t old_second_vertex() const | |
398 | { | |
399 | return pimpl->old_handles.second_vertex; | |
400 | } | |
401 | ||
402 | inline edge_t old_first_edge() const | |
403 | { | |
404 | return pimpl->old_handles.first_edge; | |
405 | } | |
406 | ||
407 | inline edge_t old_second_edge() const | |
408 | { | |
409 | return pimpl->old_handles.second_edge; | |
410 | } | |
411 | ||
412 | inline edge_t first_edge() const | |
413 | { | |
414 | return pimpl->cached_first_edge; | |
415 | } | |
416 | ||
417 | inline edge_t second_edge() const | |
418 | { | |
419 | return pimpl->cached_second_edge; | |
420 | } | |
421 | ||
422 | inline vertex_t get_anchor() const | |
423 | { | |
424 | return pimpl->anchor; | |
425 | } | |
426 | ||
427 | void glue_first_to_second | |
428 | (face_handle<Graph,StoreOldHandlesPolicy,StoreEmbeddingPolicy>& bottom) | |
429 | { | |
430 | pimpl->edge_list.concat_front(bottom.pimpl->edge_list); | |
431 | pimpl->true_first_vertex = bottom.pimpl->true_first_vertex; | |
432 | pimpl->cached_first_vertex = bottom.pimpl->cached_first_vertex; | |
433 | pimpl->cached_first_edge = bottom.pimpl->cached_first_edge; | |
434 | } | |
435 | ||
436 | void glue_second_to_first | |
437 | (face_handle<Graph,StoreOldHandlesPolicy,StoreEmbeddingPolicy>& bottom) | |
438 | { | |
439 | pimpl->edge_list.concat_back(bottom.pimpl->edge_list); | |
440 | pimpl->true_second_vertex = bottom.pimpl->true_second_vertex; | |
441 | pimpl->cached_second_vertex = bottom.pimpl->cached_second_vertex; | |
442 | pimpl->cached_second_edge = bottom.pimpl->cached_second_edge; | |
443 | } | |
444 | ||
445 | void flip() | |
446 | { | |
447 | pimpl->edge_list.reverse(); | |
448 | std::swap(pimpl->true_first_vertex, pimpl->true_second_vertex); | |
449 | std::swap(pimpl->cached_first_vertex, pimpl->cached_second_vertex); | |
450 | std::swap(pimpl->cached_first_edge, pimpl->cached_second_edge); | |
451 | } | |
452 | ||
453 | template <typename OutputIterator> | |
454 | void get_list(OutputIterator o_itr) | |
455 | { | |
456 | pimpl->edge_list.get_list(o_itr); | |
457 | } | |
458 | ||
459 | void reset_vertex_cache() | |
460 | { | |
461 | pimpl->cached_first_vertex = pimpl->true_first_vertex; | |
462 | pimpl->cached_second_vertex = pimpl->true_second_vertex; | |
463 | } | |
464 | ||
465 | inline void set_first_vertex(vertex_t v) | |
466 | { | |
467 | pimpl->cached_first_vertex = v; | |
468 | } | |
469 | ||
470 | inline void set_second_vertex(vertex_t v) | |
471 | { | |
472 | pimpl->cached_second_vertex = v; | |
473 | } | |
474 | ||
475 | private: | |
476 | ||
477 | void store_old_face_handles_dispatch(store_old_handles) | |
478 | { | |
479 | pimpl->old_handles.first_vertex = pimpl->true_first_vertex; | |
480 | pimpl->old_handles.second_vertex = pimpl->true_second_vertex; | |
481 | pimpl->old_handles.first_edge = pimpl->cached_first_edge; | |
482 | pimpl->old_handles.second_edge = pimpl->cached_second_edge; | |
483 | } | |
484 | ||
485 | void store_old_face_handles_dispatch(no_old_handles) {} | |
486 | ||
487 | ||
488 | ||
489 | boost::shared_ptr<impl_t> pimpl; | |
490 | ||
491 | }; | |
492 | ||
493 | ||
494 | } /* namespace detail */ } /* namespace graph */ } /* namespace boost */ | |
495 | ||
496 | ||
497 | #endif //__FACE_HANDLES_HPP__ |