]>
Commit | Line | Data |
---|---|---|
7c673cae FG |
1 | // |
2 | // detail/hash_map.hpp | |
3 | // ~~~~~~~~~~~~~~~~~~~ | |
4 | // | |
5 | // Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com) | |
6 | // | |
7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
9 | // | |
10 | ||
11 | #ifndef BOOST_ASIO_DETAIL_HASH_MAP_HPP | |
12 | #define BOOST_ASIO_DETAIL_HASH_MAP_HPP | |
13 | ||
14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) | |
15 | # pragma once | |
16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) | |
17 | ||
18 | #include <boost/asio/detail/config.hpp> | |
19 | #include <list> | |
20 | #include <utility> | |
21 | #include <boost/asio/detail/assert.hpp> | |
22 | #include <boost/asio/detail/noncopyable.hpp> | |
23 | ||
24 | #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__) | |
25 | # include <boost/asio/detail/socket_types.hpp> | |
26 | #endif // defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__) | |
27 | ||
28 | #include <boost/asio/detail/push_options.hpp> | |
29 | ||
30 | namespace boost { | |
31 | namespace asio { | |
32 | namespace detail { | |
33 | ||
34 | inline std::size_t calculate_hash_value(int i) | |
35 | { | |
36 | return static_cast<std::size_t>(i); | |
37 | } | |
38 | ||
39 | inline std::size_t calculate_hash_value(void* p) | |
40 | { | |
41 | return reinterpret_cast<std::size_t>(p) | |
42 | + (reinterpret_cast<std::size_t>(p) >> 3); | |
43 | } | |
44 | ||
45 | #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__) | |
46 | inline std::size_t calculate_hash_value(SOCKET s) | |
47 | { | |
48 | return static_cast<std::size_t>(s); | |
49 | } | |
50 | #endif // defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__) | |
51 | ||
52 | // Note: assumes K and V are POD types. | |
53 | template <typename K, typename V> | |
54 | class hash_map | |
55 | : private noncopyable | |
56 | { | |
57 | public: | |
58 | // The type of a value in the map. | |
59 | typedef std::pair<K, V> value_type; | |
60 | ||
61 | // The type of a non-const iterator over the hash map. | |
62 | typedef typename std::list<value_type>::iterator iterator; | |
63 | ||
64 | // The type of a const iterator over the hash map. | |
65 | typedef typename std::list<value_type>::const_iterator const_iterator; | |
66 | ||
67 | // Constructor. | |
68 | hash_map() | |
69 | : size_(0), | |
70 | buckets_(0), | |
71 | num_buckets_(0) | |
72 | { | |
73 | } | |
74 | ||
75 | // Destructor. | |
76 | ~hash_map() | |
77 | { | |
78 | delete[] buckets_; | |
79 | } | |
80 | ||
81 | // Get an iterator for the beginning of the map. | |
82 | iterator begin() | |
83 | { | |
84 | return values_.begin(); | |
85 | } | |
86 | ||
87 | // Get an iterator for the beginning of the map. | |
88 | const_iterator begin() const | |
89 | { | |
90 | return values_.begin(); | |
91 | } | |
92 | ||
93 | // Get an iterator for the end of the map. | |
94 | iterator end() | |
95 | { | |
96 | return values_.end(); | |
97 | } | |
98 | ||
99 | // Get an iterator for the end of the map. | |
100 | const_iterator end() const | |
101 | { | |
102 | return values_.end(); | |
103 | } | |
104 | ||
105 | // Check whether the map is empty. | |
106 | bool empty() const | |
107 | { | |
108 | return values_.empty(); | |
109 | } | |
110 | ||
111 | // Find an entry in the map. | |
112 | iterator find(const K& k) | |
113 | { | |
114 | if (num_buckets_) | |
115 | { | |
116 | size_t bucket = calculate_hash_value(k) % num_buckets_; | |
117 | iterator it = buckets_[bucket].first; | |
118 | if (it == values_.end()) | |
119 | return values_.end(); | |
120 | iterator end_it = buckets_[bucket].last; | |
121 | ++end_it; | |
122 | while (it != end_it) | |
123 | { | |
124 | if (it->first == k) | |
125 | return it; | |
126 | ++it; | |
127 | } | |
128 | } | |
129 | return values_.end(); | |
130 | } | |
131 | ||
132 | // Find an entry in the map. | |
133 | const_iterator find(const K& k) const | |
134 | { | |
135 | if (num_buckets_) | |
136 | { | |
137 | size_t bucket = calculate_hash_value(k) % num_buckets_; | |
138 | const_iterator it = buckets_[bucket].first; | |
139 | if (it == values_.end()) | |
140 | return it; | |
141 | const_iterator end_it = buckets_[bucket].last; | |
142 | ++end_it; | |
143 | while (it != end_it) | |
144 | { | |
145 | if (it->first == k) | |
146 | return it; | |
147 | ++it; | |
148 | } | |
149 | } | |
150 | return values_.end(); | |
151 | } | |
152 | ||
153 | // Insert a new entry into the map. | |
154 | std::pair<iterator, bool> insert(const value_type& v) | |
155 | { | |
156 | if (size_ + 1 >= num_buckets_) | |
157 | rehash(hash_size(size_ + 1)); | |
158 | size_t bucket = calculate_hash_value(v.first) % num_buckets_; | |
159 | iterator it = buckets_[bucket].first; | |
160 | if (it == values_.end()) | |
161 | { | |
162 | buckets_[bucket].first = buckets_[bucket].last = | |
163 | values_insert(values_.end(), v); | |
164 | ++size_; | |
165 | return std::pair<iterator, bool>(buckets_[bucket].last, true); | |
166 | } | |
167 | iterator end_it = buckets_[bucket].last; | |
168 | ++end_it; | |
169 | while (it != end_it) | |
170 | { | |
171 | if (it->first == v.first) | |
172 | return std::pair<iterator, bool>(it, false); | |
173 | ++it; | |
174 | } | |
175 | buckets_[bucket].last = values_insert(end_it, v); | |
176 | ++size_; | |
177 | return std::pair<iterator, bool>(buckets_[bucket].last, true); | |
178 | } | |
179 | ||
180 | // Erase an entry from the map. | |
181 | void erase(iterator it) | |
182 | { | |
183 | BOOST_ASIO_ASSERT(it != values_.end()); | |
184 | BOOST_ASIO_ASSERT(num_buckets_ != 0); | |
185 | ||
186 | size_t bucket = calculate_hash_value(it->first) % num_buckets_; | |
187 | bool is_first = (it == buckets_[bucket].first); | |
188 | bool is_last = (it == buckets_[bucket].last); | |
189 | if (is_first && is_last) | |
190 | buckets_[bucket].first = buckets_[bucket].last = values_.end(); | |
191 | else if (is_first) | |
192 | ++buckets_[bucket].first; | |
193 | else if (is_last) | |
194 | --buckets_[bucket].last; | |
195 | ||
196 | values_erase(it); | |
197 | --size_; | |
198 | } | |
199 | ||
200 | // Erase a key from the map. | |
201 | void erase(const K& k) | |
202 | { | |
203 | iterator it = find(k); | |
204 | if (it != values_.end()) | |
205 | erase(it); | |
206 | } | |
207 | ||
208 | // Remove all entries from the map. | |
209 | void clear() | |
210 | { | |
211 | // Clear the values. | |
212 | values_.clear(); | |
213 | size_ = 0; | |
214 | ||
215 | // Initialise all buckets to empty. | |
216 | iterator end_it = values_.end(); | |
217 | for (size_t i = 0; i < num_buckets_; ++i) | |
218 | buckets_[i].first = buckets_[i].last = end_it; | |
219 | } | |
220 | ||
221 | private: | |
222 | // Calculate the hash size for the specified number of elements. | |
223 | static std::size_t hash_size(std::size_t num_elems) | |
224 | { | |
225 | static std::size_t sizes[] = | |
226 | { | |
227 | #if defined(BOOST_ASIO_HASH_MAP_BUCKETS) | |
228 | BOOST_ASIO_HASH_MAP_BUCKETS | |
229 | #else // BOOST_ASIO_HASH_MAP_BUCKETS | |
230 | 3, 13, 23, 53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593, | |
231 | 49157, 98317, 196613, 393241, 786433, 1572869, 3145739, 6291469, | |
232 | 12582917, 25165843 | |
233 | #endif // BOOST_ASIO_HASH_MAP_BUCKETS | |
234 | }; | |
235 | const std::size_t nth_size = sizeof(sizes) / sizeof(std::size_t) - 1; | |
236 | for (std::size_t i = 0; i < nth_size; ++i) | |
237 | if (num_elems < sizes[i]) | |
238 | return sizes[i]; | |
239 | return sizes[nth_size]; | |
240 | } | |
241 | ||
242 | // Re-initialise the hash from the values already contained in the list. | |
243 | void rehash(std::size_t num_buckets) | |
244 | { | |
245 | if (num_buckets == num_buckets_) | |
246 | return; | |
247 | num_buckets_ = num_buckets; | |
248 | BOOST_ASIO_ASSERT(num_buckets_ != 0); | |
249 | ||
250 | iterator end_iter = values_.end(); | |
251 | ||
252 | // Update number of buckets and initialise all buckets to empty. | |
253 | bucket_type* tmp = new bucket_type[num_buckets_]; | |
254 | delete[] buckets_; | |
255 | buckets_ = tmp; | |
256 | for (std::size_t i = 0; i < num_buckets_; ++i) | |
257 | buckets_[i].first = buckets_[i].last = end_iter; | |
258 | ||
259 | // Put all values back into the hash. | |
260 | iterator iter = values_.begin(); | |
261 | while (iter != end_iter) | |
262 | { | |
263 | std::size_t bucket = calculate_hash_value(iter->first) % num_buckets_; | |
264 | if (buckets_[bucket].last == end_iter) | |
265 | { | |
266 | buckets_[bucket].first = buckets_[bucket].last = iter++; | |
267 | } | |
268 | else if (++buckets_[bucket].last == iter) | |
269 | { | |
270 | ++iter; | |
271 | } | |
272 | else | |
273 | { | |
274 | values_.splice(buckets_[bucket].last, values_, iter++); | |
275 | --buckets_[bucket].last; | |
276 | } | |
277 | } | |
278 | } | |
279 | ||
280 | // Insert an element into the values list by splicing from the spares list, | |
281 | // if a spare is available, and otherwise by inserting a new element. | |
282 | iterator values_insert(iterator it, const value_type& v) | |
283 | { | |
284 | if (spares_.empty()) | |
285 | { | |
286 | return values_.insert(it, v); | |
287 | } | |
288 | else | |
289 | { | |
290 | spares_.front() = v; | |
291 | values_.splice(it, spares_, spares_.begin()); | |
292 | return --it; | |
293 | } | |
294 | } | |
295 | ||
296 | // Erase an element from the values list by splicing it to the spares list. | |
297 | void values_erase(iterator it) | |
298 | { | |
299 | *it = value_type(); | |
300 | spares_.splice(spares_.begin(), values_, it); | |
301 | } | |
302 | ||
303 | // The number of elements in the hash. | |
304 | std::size_t size_; | |
305 | ||
306 | // The list of all values in the hash map. | |
307 | std::list<value_type> values_; | |
308 | ||
309 | // The list of spare nodes waiting to be recycled. Assumes that POD types only | |
310 | // are stored in the hash map. | |
311 | std::list<value_type> spares_; | |
312 | ||
313 | // The type for a bucket in the hash table. | |
314 | struct bucket_type | |
315 | { | |
316 | iterator first; | |
317 | iterator last; | |
318 | }; | |
319 | ||
320 | // The buckets in the hash. | |
321 | bucket_type* buckets_; | |
322 | ||
323 | // The number of buckets in the hash. | |
324 | std::size_t num_buckets_; | |
325 | }; | |
326 | ||
327 | } // namespace detail | |
328 | } // namespace asio | |
329 | } // namespace boost | |
330 | ||
331 | #include <boost/asio/detail/pop_options.hpp> | |
332 | ||
333 | #endif // BOOST_ASIO_DETAIL_HASH_MAP_HPP |