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1 // Copyright (c) 2005, Google Inc.
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are
6 // met:
7 //
8 // * Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above
11 // copyright notice, this list of conditions and the following disclaimer
12 // in the documentation and/or other materials provided with the
13 // distribution.
14 // * Neither the name of Google Inc. nor the names of its
15 // contributors may be used to endorse or promote products derived from
16 // this software without specific prior written permission.
17 //
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30 // ---
31 // Author: Craig Silverstein
32 //
33 // This is just a very thin wrapper over sparsehashtable.h, just
34 // like sgi stl's stl_hash_set is a very thin wrapper over
35 // stl_hashtable. The major thing we define is operator[], because
36 // we have a concept of a data_type which stl_hashtable doesn't
37 // (it only has a key and a value).
38 //
39 // This is more different from sparse_hash_map than you might think,
40 // because all iterators for sets are const (you obviously can't
41 // change the key, and for sets there is no value).
42 //
43 // We adhere mostly to the STL semantics for hash-set. One important
44 // exception is that insert() invalidates iterators entirely. On the
45 // plus side, though, delete() doesn't invalidate iterators at all, or
46 // even change the ordering of elements.
47 //
48 // Here are a few "power user" tips:
49 //
50 // 1) set_deleted_key():
51 // Unlike STL's hash_map, if you want to use erase() you
52 // must call set_deleted_key() after construction.
53 //
54 // 2) resize(0):
55 // When an item is deleted, its memory isn't freed right
56 // away. This allows you to iterate over a hashtable,
57 // and call erase(), without invalidating the iterator.
58 // To force the memory to be freed, call resize(0).
59 //
60 // 3) set_resizing_parameters(0.0, 0.8):
61 // Setting the shrink_resize_percent to 0.0 guarantees
62 // that the hash table will never shrink.
63 //
64 // Guide to what kind of hash_set to use:
65 // (1) dense_hash_set: fastest, uses the most memory
66 // (2) sparse_hash_set: slowest, uses the least memory
67 // (3) hash_set (STL): in the middle
68 // Typically I use sparse_hash_set when I care about space and/or when
69 // I need to save the hashtable on disk. I use hash_set otherwise. I
70 // don't personally use dense_hash_set ever; the only use of
71 // dense_hash_set I know of is to work around malloc() bugs in some
72 // systems (dense_hash_set has a particularly simple allocation scheme).
73 //
74 // - dense_hash_set has, typically, a factor of 2 memory overhead (if your
75 // data takes up X bytes, the hash_set uses X more bytes in overhead).
76 // - sparse_hash_set has about 2 bits overhead per entry.
77 // - sparse_hash_map can be 3-7 times slower than the others for lookup and,
78 // especially, inserts. See time_hash_map.cc for details.
79 //
80 // See /usr/(local/)?doc/sparsehash-0.1/sparse_hash_set.html
81 // for information about how to use this class.
82
83 #ifndef _SPARSE_HASH_SET_H_
84 #define _SPARSE_HASH_SET_H_
85
86 #include <google/sparsehash/sparseconfig.h>
87 #include <stdio.h> // for FILE * in read()/write()
88 #include <algorithm> // for the default template args
89 #include <functional> // for equal_to
90 #include <memory> // for alloc<>
91 #include <utility> // for pair<>
92 #include HASH_FUN_H // defined in config.h
93 #include <google/sparsehash/sparsehashtable.h>
94
95 _START_GOOGLE_NAMESPACE_
96
97 using STL_NAMESPACE::pair;
98
99 template <class Value,
100 class HashFcn = SPARSEHASH_HASH<Value>, // defined in sparseconfig.h
101 class EqualKey = STL_NAMESPACE::equal_to<Value>,
102 class Alloc = STL_NAMESPACE::allocator<Value> >
103 class sparse_hash_set {
104 private:
105 // Apparently identity is not stl-standard, so we define our own
106 struct Identity {
107 Value& operator()(Value& v) const { return v; }
108 const Value& operator()(const Value& v) const { return v; }
109 };
110
111 // The actual data
112 typedef sparse_hashtable<Value, Value, HashFcn, Identity, EqualKey, Alloc> ht;
113 ht rep;
114
115 public:
116 typedef typename ht::key_type key_type;
117 typedef typename ht::value_type value_type;
118 typedef typename ht::hasher hasher;
119 typedef typename ht::key_equal key_equal;
120
121 typedef typename ht::size_type size_type;
122 typedef typename ht::difference_type difference_type;
123 typedef typename ht::const_pointer pointer;
124 typedef typename ht::const_pointer const_pointer;
125 typedef typename ht::const_reference reference;
126 typedef typename ht::const_reference const_reference;
127
128 typedef typename ht::const_iterator iterator;
129 typedef typename ht::const_iterator const_iterator;
130
131
132 // Iterator functions -- recall all iterators are const
133 iterator begin() const { return rep.begin(); }
134 iterator end() const { return rep.end(); }
135
136
137 // Accessor functions
138 hasher hash_funct() const { return rep.hash_funct(); }
139 key_equal key_eq() const { return rep.key_eq(); }
140
141
142 // Constructors
143 explicit sparse_hash_set(size_type expected_max_items_in_table = 0,
144 const hasher& hf = hasher(),
145 const key_equal& eql = key_equal())
146 : rep(expected_max_items_in_table, hf, eql) { }
147
148 template <class InputIterator>
149 sparse_hash_set(InputIterator f, InputIterator l,
150 size_type expected_max_items_in_table = 0,
151 const hasher& hf = hasher(),
152 const key_equal& eql = key_equal())
153 : rep(expected_max_items_in_table, hf, eql) {
154 rep.insert(f, l);
155 }
156 // We use the default copy constructor
157 // We use the default operator=()
158 // We use the default destructor
159
160 void clear() { rep.clear(); }
161 void swap(sparse_hash_set& hs) { rep.swap(hs.rep); }
162
163
164 // Functions concerning size
165 size_type size() const { return rep.size(); }
166 size_type max_size() const { return rep.max_size(); }
167 bool empty() const { return rep.empty(); }
168 size_type bucket_count() const { return rep.bucket_count(); }
169 size_type max_bucket_count() const { return rep.max_bucket_count(); }
170
171 void resize(size_type hint) { rep.resize(hint); }
172
173 void set_resizing_parameters(float shrink, float grow) {
174 return rep.set_resizing_parameters(shrink, grow);
175 }
176
177 // Lookup routines
178 iterator find(const key_type& key) const { return rep.find(key); }
179
180 size_type count(const key_type& key) const { return rep.count(key); }
181
182 pair<iterator, iterator> equal_range(const key_type& key) const {
183 return rep.equal_range(key);
184 }
185
186 // Insertion routines
187 pair<iterator, bool> insert(const value_type& obj) {
188 pair<typename ht::iterator, bool> p = rep.insert(obj);
189 return pair<iterator, bool>(p.first, p.second); // const to non-const
190 }
191 template <class InputIterator>
192 void insert(InputIterator f, InputIterator l) { rep.insert(f, l); }
193 void insert(const_iterator f, const_iterator l) { rep.insert(f, l); }
194 // required for std::insert_iterator; the passed-in iterator is ignored
195 iterator insert(iterator, const value_type& obj) { return insert(obj).first; }
196
197
198 // Deletion routines
199 // THESE ARE NON-STANDARD! I make you specify an "impossible" key
200 // value to identify deleted buckets. You can change the key as
201 // time goes on, or get rid of it entirely to be insert-only.
202 void set_deleted_key(const key_type& key) { rep.set_deleted_key(key); }
203 void clear_deleted_key() { rep.clear_deleted_key(); }
204
205 // These are standard
206 size_type erase(const key_type& key) { return rep.erase(key); }
207 void erase(iterator it) { rep.erase(it); }
208 void erase(iterator f, iterator l) { rep.erase(f, l); }
209
210
211 // Comparison
212 bool operator==(const sparse_hash_set& hs) const { return rep == hs.rep; }
213 bool operator!=(const sparse_hash_set& hs) const { return rep != hs.rep; }
214
215
216 // I/O -- this is an add-on for writing metainformation to disk
217 bool write_metadata(FILE *fp) { return rep.write_metadata(fp); }
218 bool read_metadata(FILE *fp) { return rep.read_metadata(fp); }
219 bool write_nopointer_data(FILE *fp) { return rep.write_nopointer_data(fp); }
220 bool read_nopointer_data(FILE *fp) { return rep.read_nopointer_data(fp); }
221 };
222
223 template <class Val, class HashFcn, class EqualKey, class Alloc>
224 inline void swap(sparse_hash_set<Val, HashFcn, EqualKey, Alloc>& hs1,
225 sparse_hash_set<Val, HashFcn, EqualKey, Alloc>& hs2) {
226 hs1.swap(hs2);
227 }
228
229 _END_GOOGLE_NAMESPACE_
230
231 #endif /* _SPARSE_HASH_SET_H_ */

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