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comparison: security/sandbox/chromium/base/containers/hash_tables.h

security/sandbox/chromium/base/containers/hash_tables.h

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TOR_BUG_9701
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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 //
5
6 //
7 // Deal with the differences between Microsoft and GNU implemenations
8 // of hash_map. Allows all platforms to use |base::hash_map| and
9 // |base::hash_set|.
10 // eg:
11 // base::hash_map<int> my_map;
12 // base::hash_set<int> my_set;
13 //
14 // NOTE: It is an explicit non-goal of this class to provide a generic hash
15 // function for pointers. If you want to hash a pointers to a particular class,
16 // please define the template specialization elsewhere (for example, in its
17 // header file) and keep it specific to just pointers to that class. This is
18 // because identity hashes are not desirable for all types that might show up
19 // in containers as pointers.
20
21 #ifndef BASE_CONTAINERS_HASH_TABLES_H_
22 #define BASE_CONTAINERS_HASH_TABLES_H_
23
24 #include <utility>
25
26 #include "base/basictypes.h"
27 #include "base/strings/string16.h"
28 #include "build/build_config.h"
29
30 #if defined(COMPILER_MSVC)
31 #include <hash_map>
32 #include <hash_set>
33
34 #define BASE_HASH_NAMESPACE stdext
35
36 #elif defined(COMPILER_GCC)
37 #if defined(OS_ANDROID)
38 #define BASE_HASH_NAMESPACE std
39 #else
40 #define BASE_HASH_NAMESPACE __gnu_cxx
41 #endif
42
43 // This is a hack to disable the gcc 4.4 warning about hash_map and hash_set
44 // being deprecated. We can get rid of this when we upgrade to VS2008 and we
45 // can use <tr1/unordered_map> and <tr1/unordered_set>.
46 #ifdef __DEPRECATED
47 #define CHROME_OLD__DEPRECATED __DEPRECATED
48 #undef __DEPRECATED
49 #endif
50
51 #if defined(OS_ANDROID)
52 #include <hash_map>
53 #include <hash_set>
54 #else
55 #include <ext/hash_map>
56 #include <ext/hash_set>
57 #endif
58
59 #include <string>
60
61 #ifdef CHROME_OLD__DEPRECATED
62 #define __DEPRECATED CHROME_OLD__DEPRECATED
63 #undef CHROME_OLD__DEPRECATED
64 #endif
65
66 namespace BASE_HASH_NAMESPACE {
67
68 #if !defined(OS_ANDROID)
69 // The GNU C++ library provides identity hash functions for many integral types,
70 // but not for |long long|. This hash function will truncate if |size_t| is
71 // narrower than |long long|. This is probably good enough for what we will
72 // use it for.
73
74 #define DEFINE_TRIVIAL_HASH(integral_type) \
75 template<> \
76 struct hash<integral_type> { \
77 std::size_t operator()(integral_type value) const { \
78 return static_cast<std::size_t>(value); \
79 } \
80 }
81
82 DEFINE_TRIVIAL_HASH(long long);
83 DEFINE_TRIVIAL_HASH(unsigned long long);
84
85 #undef DEFINE_TRIVIAL_HASH
86 #endif // !defined(OS_ANDROID)
87
88 // Implement string hash functions so that strings of various flavors can
89 // be used as keys in STL maps and sets. The hash algorithm comes from the
90 // GNU C++ library, in <tr1/functional>. It is duplicated here because GCC
91 // versions prior to 4.3.2 are unable to compile <tr1/functional> when RTTI
92 // is disabled, as it is in our build.
93
94 #define DEFINE_STRING_HASH(string_type) \
95 template<> \
96 struct hash<string_type> { \
97 std::size_t operator()(const string_type& s) const { \
98 std::size_t result = 0; \
99 for (string_type::const_iterator i = s.begin(); i != s.end(); ++i) \
100 result = (result * 131) + *i; \
101 return result; \
102 } \
103 }
104
105 DEFINE_STRING_HASH(std::string);
106 DEFINE_STRING_HASH(string16);
107
108 #undef DEFINE_STRING_HASH
109
110 } // namespace BASE_HASH_NAMESPACE
111
112 #else // COMPILER
113 #error define BASE_HASH_NAMESPACE for your compiler
114 #endif // COMPILER
115
116 namespace base {
117 using BASE_HASH_NAMESPACE::hash_map;
118 using BASE_HASH_NAMESPACE::hash_multimap;
119 using BASE_HASH_NAMESPACE::hash_multiset;
120 using BASE_HASH_NAMESPACE::hash_set;
121
122 // Implement hashing for pairs of at-most 32 bit integer values.
123 // When size_t is 32 bits, we turn the 64-bit hash code into 32 bits by using
124 // multiply-add hashing. This algorithm, as described in
125 // Theorem 4.3.3 of the thesis "Über die Komplexität der Multiplikation in
126 // eingeschränkten Branchingprogrammmodellen" by Woelfel, is:
127 //
128 // h32(x32, y32) = (h64(x32, y32) * rand_odd64 + rand16 * 2^16) % 2^64 / 2^32
129 //
130 // Contact danakj@chromium.org for any questions.
131 inline std::size_t HashInts32(uint32 value1, uint32 value2) {
132 uint64 value1_64 = value1;
133 uint64 hash64 = (value1_64 << 32) | value2;
134
135 if (sizeof(std::size_t) >= sizeof(uint64))
136 return static_cast<std::size_t>(hash64);
137
138 uint64 odd_random = 481046412LL << 32 | 1025306955LL;
139 uint32 shift_random = 10121U << 16;
140
141 hash64 = hash64 * odd_random + shift_random;
142 std::size_t high_bits = static_cast<std::size_t>(
143 hash64 >> (sizeof(uint64) - sizeof(std::size_t)));
144 return high_bits;
145 }
146
147 // Implement hashing for pairs of up-to 64-bit integer values.
148 // We use the compound integer hash method to produce a 64-bit hash code, by
149 // breaking the two 64-bit inputs into 4 32-bit values:
150 // http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000
151 // Then we reduce our result to 32 bits if required, similar to above.
152 inline std::size_t HashInts64(uint64 value1, uint64 value2) {
153 uint32 short_random1 = 842304669U;
154 uint32 short_random2 = 619063811U;
155 uint32 short_random3 = 937041849U;
156 uint32 short_random4 = 3309708029U;
157
158 uint32 value1a = static_cast<uint32>(value1 & 0xffffffff);
159 uint32 value1b = static_cast<uint32>((value1 >> 32) & 0xffffffff);
160 uint32 value2a = static_cast<uint32>(value2 & 0xffffffff);
161 uint32 value2b = static_cast<uint32>((value2 >> 32) & 0xffffffff);
162
163 uint64 product1 = static_cast<uint64>(value1a) * short_random1;
164 uint64 product2 = static_cast<uint64>(value1b) * short_random2;
165 uint64 product3 = static_cast<uint64>(value2a) * short_random3;
166 uint64 product4 = static_cast<uint64>(value2b) * short_random4;
167
168 uint64 hash64 = product1 + product2 + product3 + product4;
169
170 if (sizeof(std::size_t) >= sizeof(uint64))
171 return static_cast<std::size_t>(hash64);
172
173 uint64 odd_random = 1578233944LL << 32 | 194370989LL;
174 uint32 shift_random = 20591U << 16;
175
176 hash64 = hash64 * odd_random + shift_random;
177 std::size_t high_bits = static_cast<std::size_t>(
178 hash64 >> (sizeof(uint64) - sizeof(std::size_t)));
179 return high_bits;
180 }
181
182 #define DEFINE_32BIT_PAIR_HASH(Type1, Type2) \
183 inline std::size_t HashPair(Type1 value1, Type2 value2) { \
184 return HashInts32(value1, value2); \
185 }
186
187 DEFINE_32BIT_PAIR_HASH(int16, int16);
188 DEFINE_32BIT_PAIR_HASH(int16, uint16);
189 DEFINE_32BIT_PAIR_HASH(int16, int32);
190 DEFINE_32BIT_PAIR_HASH(int16, uint32);
191 DEFINE_32BIT_PAIR_HASH(uint16, int16);
192 DEFINE_32BIT_PAIR_HASH(uint16, uint16);
193 DEFINE_32BIT_PAIR_HASH(uint16, int32);
194 DEFINE_32BIT_PAIR_HASH(uint16, uint32);
195 DEFINE_32BIT_PAIR_HASH(int32, int16);
196 DEFINE_32BIT_PAIR_HASH(int32, uint16);
197 DEFINE_32BIT_PAIR_HASH(int32, int32);
198 DEFINE_32BIT_PAIR_HASH(int32, uint32);
199 DEFINE_32BIT_PAIR_HASH(uint32, int16);
200 DEFINE_32BIT_PAIR_HASH(uint32, uint16);
201 DEFINE_32BIT_PAIR_HASH(uint32, int32);
202 DEFINE_32BIT_PAIR_HASH(uint32, uint32);
203
204 #undef DEFINE_32BIT_PAIR_HASH
205
206 #define DEFINE_64BIT_PAIR_HASH(Type1, Type2) \
207 inline std::size_t HashPair(Type1 value1, Type2 value2) { \
208 return HashInts64(value1, value2); \
209 }
210
211 DEFINE_64BIT_PAIR_HASH(int16, int64);
212 DEFINE_64BIT_PAIR_HASH(int16, uint64);
213 DEFINE_64BIT_PAIR_HASH(uint16, int64);
214 DEFINE_64BIT_PAIR_HASH(uint16, uint64);
215 DEFINE_64BIT_PAIR_HASH(int32, int64);
216 DEFINE_64BIT_PAIR_HASH(int32, uint64);
217 DEFINE_64BIT_PAIR_HASH(uint32, int64);
218 DEFINE_64BIT_PAIR_HASH(uint32, uint64);
219 DEFINE_64BIT_PAIR_HASH(int64, int16);
220 DEFINE_64BIT_PAIR_HASH(int64, uint16);
221 DEFINE_64BIT_PAIR_HASH(int64, int32);
222 DEFINE_64BIT_PAIR_HASH(int64, uint32);
223 DEFINE_64BIT_PAIR_HASH(int64, int64);
224 DEFINE_64BIT_PAIR_HASH(int64, uint64);
225 DEFINE_64BIT_PAIR_HASH(uint64, int16);
226 DEFINE_64BIT_PAIR_HASH(uint64, uint16);
227 DEFINE_64BIT_PAIR_HASH(uint64, int32);
228 DEFINE_64BIT_PAIR_HASH(uint64, uint32);
229 DEFINE_64BIT_PAIR_HASH(uint64, int64);
230 DEFINE_64BIT_PAIR_HASH(uint64, uint64);
231
232 #undef DEFINE_64BIT_PAIR_HASH
233 } // namespace base
234
235 namespace BASE_HASH_NAMESPACE {
236
237 // Implement methods for hashing a pair of integers, so they can be used as
238 // keys in STL containers.
239
240 #if defined(COMPILER_MSVC)
241
242 template<typename Type1, typename Type2>
243 inline std::size_t hash_value(const std::pair<Type1, Type2>& value) {
244 return base::HashPair(value.first, value.second);
245 }
246
247 #elif defined(COMPILER_GCC)
248 template<typename Type1, typename Type2>
249 struct hash<std::pair<Type1, Type2> > {
250 std::size_t operator()(std::pair<Type1, Type2> value) const {
251 return base::HashPair(value.first, value.second);
252 }
253 };
254
255 #else
256 #error define hash<std::pair<Type1, Type2> > for your compiler
257 #endif // COMPILER
258
259 }
260
261 #undef DEFINE_PAIR_HASH_FUNCTION_START
262 #undef DEFINE_PAIR_HASH_FUNCTION_END
263
264 #endif // BASE_CONTAINERS_HASH_TABLES_H_

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