1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc. All rights reserved.
3// https://developers.google.com/protocol-buffers/
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are
7// met:
8//
9// * Redistributions of source code must retain the above copyright
10// notice, this list of conditions and the following disclaimer.
11// * Redistributions in binary form must reproduce the above
12// copyright notice, this list of conditions and the following disclaimer
13// in the documentation and/or other materials provided with the
14// distribution.
15// * Neither the name of Google Inc. nor the names of its
16// contributors may be used to endorse or promote products derived from
17// this software without specific prior written permission.
18//
19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31// Author: kenton@google.com (Kenton Varda)
32
33#ifndef GOOGLE_PROTOBUF_STUBS_HASH_H__
34#define GOOGLE_PROTOBUF_STUBS_HASH_H__
35
36#include <cstring>
37#include <string>
38#include <unordered_map>
39#include <unordered_set>
40
41# define GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_START \
42 namespace google { \
43 namespace protobuf {
44# define GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_END }}
45
46namespace google {
47namespace protobuf {
48
49template <typename Key>
50struct hash : public std::hash<Key> {};
51
52template <typename Key>
53struct hash<const Key*> {
54 inline size_t operator()(const Key* key) const {
55 return reinterpret_cast<size_t>(key);
56 }
57};
58
59// Unlike the old SGI version, the TR1 "hash" does not special-case char*. So,
60// we go ahead and provide our own implementation.
61template <>
62struct hash<const char*> {
63 inline size_t operator()(const char* str) const {
64 size_t result = 0;
65 for (; *str != '\0'; str++) {
66 result = 5 * result + static_cast<size_t>(*str);
67 }
68 return result;
69 }
70};
71
72template<>
73struct hash<bool> {
74 size_t operator()(bool x) const {
75 return static_cast<size_t>(x);
76 }
77};
78
79template <>
80struct hash<std::string> {
81 inline size_t operator()(const std::string& key) const {
82 return hash<const char*>()(key.c_str());
83 }
84
85 static const size_t bucket_size = 4;
86 static const size_t min_buckets = 8;
87 inline bool operator()(const std::string& a, const std::string& b) const {
88 return a < b;
89 }
90};
91
92template <typename First, typename Second>
93struct hash<std::pair<First, Second> > {
94 inline size_t operator()(const std::pair<First, Second>& key) const {
95 size_t first_hash = hash<First>()(key.first);
96 size_t second_hash = hash<Second>()(key.second);
97
98 // FIXME(kenton): What is the best way to compute this hash? I have
99 // no idea! This seems a bit better than an XOR.
100 return first_hash * ((1 << 16) - 1) + second_hash;
101 }
102
103 static const size_t bucket_size = 4;
104 static const size_t min_buckets = 8;
105 inline bool operator()(const std::pair<First, Second>& a,
106 const std::pair<First, Second>& b) const {
107 return a < b;
108 }
109};
110
111} // namespace protobuf
112} // namespace google
113
114#endif // GOOGLE_PROTOBUF_STUBS_HASH_H__
115