tlx
hash_djb2.hpp
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1 /*******************************************************************************
2  * tlx/string/hash_djb2.hpp
3  *
4  * Part of tlx - http://panthema.net/tlx
5  *
6  * Copyright (C) 2019 Timo Bingmann <tb@panthema.net>
7  *
8  * All rights reserved. Published under the Boost Software License, Version 1.0
9  ******************************************************************************/
10 
11 #ifndef TLX_STRING_HASH_DJB2_HEADER
12 #define TLX_STRING_HASH_DJB2_HEADER
13 
14 #include <string>
15 
16 namespace tlx {
17 
18 //! \addtogroup tlx_string
19 //! \{
20 
21 /*!
22  * Simple, fast, but "insecure" string hash method by Dan Bernstein from
23  * http://www.cse.yorku.ca/~oz/hash.html
24  */
25 static inline
26 uint32_t hash_djb2(const unsigned char* str) {
27  uint32_t hash = 5381;
28  unsigned char c;
29  while ((c = *str++) != 0) {
30  // hash * 33 + c
31  hash = ((hash << 5) + hash) + c;
32  }
33  return hash;
34 }
35 
36 /*!
37  * Simple, fast, but "insecure" string hash method by Dan Bernstein from
38  * http://www.cse.yorku.ca/~oz/hash.html
39  */
40 static inline
41 uint32_t hash_djb2(const char* str) {
42  return hash_djb2(reinterpret_cast<const unsigned char*>(str));
43 }
44 
45 /*!
46  * Simple, fast, but "insecure" string hash method by Dan Bernstein from
47  * http://www.cse.yorku.ca/~oz/hash.html
48  */
49 static inline
50 uint32_t hash_djb2(const unsigned char* str, size_t size) {
51  uint32_t hash = 5381;
52  while (size-- > 0) {
53  // hash * 33 + c
54  hash = ((hash << 5) + hash) + static_cast<unsigned char>(*str++);
55  }
56  return hash;
57 }
58 
59 /*!
60  * Simple, fast, but "insecure" string hash method by Dan Bernstein from
61  * http://www.cse.yorku.ca/~oz/hash.html
62  */
63 static inline
64 uint32_t hash_djb2(const char* str, size_t size) {
65  return hash_djb2(reinterpret_cast<const unsigned char*>(str), size);
66 }
67 
68 /*!
69  * Simple, fast, but "insecure" string hash method by Dan Bernstein from
70  * http://www.cse.yorku.ca/~oz/hash.html
71  */
72 static inline
73 uint32_t hash_djb2(const std::string& str) {
74  return hash_djb2(str.data(), str.size());
75 }
76 
77 //! \}
78 
79 } // namespace tlx
80 
81 #endif // !TLX_STRING_HASH_DJB2_HEADER
82 
83 /******************************************************************************/
tlx::hash_djb2
static uint32_t hash_djb2(const unsigned char *str)
Simple, fast, but "insecure" string hash method by Dan Bernstein from http://www.cse.yorku.ca/~oz/hash.html.
Definition: hash_djb2.hpp:26