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refine docs for hash_key.h - issue #548
563 | 1 | /* |
2 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. | |
3 | * | |
4 | * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved. | |
5 | * | |
6 | * Redistribution and use in source and binary forms, with or without | |
7 | * modification, are permitted provided that the following conditions are met: | |
8 | * | |
9 | * 1. Redistributions of source code must retain the above copyright | |
10 | * notice, this list of conditions and the following disclaimer. | |
11 | * | |
12 | * 2. Redistributions in binary form must reproduce the above copyright | |
13 | * notice, this list of conditions and the following disclaimer in the | |
14 | * documentation and/or other materials provided with the distribution. | |
15 | * | |
16 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
17 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE | |
20 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
26 | * POSSIBILITY OF SUCH DAMAGE. | |
27 | */ | |
28 | /** | |
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29 | * @file hash_key.h |
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30 | * @brief Interface for map implementations. |
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31 | * @author Mike Becker |
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32 | * @author Olaf Wintermann |
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33 | * @copyright 2-Clause BSD License |
563 | 34 | */ |
35 | ||
36 | ||
37 | #ifndef UCX_HASH_KEY_H | |
38 | #define UCX_HASH_KEY_H | |
39 | ||
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40 | #include "common.h" |
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41 | #include "string.h" |
563 | 42 | |
43 | #ifdef __cplusplus | |
44 | extern "C" { | |
45 | #endif | |
46 | ||
47 | /** Internal structure for a key within a hash map. */ | |
48 | struct cx_hash_key_s { | |
49 | /** The key data. */ | |
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50 | const void *data; |
563 | 51 | /** |
52 | * The key data length. | |
53 | */ | |
54 | size_t len; | |
55 | /** The hash value of the key data. */ | |
56 | unsigned hash; | |
57 | }; | |
58 | ||
59 | /** | |
60 | * Type for a hash key. | |
61 | */ | |
62 | typedef struct cx_hash_key_s CxHashKey; | |
63 | ||
64 | /** | |
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65 | * Computes a murmur2 32-bit hash. |
563 | 66 | * |
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67 | * You need to initialize @c data and @c len in the key struct. |
563 | 68 | * The hash is then directly written to that struct. |
69 | * | |
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70 | * Usually you should not need this function. |
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71 | * Use cx_hash_key(), instead. |
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72 | * |
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73 | * @note If @c data is @c NULL, the hash is defined as 1574210520. |
604 | 74 | * |
563 | 75 | * @param key the key, the hash shall be computed for |
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76 | * @see cx_hash_key() |
563 | 77 | */ |
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78 | cx_attr_nonnull |
563 | 79 | void cx_hash_murmur(CxHashKey *key); |
80 | ||
81 | /** | |
82 | * Computes a hash key from a string. | |
83 | * | |
84 | * The string needs to be zero-terminated. | |
85 | * | |
86 | * @param str the string | |
87 | * @return the hash key | |
88 | */ | |
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89 | cx_attr_nodiscard |
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90 | cx_attr_cstr_arg(1) |
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91 | CxHashKey cx_hash_key_str(const char *str); |
563 | 92 | |
93 | /** | |
94 | * Computes a hash key from a byte array. | |
95 | * | |
96 | * @param bytes the array | |
97 | * @param len the length | |
98 | * @return the hash key | |
99 | */ | |
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100 | cx_attr_nodiscard |
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101 | cx_attr_access_r(1, 2) |
563 | 102 | CxHashKey cx_hash_key_bytes( |
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103 | const unsigned char *bytes, |
563 | 104 | size_t len |
105 | ); | |
106 | ||
107 | /** | |
108 | * Computes a hash key for an arbitrary object. | |
109 | * | |
110 | * The computation uses the in-memory representation that might not be | |
111 | * the same on different platforms. Therefore, this hash should not be | |
112 | * used for data exchange with different machines. | |
113 | * | |
114 | * @param obj a pointer to an arbitrary object | |
115 | * @param len the length of object in memory | |
116 | * @return the hash key | |
117 | */ | |
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118 | cx_attr_nodiscard |
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119 | cx_attr_access_r(1, 2) |
563 | 120 | CxHashKey cx_hash_key( |
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121 | const void *obj, |
563 | 122 | size_t len |
123 | ); | |
124 | ||
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125 | /** |
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126 | * Computes a hash key from a UCX string. |
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127 | * |
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128 | * @param str the string |
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129 | * @return the hash key |
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130 | */ |
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131 | cx_attr_nodiscard |
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132 | static inline CxHashKey cx_hash_key_cxstr(cxstring str) { |
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133 | return cx_hash_key(str.ptr, str.length); |
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134 | } |
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135 | |
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136 | /** |
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137 | * Computes a hash key from a UCX string. |
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138 | * |
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139 | * @param str (@c cxstring or @c cxmutstr) the string |
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140 | * @return (@c CxHashKey) the hash key |
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141 | */ |
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142 | #define cx_hash_key_cxstr(str) cx_hash_key_cxstr(cx_strcast(str)) |
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143 | |
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144 | #ifdef __cplusplus |
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145 | } // extern "C" |
563 | 146 | #endif |
147 | ||
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148 | #endif // UCX_HASH_KEY_H |