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5191 | serge | 1 | /* An expandable hash tables datatype. |
6324 | serge | 2 | Copyright (C) 1999-2015 Free Software Foundation, Inc. |
5191 | serge | 3 | Contributed by Vladimir Makarov (vmakarov@cygnus.com). |
4 | |||
5 | This program is free software; you can redistribute it and/or modify |
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6 | it under the terms of the GNU General Public License as published by |
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7 | the Free Software Foundation; either version 2 of the License, or |
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8 | (at your option) any later version. |
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9 | |||
10 | This program is distributed in the hope that it will be useful, |
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11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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13 | GNU General Public License for more details. |
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14 | |||
15 | You should have received a copy of the GNU General Public License |
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16 | along with this program; if not, write to the Free Software |
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17 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ |
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18 | |||
19 | /* This package implements basic hash table functionality. It is possible |
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20 | to search for an entry, create an entry and destroy an entry. |
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21 | |||
22 | Elements in the table are generic pointers. |
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23 | |||
24 | The size of the table is not fixed; if the occupancy of the table |
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25 | grows too high the hash table will be expanded. |
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26 | |||
27 | The abstract data implementation is based on generalized Algorithm D |
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28 | from Knuth's book "The art of computer programming". Hash table is |
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29 | expanded by creation of new hash table and transferring elements from |
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30 | the old table to the new table. */ |
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31 | |||
32 | #ifndef __HASHTAB_H__ |
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33 | #define __HASHTAB_H__ |
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34 | |||
35 | #ifdef __cplusplus |
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36 | extern "C" { |
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37 | #endif /* __cplusplus */ |
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38 | |||
39 | #include "ansidecl.h" |
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40 | |||
41 | /* The type for a hash code. */ |
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42 | typedef unsigned int hashval_t; |
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43 | |||
44 | /* Callback function pointer types. */ |
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45 | |||
46 | /* Calculate hash of a table entry. */ |
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47 | typedef hashval_t (*htab_hash) (const void *); |
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48 | |||
49 | /* Compare a table entry with a possible entry. The entry already in |
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50 | the table always comes first, so the second element can be of a |
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51 | different type (but in this case htab_find and htab_find_slot |
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52 | cannot be used; instead the variants that accept a hash value |
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53 | must be used). */ |
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54 | typedef int (*htab_eq) (const void *, const void *); |
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55 | |||
56 | /* Cleanup function called whenever a live element is removed from |
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57 | the hash table. */ |
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58 | typedef void (*htab_del) (void *); |
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59 | |||
60 | /* Function called by htab_traverse for each live element. The first |
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61 | arg is the slot of the element (which can be passed to htab_clear_slot |
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62 | if desired), the second arg is the auxiliary pointer handed to |
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63 | htab_traverse. Return 1 to continue scan, 0 to stop. */ |
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64 | typedef int (*htab_trav) (void **, void *); |
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65 | |||
66 | /* Memory-allocation function, with the same functionality as calloc(). |
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67 | Iff it returns NULL, the hash table implementation will pass an error |
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68 | code back to the user, so if your code doesn't handle errors, |
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69 | best if you use xcalloc instead. */ |
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70 | typedef void *(*htab_alloc) (size_t, size_t); |
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71 | |||
72 | /* We also need a free() routine. */ |
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73 | typedef void (*htab_free) (void *); |
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74 | |||
75 | /* Memory allocation and deallocation; variants which take an extra |
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76 | argument. */ |
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77 | typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t); |
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78 | typedef void (*htab_free_with_arg) (void *, void *); |
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79 | |||
80 | /* This macro defines reserved value for empty table entry. */ |
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81 | |||
82 | #define HTAB_EMPTY_ENTRY ((PTR) 0) |
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83 | |||
84 | /* This macro defines reserved value for table entry which contained |
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85 | a deleted element. */ |
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86 | |||
87 | #define HTAB_DELETED_ENTRY ((PTR) 1) |
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88 | |||
89 | /* Hash tables are of the following type. The structure |
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90 | (implementation) of this type is not needed for using the hash |
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91 | tables. All work with hash table should be executed only through |
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92 | functions mentioned below. The size of this structure is subject to |
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93 | change. */ |
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94 | |||
6324 | serge | 95 | struct htab { |
5191 | serge | 96 | /* Pointer to hash function. */ |
97 | htab_hash hash_f; |
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98 | |||
99 | /* Pointer to comparison function. */ |
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100 | htab_eq eq_f; |
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101 | |||
102 | /* Pointer to cleanup function. */ |
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103 | htab_del del_f; |
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104 | |||
105 | /* Table itself. */ |
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6324 | serge | 106 | void **entries; |
5191 | serge | 107 | |
108 | /* Current size (in entries) of the hash table. */ |
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109 | size_t size; |
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110 | |||
111 | /* Current number of elements including also deleted elements. */ |
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112 | size_t n_elements; |
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113 | |||
114 | /* Current number of deleted elements in the table. */ |
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115 | size_t n_deleted; |
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116 | |||
117 | /* The following member is used for debugging. Its value is number |
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118 | of all calls of `htab_find_slot' for the hash table. */ |
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119 | unsigned int searches; |
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120 | |||
121 | /* The following member is used for debugging. Its value is number |
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122 | of collisions fixed for time of work with the hash table. */ |
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123 | unsigned int collisions; |
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124 | |||
125 | /* Pointers to allocate/free functions. */ |
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126 | htab_alloc alloc_f; |
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127 | htab_free free_f; |
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128 | |||
129 | /* Alternate allocate/free functions, which take an extra argument. */ |
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6324 | serge | 130 | void *alloc_arg; |
5191 | serge | 131 | htab_alloc_with_arg alloc_with_arg_f; |
132 | htab_free_with_arg free_with_arg_f; |
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133 | |||
134 | /* Current size (in entries) of the hash table, as an index into the |
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135 | table of primes. */ |
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136 | unsigned int size_prime_index; |
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137 | }; |
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138 | |||
139 | typedef struct htab *htab_t; |
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140 | |||
141 | /* An enum saying whether we insert into the hash table or not. */ |
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142 | enum insert_option {NO_INSERT, INSERT}; |
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143 | |||
144 | /* The prototypes of the package functions. */ |
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145 | |||
146 | extern htab_t htab_create_alloc (size_t, htab_hash, |
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147 | htab_eq, htab_del, |
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148 | htab_alloc, htab_free); |
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149 | |||
150 | extern htab_t htab_create_alloc_ex (size_t, htab_hash, |
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151 | htab_eq, htab_del, |
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152 | void *, htab_alloc_with_arg, |
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153 | htab_free_with_arg); |
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154 | |||
155 | extern htab_t htab_create_typed_alloc (size_t, htab_hash, htab_eq, htab_del, |
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156 | htab_alloc, htab_alloc, htab_free); |
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157 | |||
158 | /* Backward-compatibility functions. */ |
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159 | extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del); |
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160 | extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del); |
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161 | |||
162 | extern void htab_set_functions_ex (htab_t, htab_hash, |
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163 | htab_eq, htab_del, |
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164 | void *, htab_alloc_with_arg, |
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165 | htab_free_with_arg); |
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166 | |||
167 | extern void htab_delete (htab_t); |
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168 | extern void htab_empty (htab_t); |
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169 | |||
170 | extern void * htab_find (htab_t, const void *); |
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171 | extern void ** htab_find_slot (htab_t, const void *, enum insert_option); |
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172 | extern void * htab_find_with_hash (htab_t, const void *, hashval_t); |
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173 | extern void ** htab_find_slot_with_hash (htab_t, const void *, |
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174 | hashval_t, enum insert_option); |
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175 | extern void htab_clear_slot (htab_t, void **); |
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176 | extern void htab_remove_elt (htab_t, void *); |
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177 | extern void htab_remove_elt_with_hash (htab_t, void *, hashval_t); |
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178 | |||
179 | extern void htab_traverse (htab_t, htab_trav, void *); |
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180 | extern void htab_traverse_noresize (htab_t, htab_trav, void *); |
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181 | |||
182 | extern size_t htab_size (htab_t); |
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183 | extern size_t htab_elements (htab_t); |
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184 | extern double htab_collisions (htab_t); |
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185 | |||
186 | /* A hash function for pointers. */ |
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187 | extern htab_hash htab_hash_pointer; |
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188 | |||
189 | /* An equality function for pointers. */ |
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190 | extern htab_eq htab_eq_pointer; |
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191 | |||
192 | /* A hash function for null-terminated strings. */ |
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193 | extern hashval_t htab_hash_string (const void *); |
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194 | |||
195 | /* An iterative hash function for arbitrary data. */ |
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196 | extern hashval_t iterative_hash (const void *, size_t, hashval_t); |
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197 | /* Shorthand for hashing something with an intrinsic size. */ |
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198 | #define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT) |
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199 | |||
200 | #ifdef __cplusplus |
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201 | } |
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202 | #endif /* __cplusplus */ |
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203 | |||
204 | #endif /* __HASHTAB_H */ |