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1 /* An expandable hash tables datatype.
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2 Copyright (C) 1999, 2000, 2002, 2003, 2004 Free Software Foundation, Inc.
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3 Contributed by Vladimir Makarov (vmakarov@cygnus.com).
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4
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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
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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
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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
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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
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22 Elements in the table are generic pointers.
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23
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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
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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
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32 #ifndef __HASHTAB_H__
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33 #define __HASHTAB_H__
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34
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35 #ifdef __cplusplus
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36 extern "C" {
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37 #endif /* __cplusplus */
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38
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39 #include "ansidecl.h"
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40
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41 #ifndef GTY
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42 #define GTY(X)
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43 #endif
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44
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45 /* The type for a hash code. */
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46 typedef unsigned int hashval_t;
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47
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48 /* Callback function pointer types. */
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49
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50 /* Calculate hash of a table entry. */
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51 typedef hashval_t (*htab_hash) (const void *);
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52
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53 /* Compare a table entry with a possible entry. The entry already in
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54 the table always comes first, so the second element can be of a
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55 different type (but in this case htab_find and htab_find_slot
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56 cannot be used; instead the variants that accept a hash value
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57 must be used). */
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58 typedef int (*htab_eq) (const void *, const void *);
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59
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60 /* Cleanup function called whenever a live element is removed from
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61 the hash table. */
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62 typedef void (*htab_del) (void *);
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63
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64 /* Function called by htab_traverse for each live element. The first
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65 arg is the slot of the element (which can be passed to htab_clear_slot
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66 if desired), the second arg is the auxiliary pointer handed to
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67 htab_traverse. Return 1 to continue scan, 0 to stop. */
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68 typedef int (*htab_trav) (void **, void *);
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69
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70 /* Memory-allocation function, with the same functionality as calloc().
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71 Iff it returns NULL, the hash table implementation will pass an error
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72 code back to the user, so if your code doesn't handle errors,
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73 best if you use xcalloc instead. */
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74 typedef void *(*htab_alloc) (size_t, size_t);
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75
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76 /* We also need a free() routine. */
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77 typedef void (*htab_free) (void *);
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78
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79 /* Memory allocation and deallocation; variants which take an extra
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80 argument. */
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81 typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t);
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82 typedef void (*htab_free_with_arg) (void *, void *);
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83
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84 /* This macro defines reserved value for empty table entry. */
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85
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86 #define HTAB_EMPTY_ENTRY ((PTR) 0)
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87
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88 /* This macro defines reserved value for table entry which contained
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89 a deleted element. */
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90
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91 #define HTAB_DELETED_ENTRY ((PTR) 1)
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92
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93 /* Hash tables are of the following type. The structure
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94 (implementation) of this type is not needed for using the hash
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95 tables. All work with hash table should be executed only through
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96 functions mentioned below. The size of this structure is subject to
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97 change. */
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98
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99 struct htab GTY(())
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100 {
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101 /* Pointer to hash function. */
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102 htab_hash hash_f;
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103
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104 /* Pointer to comparison function. */
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105 htab_eq eq_f;
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106
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107 /* Pointer to cleanup function. */
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108 htab_del del_f;
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109
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110 /* Table itself. */
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111 void ** GTY ((use_param, length ("%h.size"))) entries;
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112
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113 /* Current size (in entries) of the hash table. */
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114 size_t size;
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115
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116 /* Current number of elements including also deleted elements. */
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117 size_t n_elements;
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118
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119 /* Current number of deleted elements in the table. */
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120 size_t n_deleted;
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121
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122 /* The following member is used for debugging. Its value is number
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123 of all calls of `htab_find_slot' for the hash table. */
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124 unsigned int searches;
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125
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126 /* The following member is used for debugging. Its value is number
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127 of collisions fixed for time of work with the hash table. */
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128 unsigned int collisions;
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129
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130 /* Pointers to allocate/free functions. */
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131 htab_alloc alloc_f;
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132 htab_free free_f;
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133
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134 /* Alternate allocate/free functions, which take an extra argument. */
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135 void * GTY((skip)) alloc_arg;
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136 htab_alloc_with_arg alloc_with_arg_f;
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137 htab_free_with_arg free_with_arg_f;
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138
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139 /* Current size (in entries) of the hash table, as an index into the
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140 table of primes. */
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141 unsigned int size_prime_index;
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142 };
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143
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144 typedef struct htab *htab_t;
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145
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146 /* An enum saying whether we insert into the hash table or not. */
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147 enum insert_option {NO_INSERT, INSERT};
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148
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149 /* The prototypes of the package functions. */
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150
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151 extern htab_t htab_create_alloc (size_t, htab_hash,
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152 htab_eq, htab_del,
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153 htab_alloc, htab_free);
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154
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155 extern htab_t htab_create_alloc_ex (size_t, htab_hash,
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156 htab_eq, htab_del,
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157 void *, htab_alloc_with_arg,
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158 htab_free_with_arg);
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159
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160 /* Backward-compatibility functions. */
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161 extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del);
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162 extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del);
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163
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164 extern void htab_set_functions_ex (htab_t, htab_hash,
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165 htab_eq, htab_del,
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166 void *, htab_alloc_with_arg,
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167 htab_free_with_arg);
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168
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169 extern void htab_delete (htab_t);
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170 extern void htab_empty (htab_t);
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171
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172 extern void * htab_find (htab_t, const void *);
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173 extern void ** htab_find_slot (htab_t, const void *, enum insert_option);
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174 extern void * htab_find_with_hash (htab_t, const void *, hashval_t);
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175 extern void ** htab_find_slot_with_hash (htab_t, const void *,
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176 hashval_t, enum insert_option);
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177 extern void htab_clear_slot (htab_t, void **);
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178 extern void htab_remove_elt (htab_t, void *);
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179 extern void htab_remove_elt_with_hash (htab_t, void *, hashval_t);
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180
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181 extern void htab_traverse (htab_t, htab_trav, void *);
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182 extern void htab_traverse_noresize (htab_t, htab_trav, void *);
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183
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184 extern size_t htab_size (htab_t);
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185 extern size_t htab_elements (htab_t);
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186 extern double htab_collisions (htab_t);
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187
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188 /* A hash function for pointers. */
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189 extern htab_hash htab_hash_pointer;
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190
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191 /* An equality function for pointers. */
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192 extern htab_eq htab_eq_pointer;
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193
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194 /* A hash function for null-terminated strings. */
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195 extern hashval_t htab_hash_string (const void *);
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196
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197 /* An iterative hash function for arbitrary data. */
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198 extern hashval_t iterative_hash (const void *, size_t, hashval_t);
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199 /* Shorthand for hashing something with an intrinsic size. */
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200 #define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT)
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201
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202 #ifdef __cplusplus
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203 }
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204 #endif /* __cplusplus */
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205
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206 #endif /* __HASHTAB_H */
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