annotate src/hashtab.c @ 12525:626fb8e8bb8a v8.0.1141

patch 8.0.1141: MS-Windows build dependencies are incomplete commit https://github.com/vim/vim/commit/96e7a6ee4569526c71b1e89f641526775831ac63 Author: Bram Moolenaar <Bram@vim.org> Date: Sat Sep 23 19:48:29 2017 +0200 patch 8.0.1141: MS-Windows build dependencies are incomplete Problem: MS-Windows build dependencies are incomplete. Solution: Fix the dependencies. (Ken Takata)
author Christian Brabandt <cb@256bit.org>
date Sat, 23 Sep 2017 20:00:04 +0200
parents 9279c939391b
children 55ccc2d353bd
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1 /* vi:set ts=8 sts=4 sw=4 noet:
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2 *
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3 * VIM - Vi IMproved by Bram Moolenaar
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4 *
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5 * Do ":help uganda" in Vim to read copying and usage conditions.
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6 * Do ":help credits" in Vim to see a list of people who contributed.
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7 * See README.txt for an overview of the Vim source code.
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8 */
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9
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10 /*
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11 * hashtab.c: Handling of a hashtable with Vim-specific properties.
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12 *
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13 * Each item in a hashtable has a NUL terminated string key. A key can appear
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14 * only once in the table.
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15 *
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16 * A hash number is computed from the key for quick lookup. When the hashes
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17 * of two different keys point to the same entry an algorithm is used to
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18 * iterate over other entries in the table until the right one is found.
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19 * To make the iteration work removed keys are different from entries where a
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20 * key was never present.
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21 *
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22 * The mechanism has been partly based on how Python Dictionaries are
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23 * implemented. The algorithm is from Knuth Vol. 3, Sec. 6.4.
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24 *
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25 * The hashtable grows to accommodate more entries when needed. At least 1/3
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26 * of the entries is empty to keep the lookup efficient (at the cost of extra
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27 * memory).
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28 */
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29
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30 #include "vim.h"
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31
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32 #if 0
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33 # define HT_DEBUG /* extra checks for table consistency and statistics */
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34
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35 static long hash_count_lookup = 0; /* count number of hashtab lookups */
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36 static long hash_count_perturb = 0; /* count number of "misses" */
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37 #endif
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38
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39 /* Magic value for algorithm that walks through the array. */
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40 #define PERTURB_SHIFT 5
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41
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42 static int hash_may_resize(hashtab_T *ht, int minitems);
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43
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44 #if 0 /* currently not used */
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45 /*
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46 * Create an empty hash table.
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47 * Returns NULL when out of memory.
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48 */
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49 hashtab_T *
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50 hash_create(void)
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51 {
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52 hashtab_T *ht;
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53
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54 ht = (hashtab_T *)alloc(sizeof(hashtab_T));
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55 if (ht != NULL)
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56 hash_init(ht);
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57 return ht;
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58 }
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59 #endif
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60
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61 /*
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62 * Initialize an empty hash table.
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63 */
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64 void
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65 hash_init(hashtab_T *ht)
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66 {
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67 /* This zeroes all "ht_" entries and all the "hi_key" in "ht_smallarray". */
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68 vim_memset(ht, 0, sizeof(hashtab_T));
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69 ht->ht_array = ht->ht_smallarray;
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70 ht->ht_mask = HT_INIT_SIZE - 1;
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71 }
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72
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73 /*
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74 * Free the array of a hash table. Does not free the items it contains!
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75 * If "ht" is not freed then you should call hash_init() next!
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76 */
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77 void
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78 hash_clear(hashtab_T *ht)
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79 {
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80 if (ht->ht_array != ht->ht_smallarray)
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81 vim_free(ht->ht_array);
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82 }
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83
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84 /*
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85 * Free the array of a hash table and all the keys it contains. The keys must
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86 * have been allocated. "off" is the offset from the start of the allocate
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87 * memory to the location of the key (it's always positive).
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88 */
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89 void
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90 hash_clear_all(hashtab_T *ht, int off)
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91 {
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92 long todo;
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93 hashitem_T *hi;
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94
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95 todo = (long)ht->ht_used;
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96 for (hi = ht->ht_array; todo > 0; ++hi)
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97 {
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98 if (!HASHITEM_EMPTY(hi))
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99 {
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100 vim_free(hi->hi_key - off);
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101 --todo;
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102 }
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103 }
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104 hash_clear(ht);
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105 }
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106
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107 /*
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108 * Find "key" in hashtable "ht". "key" must not be NULL.
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109 * Always returns a pointer to a hashitem. If the item was not found then
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110 * HASHITEM_EMPTY() is TRUE. The pointer is then the place where the key
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111 * would be added.
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112 * WARNING: The returned pointer becomes invalid when the hashtable is changed
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113 * (adding, setting or removing an item)!
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114 */
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115 hashitem_T *
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116 hash_find(hashtab_T *ht, char_u *key)
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117 {
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118 return hash_lookup(ht, key, hash_hash(key));
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119 }
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120
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121 /*
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122 * Like hash_find(), but caller computes "hash".
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123 */
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124 hashitem_T *
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125 hash_lookup(hashtab_T *ht, char_u *key, hash_T hash)
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126 {
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127 hash_T perturb;
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128 hashitem_T *freeitem;
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129 hashitem_T *hi;
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130 unsigned idx;
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131
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132 #ifdef HT_DEBUG
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133 ++hash_count_lookup;
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134 #endif
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135
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136 /*
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137 * Quickly handle the most common situations:
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138 * - return if there is no item at all
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139 * - skip over a removed item
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140 * - return if the item matches
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141 */
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142 idx = (unsigned)(hash & ht->ht_mask);
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143 hi = &ht->ht_array[idx];
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144
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145 if (hi->hi_key == NULL)
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146 return hi;
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147 if (hi->hi_key == HI_KEY_REMOVED)
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148 freeitem = hi;
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149 else if (hi->hi_hash == hash && STRCMP(hi->hi_key, key) == 0)
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150 return hi;
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151 else
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152 freeitem = NULL;
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153
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154 /*
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155 * Need to search through the table to find the key. The algorithm
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156 * to step through the table starts with large steps, gradually becoming
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157 * smaller down to (1/4 table size + 1). This means it goes through all
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158 * table entries in the end.
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159 * When we run into a NULL key it's clear that the key isn't there.
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160 * Return the first available slot found (can be a slot of a removed
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161 * item).
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162 */
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163 for (perturb = hash; ; perturb >>= PERTURB_SHIFT)
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164 {
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165 #ifdef HT_DEBUG
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166 ++hash_count_perturb; /* count a "miss" for hashtab lookup */
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167 #endif
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168 idx = (unsigned)((idx << 2U) + idx + perturb + 1U);
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169 hi = &ht->ht_array[idx & ht->ht_mask];
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170 if (hi->hi_key == NULL)
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171 return freeitem == NULL ? hi : freeitem;
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172 if (hi->hi_hash == hash
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173 && hi->hi_key != HI_KEY_REMOVED
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174 && STRCMP(hi->hi_key, key) == 0)
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175 return hi;
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176 if (hi->hi_key == HI_KEY_REMOVED && freeitem == NULL)
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177 freeitem = hi;
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178 }
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179 }
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180
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181 /*
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182 * Print the efficiency of hashtable lookups.
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183 * Useful when trying different hash algorithms.
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184 * Called when exiting.
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185 */
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186 void
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187 hash_debug_results(void)
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188 {
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189 #ifdef HT_DEBUG
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190 fprintf(stderr, "\r\n\r\n\r\n\r\n");
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191 fprintf(stderr, "Number of hashtable lookups: %ld\r\n", hash_count_lookup);
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192 fprintf(stderr, "Number of perturb loops: %ld\r\n", hash_count_perturb);
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193 fprintf(stderr, "Percentage of perturb loops: %ld%%\r\n",
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194 hash_count_perturb * 100 / hash_count_lookup);
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195 #endif
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196 }
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197
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198 /*
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199 * Add item with key "key" to hashtable "ht".
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200 * Returns FAIL when out of memory or the key is already present.
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201 */
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202 int
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203 hash_add(hashtab_T *ht, char_u *key)
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204 {
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205 hash_T hash = hash_hash(key);
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206 hashitem_T *hi;
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207
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208 hi = hash_lookup(ht, key, hash);
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209 if (!HASHITEM_EMPTY(hi))
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210 {
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211 internal_error("hash_add()");
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212 return FAIL;
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213 }
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214 return hash_add_item(ht, hi, key, hash);
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215 }
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216
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217 /*
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218 * Add item "hi" with "key" to hashtable "ht". "key" must not be NULL and
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219 * "hi" must have been obtained with hash_lookup() and point to an empty item.
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220 * "hi" is invalid after this!
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221 * Returns OK or FAIL (out of memory).
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222 */
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223 int
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224 hash_add_item(
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225 hashtab_T *ht,
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226 hashitem_T *hi,
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227 char_u *key,
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228 hash_T hash)
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229 {
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230 /* If resizing failed before and it fails again we can't add an item. */
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231 if (ht->ht_error && hash_may_resize(ht, 0) == FAIL)
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232 return FAIL;
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233
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234 ++ht->ht_used;
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235 if (hi->hi_key == NULL)
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236 ++ht->ht_filled;
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237 hi->hi_key = key;
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238 hi->hi_hash = hash;
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239
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240 /* When the space gets low may resize the array. */
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241 return hash_may_resize(ht, 0);
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242 }
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243
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244 #if 0 /* not used */
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245 /*
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246 * Overwrite hashtable item "hi" with "key". "hi" must point to the item that
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247 * is to be overwritten. Thus the number of items in the hashtable doesn't
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248 * change.
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249 * Although the key must be identical, the pointer may be different, thus it's
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250 * set anyway (the key is part of an item with that key).
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251 * The caller must take care of freeing the old item.
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252 * "hi" is invalid after this!
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253 */
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254 void
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255 hash_set(hashitem_T *hi, char_u *key)
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256 {
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257 hi->hi_key = key;
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258 }
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259 #endif
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260
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261 /*
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262 * Remove item "hi" from hashtable "ht". "hi" must have been obtained with
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263 * hash_lookup().
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264 * The caller must take care of freeing the item itself.
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265 */
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266 void
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267 hash_remove(hashtab_T *ht, hashitem_T *hi)
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268 {
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269 --ht->ht_used;
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270 hi->hi_key = HI_KEY_REMOVED;
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271 hash_may_resize(ht, 0);
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272 }
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273
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274 /*
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275 * Lock a hashtable: prevent that ht_array changes.
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276 * Don't use this when items are to be added!
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277 * Must call hash_unlock() later.
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278 */
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279 void
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280 hash_lock(hashtab_T *ht)
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281 {
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282 ++ht->ht_locked;
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283 }
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284
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285 #if 0 /* currently not used */
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286 /*
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287 * Lock a hashtable at the specified number of entries.
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288 * Caller must make sure no more than "size" entries will be added.
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289 * Must call hash_unlock() later.
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290 */
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291 void
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292 hash_lock_size(hashtab_T *ht, int size)
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293 {
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294 (void)hash_may_resize(ht, size);
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295 ++ht->ht_locked;
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296 }
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297 #endif
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298
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299 /*
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300 * Unlock a hashtable: allow ht_array changes again.
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301 * Table will be resized (shrink) when necessary.
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302 * This must balance a call to hash_lock().
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303 */
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304 void
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305 hash_unlock(hashtab_T *ht)
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306 {
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307 --ht->ht_locked;
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308 (void)hash_may_resize(ht, 0);
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309 }
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310
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311 /*
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312 * Shrink a hashtable when there is too much empty space.
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313 * Grow a hashtable when there is not enough empty space.
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314 * Returns OK or FAIL (out of memory).
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315 */
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316 static int
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317 hash_may_resize(
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318 hashtab_T *ht,
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319 int minitems) /* minimal number of items */
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320 {
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321 hashitem_T temparray[HT_INIT_SIZE];
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322 hashitem_T *oldarray, *newarray;
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323 hashitem_T *olditem, *newitem;
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324 unsigned newi;
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325 int todo;
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326 long_u oldsize, newsize;
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327 long_u minsize;
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328 long_u newmask;
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329 hash_T perturb;
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330
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331 /* Don't resize a locked table. */
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332 if (ht->ht_locked > 0)
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333 return OK;
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334
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335 #ifdef HT_DEBUG
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336 if (ht->ht_used > ht->ht_filled)
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337 EMSG("hash_may_resize(): more used than filled");
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338 if (ht->ht_filled >= ht->ht_mask + 1)
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339 EMSG("hash_may_resize(): table completely filled");
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340 #endif
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341
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342 if (minitems == 0)
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343 {
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344 /* Return quickly for small tables with at least two NULL items. NULL
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345 * items are required for the lookup to decide a key isn't there. */
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346 if (ht->ht_filled < HT_INIT_SIZE - 1
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347 && ht->ht_array == ht->ht_smallarray)
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348 return OK;
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349
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350 /*
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351 * Grow or refill the array when it's more than 2/3 full (including
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352 * removed items, so that they get cleaned up).
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353 * Shrink the array when it's less than 1/5 full. When growing it is
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354 * at least 1/4 full (avoids repeated grow-shrink operations)
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355 */
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356 oldsize = ht->ht_mask + 1;
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357 if (ht->ht_filled * 3 < oldsize * 2 && ht->ht_used > oldsize / 5)
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diff changeset
358 return OK;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
359
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
360 if (ht->ht_used > 1000)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
361 minsize = ht->ht_used * 2; /* it's big, don't make too much room */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
362 else
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
363 minsize = ht->ht_used * 4; /* make plenty of room */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
364 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
365 else
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
366 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
367 /* Use specified size. */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
368 if ((long_u)minitems < ht->ht_used) /* just in case... */
835
8bebcabccc2c updated for version 7.0e01
vimboss
parents: 799
diff changeset
369 minitems = (int)ht->ht_used;
799
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
370 minsize = minitems * 3 / 2; /* array is up to 2/3 full */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
371 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
372
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
373 newsize = HT_INIT_SIZE;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
374 while (newsize < minsize)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
375 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
376 newsize <<= 1; /* make sure it's always a power of 2 */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
377 if (newsize == 0)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
378 return FAIL; /* overflow */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
379 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
380
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
381 if (newsize == HT_INIT_SIZE)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
382 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
383 /* Use the small array inside the hashdict structure. */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
384 newarray = ht->ht_smallarray;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
385 if (ht->ht_array == newarray)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
386 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
387 /* Moving from ht_smallarray to ht_smallarray! Happens when there
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
388 * are many removed items. Copy the items to be able to clean up
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
389 * removed items. */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
390 mch_memmove(temparray, newarray, sizeof(temparray));
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
391 oldarray = temparray;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
392 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
393 else
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
394 oldarray = ht->ht_array;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
395 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
396 else
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
397 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
398 /* Allocate an array. */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
399 newarray = (hashitem_T *)alloc((unsigned)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
400 (sizeof(hashitem_T) * newsize));
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
401 if (newarray == NULL)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
402 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
403 /* Out of memory. When there are NULL items still return OK.
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
404 * Otherwise set ht_error, because lookup may result in a hang if
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
405 * we add another item. */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
406 if (ht->ht_filled < ht->ht_mask)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
407 return OK;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
408 ht->ht_error = TRUE;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
409 return FAIL;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
410 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
411 oldarray = ht->ht_array;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
412 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
413 vim_memset(newarray, 0, (size_t)(sizeof(hashitem_T) * newsize));
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
414
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
415 /*
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
416 * Move all the items from the old array to the new one, placing them in
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
417 * the right spot. The new array won't have any removed items, thus this
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
418 * is also a cleanup action.
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
419 */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
420 newmask = newsize - 1;
835
8bebcabccc2c updated for version 7.0e01
vimboss
parents: 799
diff changeset
421 todo = (int)ht->ht_used;
799
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
422 for (olditem = oldarray; todo > 0; ++olditem)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
423 if (!HASHITEM_EMPTY(olditem))
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
424 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
425 /*
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
426 * The algorithm to find the spot to add the item is identical to
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
427 * the algorithm to find an item in hash_lookup(). But we only
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
428 * need to search for a NULL key, thus it's simpler.
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
429 */
3970
2c12cd5c1381 updated for version 7.3.740
Bram Moolenaar <bram@vim.org>
parents: 2520
diff changeset
430 newi = (unsigned)(olditem->hi_hash & newmask);
799
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
431 newitem = &newarray[newi];
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
432
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
433 if (newitem->hi_key != NULL)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
434 for (perturb = olditem->hi_hash; ; perturb >>= PERTURB_SHIFT)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
435 {
3970
2c12cd5c1381 updated for version 7.3.740
Bram Moolenaar <bram@vim.org>
parents: 2520
diff changeset
436 newi = (unsigned)((newi << 2U) + newi + perturb + 1U);
799
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
437 newitem = &newarray[newi & newmask];
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
438 if (newitem->hi_key == NULL)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
439 break;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
440 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
441 *newitem = *olditem;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
442 --todo;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
443 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
444
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
445 if (ht->ht_array != ht->ht_smallarray)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
446 vim_free(ht->ht_array);
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
447 ht->ht_array = newarray;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
448 ht->ht_mask = newmask;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
449 ht->ht_filled = ht->ht_used;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
450 ht->ht_error = FALSE;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
451
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
452 return OK;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
453 }
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
454
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
455 /*
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
456 * Get the hash number for a key.
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
457 * If you think you know a better hash function: Compile with HT_DEBUG set and
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
458 * run a script that uses hashtables a lot. Vim will then print statistics
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
459 * when exiting. Try that with the current hash algorithm and yours. The
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
460 * lower the percentage the better.
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
461 */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
462 hash_T
7823
bcef391c101c commit https://github.com/vim/vim/commit/68c2f638e65d914dc6e84eb7ce2624f08af525c0
Christian Brabandt <cb@256bit.org>
parents: 7803
diff changeset
463 hash_hash(char_u *key)
799
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
464 {
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
465 hash_T hash;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
466 char_u *p;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
467
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
468 if ((hash = *key) == 0)
8839
9fa567d13551 commit https://github.com/vim/vim/commit/0921ecff1c5a74541bad6c073e8ade32247403d8
Christian Brabandt <cb@256bit.org>
parents: 7823
diff changeset
469 return (hash_T)0;
799
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
470 p = key + 1;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
471
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
472 /* A simplistic algorithm that appears to do very well.
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
473 * Suggested by George Reilly. */
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
474 while (*p != NUL)
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
475 hash = hash * 101 + *p++;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
476
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
477 return hash;
6beb2c667935 updated for version 7.0b
vimboss
parents:
diff changeset
478 }