1 | /* hashlib.c -- functions to manage and access hash tables for bash. */ |
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2 | |
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3 | /* Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc. |
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4 | |
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5 | This file is part of GNU Bash, the Bourne Again SHell. |
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6 | |
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7 | Bash is free software; you can redistribute it and/or modify it under |
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8 | the terms of the GNU General Public License as published by the Free |
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9 | Software Foundation; either version 2, or (at your option) any later |
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10 | version. |
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11 | |
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12 | Bash is distributed in the hope that it will be useful, but WITHOUT ANY |
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13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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15 | for more details. |
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16 | |
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17 | You should have received a copy of the GNU General Public License along |
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18 | with Bash; see the file COPYING. If not, write to the Free Software |
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19 | Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */ |
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20 | |
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21 | #include <config.h> |
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22 | |
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23 | #include "bashansi.h" |
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24 | |
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25 | #if defined (HAVE_UNISTD_H) |
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26 | # ifdef _MINIX |
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27 | # include <sys/types.h> |
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28 | # endif |
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29 | # include <unistd.h> |
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30 | #endif |
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31 | |
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32 | #include <stdio.h> |
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33 | |
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34 | #include "shell.h" |
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35 | #include "hashlib.h" |
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36 | |
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37 | /* Rely on properties of unsigned division (unsigned/int -> unsigned) and |
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38 | don't discard the upper 32 bits of the value, if present. */ |
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39 | #define HASH_BUCKET(s, t, h) (((h) = hash_string (s)) & ((t)->nbuckets - 1)) |
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40 | |
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41 | static BUCKET_CONTENTS *copy_bucket_array __P((BUCKET_CONTENTS *, sh_string_func_t *)); |
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42 | |
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43 | /* Make a new hash table with BUCKETS number of buckets. Initialize |
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44 | each slot in the table to NULL. */ |
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45 | HASH_TABLE * |
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46 | hash_create (buckets) |
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47 | int buckets; |
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48 | { |
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49 | HASH_TABLE *new_table; |
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50 | register int i; |
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51 | |
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52 | new_table = (HASH_TABLE *)xmalloc (sizeof (HASH_TABLE)); |
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53 | if (buckets == 0) |
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54 | buckets = DEFAULT_HASH_BUCKETS; |
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55 | |
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56 | new_table->bucket_array = |
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57 | (BUCKET_CONTENTS **)xmalloc (buckets * sizeof (BUCKET_CONTENTS *)); |
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58 | new_table->nbuckets = buckets; |
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59 | new_table->nentries = 0; |
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60 | |
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61 | for (i = 0; i < buckets; i++) |
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62 | new_table->bucket_array[i] = (BUCKET_CONTENTS *)NULL; |
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63 | |
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64 | return (new_table); |
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65 | } |
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66 | |
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67 | int |
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68 | hash_size (table) |
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69 | HASH_TABLE *table; |
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70 | { |
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71 | return (HASH_ENTRIES(table)); |
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72 | } |
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73 | |
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74 | static BUCKET_CONTENTS * |
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75 | copy_bucket_array (ba, cpdata) |
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76 | BUCKET_CONTENTS *ba; |
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77 | sh_string_func_t *cpdata; /* data copy function */ |
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78 | { |
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79 | BUCKET_CONTENTS *new_bucket, *n, *e; |
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80 | |
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81 | if (ba == 0) |
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82 | return ((BUCKET_CONTENTS *)0); |
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83 | |
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84 | for (n = (BUCKET_CONTENTS *)0, e = ba; e; e = e->next) |
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85 | { |
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86 | if (n == 0) |
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87 | { |
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88 | new_bucket = (BUCKET_CONTENTS *)xmalloc (sizeof (BUCKET_CONTENTS)); |
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89 | n = new_bucket; |
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90 | } |
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91 | else |
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92 | { |
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93 | n->next = (BUCKET_CONTENTS *)xmalloc (sizeof (BUCKET_CONTENTS)); |
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94 | n = n->next; |
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95 | } |
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96 | |
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97 | n->key = savestring (e->key); |
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98 | n->data = e->data ? (cpdata ? (*cpdata) (e->data) : savestring (e->data)) |
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99 | : NULL; |
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100 | n->khash = e->khash; |
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101 | n->times_found = e->times_found; |
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102 | n->next = (BUCKET_CONTENTS *)NULL; |
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103 | } |
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104 | |
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105 | return new_bucket; |
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106 | } |
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107 | |
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108 | HASH_TABLE * |
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109 | hash_copy (table, cpdata) |
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110 | HASH_TABLE *table; |
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111 | sh_string_func_t *cpdata; |
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112 | { |
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113 | HASH_TABLE *new_table; |
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114 | int i; |
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115 | |
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116 | if (table == 0) |
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117 | return ((HASH_TABLE *)NULL); |
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118 | |
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119 | new_table = hash_create (table->nbuckets); |
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120 | |
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121 | for (i = 0; i < table->nbuckets; i++) |
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122 | new_table->bucket_array[i] = copy_bucket_array (table->bucket_array[i], cpdata); |
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123 | |
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124 | new_table->nentries = table->nentries; |
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125 | return new_table; |
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126 | } |
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127 | |
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128 | /* The `khash' check below requires that strings that compare equally with |
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129 | strcmp hash to the same value. */ |
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130 | unsigned int |
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131 | hash_string (s) |
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132 | const char *s; |
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133 | { |
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134 | register unsigned int i; |
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135 | |
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136 | /* This is the best string hash function I found. |
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137 | |
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138 | The magic is in the interesting relationship between the special prime |
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139 | 16777619 (2^24 + 403) and 2^32 and 2^8. */ |
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140 | |
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141 | for (i = 0; *s; s++) |
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142 | { |
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143 | i *= 16777619; |
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144 | i ^= *s; |
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145 | } |
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146 | |
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147 | return i; |
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148 | } |
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149 | |
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150 | /* Return the location of the bucket which should contain the data |
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151 | for STRING. TABLE is a pointer to a HASH_TABLE. */ |
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152 | |
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153 | int |
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154 | hash_bucket (string, table) |
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155 | const char *string; |
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156 | HASH_TABLE *table; |
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157 | { |
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158 | unsigned int h; |
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159 | |
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160 | return (HASH_BUCKET (string, table, h)); |
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161 | } |
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162 | |
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163 | /* Return a pointer to the hashed item. If the HASH_CREATE flag is passed, |
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164 | create a new hash table entry for STRING, otherwise return NULL. */ |
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165 | BUCKET_CONTENTS * |
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166 | hash_search (string, table, flags) |
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167 | const char *string; |
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168 | HASH_TABLE *table; |
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169 | int flags; |
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170 | { |
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171 | BUCKET_CONTENTS *list; |
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172 | int bucket; |
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173 | unsigned int hv; |
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174 | |
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175 | if (table == 0 || ((flags & HASH_CREATE) == 0 && HASH_ENTRIES (table) == 0)) |
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176 | return (BUCKET_CONTENTS *)NULL; |
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177 | |
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178 | bucket = HASH_BUCKET (string, table, hv); |
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179 | |
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180 | for (list = table->bucket_array[bucket]; list; list = list->next) |
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181 | { |
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182 | if (hv == list->khash && STREQ (list->key, string)) |
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183 | { |
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184 | list->times_found++; |
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185 | return (list); |
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186 | } |
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187 | } |
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188 | |
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189 | if (flags & HASH_CREATE) |
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190 | { |
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191 | list = (BUCKET_CONTENTS *)xmalloc (sizeof (BUCKET_CONTENTS)); |
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192 | list->next = table->bucket_array[bucket]; |
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193 | table->bucket_array[bucket] = list; |
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194 | |
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195 | list->data = NULL; |
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196 | list->key = (char *)string; /* XXX fix later */ |
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197 | list->khash = hv; |
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198 | list->times_found = 0; |
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199 | |
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200 | table->nentries++; |
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201 | return (list); |
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202 | } |
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203 | |
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204 | return (BUCKET_CONTENTS *)NULL; |
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205 | } |
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206 | |
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207 | /* Remove the item specified by STRING from the hash table TABLE. |
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208 | The item removed is returned, so you can free its contents. If |
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209 | the item isn't in this table NULL is returned. */ |
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210 | BUCKET_CONTENTS * |
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211 | hash_remove (string, table, flags) |
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212 | const char *string; |
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213 | HASH_TABLE *table; |
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214 | int flags; |
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215 | { |
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216 | int bucket; |
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217 | BUCKET_CONTENTS *prev, *temp; |
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218 | unsigned int hv; |
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219 | |
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220 | if (table == 0 || HASH_ENTRIES (table) == 0) |
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221 | return (BUCKET_CONTENTS *)NULL; |
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222 | |
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223 | bucket = HASH_BUCKET (string, table, hv); |
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224 | prev = (BUCKET_CONTENTS *)NULL; |
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225 | for (temp = table->bucket_array[bucket]; temp; temp = temp->next) |
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226 | { |
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227 | if (hv == temp->khash && STREQ (temp->key, string)) |
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228 | { |
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229 | if (prev) |
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230 | prev->next = temp->next; |
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231 | else |
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232 | table->bucket_array[bucket] = temp->next; |
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233 | |
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234 | table->nentries--; |
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235 | return (temp); |
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236 | } |
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237 | prev = temp; |
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238 | } |
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239 | return ((BUCKET_CONTENTS *) NULL); |
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240 | } |
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241 | |
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242 | /* Create an entry for STRING, in TABLE. If the entry already |
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243 | exists, then return it (unless the HASH_NOSRCH flag is set). */ |
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244 | BUCKET_CONTENTS * |
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245 | hash_insert (string, table, flags) |
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246 | char *string; |
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247 | HASH_TABLE *table; |
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248 | int flags; |
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249 | { |
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250 | BUCKET_CONTENTS *item; |
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251 | int bucket; |
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252 | unsigned int hv; |
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253 | |
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254 | if (table == 0) |
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255 | table = hash_create (0); |
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256 | |
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257 | item = (flags & HASH_NOSRCH) ? (BUCKET_CONTENTS *)NULL |
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258 | : hash_search (string, table, 0); |
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259 | |
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260 | if (item == 0) |
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261 | { |
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262 | bucket = HASH_BUCKET (string, table, hv); |
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263 | |
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264 | item = (BUCKET_CONTENTS *)xmalloc (sizeof (BUCKET_CONTENTS)); |
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265 | item->next = table->bucket_array[bucket]; |
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266 | table->bucket_array[bucket] = item; |
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267 | |
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268 | item->data = NULL; |
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269 | item->key = string; |
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270 | item->khash = hv; |
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271 | item->times_found = 0; |
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272 | |
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273 | table->nentries++; |
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274 | } |
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275 | |
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276 | return (item); |
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277 | } |
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278 | |
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279 | /* Remove and discard all entries in TABLE. If FREE_DATA is non-null, it |
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280 | is a function to call to dispose of a hash item's data. Otherwise, |
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281 | free() is called. */ |
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282 | void |
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283 | hash_flush (table, free_data) |
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284 | HASH_TABLE *table; |
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285 | sh_free_func_t *free_data; |
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286 | { |
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287 | int i; |
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288 | register BUCKET_CONTENTS *bucket, *item; |
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289 | |
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290 | if (table == 0 || HASH_ENTRIES (table) == 0) |
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291 | return; |
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292 | |
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293 | for (i = 0; i < table->nbuckets; i++) |
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294 | { |
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295 | bucket = table->bucket_array[i]; |
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296 | |
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297 | while (bucket) |
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298 | { |
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299 | item = bucket; |
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300 | bucket = bucket->next; |
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301 | |
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302 | if (free_data) |
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303 | (*free_data) (item->data); |
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304 | else |
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305 | free (item->data); |
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306 | free (item->key); |
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307 | free (item); |
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308 | } |
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309 | table->bucket_array[i] = (BUCKET_CONTENTS *)NULL; |
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310 | } |
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311 | |
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312 | table->nentries = 0; |
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313 | } |
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314 | |
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315 | /* Free the hash table pointed to by TABLE. */ |
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316 | void |
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317 | hash_dispose (table) |
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318 | HASH_TABLE *table; |
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319 | { |
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320 | free (table->bucket_array); |
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321 | free (table); |
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322 | } |
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323 | |
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324 | void |
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325 | hash_walk (table, func) |
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326 | HASH_TABLE *table; |
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327 | hash_wfunc *func; |
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328 | { |
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329 | register int i; |
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330 | BUCKET_CONTENTS *item; |
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331 | |
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332 | if (table == 0 || HASH_ENTRIES (table) == 0) |
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333 | return; |
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334 | |
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335 | for (i = 0; i < table->nbuckets; i++) |
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336 | { |
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337 | for (item = hash_items (i, table); item; item = item->next) |
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338 | if ((*func) (item) < 0) |
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339 | return; |
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340 | } |
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341 | } |
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342 | |
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343 | #if defined (DEBUG) || defined (TEST_HASHING) |
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344 | void |
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345 | hash_pstats (table, name) |
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346 | HASH_TABLE *table; |
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347 | char *name; |
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348 | { |
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349 | register int slot, bcount; |
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350 | register BUCKET_CONTENTS *bc; |
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351 | |
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352 | if (name == 0) |
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353 | name = "unknown hash table"; |
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354 | |
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355 | fprintf (stderr, "%s: %d buckets; %d items\n", name, table->nbuckets, table->nentries); |
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356 | |
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357 | /* Print out a count of how many strings hashed to each bucket, so we can |
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358 | see how even the distribution is. */ |
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359 | for (slot = 0; slot < table->nbuckets; slot++) |
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360 | { |
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361 | bc = hash_items (slot, table); |
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362 | |
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363 | fprintf (stderr, "\tslot %3d: ", slot); |
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364 | for (bcount = 0; bc; bc = bc->next) |
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365 | bcount++; |
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366 | |
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367 | fprintf (stderr, "%d\n", bcount); |
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368 | } |
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369 | } |
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370 | #endif |
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371 | |
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372 | #ifdef TEST_HASHING |
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373 | |
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374 | /* link with xmalloc.o and lib/malloc/libmalloc.a */ |
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375 | #undef NULL |
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376 | #include <stdio.h> |
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377 | |
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378 | #ifndef NULL |
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379 | #define NULL 0 |
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380 | #endif |
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381 | |
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382 | HASH_TABLE *table, *ntable; |
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383 | |
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384 | int interrupt_immediately = 0; |
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385 | |
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386 | int |
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387 | signal_is_trapped (s) |
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388 | int s; |
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389 | { |
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390 | return (0); |
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391 | } |
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392 | |
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393 | void |
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394 | programming_error (const char *format, ...) |
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395 | { |
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396 | abort(); |
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397 | } |
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398 | |
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399 | void |
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400 | fatal_error (const char *format, ...) |
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401 | { |
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402 | abort(); |
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403 | } |
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404 | |
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405 | main () |
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406 | { |
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407 | char string[256]; |
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408 | int count = 0; |
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409 | BUCKET_CONTENTS *tt; |
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410 | |
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411 | table = hash_create (0); |
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412 | |
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413 | for (;;) |
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414 | { |
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415 | char *temp_string; |
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416 | if (fgets (string, sizeof (string), stdin) == 0) |
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417 | break; |
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418 | if (!*string) |
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419 | break; |
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420 | temp_string = savestring (string); |
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421 | tt = hash_insert (temp_string, table, 0); |
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422 | if (tt->times_found) |
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423 | { |
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424 | fprintf (stderr, "You have already added item `%s'\n", string); |
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425 | free (temp_string); |
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426 | } |
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427 | else |
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428 | { |
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429 | count++; |
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430 | } |
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431 | } |
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432 | |
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433 | hash_pstats (table, "hash test"); |
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434 | |
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435 | ntable = hash_copy (table, (sh_string_func_t *)NULL); |
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436 | hash_flush (table, (sh_free_func_t *)NULL); |
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437 | hash_pstats (ntable, "hash copy test"); |
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438 | |
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439 | exit (0); |
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440 | } |
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441 | |
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442 | #endif /* TEST_HASHING */ |
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