1 | /* |
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2 | * tree234.h: header defining functions in tree234.c. |
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3 | * |
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4 | * This file is copyright 1999-2001 Simon Tatham. |
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5 | * |
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6 | * Permission is hereby granted, free of charge, to any person |
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7 | * obtaining a copy of this software and associated documentation |
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8 | * files (the "Software"), to deal in the Software without |
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9 | * restriction, including without limitation the rights to use, |
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10 | * copy, modify, merge, publish, distribute, sublicense, and/or |
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11 | * sell copies of the Software, and to permit persons to whom the |
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12 | * Software is furnished to do so, subject to the following |
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13 | * conditions: |
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14 | * |
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15 | * The above copyright notice and this permission notice shall be |
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16 | * included in all copies or substantial portions of the Software. |
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17 | * |
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18 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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19 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES |
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20 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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21 | * NONINFRINGEMENT. IN NO EVENT SHALL SIMON TATHAM BE LIABLE FOR |
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22 | * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF |
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23 | * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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24 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
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25 | * SOFTWARE. |
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26 | */ |
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27 | |
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28 | #ifndef TREE234_H |
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29 | #define TREE234_H |
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30 | |
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31 | /* |
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32 | * This typedef is opaque outside tree234.c itself. |
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33 | */ |
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34 | typedef struct tree234_Tag tree234; |
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35 | |
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36 | typedef int (*cmpfn234) (void *, void *); |
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37 | |
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38 | /* |
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39 | * Create a 2-3-4 tree. If `cmp' is NULL, the tree is unsorted, and |
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40 | * lookups by key will fail: you can only look things up by numeric |
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41 | * index, and you have to use addpos234() and delpos234(). |
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42 | */ |
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43 | tree234 *newtree234(cmpfn234 cmp); |
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44 | |
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45 | /* |
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46 | * Free a 2-3-4 tree (not including freeing the elements). |
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47 | */ |
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48 | void freetree234(tree234 * t); |
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49 | |
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50 | /* |
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51 | * Add an element e to a sorted 2-3-4 tree t. Returns e on success, |
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52 | * or if an existing element compares equal, returns that. |
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53 | */ |
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54 | void *add234(tree234 * t, void *e); |
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55 | |
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56 | /* |
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57 | * Add an element e to an unsorted 2-3-4 tree t. Returns e on |
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58 | * success, NULL on failure. (Failure should only occur if the |
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59 | * index is out of range or the tree is sorted.) |
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60 | * |
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61 | * Index range can be from 0 to the tree's current element count, |
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62 | * inclusive. |
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63 | */ |
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64 | void *addpos234(tree234 * t, void *e, int index); |
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65 | |
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66 | /* |
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67 | * Look up the element at a given numeric index in a 2-3-4 tree. |
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68 | * Returns NULL if the index is out of range. |
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69 | * |
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70 | * One obvious use for this function is in iterating over the whole |
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71 | * of a tree (sorted or unsorted): |
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72 | * |
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73 | * for (i = 0; (p = index234(tree, i)) != NULL; i++) consume(p); |
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74 | * |
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75 | * or |
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76 | * |
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77 | * int maxcount = count234(tree); |
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78 | * for (i = 0; i < maxcount; i++) { |
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79 | * p = index234(tree, i); |
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80 | * assert(p != NULL); |
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81 | * consume(p); |
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82 | * } |
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83 | */ |
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84 | void *index234(tree234 * t, int index); |
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85 | |
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86 | /* |
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87 | * Find an element e in a sorted 2-3-4 tree t. Returns NULL if not |
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88 | * found. e is always passed as the first argument to cmp, so cmp |
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89 | * can be an asymmetric function if desired. cmp can also be passed |
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90 | * as NULL, in which case the compare function from the tree proper |
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91 | * will be used. |
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92 | * |
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93 | * Three of these functions are special cases of findrelpos234. The |
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94 | * non-`pos' variants lack the `index' parameter: if the parameter |
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95 | * is present and non-NULL, it must point to an integer variable |
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96 | * which will be filled with the numeric index of the returned |
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97 | * element. |
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98 | * |
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99 | * The non-`rel' variants lack the `relation' parameter. This |
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100 | * parameter allows you to specify what relation the element you |
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101 | * provide has to the element you're looking for. This parameter |
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102 | * can be: |
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103 | * |
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104 | * REL234_EQ - find only an element that compares equal to e |
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105 | * REL234_LT - find the greatest element that compares < e |
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106 | * REL234_LE - find the greatest element that compares <= e |
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107 | * REL234_GT - find the smallest element that compares > e |
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108 | * REL234_GE - find the smallest element that compares >= e |
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109 | * |
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110 | * Non-`rel' variants assume REL234_EQ. |
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111 | * |
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112 | * If `rel' is REL234_GT or REL234_LT, the `e' parameter may be |
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113 | * NULL. In this case, REL234_GT will return the smallest element |
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114 | * in the tree, and REL234_LT will return the greatest. This gives |
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115 | * an alternative means of iterating over a sorted tree, instead of |
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116 | * using index234: |
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117 | * |
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118 | * // to loop forwards |
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119 | * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_GT)) != NULL ;) |
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120 | * consume(p); |
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121 | * |
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122 | * // to loop backwards |
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123 | * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_LT)) != NULL ;) |
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124 | * consume(p); |
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125 | */ |
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126 | enum { |
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127 | REL234_EQ, REL234_LT, REL234_LE, REL234_GT, REL234_GE |
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128 | }; |
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129 | void *find234(tree234 * t, void *e, cmpfn234 cmp); |
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130 | void *findrel234(tree234 * t, void *e, cmpfn234 cmp, int relation); |
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131 | void *findpos234(tree234 * t, void *e, cmpfn234 cmp, int *index); |
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132 | void *findrelpos234(tree234 * t, void *e, cmpfn234 cmp, int relation, |
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133 | int *index); |
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134 | |
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135 | /* |
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136 | * Delete an element e in a 2-3-4 tree. Does not free the element, |
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137 | * merely removes all links to it from the tree nodes. |
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138 | * |
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139 | * delpos234 deletes the element at a particular tree index: it |
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140 | * works on both sorted and unsorted trees. |
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141 | * |
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142 | * del234 deletes the element passed to it, so it only works on |
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143 | * sorted trees. (It's equivalent to using findpos234 to determine |
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144 | * the index of an element, and then passing that index to |
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145 | * delpos234.) |
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146 | * |
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147 | * Both functions return a pointer to the element they delete, for |
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148 | * the user to free or pass on elsewhere or whatever. If the index |
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149 | * is out of range (delpos234) or the element is already not in the |
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150 | * tree (del234) then they return NULL. |
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151 | */ |
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152 | void *del234(tree234 * t, void *e); |
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153 | void *delpos234(tree234 * t, int index); |
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154 | |
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155 | /* |
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156 | * Return the total element count of a tree234. |
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157 | */ |
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158 | int count234(tree234 * t); |
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159 | |
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160 | #endif /* TREE234_H */ |
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