1 /* 2 * tree234.h: header defining functions in tree234.c. 3 * 4 * This file is copyright 1999-2001 Simon Tatham. 5 * 6 * Permission is hereby granted, free of charge, to any person 7 * obtaining a copy of this software and associated documentation 8 * files (the "Software"), to deal in the Software without 9 * restriction, including without limitation the rights to use, 10 * copy, modify, merge, publish, distribute, sublicense, and/or 11 * sell copies of the Software, and to permit persons to whom the 12 * Software is furnished to do so, subject to the following 13 * conditions: 14 * 15 * The above copyright notice and this permission notice shall be 16 * included in all copies or substantial portions of the Software. 17 * 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 19 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 20 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 21 * NONINFRINGEMENT. IN NO EVENT SHALL SIMON TATHAM BE LIABLE FOR 22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF 23 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 24 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 25 * SOFTWARE. 26 */ 27 28 #ifndef TREE234_H 29 #define TREE234_H 30 31 /* 32 * This typedef is opaque outside tree234.c itself. 33 */ 34 typedef struct tree234_Tag tree234; 35 36 typedef int (*cmpfn234)(void *, void *); 37 38 typedef void *(*copyfn234)(void *state, void *element); 39 40 /* 41 * Create a 2-3-4 tree. If `cmp' is NULL, the tree is unsorted, and 42 * lookups by key will fail: you can only look things up by numeric 43 * index, and you have to use addpos234() and delpos234(). 44 */ 45 tree234 *newtree234(cmpfn234 cmp); 46 47 /* 48 * Free a 2-3-4 tree (not including freeing the elements). 49 */ 50 void freetree234(tree234 *t); 51 52 /* 53 * Add an element e to a sorted 2-3-4 tree t. Returns e on success, 54 * or if an existing element compares equal, returns that. 55 */ 56 void *add234(tree234 *t, void *e); 57 58 /* 59 * Add an element e to an unsorted 2-3-4 tree t. Returns e on 60 * success, NULL on failure. (Failure should only occur if the 61 * index is out of range or the tree is sorted.) 62 * 63 * Index range can be from 0 to the tree's current element count, 64 * inclusive. 65 */ 66 void *addpos234(tree234 *t, void *e, int index); 67 68 /* 69 * Look up the element at a given numeric index in a 2-3-4 tree. 70 * Returns NULL if the index is out of range. 71 * 72 * One obvious use for this function is in iterating over the whole 73 * of a tree (sorted or unsorted): 74 * 75 * for (i = 0; (p = index234(tree, i)) != NULL; i++) consume(p); 76 * 77 * or 78 * 79 * int maxcount = count234(tree); 80 * for (i = 0; i < maxcount; i++) { 81 * p = index234(tree, i); 82 * assert(p != NULL); 83 * consume(p); 84 * } 85 */ 86 void *index234(tree234 *t, int index); 87 88 /* 89 * Find an element e in a sorted 2-3-4 tree t. Returns NULL if not 90 * found. e is always passed as the first argument to cmp, so cmp 91 * can be an asymmetric function if desired. cmp can also be passed 92 * as NULL, in which case the compare function from the tree proper 93 * will be used. 94 * 95 * Three of these functions are special cases of findrelpos234. The 96 * non-`pos' variants lack the `index' parameter: if the parameter 97 * is present and non-NULL, it must point to an integer variable 98 * which will be filled with the numeric index of the returned 99 * element. 100 * 101 * The non-`rel' variants lack the `relation' parameter. This 102 * parameter allows you to specify what relation the element you 103 * provide has to the element you're looking for. This parameter 104 * can be: 105 * 106 * REL234_EQ - find only an element that compares equal to e 107 * REL234_LT - find the greatest element that compares < e 108 * REL234_LE - find the greatest element that compares <= e 109 * REL234_GT - find the smallest element that compares > e 110 * REL234_GE - find the smallest element that compares >= e 111 * 112 * Non-`rel' variants assume REL234_EQ. 113 * 114 * If `rel' is REL234_GT or REL234_LT, the `e' parameter may be 115 * NULL. In this case, REL234_GT will return the smallest element 116 * in the tree, and REL234_LT will return the greatest. This gives 117 * an alternative means of iterating over a sorted tree, instead of 118 * using index234: 119 * 120 * // to loop forwards 121 * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_GT)) != NULL ;) 122 * consume(p); 123 * 124 * // to loop backwards 125 * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_LT)) != NULL ;) 126 * consume(p); 127 */ 128 enum { 129 REL234_EQ, REL234_LT, REL234_LE, REL234_GT, REL234_GE 130 }; 131 void *find234(tree234 *t, void *e, cmpfn234 cmp); 132 void *findrel234(tree234 *t, void *e, cmpfn234 cmp, int relation); 133 void *findpos234(tree234 *t, void *e, cmpfn234 cmp, int *index); 134 void *findrelpos234(tree234 *t, void *e, cmpfn234 cmp, int relation, 135 int *index); 136 137 /* 138 * Delete an element e in a 2-3-4 tree. Does not free the element, 139 * merely removes all links to it from the tree nodes. 140 * 141 * delpos234 deletes the element at a particular tree index: it 142 * works on both sorted and unsorted trees. 143 * 144 * del234 deletes the element passed to it, so it only works on 145 * sorted trees. (It's equivalent to using findpos234 to determine 146 * the index of an element, and then passing that index to 147 * delpos234.) 148 * 149 * Both functions return a pointer to the element they delete, for 150 * the user to free or pass on elsewhere or whatever. If the index 151 * is out of range (delpos234) or the element is already not in the 152 * tree (del234) then they return NULL. 153 */ 154 void *del234(tree234 *t, void *e); 155 void *delpos234(tree234 *t, int index); 156 157 /* 158 * Return the total element count of a tree234. 159 */ 160 int count234(tree234 *t); 161 162 /* 163 * Split a tree234 into two valid tree234s. 164 * 165 * splitpos234 splits at a given index. If `before' is TRUE, the 166 * items at and after that index are left in t and the ones before 167 * are returned; if `before' is FALSE, the items before that index 168 * are left in t and the rest are returned. 169 * 170 * split234 splits at a given key. You can pass any of the 171 * relations used with findrel234, except for REL234_EQ. The items 172 * in the tree that satisfy the relation are returned; the 173 * remainder are left. 174 */ 175 tree234 *splitpos234(tree234 *t, int index, int before); 176 tree234 *split234(tree234 *t, void *e, cmpfn234 cmp, int rel); 177 178 /* 179 * Join two tree234s together into a single one. 180 * 181 * All the elements in t1 are placed to the left of all the 182 * elements in t2. If the trees are sorted, there will be a test to 183 * ensure that this satisfies the ordering criterion, and NULL will 184 * be returned otherwise. If the trees are unsorted, there is no 185 * restriction on the use of join234. 186 * 187 * The tree returned is t1 (join234) or t2 (join234r), if the 188 * operation is successful. 189 */ 190 tree234 *join234(tree234 *t1, tree234 *t2); 191 tree234 *join234r(tree234 *t1, tree234 *t2); 192 193 /* 194 * Make a complete copy of a tree234. Element pointers will be 195 * reused unless copyfn is non-NULL, in which case it will be used 196 * to copy each element. (copyfn takes two `void *' parameters; the 197 * first is private state and the second is the element. A simple 198 * copy routine probably won't need private state.) 199 */ 200 tree234 *copytree234(tree234 *t, copyfn234 copyfn, void *copyfnstate); 201 202 #endif /* TREE234_H */ 203