tree234.h

   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 */