ref: 5a0a2b9166a144b1775411a47060efa483e61971
dir: /tree234.h/
/* * tree234.h: header defining functions in tree234.c. * * This file is copyright 1999-2001 Simon Tatham. * * Permission is hereby granted, free of charge, to any person * obtaining a copy of this software and associated documentation * files (the "Software"), to deal in the Software without * restriction, including without limitation the rights to use, * copy, modify, merge, publish, distribute, sublicense, and/or * sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following * conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL SIMON TATHAM BE LIABLE FOR * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #ifndef TREE234_H #define TREE234_H #include <stdbool.h> /* * This typedef is opaque outside tree234.c itself. */ typedef struct tree234_Tag tree234; typedef int (*cmpfn234)(void *, void *); typedef void *(*copyfn234)(void *state, void *element); /* * Create a 2-3-4 tree. If `cmp' is NULL, the tree is unsorted, and * lookups by key will fail: you can only look things up by numeric * index, and you have to use addpos234() and delpos234(). */ tree234 *newtree234(cmpfn234 cmp); /* * Free a 2-3-4 tree (not including freeing the elements). */ void freetree234(tree234 *t); /* * Add an element e to a sorted 2-3-4 tree t. Returns e on success, * or if an existing element compares equal, returns that. */ void *add234(tree234 *t, void *e); /* * Add an element e to an unsorted 2-3-4 tree t. Returns e on * success, NULL on failure. (Failure should only occur if the * index is out of range or the tree is sorted.) * * Index range can be from 0 to the tree's current element count, * inclusive. */ void *addpos234(tree234 *t, void *e, int index); /* * Look up the element at a given numeric index in a 2-3-4 tree. * Returns NULL if the index is out of range. * * One obvious use for this function is in iterating over the whole * of a tree (sorted or unsorted): * * for (i = 0; (p = index234(tree, i)) != NULL; i++) consume(p); * * or * * int maxcount = count234(tree); * for (i = 0; i < maxcount; i++) { * p = index234(tree, i); * assert(p != NULL); * consume(p); * } */ void *index234(tree234 *t, int index); /* * Find an element e in a sorted 2-3-4 tree t. Returns NULL if not * found. e is always passed as the first argument to cmp, so cmp * can be an asymmetric function if desired. cmp can also be passed * as NULL, in which case the compare function from the tree proper * will be used. * * Three of these functions are special cases of findrelpos234. The * non-`pos' variants lack the `index' parameter: if the parameter * is present and non-NULL, it must point to an integer variable * which will be filled with the numeric index of the returned * element. * * The non-`rel' variants lack the `relation' parameter. This * parameter allows you to specify what relation the element you * provide has to the element you're looking for. This parameter * can be: * * REL234_EQ - find only an element that compares equal to e * REL234_LT - find the greatest element that compares < e * REL234_LE - find the greatest element that compares <= e * REL234_GT - find the smallest element that compares > e * REL234_GE - find the smallest element that compares >= e * * Non-`rel' variants assume REL234_EQ. * * If `rel' is REL234_GT or REL234_LT, the `e' parameter may be * NULL. In this case, REL234_GT will return the smallest element * in the tree, and REL234_LT will return the greatest. This gives * an alternative means of iterating over a sorted tree, instead of * using index234: * * // to loop forwards * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_GT)) != NULL ;) * consume(p); * * // to loop backwards * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_LT)) != NULL ;) * consume(p); */ enum { REL234_EQ, REL234_LT, REL234_LE, REL234_GT, REL234_GE }; void *find234(tree234 *t, void *e, cmpfn234 cmp); void *findrel234(tree234 *t, void *e, cmpfn234 cmp, int relation); void *findpos234(tree234 *t, void *e, cmpfn234 cmp, int *index); void *findrelpos234(tree234 *t, void *e, cmpfn234 cmp, int relation, int *index); /* * Delete an element e in a 2-3-4 tree. Does not free the element, * merely removes all links to it from the tree nodes. * * delpos234 deletes the element at a particular tree index: it * works on both sorted and unsorted trees. * * del234 deletes the element passed to it, so it only works on * sorted trees. (It's equivalent to using findpos234 to determine * the index of an element, and then passing that index to * delpos234.) * * Both functions return a pointer to the element they delete, for * the user to free or pass on elsewhere or whatever. If the index * is out of range (delpos234) or the element is already not in the * tree (del234) then they return NULL. */ void *del234(tree234 *t, void *e); void *delpos234(tree234 *t, int index); /* * Return the total element count of a tree234. */ int count234(tree234 *t); /* * Split a tree234 into two valid tree234s. * * splitpos234 splits at a given index. If `before' is true, the * items at and after that index are left in t and the ones before * are returned; if `before' is false, the items before that index * are left in t and the rest are returned. * * split234 splits at a given key. You can pass any of the * relations used with findrel234, except for REL234_EQ. The items * in the tree that satisfy the relation are returned; the * remainder are left. */ tree234 *splitpos234(tree234 *t, int index, bool before); tree234 *split234(tree234 *t, void *e, cmpfn234 cmp, int rel); /* * Join two tree234s together into a single one. * * All the elements in t1 are placed to the left of all the * elements in t2. If the trees are sorted, there will be a test to * ensure that this satisfies the ordering criterion, and NULL will * be returned otherwise. If the trees are unsorted, there is no * restriction on the use of join234. * * The tree returned is t1 (join234) or t2 (join234r), if the * operation is successful. */ tree234 *join234(tree234 *t1, tree234 *t2); tree234 *join234r(tree234 *t1, tree234 *t2); /* * Make a complete copy of a tree234. Element pointers will be * reused unless copyfn is non-NULL, in which case it will be used * to copy each element. (copyfn takes two `void *' parameters; the * first is private state and the second is the element. A simple * copy routine probably won't need private state.) */ tree234 *copytree234(tree234 *t, copyfn234 copyfn, void *copyfnstate); #endif /* TREE234_H */