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- /*
- * 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
- /*
- * This typedef is opaque outside tree234.c itself.
- */
- typedef struct tree234_Tag tree234;
- typedef int (*cmpfn234) (void *, void *);
- /*
- * 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);
- /*
- * A more general search type still. Use search234_start() to
- * initialise one of these state structures; it will fill in
- * state->element with an element of the tree, and state->index with
- * the index of that element. If you don't like that element, call
- * search234_step, with direction == -1 if you want an element earlier
- * in the tree, or +1 if you want a later one.
- *
- * If either function returns state->element == NULL, then you've
- * narrowed the search to a point between two adjacent elements, so
- * there are no further elements left to return consistent with the
- * constraints you've imposed. In this case, state->index tells you
- * how many elements come before the point you narrowed down to. After
- * this, you mustn't call search234_step again (unless the state
- * structure is first reinitialised).
- *
- * The use of this search system is that you get both the candidate
- * element _and_ its index at every stage, so you can use both of them
- * to make your decision. Also, you can remember element pointers from
- * earlier in the search.
- *
- * The fields beginning with underscores are private to the
- * implementation, and only exposed so that clients can know how much
- * space to allocate for the structure as a whole. Don't modify them.
- * (Except that it's safe to copy the whole structure.)
- */
- typedef struct search234_state {
- void *element;
- int index;
- int _lo, _hi, _last, _base;
- void *_node;
- } search234_state;
- void search234_start(search234_state *state, tree234 *t);
- void search234_step(search234_state *state, int direction);
- /*
- * 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);
- #endif /* TREE234_H */
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