ref: cef5fe0310139ee6d16db580e30cb0bc5657c54b
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 typically opaque outside tree234.c itself. But you
* can define TREE234_INTERNALS to get a definition of it and its
* subsidiary node structure, as long as you're prepared to commit to
* responding to changes in the internals (which probably means you're
* tree234.c itself or tree234-test.c).
*/
typedef struct tree234_Tag tree234;
#ifdef __plan9__
#pragma incomplete tree234
#endif
typedef int (*cmpfn234)(void *, void *);
typedef void *(*copyfn234)(void *state, void *element);
#ifdef TREE234_INTERNALS
typedef struct node234_Tag node234;
struct tree234_Tag {
node234 *root;
cmpfn234 cmp;
};
struct node234_Tag {
node234 *parent;
node234 *kids[4];
int counts[4];
void *elems[3];
};
int height234(tree234 *t);
#endif
/*
* 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 */