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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#include <stdbool.h>
32
33/*
34 * This typedef is typically opaque outside tree234.c itself. But you
35 * can define TREE234_INTERNALS to get a definition of it and its
36 * subsidiary node structure, as long as you're prepared to commit to
37 * responding to changes in the internals (which probably means you're
38 * tree234.c itself or tree234-test.c).
39 */
40typedef struct tree234_Tag tree234;
41
42typedef int (*cmpfn234)(void *, void *);
43
44typedef void *(*copyfn234)(void *state, void *element);
45
46#ifdef TREE234_INTERNALS
47typedef struct node234_Tag node234;
48
49struct tree234_Tag {
50 node234 *root;
51 cmpfn234 cmp;
52};
53
54struct node234_Tag {
55 node234 *parent;
56 node234 *kids[4];
57 int counts[4];
58 void *elems[3];
59};
60
61int height234(tree234 *t);
62#endif
63
64/*
65 * Create a 2-3-4 tree. If `cmp' is NULL, the tree is unsorted, and
66 * lookups by key will fail: you can only look things up by numeric
67 * index, and you have to use addpos234() and delpos234().
68 */
69tree234 *newtree234(cmpfn234 cmp);
70
71/*
72 * Free a 2-3-4 tree (not including freeing the elements).
73 */
74void freetree234(tree234 *t);
75
76/*
77 * Add an element e to a sorted 2-3-4 tree t. Returns e on success,
78 * or if an existing element compares equal, returns that.
79 */
80void *add234(tree234 *t, void *e);
81
82/*
83 * Add an element e to an unsorted 2-3-4 tree t. Returns e on
84 * success, NULL on failure. (Failure should only occur if the
85 * index is out of range or the tree is sorted.)
86 *
87 * Index range can be from 0 to the tree's current element count,
88 * inclusive.
89 */
90void *addpos234(tree234 *t, void *e, int index);
91
92/*
93 * Look up the element at a given numeric index in a 2-3-4 tree.
94 * Returns NULL if the index is out of range.
95 *
96 * One obvious use for this function is in iterating over the whole
97 * of a tree (sorted or unsorted):
98 *
99 * for (i = 0; (p = index234(tree, i)) != NULL; i++) consume(p);
100 *
101 * or
102 *
103 * int maxcount = count234(tree);
104 * for (i = 0; i < maxcount; i++) {
105 * p = index234(tree, i);
106 * assert(p != NULL);
107 * consume(p);
108 * }
109 */
110void *index234(tree234 *t, int index);
111
112/*
113 * Find an element e in a sorted 2-3-4 tree t. Returns NULL if not
114 * found. e is always passed as the first argument to cmp, so cmp
115 * can be an asymmetric function if desired. cmp can also be passed
116 * as NULL, in which case the compare function from the tree proper
117 * will be used.
118 *
119 * Three of these functions are special cases of findrelpos234. The
120 * non-`pos' variants lack the `index' parameter: if the parameter
121 * is present and non-NULL, it must point to an integer variable
122 * which will be filled with the numeric index of the returned
123 * element.
124 *
125 * The non-`rel' variants lack the `relation' parameter. This
126 * parameter allows you to specify what relation the element you
127 * provide has to the element you're looking for. This parameter
128 * can be:
129 *
130 * REL234_EQ - find only an element that compares equal to e
131 * REL234_LT - find the greatest element that compares < e
132 * REL234_LE - find the greatest element that compares <= e
133 * REL234_GT - find the smallest element that compares > e
134 * REL234_GE - find the smallest element that compares >= e
135 *
136 * Non-`rel' variants assume REL234_EQ.
137 *
138 * If `rel' is REL234_GT or REL234_LT, the `e' parameter may be
139 * NULL. In this case, REL234_GT will return the smallest element
140 * in the tree, and REL234_LT will return the greatest. This gives
141 * an alternative means of iterating over a sorted tree, instead of
142 * using index234:
143 *
144 * // to loop forwards
145 * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_GT)) != NULL ;)
146 * consume(p);
147 *
148 * // to loop backwards
149 * for (p = NULL; (p = findrel234(tree, p, NULL, REL234_LT)) != NULL ;)
150 * consume(p);
151 */
152enum {
153 REL234_EQ, REL234_LT, REL234_LE, REL234_GT, REL234_GE
154};
155void *find234(tree234 *t, void *e, cmpfn234 cmp);
156void *findrel234(tree234 *t, void *e, cmpfn234 cmp, int relation);
157void *findpos234(tree234 *t, void *e, cmpfn234 cmp, int *index);
158void *findrelpos234(tree234 *t, void *e, cmpfn234 cmp, int relation,
159 int *index);
160
161/*
162 * Delete an element e in a 2-3-4 tree. Does not free the element,
163 * merely removes all links to it from the tree nodes.
164 *
165 * delpos234 deletes the element at a particular tree index: it
166 * works on both sorted and unsorted trees.
167 *
168 * del234 deletes the element passed to it, so it only works on
169 * sorted trees. (It's equivalent to using findpos234 to determine
170 * the index of an element, and then passing that index to
171 * delpos234.)
172 *
173 * Both functions return a pointer to the element they delete, for
174 * the user to free or pass on elsewhere or whatever. If the index
175 * is out of range (delpos234) or the element is already not in the
176 * tree (del234) then they return NULL.
177 */
178void *del234(tree234 *t, void *e);
179void *delpos234(tree234 *t, int index);
180
181/*
182 * Return the total element count of a tree234.
183 */
184int count234(tree234 *t);
185
186/*
187 * Split a tree234 into two valid tree234s.
188 *
189 * splitpos234 splits at a given index. If `before' is true, the
190 * items at and after that index are left in t and the ones before
191 * are returned; if `before' is false, the items before that index
192 * are left in t and the rest are returned.
193 *
194 * split234 splits at a given key. You can pass any of the
195 * relations used with findrel234, except for REL234_EQ. The items
196 * in the tree that satisfy the relation are returned; the
197 * remainder are left.
198 */
199tree234 *splitpos234(tree234 *t, int index, bool before);
200tree234 *split234(tree234 *t, void *e, cmpfn234 cmp, int rel);
201
202/*
203 * Join two tree234s together into a single one.
204 *
205 * All the elements in t1 are placed to the left of all the
206 * elements in t2. If the trees are sorted, there will be a test to
207 * ensure that this satisfies the ordering criterion, and NULL will
208 * be returned otherwise. If the trees are unsorted, there is no
209 * restriction on the use of join234.
210 *
211 * The tree returned is t1 (join234) or t2 (join234r), if the
212 * operation is successful.
213 */
214tree234 *join234(tree234 *t1, tree234 *t2);
215tree234 *join234r(tree234 *t1, tree234 *t2);
216
217/*
218 * Make a complete copy of a tree234. Element pointers will be
219 * reused unless copyfn is non-NULL, in which case it will be used
220 * to copy each element. (copyfn takes two `void *' parameters; the
221 * first is private state and the second is the element. A simple
222 * copy routine probably won't need private state.)
223 */
224tree234 *copytree234(tree234 *t, copyfn234 copyfn, void *copyfnstate);
225
226#endif /* TREE234_H */