d7482997 |
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 */ |