1 /* Abstract ordered set data type.
2 Copyright (C) 2006-2007 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2006.
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
29 /* gl_oset is an abstract ordered set data type. It can contain any number
30 of objects ('void *' or 'const void *' pointers) in the order of a given
31 comparator function. Duplicates (in the sense of the comparator) are
34 There are several implementations of this ordered set datatype, optimized
35 for different operations or for memory. You can start using the simplest
36 ordered set implementation, GL_ARRAY_OSET, and switch to a different
37 implementation later, when you realize which operations are performed
38 the most frequently. The API of the different implementations is exactly
39 the same; when switching to a different implementation, you only have to
40 change the gl_oset_create call.
42 The implementations are:
43 GL_ARRAY_OSET a growable array
44 GL_AVLTREE_OSET a binary tree (AVL tree)
45 GL_RBTREE_OSET a binary tree (red-black tree)
47 The memory consumption is asymptotically the same: O(1) for every object
48 in the set. When looking more closely at the average memory consumed
49 for an object, GL_ARRAY_OSET is the most compact representation, and
50 GL_AVLTREE_OSET, GL_RBTREE_OSET need more memory.
52 The guaranteed average performance of the operations is, for a set of
57 gl_oset_size O(1) O(1)
58 gl_oset_add O(n) O(log n)
59 gl_oset_remove O(n) O(log n)
60 gl_oset_search O(log n) O(log n)
61 gl_oset_search_atleast O(log n) O(log n)
62 gl_oset_iterator O(1) O(log n)
63 gl_oset_iterator_next O(1) O(log n)
66 /* -------------------------- gl_oset_t Data Type -------------------------- */
68 /* Type of function used to compare two elements. Same as for qsort().
69 NULL denotes pointer comparison. */
70 typedef int (*gl_setelement_compar_fn) (const void *elt1, const void *elt2);
72 /* Type of function used to dispose an element once it's removed from a set.
73 NULL denotes a no-op. */
74 typedef void (*gl_setelement_dispose_fn) (const void *elt);
76 /* Type of function used to compare an element with a threshold.
77 Return true if the element is greater or equal than the threshold. */
78 typedef bool (*gl_setelement_threshold_fn) (const void *elt, const void *threshold);
81 /* Type representing an entire ordered set. */
82 typedef struct gl_oset_impl * gl_oset_t;
84 struct gl_oset_implementation;
85 /* Type representing a ordered set datatype implementation. */
86 typedef const struct gl_oset_implementation * gl_oset_implementation_t;
88 /* Create an empty set.
89 IMPLEMENTATION is one of GL_ARRAY_OSET, GL_AVLTREE_OSET, GL_RBTREE_OSET.
90 COMPAR_FN is an element comparison function or NULL.
91 DISPOSE_FN is an element disposal function or NULL. */
92 extern gl_oset_t gl_oset_create_empty (gl_oset_implementation_t implementation,
93 gl_setelement_compar_fn compar_fn,
94 gl_setelement_dispose_fn dispose_fn);
96 /* Return the current number of elements in an ordered set. */
97 extern size_t gl_oset_size (gl_oset_t set);
99 /* Search whether an element is already in the ordered set.
100 Return true if found, or false if not present in the set. */
101 extern bool gl_oset_search (gl_oset_t set, const void *elt);
103 /* Search the least element in the ordered set that compares greater or equal
104 to the given THRESHOLD. The representation of the THRESHOLD is defined
106 Return true and store the found element in *ELTP if found, otherwise return
108 extern bool gl_oset_search_atleast (gl_oset_t set,
109 gl_setelement_threshold_fn threshold_fn,
110 const void *threshold,
113 /* Add an element to an ordered set.
114 Return true if it was not already in the set and added. */
115 extern bool gl_oset_add (gl_oset_t set, const void *elt);
117 /* Remove an element from an ordered set.
118 Return true if it was found and removed. */
119 extern bool gl_oset_remove (gl_oset_t set, const void *elt);
121 /* Free an entire ordered set.
122 (But this call does not free the elements of the set.) */
123 extern void gl_oset_free (gl_oset_t set);
125 /* --------------------- gl_oset_iterator_t Data Type --------------------- */
127 /* Functions for iterating through an ordered set. */
129 /* Type of an iterator that traverses an ordered set.
130 This is a fixed-size struct, so that creation of an iterator doesn't need
131 memory allocation on the heap. */
134 /* For fast dispatch of gl_oset_iterator_next. */
135 const struct gl_oset_implementation *vtable;
136 /* For detecting whether the last returned element was removed. */
139 /* Other, implementation-private fields. */
142 } gl_oset_iterator_t;
144 /* Create an iterator traversing an ordered set.
145 The set's contents must not be modified while the iterator is in use,
146 except for removing the last returned element. */
147 extern gl_oset_iterator_t gl_oset_iterator (gl_oset_t set);
149 /* If there is a next element, store the next element in *ELTP, advance the
150 iterator and return true. Otherwise, return false. */
151 extern bool gl_oset_iterator_next (gl_oset_iterator_t *iterator,
154 /* Free an iterator. */
155 extern void gl_oset_iterator_free (gl_oset_iterator_t *iterator);
157 /* ------------------------ Implementation Details ------------------------ */
159 struct gl_oset_implementation
161 /* gl_oset_t functions. */
162 gl_oset_t (*create_empty) (gl_oset_implementation_t implementation,
163 gl_setelement_compar_fn compar_fn,
164 gl_setelement_dispose_fn dispose_fn);
165 size_t (*size) (gl_oset_t set);
166 bool (*search) (gl_oset_t set, const void *elt);
167 bool (*search_atleast) (gl_oset_t set,
168 gl_setelement_threshold_fn threshold_fn,
169 const void *threshold, const void **eltp);
170 bool (*add) (gl_oset_t set, const void *elt);
171 bool (*remove) (gl_oset_t set, const void *elt);
172 void (*oset_free) (gl_oset_t set);
173 /* gl_oset_iterator_t functions. */
174 gl_oset_iterator_t (*iterator) (gl_oset_t set);
175 bool (*iterator_next) (gl_oset_iterator_t *iterator, const void **eltp);
176 void (*iterator_free) (gl_oset_iterator_t *iterator);
179 struct gl_oset_impl_base
181 const struct gl_oset_implementation *vtable;
182 gl_setelement_compar_fn compar_fn;
183 gl_setelement_dispose_fn dispose_fn;
188 /* Define all functions of this file as inline accesses to the
189 struct gl_oset_implementation.
190 Use #define to avoid a warning because of extern vs. static. */
192 # define gl_oset_create_empty gl_oset_create_empty_inline
193 static inline gl_oset_t
194 gl_oset_create_empty (gl_oset_implementation_t implementation,
195 gl_setelement_compar_fn compar_fn,
196 gl_setelement_dispose_fn dispose_fn)
198 return implementation->create_empty (implementation, compar_fn, dispose_fn);
201 # define gl_oset_size gl_oset_size_inline
203 gl_oset_size (gl_oset_t set)
205 return ((const struct gl_oset_impl_base *) set)->vtable->size (set);
208 # define gl_oset_search gl_oset_search_inline
210 gl_oset_search (gl_oset_t set, const void *elt)
212 return ((const struct gl_oset_impl_base *) set)->vtable->search (set, elt);
215 # define gl_oset_search_atleast gl_oset_search_atleast_inline
217 gl_oset_search_atleast (gl_oset_t set,
218 gl_setelement_threshold_fn threshold_fn,
219 const void *threshold, const void **eltp)
221 return ((const struct gl_oset_impl_base *) set)->vtable
222 ->search_atleast (set, threshold_fn, threshold, eltp);
225 # define gl_oset_add gl_oset_add_inline
227 gl_oset_add (gl_oset_t set, const void *elt)
229 return ((const struct gl_oset_impl_base *) set)->vtable->add (set, elt);
232 # define gl_oset_remove gl_oset_remove_inline
234 gl_oset_remove (gl_oset_t set, const void *elt)
236 return ((const struct gl_oset_impl_base *) set)->vtable->remove (set, elt);
239 # define gl_oset_free gl_oset_free_inline
241 gl_oset_free (gl_oset_t set)
243 ((const struct gl_oset_impl_base *) set)->vtable->oset_free (set);
246 # define gl_oset_iterator gl_oset_iterator_inline
247 static inline gl_oset_iterator_t
248 gl_oset_iterator (gl_oset_t set)
250 return ((const struct gl_oset_impl_base *) set)->vtable->iterator (set);
253 # define gl_oset_iterator_next gl_oset_iterator_next_inline
255 gl_oset_iterator_next (gl_oset_iterator_t *iterator, const void **eltp)
257 return iterator->vtable->iterator_next (iterator, eltp);
260 # define gl_oset_iterator_free gl_oset_iterator_free_inline
262 gl_oset_iterator_free (gl_oset_iterator_t *iterator)
264 iterator->vtable->iterator_free (iterator);
273 #endif /* _GL_OSET_H */