1 /* Abstract ordered set data type.
2 Copyright (C) 2006-2007, 2009-2010 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 #if 0 /* declared in gl_xoset.h */
93 extern gl_oset_t gl_oset_create_empty (gl_oset_implementation_t implementation,
94 gl_setelement_compar_fn compar_fn,
95 gl_setelement_dispose_fn dispose_fn);
97 /* Likewise. Return NULL upon out-of-memory. */
98 extern gl_oset_t gl_oset_nx_create_empty (gl_oset_implementation_t implementation,
99 gl_setelement_compar_fn compar_fn,
100 gl_setelement_dispose_fn dispose_fn);
102 /* Return the current number of elements in an ordered set. */
103 extern size_t gl_oset_size (gl_oset_t set);
105 /* Search whether an element is already in the ordered set.
106 Return true if found, or false if not present in the set. */
107 extern bool gl_oset_search (gl_oset_t set, const void *elt);
109 /* Search the least element in the ordered set that compares greater or equal
110 to the given THRESHOLD. The representation of the THRESHOLD is defined
112 Return true and store the found element in *ELTP if found, otherwise return
114 extern bool gl_oset_search_atleast (gl_oset_t set,
115 gl_setelement_threshold_fn threshold_fn,
116 const void *threshold,
119 /* Add an element to an ordered set.
120 Return true if it was not already in the set and added, false otherwise. */
121 #if 0 /* declared in gl_xoset.h */
122 extern bool gl_oset_add (gl_oset_t set, const void *elt);
124 /* Likewise. Return -1 upon out-of-memory. */
125 extern int gl_oset_nx_add (gl_oset_t set, const void *elt)
126 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
127 __attribute__ ((__warn_unused_result__))
131 /* Remove an element from an ordered set.
132 Return true if it was found and removed. */
133 extern bool gl_oset_remove (gl_oset_t set, const void *elt);
135 /* Free an entire ordered set.
136 (But this call does not free the elements of the set.) */
137 extern void gl_oset_free (gl_oset_t set);
139 /* --------------------- gl_oset_iterator_t Data Type --------------------- */
141 /* Functions for iterating through an ordered set. */
143 /* Type of an iterator that traverses an ordered set.
144 This is a fixed-size struct, so that creation of an iterator doesn't need
145 memory allocation on the heap. */
148 /* For fast dispatch of gl_oset_iterator_next. */
149 const struct gl_oset_implementation *vtable;
150 /* For detecting whether the last returned element was removed. */
153 /* Other, implementation-private fields. */
156 } gl_oset_iterator_t;
158 /* Create an iterator traversing an ordered set.
159 The set's contents must not be modified while the iterator is in use,
160 except for removing the last returned element. */
161 extern gl_oset_iterator_t gl_oset_iterator (gl_oset_t set);
163 /* If there is a next element, store the next element in *ELTP, advance the
164 iterator and return true. Otherwise, return false. */
165 extern bool gl_oset_iterator_next (gl_oset_iterator_t *iterator,
168 /* Free an iterator. */
169 extern void gl_oset_iterator_free (gl_oset_iterator_t *iterator);
171 /* ------------------------ Implementation Details ------------------------ */
173 struct gl_oset_implementation
175 /* gl_oset_t functions. */
176 gl_oset_t (*nx_create_empty) (gl_oset_implementation_t implementation,
177 gl_setelement_compar_fn compar_fn,
178 gl_setelement_dispose_fn dispose_fn);
179 size_t (*size) (gl_oset_t set);
180 bool (*search) (gl_oset_t set, const void *elt);
181 bool (*search_atleast) (gl_oset_t set,
182 gl_setelement_threshold_fn threshold_fn,
183 const void *threshold, const void **eltp);
184 int (*nx_add) (gl_oset_t set, const void *elt);
185 bool (*remove_elt) (gl_oset_t set, const void *elt);
186 void (*oset_free) (gl_oset_t set);
187 /* gl_oset_iterator_t functions. */
188 gl_oset_iterator_t (*iterator) (gl_oset_t set);
189 bool (*iterator_next) (gl_oset_iterator_t *iterator, const void **eltp);
190 void (*iterator_free) (gl_oset_iterator_t *iterator);
193 struct gl_oset_impl_base
195 const struct gl_oset_implementation *vtable;
196 gl_setelement_compar_fn compar_fn;
197 gl_setelement_dispose_fn dispose_fn;
202 /* Define all functions of this file as inline accesses to the
203 struct gl_oset_implementation.
204 Use #define to avoid a warning because of extern vs. static. */
206 # define gl_oset_nx_create_empty gl_oset_nx_create_empty_inline
207 static inline gl_oset_t
208 gl_oset_nx_create_empty (gl_oset_implementation_t implementation,
209 gl_setelement_compar_fn compar_fn,
210 gl_setelement_dispose_fn dispose_fn)
212 return implementation->nx_create_empty (implementation, compar_fn,
216 # define gl_oset_size gl_oset_size_inline
218 gl_oset_size (gl_oset_t set)
220 return ((const struct gl_oset_impl_base *) set)->vtable->size (set);
223 # define gl_oset_search gl_oset_search_inline
225 gl_oset_search (gl_oset_t set, const void *elt)
227 return ((const struct gl_oset_impl_base *) set)->vtable->search (set, elt);
230 # define gl_oset_search_atleast gl_oset_search_atleast_inline
232 gl_oset_search_atleast (gl_oset_t set,
233 gl_setelement_threshold_fn threshold_fn,
234 const void *threshold, const void **eltp)
236 return ((const struct gl_oset_impl_base *) set)->vtable
237 ->search_atleast (set, threshold_fn, threshold, eltp);
240 # define gl_oset_nx_add gl_oset_nx_add_inline
242 gl_oset_nx_add (gl_oset_t set, const void *elt)
244 return ((const struct gl_oset_impl_base *) set)->vtable->nx_add (set, elt);
247 # define gl_oset_remove gl_oset_remove_inline
249 gl_oset_remove (gl_oset_t set, const void *elt)
251 return ((const struct gl_oset_impl_base *) set)->vtable
252 ->remove_elt (set, elt);
255 # define gl_oset_free gl_oset_free_inline
257 gl_oset_free (gl_oset_t set)
259 ((const struct gl_oset_impl_base *) set)->vtable->oset_free (set);
262 # define gl_oset_iterator gl_oset_iterator_inline
263 static inline gl_oset_iterator_t
264 gl_oset_iterator (gl_oset_t set)
266 return ((const struct gl_oset_impl_base *) set)->vtable->iterator (set);
269 # define gl_oset_iterator_next gl_oset_iterator_next_inline
271 gl_oset_iterator_next (gl_oset_iterator_t *iterator, const void **eltp)
273 return iterator->vtable->iterator_next (iterator, eltp);
276 # define gl_oset_iterator_free gl_oset_iterator_free_inline
278 gl_oset_iterator_free (gl_oset_iterator_t *iterator)
280 iterator->vtable->iterator_free (iterator);
289 #endif /* _GL_OSET_H */