src/cx/iterator.h@475335643af4
src/cx/iterator.h
Mon, 18 Dec 2023 14:14:47 +0100
- author
- Mike Becker <universe@uap-core.de>
- date
- Mon, 18 Dec 2023 14:14:47 +0100
- changeset 759
- 475335643af4
- parent 740
- 378578666c83
- child 829
- 7d4e31d295af
- permissions
- -rw-r--r--
increase version number to 3.1
remove per-file version information
from Doxygen output
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28 /**
29 * \file iterator.h
30 * \brief Interface for iterator implementations.
31 * \author Mike Becker
32 * \author Olaf Wintermann
33 * \copyright 2-Clause BSD License
34 */
36 #ifndef UCX_ITERATOR_H
37 #define UCX_ITERATOR_H
39 #include "common.h"
41 /**
42 * The base of mutating and non-mutating iterators.
43 */
44 struct cx_iterator_base_s {
45 /**
46 * True iff the iterator points to valid data.
47 */
48 __attribute__ ((__nonnull__))
49 bool (*valid)(void const *);
51 /**
52 * Returns a pointer to the current element.
53 *
54 * When valid returns false, the behavior of this function is undefined.
55 */
56 __attribute__ ((__nonnull__))
57 void *(*current)(void const *);
59 /**
60 * Original implementation in case the function needs to be wrapped.
61 */
62 __attribute__ ((__nonnull__))
63 void *(*current_impl)(void const *);
65 /**
66 * Advances the iterator.
67 *
68 * When valid returns false, the behavior of this function is undefined.
69 */
70 __attribute__ ((__nonnull__))
71 void (*next)(void *);
73 /**
74 * Flag current element for removal, if possible.
75 *
76 * When valid returns false, the behavior of this function is undefined.
77 */
78 __attribute__ ((__nonnull__))
79 bool (*flag_removal)(void *);
81 /**
82 * Indicates whether this iterator may remove elements.
83 */
84 bool mutating;
86 /**
87 * Internal flag for removing the current element when advancing.
88 */
89 bool remove;
90 };
92 /**
93 * Internal iterator struct - use CxMutIterator.
94 */
95 struct cx_mut_iterator_s {
97 /**
98 * The base properties of this iterator.
99 */
100 struct cx_iterator_base_s base;
102 /**
103 * Handle for the current element, if required.
104 */
105 void *elem_handle;
107 /**
108 * Handle for the source collection, if any.
109 */
110 void *src_handle;
112 /**
113 * Field for storing a key-value pair.
114 * May be used by iterators that iterate over k/v-collections.
115 */
116 struct {
117 /**
118 * A pointer to the key.
119 */
120 void const *key;
121 /**
122 * A pointer to the value.
123 */
124 void *value;
125 } kv_data;
127 /**
128 * Field for storing a slot number.
129 * May be used by iterators that iterate over multi-bucket collections.
130 */
131 size_t slot;
133 /**
134 * If the iterator is position-aware, contains the index of the element in the underlying collection.
135 * Otherwise, this field is usually uninitialized.
136 */
137 size_t index;
138 };
140 /**
141 * Mutating iterator value type.
142 *
143 * An iterator points to a certain element in an (possibly unbounded) chain of elements.
144 * Iterators that are based on collections (which have a defined "first" element), are supposed
145 * to be "position-aware", which means that they keep track of the current index within the collection.
146 *
147 * @note Objects that are pointed to by an iterator are mutable through that iterator. However, if the
148 * iterator is based on a collection and the underlying collection is mutated by other means than this iterator
149 * (e.g. elements added or removed), the iterator becomes invalid (regardless of what cxIteratorValid() returns)
150 * and MUST be re-obtained from the collection.
151 *
152 * @see CxIterator
153 */
154 typedef struct cx_mut_iterator_s CxMutIterator;
156 /**
157 * Internal iterator struct - use CxIterator.
158 */
159 struct cx_iterator_s {
161 /**
162 * The base properties of this iterator.
163 */
164 struct cx_iterator_base_s base;
166 /**
167 * Handle for the current element, if required.
168 */
169 void *elem_handle;
171 /**
172 * Handle for the source collection, if any.
173 */
174 void const *src_handle;
176 /**
177 * Field for storing a key-value pair.
178 * May be used by iterators that iterate over k/v-collections.
179 */
180 struct {
181 /**
182 * A pointer to the key.
183 */
184 void const *key;
185 /**
186 * A pointer to the value.
187 */
188 void *value;
189 } kv_data;
191 /**
192 * Field for storing a slot number.
193 * May be used by iterators that iterate over multi-bucket collections.
194 */
195 size_t slot;
197 /**
198 * If the iterator is position-aware, contains the index of the element in the underlying collection.
199 * Otherwise, this field is usually uninitialized.
200 */
201 size_t index;
202 };
204 /**
205 * Iterator value type.
206 * An iterator points to a certain element in a (possibly unbounded) chain of elements.
207 * Iterators that are based on collections (which have a defined "first" element), are supposed
208 * to be "position-aware", which means that they keep track of the current index within the collection.
209 *
210 * @note Objects that are pointed to by an iterator are always mutable through that iterator. However,
211 * this iterator cannot mutate the collection itself (add or remove elements) and any mutation of the
212 * collection by other means makes this iterator invalid (regardless of what cxIteratorValid() returns).
213 *
214 * @see CxMutIterator
215 */
216 typedef struct cx_iterator_s CxIterator;
218 /**
219 * Checks if the iterator points to valid data.
220 *
221 * This is especially false for past-the-end iterators.
222 *
223 * @param iter the iterator
224 * @return true iff the iterator points to valid data
225 */
226 #define cxIteratorValid(iter) (iter).base.valid(&(iter))
228 /**
229 * Returns a pointer to the current element.
230 *
231 * The behavior is undefined if this iterator is invalid.
232 *
233 * @param iter the iterator
234 * @return a pointer to the current element
235 */
236 #define cxIteratorCurrent(iter) (iter).base.current(&iter)
238 /**
239 * Advances the iterator to the next element.
240 *
241 * @param iter the iterator
242 */
243 #define cxIteratorNext(iter) (iter).base.next(&iter)
245 /**
246 * Flags the current element for removal.
247 *
248 * @param iter the iterator
249 * @return false if this iterator cannot remove the element
250 */
251 #define cxIteratorFlagRemoval(iter) (iter).base.flag_removal(&iter)
253 /**
254 * Loops over an iterator.
255 * @param type the type of the elements
256 * @param elem the name of the iteration variable
257 * @param iter the iterator
258 */
259 #define cx_foreach(type, elem, iter) \
260 for (type elem; cxIteratorValid(iter) && (elem = (type)cxIteratorCurrent(iter)) != NULL ; cxIteratorNext(iter))
262 #endif // UCX_ITERATOR_H
