src/cx/iterator.h@2946e13c89a4
src/cx/iterator.h
Sat, 21 May 2022 11:22:47 +0200
- author
- Mike Becker <universe@uap-core.de>
- date
- Sat, 21 May 2022 11:22:47 +0200
- changeset 551
- 2946e13c89a4
- parent 516
- 7bcea73303ce
- child 628
- 1e2be40f0cb5
- permissions
- -rw-r--r--
#189 implement map iterators
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 * \version 3.0
34 * \copyright 2-Clause BSD License
35 */
37 #ifndef UCX_ITERATOR_H
38 #define UCX_ITERATOR_H
40 #include "common.h"
42 /**
43 * Internal iterator struct - use CxIterator.
44 */
45 struct cx_iterator_s {
46 /**
47 * True iff the iterator points to valid data.
48 */
49 __attribute__ ((__nonnull__))
50 bool (*valid)(struct cx_iterator_s const *);
52 /**
53 * Returns a pointer to the current element.
54 */
55 __attribute__ ((__nonnull__))
56 void *(*current)(struct cx_iterator_s const *);
58 /**
59 * Advances the iterator.
60 */
61 __attribute__ ((__nonnull__))
62 void (*next)(struct cx_iterator_s *);
64 /**
65 * Handle for the current element, if required.
66 */
67 void *elem_handle;
69 /**
70 * Handle for the source collection, if any.
71 */
72 void *src_handle;
74 /**
75 * Field for storing a key-value pair.
76 * May be used by iterators that iterate over k/v-collections.
77 */
78 struct {
79 /**
80 * A pointer to the key.
81 */
82 void *key;
83 /**
84 * A pointer to the value.
85 */
86 void *value;
87 } kv_data;
89 /**
90 * Field for storing a slot number.
91 * May be used by iterators that iterate over multi-bucket collections.
92 */
93 size_t slot;
95 /**
96 * If the iterator is position-aware, contains the index of the element in the underlying collection.
97 * Otherwise, this field is usually uninitialized.
98 */
99 size_t index;
101 /**
102 * Users may set this to true, if the current element shall be removed from the underlying collection
103 * when the iterator advances.
104 * Has no effect on iterators that are not based on a collection.
105 */
106 bool remove;
107 };
109 /**
110 * Iterator value type.
111 * An iterator points to a certain element in an (possibly unbounded) chain of elements.
112 * Iterators that are based on collections (which have a defined "first" element), are supposed
113 * to be "position-aware", which means that they keep track of the current index within the collection.
114 *
115 * @note Objects that are pointed to by an iterator are mutable through that iterator. However, if the
116 * iterator is based on a collection and the underlying collection is mutated (elements added or removed),
117 * the iterator becomes invalid (regardless of what cxIteratorValid() returns) and MUST be re-obtained
118 * from the collection.
119 */
120 typedef struct cx_iterator_s CxIterator;
122 /**
123 * Checks if the iterator points to valid data.
124 *
125 * This is especially false for past-the-end iterators.
126 *
127 * @param iter a pointer to the iterator
128 * @return true iff the iterator points to valid data
129 */
130 __attribute__ ((__nonnull__))
131 static inline bool cxIteratorValid(CxIterator const *iter) {
132 return iter->valid(iter);
133 }
135 /**
136 * Returns a pointer to the current element.
137 *
138 * The behavior is undefined if this iterator is invalid.
139 *
140 * @param iter a pointer to the iterator
141 * @return a pointer to the current element
142 */
143 __attribute__ ((__nonnull__))
144 static inline void *cxIteratorCurrent(CxIterator const *iter) {
145 return iter->current(iter);
146 }
148 /**
149 * Advances the iterator to the next element.
150 *
151 * @param iter a pointer to the iterator
152 */
153 __attribute__ ((__nonnull__))
154 static inline void cxIteratorNext(CxIterator *iter) {
155 iter->next(iter);
156 }
158 /**
159 * Loops over an iterator.
160 * @param type the type of the elements
161 * @param elem the name of the iteration variable
162 * @param iter the iterator
163 */
164 #define cx_foreach(type, elem, iter) \
165 for (type elem; cxIteratorValid(&iter) && (elem = (type)cxIteratorCurrent(&iter)) != NULL ; cxIteratorNext(&iter)) // NOLINT(bugprone-macro-parentheses)
167 #endif /* UCX_ITERATOR_H */
