Thu, 23 May 2024 18:21:36 +0200
fix documentation
relates to #389
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2024 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 */
29 #include "cx/iterator.h"
31 #include <string.h>
33 static bool cx_iter_valid(void const *it) {
34 struct cx_iterator_s const *iter = it;
35 return iter->index < iter->elem_count;
36 }
38 static void *cx_iter_current(void const *it) {
39 struct cx_iterator_s const *iter = it;
40 return iter->elem_handle;
41 }
43 static void cx_iter_next_fast(void *it) {
44 struct cx_iterator_base_s *itbase = it;
45 if (itbase->remove) {
46 struct cx_mut_iterator_s *iter = it;
47 itbase->remove = false;
48 iter->elem_count--;
49 // only move the last element when we are not currently aiming
50 // at the last element already
51 if (iter->index < iter->elem_count) {
52 void *last = ((char *) iter->src_handle)
53 + iter->elem_count * iter->elem_size;
54 memcpy(iter->elem_handle, last, iter->elem_size);
55 }
56 } else {
57 struct cx_iterator_s *iter = it;
58 iter->index++;
59 iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
60 }
61 }
63 static void cx_iter_next_slow(void *it) {
64 struct cx_iterator_base_s *itbase = it;
65 if (itbase->remove) {
66 struct cx_mut_iterator_s *iter = it;
67 itbase->remove = false;
68 iter->elem_count--;
70 // number of elements to move
71 size_t remaining = iter->elem_count - iter->index;
72 if (remaining > 0) {
73 memmove(
74 iter->elem_handle,
75 ((char *) iter->elem_handle) + iter->elem_size,
76 remaining * iter->elem_size
77 );
78 }
79 } else {
80 struct cx_iterator_s *iter = it;
81 iter->index++;
82 iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
83 }
84 }
86 CxMutIterator cxMutIterator(
87 void *array,
88 size_t elem_size,
89 size_t elem_count,
90 bool remove_keeps_order
91 ) {
92 CxMutIterator iter;
94 iter.index = 0;
95 iter.src_handle = array;
96 iter.elem_handle = array;
97 iter.elem_size = elem_size;
98 iter.elem_count = array == NULL ? 0 : elem_count;
99 iter.base.valid = cx_iter_valid;
100 iter.base.current = cx_iter_current;
101 iter.base.next = remove_keeps_order ? cx_iter_next_slow : cx_iter_next_fast;
102 iter.base.remove = false;
103 iter.base.mutating = true;
105 return iter;
106 }
108 CxIterator cxIterator(
109 void const *array,
110 size_t elem_size,
111 size_t elem_count
112 ) {
113 CxMutIterator iter = cxMutIterator((void*)array, elem_size, elem_count, false);
114 iter.base.mutating = false;
116 // we know the iterators share the same memory layout
117 CxIterator ret;
118 memcpy(&ret, &iter, sizeof(CxIterator));
119 return ret;
120 }