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 */
28
29 #include "cx/iterator.h"
30
31 #include <string.h>
32
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 }
37
38 static void *cx_iter_current(void const *it) {
39 struct cx_iterator_s const *iter = it;
40 return iter->elem_handle;
41 }
42
43 static void cx_iter_next_fast(void *it) {
44 struct cx_iterator_s *iter = it;
45 if (iter->base.remove) {
46 iter->base.remove = false;
47 iter->elem_count--;
48 // only move the last element when we are not currently aiming
49 // at the last element already
50 if (iter->index < iter->elem_count) {
51 void *last = ((char *) iter->src_handle.m)
52 + iter->elem_count * iter->elem_size;
53 memcpy(iter->elem_handle, last, iter->elem_size);
54 }
55 } else {
56 iter->index++;
57 iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
58 }
59 }
60
61 static void cx_iter_next_slow(void *it) {
62 struct cx_iterator_s *iter = it;
63 if (iter->base.remove) {
64 iter->base.remove = false;
65 iter->elem_count--;
66
67 // number of elements to move
68 size_t remaining = iter->elem_count - iter->index;
69 if (remaining > 0) {
70 memmove(
71 iter->elem_handle,
72 ((char *) iter->elem_handle) + iter->elem_size,
73 remaining * iter->elem_size
74 );
75 }
76 } else {
77 iter->index++;
78 iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
79 }
80 }
81
82 CxIterator cxMutIterator(
83 void *array,
84 size_t elem_size,
85 size_t elem_count,
86 bool remove_keeps_order
87 ) {
88 CxIterator iter;
89
90 iter.index = 0;
91 iter.src_handle.m = array;
92 iter.elem_handle = array;
93 iter.elem_size = elem_size;
94 iter.elem_count = array == NULL ? 0 : elem_count;
95 iter.base.valid = cx_iter_valid;
96 iter.base.current = cx_iter_current;
97 iter.base.next = remove_keeps_order ? cx_iter_next_slow : cx_iter_next_fast;
98 iter.base.remove = false;
99 iter.base.mutating = true;
100
101 return iter;
102 }
103
104 CxIterator cxIterator(
105 void const *array,
106 size_t elem_size,
107 size_t elem_count
108 ) {
109 CxIterator iter = cxMutIterator((void*)array, elem_size, elem_count, false);
110 iter.base.mutating = false;
111 return iter;
112 }
113