ucx/iterator.c

Sun, 13 Oct 2024 21:28:09 +0200

author
Olaf Wintermann <olaf.wintermann@gmail.com>
date
Sun, 13 Oct 2024 21:28:09 +0200
branch
newapi
changeset 339
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parent 324
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1 /*
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2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
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3 *
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4 * Copyright 2024 Mike Becker, Olaf Wintermann All rights reserved.
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5 *
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6 * Redistribution and use in source and binary forms, with or without
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7 * modification, are permitted provided that the following conditions are met:
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8 *
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9 * 1. Redistributions of source code must retain the above copyright
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10 * notice, this list of conditions and the following disclaimer.
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11 *
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12 * 2. Redistributions in binary form must reproduce the above copyright
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13 * notice, this list of conditions and the following disclaimer in the
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14 * documentation and/or other materials provided with the distribution.
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15 *
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16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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26 * POSSIBILITY OF SUCH DAMAGE.
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27 */
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28
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29 #include "cx/iterator.h"
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30
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31 #include <string.h>
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32
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33 static bool cx_iter_valid(const void *it) {
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34 const struct cx_iterator_s *iter = it;
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35 return iter->index < iter->elem_count;
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36 }
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37
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38 static void *cx_iter_current(const void *it) {
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39 const struct cx_iterator_s *iter = it;
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40 return iter->elem_handle;
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41 }
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42
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43 static void cx_iter_next_fast(void *it) {
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44 struct cx_iterator_s *iter = it;
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45 if (iter->base.remove) {
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46 iter->base.remove = false;
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47 iter->elem_count--;
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48 // only move the last element when we are not currently aiming
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49 // at the last element already
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50 if (iter->index < iter->elem_count) {
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51 void *last = ((char *) iter->src_handle.m)
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52 + iter->elem_count * iter->elem_size;
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53 memcpy(iter->elem_handle, last, iter->elem_size);
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54 }
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55 } else {
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56 iter->index++;
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57 iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
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58 }
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59 }
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60
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61 static void cx_iter_next_slow(void *it) {
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62 struct cx_iterator_s *iter = it;
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63 if (iter->base.remove) {
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64 iter->base.remove = false;
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65 iter->elem_count--;
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66
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67 // number of elements to move
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68 size_t remaining = iter->elem_count - iter->index;
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69 if (remaining > 0) {
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70 memmove(
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71 iter->elem_handle,
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72 ((char *) iter->elem_handle) + iter->elem_size,
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73 remaining * iter->elem_size
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74 );
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75 }
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76 } else {
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77 iter->index++;
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78 iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
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79 }
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80 }
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81
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82 CxIterator cxMutIterator(
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83 void *array,
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84 size_t elem_size,
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85 size_t elem_count,
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86 bool remove_keeps_order
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87 ) {
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88 CxIterator iter;
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89
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90 iter.index = 0;
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91 iter.src_handle.m = array;
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92 iter.elem_handle = array;
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93 iter.elem_size = elem_size;
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94 iter.elem_count = array == NULL ? 0 : elem_count;
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95 iter.base.valid = cx_iter_valid;
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96 iter.base.current = cx_iter_current;
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97 iter.base.next = remove_keeps_order ? cx_iter_next_slow : cx_iter_next_fast;
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98 iter.base.remove = false;
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99 iter.base.mutating = true;
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100
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101 return iter;
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102 }
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103
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104 CxIterator cxIterator(
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105 const void *array,
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106 size_t elem_size,
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107 size_t elem_count
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108 ) {
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109 CxIterator iter = cxMutIterator((void*)array, elem_size, elem_count, false);
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110 iter.base.mutating = false;
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111 return iter;
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112 }

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