1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/iterator.c Thu May 23 15:05:24 2024 +0200
1.3 @@ -0,0 +1,106 @@
1.4 +/*
1.5 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
1.6 + *
1.7 + * Copyright 2024 Mike Becker, Olaf Wintermann All rights reserved.
1.8 + *
1.9 + * Redistribution and use in source and binary forms, with or without
1.10 + * modification, are permitted provided that the following conditions are met:
1.11 + *
1.12 + * 1. Redistributions of source code must retain the above copyright
1.13 + * notice, this list of conditions and the following disclaimer.
1.14 + *
1.15 + * 2. Redistributions in binary form must reproduce the above copyright
1.16 + * notice, this list of conditions and the following disclaimer in the
1.17 + * documentation and/or other materials provided with the distribution.
1.18 + *
1.19 + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.20 + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.21 + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.22 + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
1.23 + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.24 + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.25 + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.26 + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.27 + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.28 + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.29 + * POSSIBILITY OF SUCH DAMAGE.
1.30 + */
1.31 +
1.32 +#include "cx/iterator.h"
1.33 +
1.34 +#include <string.h>
1.35 +
1.36 +static bool cx_iter_valid(void const *it) {
1.37 + struct cx_iterator_s const *iter = it;
1.38 + return iter->index < iter->elem_count;
1.39 +}
1.40 +
1.41 +static void *cx_iter_current(void const *it) {
1.42 + struct cx_iterator_s const *iter = it;
1.43 + return iter->elem_handle;
1.44 +}
1.45 +
1.46 +static void cx_iter_next_fast(void *it) {
1.47 + struct cx_iterator_base_s *itbase = it;
1.48 + if (itbase->remove) {
1.49 + struct cx_mut_iterator_s *iter = it;
1.50 + itbase->remove = false;
1.51 + iter->elem_count--;
1.52 + // only move the last element when we are not currently aiming
1.53 + // at the last element already
1.54 + if (iter->index < iter->elem_count) {
1.55 + void *last = ((char *) iter->src_handle)
1.56 + + iter->elem_count * iter->elem_size;
1.57 + memcpy(iter->elem_handle, last, iter->elem_size);
1.58 + }
1.59 + } else {
1.60 + struct cx_iterator_s *iter = it;
1.61 + iter->index++;
1.62 + iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
1.63 + }
1.64 +}
1.65 +
1.66 +static void cx_iter_next_slow(void *it) {
1.67 + struct cx_iterator_base_s *itbase = it;
1.68 + if (itbase->remove) {
1.69 + struct cx_mut_iterator_s *iter = it;
1.70 + itbase->remove = false;
1.71 + iter->elem_count--;
1.72 +
1.73 + // number of elements to move
1.74 + size_t remaining = iter->elem_count - iter->index;
1.75 + if (remaining > 0) {
1.76 + memmove(
1.77 + iter->elem_handle,
1.78 + ((char *) iter->elem_handle) + iter->elem_size,
1.79 + remaining * iter->elem_size
1.80 + );
1.81 + }
1.82 + } else {
1.83 + struct cx_iterator_s *iter = it;
1.84 + iter->index++;
1.85 + iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
1.86 + }
1.87 +}
1.88 +
1.89 +CxMutIterator cxIterator(
1.90 + void *array,
1.91 + size_t elem_size,
1.92 + size_t elem_count,
1.93 + bool remove_keeps_order
1.94 +) {
1.95 + CxMutIterator iter;
1.96 +
1.97 + iter.index = 0;
1.98 + iter.src_handle = array;
1.99 + iter.elem_handle = array;
1.100 + iter.elem_size = elem_size;
1.101 + iter.elem_count = array == NULL ? 0 : elem_count;
1.102 + iter.base.valid = cx_iter_valid;
1.103 + iter.base.current = cx_iter_current;
1.104 + iter.base.next = remove_keeps_order ? cx_iter_next_slow : cx_iter_next_fast;
1.105 + iter.base.remove = false;
1.106 + iter.base.mutating = true;
1.107 +
1.108 + return iter;
1.109 +}
