/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2024 Mike Becker, Olaf Wintermann All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "cx/iterator.h"
#include <string.h>
static bool cx_iter_valid(const void *it) {
const struct cx_iterator_s *iter = it;
return iter->index < iter->elem_count;
}
static void *cx_iter_current(const void *it) {
const struct cx_iterator_s *iter = it;
return iter->elem_handle;
}
static void *cx_iter_current_ptr(const void *it) {
const struct cx_iterator_s *iter = it;
return *(void**)iter->elem_handle;
}
static void cx_iter_next_fast(void *it) {
struct cx_iterator_s *iter = it;
if (iter->base.remove) {
iter->base.remove = false;
iter->elem_count--;
// only move the last element when we are not currently aiming
// at the last element already
if (iter->index < iter->elem_count) {
void *last = ((char *) iter->src_handle)
+ iter->elem_count * iter->elem_size;
memcpy(iter->elem_handle, last, iter->elem_size);
}
} else {
iter->index++;
iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
}
}
static void cx_iter_next_slow(void *it) {
struct cx_iterator_s *iter = it;
if (iter->base.remove) {
iter->base.remove = false;
iter->elem_count--;
// number of elements to move
size_t remaining = iter->elem_count - iter->index;
if (remaining > 0) {
memmove(
iter->elem_handle,
((char *) iter->elem_handle) + iter->elem_size,
remaining * iter->elem_size
);
}
} else {
iter->index++;
iter->elem_handle = ((char *) iter->elem_handle) + iter->elem_size;
}
}
CxIterator cxIterator(
const void *array,
size_t elem_size,
size_t elem_count,
bool remove_keeps_order
) {
CxIterator iter;
iter.index = 0;
iter.src_handle = (void*) array;
iter.elem_handle = (void*) array;
iter.elem_size = elem_size;
iter.elem_count = array == NULL ? 0 : elem_count;
iter.base.valid = cx_iter_valid;
iter.base.current = cx_iter_current;
iter.base.next = remove_keeps_order ? cx_iter_next_slow : cx_iter_next_fast;
iter.base.remove = false;
iter.base.allow_remove = true;
return iter;
}
CxIterator cxIteratorPtr(
const void *array,
size_t elem_count,
bool remove_keeps_order
) {
CxIterator iter = cxIterator(array, sizeof(void*), elem_count, remove_keeps_order);
iter.base.current = cx_iter_current_ptr;
return iter;
}